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Antimicrobial Use and Resistance Module
AUR

Antimicrobial Use and Resistance (AUR) Module
Table of Contents
Introduction
1. Antimicrobial Use (AU) Option
Introduction
Requirements
Data Analyses
Appendix A. Table of Instructions: Antimicrobial Use
Appendix B. List of Antimicrobials
Appendix C. Example Calculations of Antimicrobial Days
Appendix D. Antimicrobial groupings for SAAR calculations
2. Antimicrobial Resistance (AR) Option
Introduction
Requirements
Data Analyses
Appendix A. List of Microorganisms for Antimicrobial Resistance
Appendix B. SNOMED Codes to Identify Eligible Specimen Types
Appendix C. Technical and Isolate Based Report Variables
Appendix D. Denominator Data Variables

1
2
2
4
8
11
12
16
19
21
21
22
27
32
38
40
42

Introduction
This module contains two options, one focused on antimicrobial use and the second on
antimicrobial resistance. To participate in either option, facility personnel responsible for
reporting antimicrobial use (AU) or resistance (AR) data to the National Healthcare Safety
Network (NHSN) must coordinate with their laboratory and/or pharmacy information software
providers to configure their system to enable the generation of standard formatted file(s) to be
imported into NHSN. The format provided for data submission follows the Health Level (HL7)
Clinical Document Architecture (CDA).7 Manual data entry is not available for the AUR
Module.
Purpose:
The NHSN AUR Module provides a mechanism for facilities to report and analyze antimicrobial
use and/or resistance as part of local or regional efforts to reduce antimicrobial resistant
infections through antimicrobial stewardship efforts or interruption of transmission of resistant
pathogens at their facility.6

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1. Antimicrobial Use (AU) Option
Introduction: Rates of resistance to antimicrobial agents continue to increase at hospitals in the
United States.1 The two main reasons for this increase are patient-to-patient transmission of
resistant organisms and selection of resistant organisms because of antimicrobial exposure.2
Previous studies have shown that feedback of reliable reports of rates of antimicrobial use and
resistance to clinicians can improve the appropriateness of antimicrobial usage.3-5
Objectives: The primary objective of the Antimicrobial Use option is to facilitate risk-adjusted
inter- and intra-facility benchmarking of antimicrobial usage. A secondary objective is to
evaluate trends of antimicrobial usage over time at the facility and national levels.
Methodology: The primary antimicrobial usage metric reported to this module is antimicrobial
days per 1000 days present. An antimicrobial day (also known as day of therapy) is defined by
any amount of a specific antimicrobial agent administered in a calendar day to a particular
patient as documented in the electronic medication administration record (eMAR) and/or bar
coding medication record (BCMA) (refer to Numerator Data Section); all antimicrobial days for
a specific agent administered across a population are summed in aggregate.8-11 Days present are
defined as the aggregate number of patients housed to a patient care location or facility anytime
throughout a day during a calendar month (refer to Denominator Data Section). For each facility,
the numerator (i.e., antimicrobial days) is aggregated by month for each patient care location and
overall for inpatient areas facility-wide (i.e., facility-wide inpatient). Similarly, the denominator
(i.e., days present) is calculated for the corresponding patient care-location-month or facilitywide inpatient-month. A secondary antimicrobial usage metric for facility-wide inpatient also
reported to this module is antimicrobial days per 100 admissions. The numerator and
denominators are further defined below and must adhere to the data format prescribed by the
HL7 CDA Implementation Guide developed by the CDC and HL7.7
Settings: NHSN encourages submission of all NHSN-defined inpatient locations, facility-wide
inpatient, and select outpatient acute-care settings (i.e., outpatient emergency department,
pediatric emergency department, 24-hour observation area) at each facility (Table 1). The patient
care areas may include adult, pediatric, or neonatal units as defined by NHSN Codes (Chapter 15
CDC Locations and Descriptions). A comprehensive submission will enable a facility to
optimize inter- and/or intra-facility comparisons among specific wards, combined wards, and
hospital-wide data. The optional and minimal requirements for participation in the Antimicrobial
Use option are listed in Table 1.
The minimal requirement for participation is submission of data for all four of the following
location types (if applicable to facility): 1) all medical critical care units(s) and surgical critical
care units(s) [if combined units, then report as medical/surgical critical care unit(s)]; 2) all
medical ward(s) and surgical ward(s) [if combined wards, then report as medical/surgical
ward(s)]; 3) at least one specialty care area; and 4) facility-wide inpatient (both days present and
admissions must be reported for this location).

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Table 1. CDC Locationa: Optional and Minimal Requirements for the AU Option
Inpatient Locations
Minimal Submission Requirements (if applicable for facility)
Requirement:
Adult Critical Care
For facilities with only adult critical care unit(s): submit all medical
Units
critical care unit(s) and surgical critical care units(s) [if combined units,
then report as medical/surgical critical care unit(s)].

Pediatric Critical
Care Units

Neonatal Units
Inpatient Specialty
Care Areas
Inpatient Adults
Wards

Inpatient Pediatric
Wards

For facilities with adult and pediatric critical care unit(s), the minimum
requirement is the submission of data from all adult and pediatric critical
care locations.
Requirement:
For facilities with only pediatric critical care unit(s): submit all medical
critical care unit(s) and surgical critical care units(s) [if combined units,
then report as medical/surgical critical care unit(s)].
For facilities with adult and pediatric critical care unit(s), the minimum
requirement is the submission of data from all adult and pediatric critical
care locations.
Optional (i.e., no minimal submission requirement)
Requirement:
At least one Specialty Care Area.
Requirement:
For facilities with only adult medical and surgical ward(s), submit all
medical ward(s) and surgical ward(s) [if combined wards, then report as
medical/surgical ward(s)].
For facilities with adult and pediatric medical and surgical ward(s), the
minimum requirement is the submission of data from all adult and
pediatric medical and surgical ward locations.
Requirement:
For facilities with only pediatric medical and surgical ward(s), submit all
medical ward(s) and surgical ward(s) [if combined wards, then report as
medical/surgical ward(s)].

For facilities with adult and pediatric medical and surgical ward(s), the
minimum requirement is the submission of data from all adult and
pediatric medical and surgical ward locations.
Optional (i.e., no minimal submission requirement)
Step Down Units
Optional (i.e., no minimal submission requirement)
Operating Rooms
Optional (i.e., no minimal submission requirement)
Chronic Care
Facility-Wide
Minimal Submission Requirements (if applicable for facility)
Facility-wide inpatient Requirement:
Facility-wide inpatient

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Outpatient Locations
Select Outpatient
Acute Care Settings

Minimal Submission Requirements (if applicable for facility)
Optional (i.e., no minimal submission requirement)
Includes outpatient emergency department, pediatric emergency
department, and 24-hour observation area.

aCDC

Location: A CDC-defined designation given to a patient care area where patients who
have similar disease conditions or are receiving care for similar medical or surgical specialties.
Each facility location that is monitored is “mapped” to one CDC Location. The specific CDC
Location code is determined by the type of patients cared for in that area according to the 80%
Rule. That is, if 80% of patients are of a certain type (e.g., pediatric patients with orthopedic
problems), then that area is designated as that type of location (in this case, an Inpatient Pediatric
Orthopedic Ward). See Locations chapter for more information regarding location mapping.

Requirements: An acceptable minimal month of data includes:
1. Each month, the facility must choose to monitor antimicrobial use data on the Patient
Safety Monthly Reporting Plan (CDC 57.106).
2. Data submitted for all four of the following locations (if applicable to facility): 1) all
medical critical care unit(s) and surgical critical care unit(s) [if combined units, then
report as medical/surgical critical care unit(s)]; 2) all medical ward(s) and surgical
ward(s) [if combined wards, then report as medical/surgical ward(s)]; 3) at least one
specialty care area; and 4) facility-wide inpatient (both days present and admissions must
be reported for this location).
3. All data fields outlined in the Table of Instructions (Appendix A) for the AU option are
completed via CDA for each location.
NHSN recommends that data be entered into NHSN for a given calendar month by the end of the
subsequent calendar month.
Numerator Data (Antimicrobial Days):
Antimicrobial Days (Days of Therapy): Defined as the aggregate sum of days for which any
amount of a specific antimicrobial agent was administered to individual patients as documented
in the eMAR and/or BCMA.8-11 Appendix B provides the full list of antimicrobial agents
collected in the NHSN AU Option. Aggregate antimicrobial days are reported monthly for
inpatient locations, facility-wide inpatient, and select outpatient acute care settings (e.g.,
outpatient emergency department, pediatric emergency department, 24-hour observation area)
for select antimicrobial agents and stratified by route of administration (e.g., intravenous,
intramuscular, digestive and respiratory). Refer to Table 2 and Table 3 for definitions of drugspecific antimicrobial days and stratification based on route of administration. For example, a
patient to whom 1 gram vancomycin is administered intravenously twice daily for three days will
be attributed three “Vancomycin Days (total)” and three “Vancomycin Days (IV)” when
stratified by intravenous route of administration. Appendix C provides additional examples for
the calculation of antimicrobial days. Table 4 summarizes the data elements for numerator
calculation.

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Please note that “zero” should be recorded when no aggregate usage occurred during a given
reporting period for a specific antimicrobial agent at a facility in which the agent is used, while
“not applicable” should be recorded when data are not available for a specific antimicrobial
agent at a facility (e.g., the agent can’t be electronically captured at that facility). A value (e.g., a
specific number, “zero”, or “not applicable”) must be reported for every antimicrobial agent
listed in Appendix B.
Table 2. Classification and Definitions of Routes of Administration for Antimicrobial Days
Classification:
Definitionb
a
Route of Administration
Intravenous (IV)
An intravascular route that begins with a vein.
Intramuscular (IM)
A route that begins within a muscle.
Digestive Tract
A route that begins anywhere in the digestive tract extending
from the mouth through rectum.
Respiratory Tract
A route that begins within the respiratory tract, including the
oropharynx and nasopharynx.
a
Other routes of administration are excluded in this module (e.g., antibiotic locks,
intraperitoneal, intraventricular, irrigation, topical).
b
Definitions per SNOMED Reference Terminology
Table 3. Example Stratification of Antimicrobial Days by Route of Administration
Month/
YearLocation
MonthYear/
Location

Antimicrobial
Agent
Tobramycin

Drug-specific Antimicrobial Days
Total a

IV

IM

Digestiveb

Respiratory

Tobramycin
Days
(Total)

Tobramycin
Days
(IV)

Tobramycin
Days
(IM)

Tobramycin
Days
(Digestive)

Tobramycin
Days
(Respiratory)

a Drug-specific

antimicrobial days (total) attributes one antimicrobial day for any route of
administration. For example, a patient to whom tobramycin was administered intravenously and
via a respiratory route on the same day would be attributed “one Tobramycin Day (Total)”; the
stratification by route of administration would be “one Tobramycin Day (IV)” and “one
Tobramycin Day (Respiratory)”.
b
For purposes of example of route stratification only (tobramycin not FDA approved for
administration via the digestive route).

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Table 4. Data Elements for Antimicrobial Days
Data Element
Antimicrobial Days
Antimicrobial Defined as select antimicrobial agents and stratified by route of administration (i.e.,
intravenous, intramuscular, digestive and respiratory). Refer to Appendix B for a
Agents
complete list of antimicrobials. The list of select antimicrobials will evolve with
time as new agents become commercially available.
Topical antimicrobial agents are not included in the NHSN AU Option.
Antimicrobial days are derived from administered data documented in the eMAR
Data source
and/or BCMA only. Usage derived from other data sources (e.g., pharmacy orders,
doses dispensed, doses billed) cannot be submitted.
Antimicrobial days are aggregated for inpatient locations, facility-wide inpatient,
Location
and select outpatient acute-care settings (i.e., outpatient emergency department,
pediatric emergency department, 24-hour observation area) per NHSN location
definitions.
Antimicrobial days for a specific antimicrobial agent and stratification by route of
Time Unit
administration are aggregated monthly per location.
Denominator Data (Days Present and Admissions): The numerator will be analyzed against
the denominators of days present as well as admissions (for facility-wide inpatient only). The
denominators are further defined below.
Days present: Defined as time period during which a given patient is at risk for antimicrobial
exposure for a given patient location. The definition of days present differs from conventional
definition of patient days used in other NHSN modules and that recommended by the
SHEA/HIPAC guidance for surveillance of multidrug-resistant organisms.12 Days present is
further defined below in context of calculation for patient care location specific analyses and
facility-wide inpatient analyses. Please note that a separate calculation for days present is
required for patient care location compared to facility-wide inpatient.
For patient care location-specific analyses, days present is calculated as the number of
patients who were present for any portion of each day of a calendar month for a patient
care location; the aggregate measure is calculated by summing up all of the days present
for that location and month. The day of admission, discharge, and transfer to and from
locations will be included in the days present count. For example, a patient admitted to
the medical ward on Monday and discharged two days later on Wednesday will be
attributed three days present on that medical ward. Another example, on the day a patient
is transferred from a medical critical care unit to a medical ward; the patient will be
attributed one day present on the medical critical care unit as well as one day present on
the medical ward. Similarly, a patient’s exposure to the operating room or emergency
department will be included in days present for these types of units. However, one patient
can account for only one day present for a specific location per calendar day (e.g., one
patient cannot contribute more than one day present to any one unique location on the
same day, but can contribute a day present to two different locations on the same day).
For example, a patient transferred from the surgical ward to the operating room and back

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to the surgical ward in a calendar day contributes one day present to the surgical ward
and one day present to the operating room.
For facility-wide inpatient analyses, days present is calculated as the number of patients
who were present for any portion of each day of a calendar month at the facility-wide
inpatient location; the aggregate measure is calculated by summing up all of the days
present for facility-wide inpatient for a given month. Thus, a sum of days present from
location-specific analyses would be higher than days present for the facility, because
transfers between wards can account for multiple location “days present” for a given
patient. Therefore, the individual summing of days present for location-specific analyses
to achieve facility-wide inpatient is not permissible. The calculation must be a separate
summation for facility-wide inpatient analyses.
Admissions: Admissions are defined as the aggregate number of patients admitted to the facility
(i.e., facility-wide inpatient) starting on first day of each calendar month through the last day of
the calendar month. This is the same definition for admissions utilized in the NHSN MDRO/CDI
Module. In the AU option, admissions are reported only for facility-wide inpatient.
Table 5. Location-specific and Facility-wide Inpatient Metrics
Metric Collected Metric Definition
Comments
Patient Care Location-Specific Analyses
Antimicrobial
Drug-specific antimicrobial days per One patient can contribute only
Days/Days
patient care location per month/Days one day present per calendar
present
present per patient care location per day for each specific location.
month
Summed total may be higher
when compared to facilitywide measure (reflecting
transfers between locations).
Facility-wide Inpatient Analyses
Antimicrobial
Drug-specific antimicrobial days for One patient can contribute only
Days/Days
a facility per month/Days present
one day present per calendar
present
per facility-wide inpatient per month day for a facility. Thus, one
denominator is obtained for an
entire facility. The day present
measure for facility-wide
inpatient may be lower when
compared to sum total from
location-specific comparison.
Antimicrobial
Drug-specific antimicrobial days for Only calculated for facilityDays/Admissions a facility per month/Admissions per wide inpatient for AU Option.
facility-wide inpatient per month

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Data Analyses:
The Standardized Antimicrobial Administration Ratio (SAAR) is a metric developed by CDC to
analyze and report antimicrobial use data in summary form. The SAAR is calculated by dividing
observed antimicrobial use by predicted antimicrobial use. The observed antimicrobial use is the
number of days of therapy, or antimicrobial days, reported by a facility for a specified category
of antimicrobial agents in a specified group of patient care locations. The predicted antimicrobial
use is calculated using predictive modules developed by CDC applied to nationally aggregated
AU data. The separate predictive models are specific to each of the five antimicrobial use
categories. The data used in the predictive models are historical AU data that have been reported
to NHSN and aggregated for analytic purposes.
SAAR = Observed (O) Antimicrobial Use
Predicted (P) Antimicrobial Use
The SAARs are generated for five specific antimicrobial groupings (see Appendix D), each of
which can serve as a high value target or high level indicator for antimicrobial stewardship
programs. Future iterations of the SAAR can extend its use as a metric to additional patient care
locations when aggregate data are sufficient for those purposes. At present, facilities with
locations mapped as adult and pediatric medical, surgical, and medical/surgical ICUs and wards
are able to generate the 16 SAARs outlined below:
SAARs for broad spectrum antibacterial agents predominantly used for hospital-onset/multidrug
resistant infections:
1. Adult medical, medical/surgical, and surgical ICUs
2. Adult medical, medical/surgical, and surgical wards
3. Pediatric medical, medical/surgical, and surgical ICUs
4. Pediatric medical, medical/surgical, and surgical wards
SAARs for broad spectrum antibacterial agents predominantly used for community-acquired
infections:
5. Adult medical, medical/surgical, and surgical ICUs
6. Adult medical, medical/surgical, and surgical wards
7. Pediatric medical, medical/surgical, and surgical ICUs
8. Pediatric medical, medical/surgical, and surgical wards
SAARs for anti-MRSA antibacterial agents:
9. Adult medical, medical/surgical, and surgical ICUs
10. Adult medical, medical/surgical, and surgical wards
11. Pediatric medical, medical/surgical, and surgical ICUs
12. Pediatric medical, medical/surgical, and surgical wards
SAARs for antibacterial agents predominantly used for surgical site infection prophylaxis:
13. Adult ICUs and wards (medical, medical/surgical, and surgical)
14. Pediatric ICUs and wards (medical, medical/surgical, and surgical)

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SAARs for all antibacterial agents:
15. Adult ICUs and wards (medical, medical/surgical, and surgical)
16. Pediatric ICUs and wards (medical, medical/surgical, and surgical)
A high SAAR that achieves statistical significance may indicate excessive antibacterial use. A
SAAR that is not statistically different from 1.0 indicates antibacterial use is equivalent to the
referent population’s antibacterial use. A low SAAR that achieves statistical significance (i.e.,
different from 1.0) may indicate antibacterial under use. Note: A SAAR alone is not a definitive
measure of the appropriateness or judiciousness of antibacterial use, and any SAAR may warrant
further investigation. For example, a SAAR above 1.0 that does not achieve statistical
significance may be associated with meaningful excess of antimicrobial use and further
investigation may be needed. Also, a SAAR that is statistically different from 1.0 does not mean
that further investigation will be productive.
Additionally, antimicrobial use data are expressed as incidence density rates of antimicrobial
days per days present stratified by patient care location and facility-wide inpatient.
Antimicrobials may be grouped during analysis by route of administration, spectrum of activity,
or drug classification.
A secondary metric, antimicrobial days per admissions, will also be analyzed for facility-wide
inpatient.

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References
1. Hidron AI, Edwards JR, Patel J, et al. Antimicrobial-resistant pathogens associated with
healthcare-associated infections: annual summary of data reported to the National
Healthcare Safety Network at the Centers for Disease Control and Prevention, 20062007. Infect Control Hosp Epidemiol 2008;29:996-1011.
2. Schwartz MN. Use of antimicrobial agents and drug resistance. N Eng J Med
1997;337:491-2.
3. Ansari F, Gray K, Nathwani D, et al. Outcomes of an intervention to improve hospital
antibiotic prescribing; interrupted time series with segmented regression analysis. J
Antimicrob Chemother 2003;52:842-8.
4. Solomon DH, Van Houten L, Glynn RJ. Academic detailing to improve use of broadspectrum antibiotics at an academic medical center. Arch Inter Med 2001;161:1897-902.
5. Fraser GL, Stogsdill P, Dickens JD Jr, et al. Antibiotic optimizations: an evaluation of
patient safety and economic outcomes. Arch Inter Med 1997;157-1689-94.
6. Dellit TH, Owens RC, McGowan JE, et al. Infectious Diseases Society of America and
the Society for Healthcare Epidemiology of America Guidelines for Developing an
Institutional Program to Enhance Antimicrobial Stewardship. Clin Infect Dis
2007;44:159-77.
7. National Healthcare Safety Network (NHSN) Patient Safety Component: Clinical
Document Architecture. http://www.cdc.gov/nhsn/CDA/index.html
8. Schwartz DN, Evans RS, Camins B, et al. Deriving measures of intensive care unit
antimicrobial use from computerized pharmacy data: methods, validation, and
overcoming barriers. Infect Control Hosp Epidemiol 2011;32:472-80.
9. Polk RE, Fox C, Mahoney A, Letcavage J, MacDougall C. Measurement of adult
Antibacterial Drug Use in 130 US Hospitals: Comparison of Defined Daily Dose and
Days of Therapy. Clin Infect Dis 2007;44:664-70.
10. Kuster SP, Ledergerber B, Hintermann A, et al. Quantitative antibiotic use in hospitals:
comparison of measurements, literature review, and recommendations for standards of
reporting. Infection 2008; 6:549-59.
11. Berrington A. Antimicrobial prescribing in hospitals: be careful what you measure. J
Antimicrob Chemother 2010:65:163-168.
12. Cohen AL, Calfee D, Fridkin SK, et al. Recommendations for metrics for multidrugresistant organisms in healthcare settings: SHEA/HICPAC position paper. Infect Control
Hosp Epidemiol 2008:29:901-13.

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Appendix A. Table of Instructions: Antimicrobial Use
Data Field
Facility
identifier
Month
Year
Location

Numerator:

Instructions for CDA of Antimicrobial Use Data
Required. Must be assigned to facility and included in the importation file prior
to submission to CDC.
Required. Record the 2-digit month during which the data were collected for
this location.
Required. Record the 4-digit year during which the data were collected for this
location.
Required. Record location; must be (if applicable to facility): 1) all medical
critical care unit(s) and surgical critical care unit(s) [if combined units, then
report as medical/surgical critical care unit(s)]; 2) all medical ward(s) and
surgical ward(s) [if combined wards, then report as medical/surgical ward(s)];
3) at least one specialty care area; and 4) facility-wide inpatient.
Required.

Antimicrobial
days per
month per
location

Antimicrobial days are defined as the aggregate sum of the days of exposure for
which a specific antimicrobial was administered. These are required to be
extracted from electronic medication administration record (eMAR) and/or bar
coding medication record (BCMA). Antimicrobials days will be collected for
select antimicrobial agents (refer to Appendix B) and stratified by route of
administration.
Denominator: Required.
Days present

Days present is defined as risk for antimicrobial exposure per time unit of
analysis stratified by location. For patient care location-specific analyses, days
present is calculated as the number of patients who were present for any portion
of each day of a calendar month for a patient care location. For facility-wide
inpatient analyses, days present is calculated as the number of patients who
were present for any portion of each day of a calendar month at the facility-wide
inpatient location

Admissions
Admissions are defined as the aggregate number of patients admitted to the
facility (i.e., facility-wide inpatient) starting on first day of each calendar month
through the last day of the calendar month. In the AU Option, admissions are
only reported for facility-wide inpatient.

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Appendix B. List of Antimicrobials
Please note that mapping of standardized terminology (RXNORM) are provided via PHIN
Vocabulary Access and Distribution System (VADS). The list of NHSN drug codes as well as
the drug values used for the development of the CDA files can be found here: Eligible
Antimicrobials.
Antimicrobial Agent
AMANTADINE

Antimicrobial
Category
Anti-influenza

AMIKACIN

Antibacterial

Antimicrobial
Classa
M2 ion channel
inhibitors
Aminoglycosides

AMOXICILLIN

Antibacterial

Penicillins

AMOXICILLIN/
CLAVULANATE
AMPHOTERICIN B

Antibacterial
Antifungal

Β-lactam/ Β-lactamase
inhibitor combination
Polyenes

AMPHOTERICIN B
LIPOSOMAL
AMPICILLIN

Antifungal

Polyenes

Antibacterial

Penicillins

AMPICILLIN/
SULBACTAM
ANIDULAFUNGIN

Antibacterial
Antifungal

Β-lactam/ Β-lactamase
inhibitor combination
Echinocandins

AZITHROMYCIN

Antibacterial

Macrolides

AZTREONAM

Antibacterial

Monobactams

CASPOFUNGIN

Antifungal

Echinocandins

CEFACLOR

Antibacterial

Cephalosporins

Cephalosporin 2rd generation

CEFADROXIL

Antibacterial

Cephalosporins

Cephalosporin 1st generation

CEFAZOLIN

Antibacterial

Cephalosporins

Cephalosporin 1st generation

CEFDINIR

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFDITOREN

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFEPIME

Antibacterial

Cephalosporins

Cephalosporin 4th generation

CEFIXIME

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFOTAXIME

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFOTETAN

Antibacterial

Cephalosporins

Cephamycin

CEFOXITIN

Antibacterial

Cephalosporins

Cephamycin

CEFPODOXIME

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFPROZIL

Antibacterial

Cephalosporins

Cephalosporin 2rd generation

CEFTAROLINE

Antibacterial

Cephalosporins

CEFTAZIDIME

Antibacterial

Cephalosporins

Cephalosporins with antiMRSA activity
Cephalosporin 3rd generation

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Antimicrobial
Subclassa

Aminopenicillin

Aminopenicillin

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Antimicrobial Agent

Antibacterial

Antimicrobial
Classa
Β-lactam/ Β-lactamase
inhibitor combination
Cephalosporins

Cephalosporin 3rd generation

CEFTIZOXIME

Antibacterial

Cephalosporins

Cephalosporin 3rd generation

CEFTOLOZANE/
TAZOBACTAM
CEFTRIAXONE

Antibacterial
Antibacterial

Β-lactam/ Β-lactamase
inhibitor combination
Cephalosporins

Cephalosporin 3rd generation

CEFUROXIME

Antibacterial

Cephalosporins

Cephalosporin 2rd generation

CEPHALEXIN

Antibacterial

Cephalosporins

Cephalosporin 1st generation

CHLORAMPHENICOL

Antibacterial

Phenicols

CIPROFLOXACIN

Antibacterial

Fluoroquinolones

CLARITHROMYCIN

Antibacterial

Macrolides

CLINDAMYCIN

Antibacterial

Lincosamides

COLISTIMETHATE

Antibacterial

Polymyxins

DALBAVANCIN

Antibacterial

Glycopeptides

DAPTOMYCIN

Antibacterial

Lipopeptides

DICLOXACILLIN

Antibacterial

Penicillins

DORIPENEM

Antibacterial

Carbapenems

DOXYCYCLINE

Antibacterial

Tetracyclines

ERTAPENEM

Antibacterial

Carbapenems

ERYTHROMYCIN

Antibacterial

Macrolides

ERYTHROMYCIN/
SULFISOXAZOLE
FIDAXOMICIN

Antibacterial
Antibacterial

Folate pathway
inhibitors
Macrocyclic

FLUCONAZOLE

Antifungal

Azoles

FOSFOMYCIN

Antibacterial

Fosfomycins

GEMIFLOXACIN

Antibacterial

Fluoroquinolones

GENTAMICIN

Antibacterial

Aminoglycosides

IMIPENEM/
CILASTATIN
ISAVUCONAZONIUM

Antibacterial

Carbapenems

Antifungal

Azoles

ITRACONAZOLE

Antifungal

Azoles

LEVOFLOXACIN

Antibacterial

Fluoroquinolones

LINEZOLID

Antibacterial

Oxazolidinones

MEROPENEM

Antibacterial

Carbapenems

CEFTAZIDIME/
AVIBACTAM
CEFTIBUTEN

January 2016

Antimicrobial
Category
Antibacterial

11-13

Antimicrobial
Subclassa

Lipoglycopeptide
Penicillinase-stable
penicillins

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Antimicrobial Agent
METRONIDAZOLE

Antimicrobial
Category
Antibacterial

Antimicrobial
Classa
Nitroimidazoles

MICAFUNGIN

Antifungal

Echinocandins

MINOCYCLINE

Antibacterial

Tetracyclines

MOXIFLOXACIN

Antibacterial

Fluoroquinolones

NAFCILLIN

Antibacterial

Penicillins

NITROFURANTOIN

Antibacterial

Nitrofurans

ORITAVANCIN

Antibacterial

Glycopeptides

OSELTAMIVIR

Anti-influenza

OXACILLIN

Antibacterial

Neuraminidase
inhibitors
Penicillins

PENICILLIN G

Antibacterial

Penicillins

Penicillinase-stable
penicillins
Penicillin

PENICILLIN V

Antibacterial

Penicillins

Penicillin

PERAMIVIR

Anti-influenza

PIPERACILLIN

Antibacterial

Neuraminidase
inhibitors
Penicillins

Ureidopenicillin

PIPERACILLIN/
TAZOBACTAM
POLYMYXIN B

Antibacterial
Antibacterial

Β-lactam/ Β-lactamase
inhibitor combination
Polymyxins

POSACONAZOLE

Antifungal

Azoles

QUINUPRISTIN/
DALFOPRISTIN
RIFAMPIN

Antibacterial

Streptogramins

Antibacterial

Rifampin

RIMANTADINE

Anti-influenza

SULFAMETHOXAZOLE/
TRIMETHOPRIM
SULFISOXAZOLE

Antibacterial

TEDIZOLID

Antibacterial

M2 ion channel
inhibitors
Folate pathway
inhibitors
Folate pathway
inhibitors
Oxazolidinones

TELAVANCIN

Antibacterial

Glycopeptides

TELITHROMYCIN

Antibacterial

Ketolides

TETRACYCLINE

Antibacterial

Tetracyclines

TICARCILLIN/
CLAVULANATE
TIGECYCLINE

Antibacterial
Antibacterial

Β-lactam/ Β-lactamase
inhibitor combination
Glycylcyclines

TINIDAZOLE

Antibacterial

Nitroimidazoles

TOBRAMYCIN

Antibacterial

Aminoglycosides

January 2016

Antibacterial

11-14

Antimicrobial
Subclassa

Penicillinase-stable
penicillins
Lipoglycopeptide

Lipoglycopeptides

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Antimicrobial Agent
VANCOMYCIN

Antimicrobial
Category
Antibacterial

Antimicrobial
Classa
Glycopeptides

VORICONAZOLE

Antifungal

Azoles

ZANAMIVIR

Anti-influenza

Neuraminidase
inhibitors

a

Adapted from CLSI January 2014

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Antimicrobial
Subclassa
Glycopeptide

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Appendix C. Example Calculations of Antimicrobial Days
Example 1. Example eMAR and Calculation of Antimicrobial Days
This example illustrates the calculation of antimicrobial days from a patient receiving
meropenem 1gram intravenously every 8 hours and amikacin 1000mg intravenously every 24
hours in the medical ward. Table 1 provides an example of administered doses for this patient
documented in eMAR. Table 2 illustrates the calculation of meropenem and amikacin days by
drug-specific (total) and stratified by route of administration based upon the administered doses
of meropenem and amikacin documented in eMAR. Table 3 illustrates the contribution of this
patient’s antimicrobial days to the aggregate monthly report per patient care location.
Table 1. Example eMAR for patient housed in Medical Ward
Medical Ward
Monday
Tuesday
December 28
December 29
Meropenem 1gram
intravenously every 8 hours

Given: 2300

Amikacin 1000mg
intravenously every 24 hours

Given: 2300

Given: 0700
Given: 1500
Given: 2300
Given: 2300

Table 2. Example of calculation of antimicrobial days
Calculation
Monday
Tuesday
December 28
December 29
Drug-specific Antimicrobial
Days (total)
Drug-specific Antimicrobial
Days by Stratification of
Route of Administration

Meropenem Days = 1
Amikacin Days = 1
Meropenem Days
(IV) = 1
Amikacin Days
(IV) = 1

Wednesday
December 30

Meropenem Days = 1
Amikacin Days = 1
Meropenem Days
(IV) = 1
Amikacin Days
(IV) = 1

Given: 0700

Wednesday
December 30
Meropenem Days = 1
Amikacin Days = 0
Meropenem Days
(IV) = 1
Amikacin Days
(IV) = 0

Table 3. Example of antimicrobial days per month per patient care location
Month/
Antimicrobial
Drug-specific Antimicrobial Days
YearAgent
Location
Total
IV
IM
Digestive
Respiratory
December
Medical Ward
December
Medical Ward

January 2016

Meropenem

3

3

0

0

0

Amikacin

2

2

0

0

0

11-16

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Example 2. Differences in Calculation for Patient Care Location and Facility-Wide
Inpatient for a Patient Transferred Between Patient Care Locations
This example illustrates the calculation of antimicrobial days from a patient receiving
vancomycin 1gram every 8 hours that was transferred from the MICU to a medical ward on
December 1. Table 1 provides an example of doses documented in eMAR administered to this
patient in the MICU and medical ward. Table 2 illustrates the calculation of vancomycin days by
drug-specific (total) and stratified by route of administration based upon the administered doses
of vancomycin documented in eMAR. Table 3 illustrates the contribution of this patient’s
vancomycin days to the aggregate monthly report per patient care location and facility-wide
inpatient.
Table 1. Example eMAR for patient transferred from MICU to Medical Ward on December 1
eMAR
Tuesday
Tuesday
December 1
December 1
Location: MICU
Location: Medical Ward
Vancomycin 1gram
intravenously every 8 hours

Given: 0700

Given: 1500
Given: 2300

Table 2. Example of calculation of antimicrobial days for December 1
Calculation
Tuesday
Tuesday
December 1
December 1
Location: MICU
Location: Medical Ward
Drug-specific Antimicrobial
Days (total)
Drug-specific Antimicrobial
Days by Stratification of Route
of Administration

Vancomycin Days = 1

Vancomycin Days = 1

Vancomycin Days
(IV) = 1

Vancomycin Days
(IV) = 1

Table 3. Example of antimicrobial days per month per patient care location and facility-wide
inpatient contributed from December 1
Month/
Antimicrobial
Drug-specific Antimicrobial Days
YearAgent
Location
Total
IV
IM
Digestive Respiratory
December
MICU
December
Medical Ward
December
Facility-wide
inpatient

January 2016

Vancomycin

1

1

0

0

0

Vancomycin

1

1

0

0

0

Vancomycin

1

1

0

0

0

11-17

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Example 3. Calculation of Antimicrobial Days for a Patient Care Location when a Patient
Admission extends over Two Different Months
This example illustrates the calculation of antimicrobial days from a patient receiving ceftriaxone
1gram intravenously every 24 hours for two days in the surgical ward (but spanning different
months). Table 1 provides an example of administered doses for this patient documented in
eMAR. Table 2 illustrates the calculation of ceftriaxone days by drug-specific (total) and
stratification of route of administration based upon the administered doses of ceftriaxone
documented in eMAR. Table 3 illustrates the contribution of this patient’s ceftriaxone days to the
aggregate monthly report per patient care location.

Table 1. Example eMAR for patient housed in Surgical Ward
eMAR
Thursday
Friday
December 31
January 1
Location: Surgical Ward
Location: Surgical Ward
Ceftriaxone gram
intravenously every 24 hours

Given: 0800

Given: 0800

Table 2. Example of calculation of antimicrobial days
Calculation
Thursday
December 31
Location: Surgical Ward
Drug-specific Antimicrobial
Days (total)
Drug-specific Antimicrobial
Days by Stratification of
Route of Administration

Friday
January 1
Location: Surgical Ward

Ceftriaxone Day = 1

Ceftriaxone Day = 1

Ceftriaxone Day
(IV) = 1

Ceftriaxone Day
(IV) = 1

Table 3. Example of antimicrobial days per month per patient care location
Month/
Antimicrobial
Drug-specific Antimicrobial Days
YearAgent
Location
Total
IV
IM
Digestive Respiratory
December/
Surgical Ward
January/
Surgical Ward

January 2016

Ceftriaxone

1

1

0

0

0

Ceftriaxone

1

1

0

0

0

11-18

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Appendix D: Antimicrobial groupings for SAAR calculations
Broad spectrum antibacterial agents predominantly used for hospital-onset/multi-drug resistant
infections
 AMIKACIN
 AZTREONAM
 CEFEPIME
 CEFTAZIDIME
 CEFTAZIDIME/AVIBACTAM
 CEFTOLOZANE/TAZOBACTAM
 COLISTIMETHATE
 DORIPENEM
 GENTAMICIN
 IMIPENEM/CILASTATIN
 MEROPENEM
 PIPERACILLIN
 PIPERACILLIN/TAZOBACTAM
 POLYMYXIN B
 TICARCILLIN/CLAVULANATE
 TIGECYCLINE
 TOBRAMYCIN
Broad spectrum antibacterial agents predominantly used for community-acquired infections
 CEFOTAXIME
 CEFTRIAXONE
 CIPROFLOXACIN



ERTAPENEM





GEMIFLOXACIN
LEVOFLOXACIN
MOXIFLOXACIN

Anti-MRSA antibacterial agents
 CEFTAROLINE
 DALBAVANCIN
 DAPTOMYCIN
 LINEZOLID
 ORITAVANCIN
 QUINUPRISTIN/DALFOPRISTIN
 TEDIZOLID
 TELAVANCIN
 VANCOMYCIN

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Antibacterial agents predominantly used for surgical site infection prophylaxis
 CEFAZOLIN
 CEFOTETAN
 CEFOXITIN
 CEFUROXIME
 CEPHALEXIN
All antibacterial agents

Includes all antibacterial agents reported into the AU Option including the agents listed in the
category specific SAARs.

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2. Antimicrobial Resistance (AR) Option
Introduction
Common measures of antimicrobial resistance include the proportion of isolates resistant to
specific antimicrobial agents. This proportion resistant (%R) is used to aid in clinical decision
making (hospital antibiograms) as well as for assessing impact of cross transmission prevention
success or antimicrobial stewardship success, although the measure may not be very sensitive to
measuring success of efforts in the short term. An additional value of measuring the proportion
resistant includes a local or regional assessment of progression or improvement of a particular
resistance problem, to guide local or regional cross-transmission prevention efforts. By using
standard methodology of aggregating proportion resistant, local and regional assessments of the
magnitude of a particular resistance phenotype will be more valid.
Objectives:
1. Facilitate evaluation of antimicrobial resistance data using a standardized approach to:
a. Provide local practitioners with an improved awareness of a variety of
antimicrobial-resistance problems to both aid in clinical decision making and
prioritize transmission prevention efforts.
b. Provide facility-specific measures in context of a regional and national
perspective (i.e., benchmarking) which can inform decisions to accelerate
transmission prevention efforts and reverse propagation of emerging or
established problematic resistant pathogens.
2. Regional and national assessment of resistance of antimicrobial resistant organisms of
public health importance including ecologic assessments and infection burden.
Methodology:
Antimicrobial resistance data are reported as a proportion and rate in this module.1 The
proportion resistant is defined as the number of resistant isolates divided by the number of
isolates tested for the specific antimicrobial agent being evaluated. In comparison, the
antimicrobial resistance rate is defined as the number of resistant isolates per 1000 patient days.
For each facility, the numerator (i.e., number of resistant isolates) is derived from isolate-level
reports submitted. The ultimate source of the isolate data included in these reports is the
laboratory information system (LIS). In healthcare settings where the LIS is directly connected to
the electronic health record system (EHRs), laboratory results data from the EHRs can be used to
populate the AR Option numerator records submitted to NHSN. The denominators of patient
days and admissions can be obtained from the ADT system (or similar system that allows for
electronic access of required data elements). The numerator and denominator are further defined
below and must adhere to the data format prescribed by the HL7 CDA Implementation Guide
developed by the CDC and HL7.2
Settings:
NHSN encourages reporting specimens from all NHSN-defined inpatient locations at each
facility. The denominators of patient days and admissions are only reported at the facility-wide

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inpatient level (FacWideIN). Eligible facilities include any facility using the Patient Safety
Component of NHSN.
Requirements:
Each month:
1. The facility must choose to monitor antimicrobial resistance data on the Patient Safety
Monthly Reporting Plan (CDC 57.106).
2. Two record types must be reported for each month of surveillance.
 One for each isolate-based report
o Isolate is defined as a population of a single organism observed in a culture
obtained from a patient specimen.
 One for the denominator data report (facility-wide inpatient-FacWideIN)
NHSN recommends that antimicrobial resistance data be submitted to NHSN for a given
calendar month by the end of the subsequent calendar month.
Isolate-based report
Report all required data each month for each eligible isolate-based report (See Appendix A).
Only isolates collected in an inpatient location of the reporting facility should be considered for
eligibility. Eligible isolate-based reports must have had susceptibility testing performed. This
should be consistent with CLSI M39 Guidance on reporting cumulative susceptibility test results.
Note: All cultures of the eligible organisms that meet the reporting guidelines outlined below
should be reported to NHSN regardless of the antimicrobial resistance of the isolated organism
(i.e., even isolates that are susceptible to all required antimicrobials as well as isolates in which
all of the required antimicrobials were not tested should be reported into NHSN).
Two distinct events should be reported on the basis of specimens obtained in inpatient locations:
1. Each eligible organism isolated from an invasive source (blood or cerebrospinal fluid
[CSF]) per patient, per 14 day period even across calendar months:
a. There should be 14 days with no positive culture result from the laboratory for the
patient and specific organism before another invasive source Antimicrobial
Resistance (AR) Event is entered into NHSN for the patient and specific
organism. NOTE: The date of specimen collection is considered Day 1.
b. After >14 days have passed with no positive culture results for that specific
organism, another positive culture from an invasive source with that specific
organism can be reported as an AR Event.
2. First eligible organism isolated from any eligible non-invasive culture source (lower
respiratory or urine), per patient, per month.
a. Only one AR event is allowed per month for the same patient/organism for lower
respiratory or urine specimens.

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A. Eligible organisms include:
 All Acinetobacter species
 Candida albicans
 Candida glabrata
 Citrobacter freundii
 All Enterobacter species
 Enterococcus faecalis
 Enterococcus faecium
 Enterococcus spp. (when not specified to the species level)
 Escherichia coli
 Group B Streptococcus
 Klebsiella oxytoca
 Klebsiella pneumoniae
 Morganella morganii
 Proteus mirabilis
 Pseudomonas aeruginosa
 Serratia marcescens
 Staphylococcus aureus
 Stenotrophomonas maltophilia
 Streptococcus pneumoniae
B. Specimen Sources (Appendix B)
Facilities and vendors should refer to the Information Data Model (IDM) provided by the
NHSN CDA Team ([email protected]) for the complete list of valid specimens.
1. Eligible invasive specimen sources include cerebrospinal fluid (CSF) and blood
specimens.
Note: Report blood or CSF cultures growing the same eligible specific organism
(genus/species) only if the patient had no positive blood or CSF culture result with that
specific organism (genus/species) within the last 14 days, even across calendar months
with no intervening positive blood or CSF.

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Table 1: Example of 14 day rule for a specific organism from a single patient in an inpatient
location
Reported to
Date
Lab Result
NHSN?
Justification
Patient’s first blood culture of
January 1
Staphylococcus aureus Yes
inpatient admission; Staphylococcus
isolated from blood
aureus is isolated; AR Event is
culture
reported into NHSN.
It has been less than 14 days since the
January 4
Staphylococcus aureus No
last positive culture (January 1) from
isolated from blood
the patient isolating Staphylococcus
culture
aureus.
January 16
Staphylococcus aureus No
It has been less than 14 days since the
isolated from CSF
last positive culture (January 4) from
culture
the patient isolating Staphylococcus
aureus.
January 31
Staphylococcus aureus Yes
It has more than 14 days since the last
isolated from blood
positive culture (January 16) from the
culture
patient isolating Staphylococcus
aureus; AR Event is reported into
NHSN.
2. Eligible non-invasive specimen sources include lower respiratory (e.g., sputum,
endotracheal, bronchoalveolar lavage) and urine specimens.
All isolate test results are evaluated using either the algorithm in Figure 1 (Invasive specimens)
or Figure 2 (Non-invasive specimens) to determine reportable AR events for each calendar
month.
 For eligible invasive specimens, there should be 14 days with no positive culture result
from the laboratory for the patient and specific organism before another invasive source
AR Event is entered into NHSN for the patient and specific organism (Figure 1). Based
on the 14 day rule, at a maximum, there would be no more than three invasive isolates
per specific organism reported per patient per month.
 For eligible non-invasive specimens, all first non-invasive isolates (chronologically) per
patient, per month, per organism are reported as an AR event (Figure 2).
Note: The AR Option protocol and associated 14 day rule applies only to those cultures collected
at an inpatient location in the reporting facility. The 14 day rule starts with the day of specimen
collection occurring in an inpatient location within the reporting facility. Outpatient locations
should not be included in the 14 day rule as cultures collected in outpatient locations cannot be
reported to the NHSN AR Option at this time. Further, cultures obtained while the patient was at
another healthcare facility should not be included in the 14 day calculations.

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Use SNOMED codes to identify eligible specimen types to be included in identification of
isolate-based report. Only those SNOMED codes listed in Appendix B should be reported (i.e.,
do not include SNOMED children specimen types unless specifically listed in Appendix B).
C. Required Data
Required data include data available from the laboratory information system, electronic
health record, and administrative data systems. The set of variables for each isolate consists
of a variable to identify the NHSN facility, isolate/patient related data, and antimicrobial
susceptibility data as outlined below.
For additional information on each variable please see Appendix C.


Facility identifier
o Unique NHSN Facility ID (Object Identifier [OID] is used in the CDA)



Isolate / Patient related data
o Patient identifier
o Date of birth
o Gender
o Date admitted to facility
o Specimen collection date
o Specimen source (Appendix B)
o Location code (mapped to CDC location codes)
o Isolate identifier (unique isolate ID in the electronic laboratory report)
o Organism (Appendix A)



Antimicrobial susceptibility data
o Antimicrobial (Appendix A)
o PBP2a-agglutination (only if Staphylococcus aureus)
o PCR mec-gene (only if Staphylococcus aureus)
o E-test sign
o E-test value & unit of measure
o Interpretation of E-test
o MIC sign
o MIC value & unit of measure
o Interpretation of MIC test
o Zone sign
o Zone value & unit of measure
o Interpretation of zone test (disk diffusion)
o Final interpretation result

Note: While many of these fields are required to be included in the CDA report, facilities unable
to electronically obtain the results of the individual laboratory tests (i.e., E-test, MIC, Zone) may
still report antimicrobial resistance data by using ‘Unknown’ or ‘Not Tested’ for these specific
tests as long as the final interpretation result can be provided for each antimicrobial tested.
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Facilities should not employ manual means of data collection to report antimicrobial resistance
data to NHSN.
Reporting Guidelines
 Interpretation of test results (E-test, MIC test, Zone test) includes the following results:
o S = Susceptible
o S-DD = Susceptible-Dose Dependent
o I = Intermediate
o R = Resistant
o NS = Non-Susceptible
o N = Not Tested
o Specific to Gentamicin and Streptomycin results for Enterococcus testing:
 S = Susceptible/Synergistic
 R = Resistant/Not Synergistic
 Only final or corrected susceptibility testing should be reported to NHSN. No preliminary
laboratory results should be used for NHSN AR Option reporting.
 In circumstances where different breakpoints are required, rely on the specimen source to
determine which susceptibility results to report. If the specimen source is CSF report the
meningitis breakpoint susceptibility. If the specimen source is blood, urine, or lower
respiratory report the non-meningitis breakpoint susceptibility.
D. Remove Same Day Duplicates
Multiple isolates of the same species from the same specimen may be processed and produce
conflicting results. Only one isolate should be reported to NHSN, retaining the unique nature
of the test results. Rules must be in place to ensure duplicate isolate reports are removed.
Duplicates are defined as same specific species or same genus, when identification to species
level is not provided, from same patient on same day. Isolates must be of the same source
type (i.e., invasive or non-invasive) to be considered duplicates.
Select the isolate to report to NHSN based on these rules:
 For invasive source isolate selection, CSF isolates should be selected over blood
isolates.
 For non-invasive source isolate selection, lower respiratory isolates should be
selected over urine isolates.
 Eliminate isolates on same day without susceptibility test results as only isolates with
complete/final laboratory testing should be reported to NHSN.
 Do not merge test results across multiple isolates (i.e., don’t summarize results across
different isolates tested on same day).
 If the same specific test is performed on the same isolate but they produce conflicting
results, report the final interpretation provided by the laboratory. If no final
interpretation is provided by the laboratory, then report the most resistant
interpretation (i.e., NS > R > I > S-DD > S > NT).

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



If specific antimicrobial tests are performed on the same isolate and produce
conflicting susceptibility interpretations, and the laboratory did not provide a final
summary interpretation, report the most resistant specific test interpretation as the
final interpretation (i.e., NS > R > I > S-DD > S > NT).
If two isolates from the same day have conflicting susceptibilities to the panel of
antimicrobials tested, report the isolate with the most resistant interpretation (i.e., NS
> R > I > S-DD > S > NT). If it cannot be determined which isolate is the most
resistant, report the isolate that was the first entered into the LIS.

Denominator data report
For each month, report facility-wide denominator data: (See Appendix D)
1. Patient Days: Number of patients present in the facility at the same time period on each
day of the month, summed across all days in the month.
2. Admissions: Number of patients admitted to the facility each month.
Since the same definitions are used for the NHSN MDRO & CDI Module, further information on
counting patient days and admissions can be found in Appendix 2 of the NHSN MDRO & CDI
Module Protocol: NHSN MDRO & CDI Module Protocol.
Minimizing Bias & Bypassing Suppression
The ultimate source of antimicrobial susceptibility test results should be the hospital laboratory
information system (LIS), but in some healthcare facilities not all susceptibility results acquired
or stored in a LIS are readily available for reporting to NHSN. Concerted efforts may be needed
to obtain antimicrobial resistance data for purposes of reporting to NHSN that might be
suppressed from clinical end users, a practice referred to as suppression. This practice can serve
to control costs or to prevent overuse of some antimicrobial agents, but it also can exert an
adverse impact on antimicrobial resistance reporting to public health surveillance systems and
infection control programs. Suppression can lead to significant biases in the antimicrobial
resistance data available for surveillance or infection control. As a result, every effort should be
made to report all antimicrobial resistance data that meets the NHSN protocol requirements,
regardless of whether those data are suppressed from clinical end users.
Data Analyses:
Antimicrobial resistance data will be expressed using several metrics at the monthly, quarterly,
semi-annual, or annual time frame depending on how rare the isolates occurred. (See Table 2) A
facility-wide antibiogram table is available in NHSN that displays the calculated percent nonsusceptible for each organism-antimicrobial combination. The antibiogram table can be stratified
by specimen source, time period, and/or by specific antimicrobial or organism.

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Table 2. Current Resistance Metrics
Metric
Definition
Facility-wide inpatient: standard output for facility and group user.
% non-susceptible Calculated for each* organism-antimicrobial pairing:
(Total # of organisms that tested resistant or intermediate for a pathogen
/ Total # of organisms tested for that pathogen)
*exceptions
1. Staphylococcus aureus test results for Oxacillin or Cefoxitin: nonsusceptible isolates are only those that tested resistant.
2. Enterococcus faecalis, Enterococcus faecium, and Enterococcus spp.
tested for Vancomycin: non-susceptible isolates for this pairing are only
those that tested resistant.
3. Escherichia coli, Klebsiella oxytoca, Klebsiella pneumonia,
Enterobacter spp. test results for Cefepime: non-susceptible isolates for
these pairings include those isolates that tested resistant, intermediate,
susceptible dose-dependent (S-DD), or non-susceptible (NS).

A line list of antimicrobial resistant events is also currently available. Additional reports and
analysis output options will be available in future releases. Requests for additional reports can be
sent to: [email protected].

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Figure 1. Test Result Algorithm for Invasive Specimen Reporting
Eligible organism isolated from invasive
source (blood or CSF) per patient

Prior (+) isolate
with same organism
from invasive
source in ≤ 14 days,
per patient
(Including across
calendar months)

Yes

No
Should
be
reported

January 2016

AR Event

Additional
AR isolate

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Should
not be
reported

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Figure 2. Test Result Algorithm for Non-Invasive Specimen Reporting
Eligible organism isolated from non-invasive
source (lower respiratory or urine) per patient

1st in calendar
month per
patient, per
organism

Yes
Should
be
reported

January 2016

No

Additional AR
isolate

AR Event

11-30

Should
not be
reported

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References
1. Schwaber MJ, De-Medina T, and Carmeli Y. Epidemiological interpretation on
antibiotic resistance studies – what are we missing? Nat Rev Microbiol 2004;2:97983.
2. National Healthcare Safety Network (NHSN) Patient Safety Component: Clinical
Document Architecture. http://www.cdc.gov/nhsn/CDA/index.html
3. CLSI. Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test
Data; Approved Guideline – Third Edition. CLSI document M39-A3. Wayne, PA:
Clinical and Laboratory Standards; 2009.
4. Council of State and Territorial Epidemiologists (CSTE). Recommendations for
strengthening public health surveillance of antimicrobial resistance in the United
States. http://c.ymcdn.com/sites/www.cste.org/resource/resmgr/PS/13-SI-01.pdf.
Accessed October 1, 2015.

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Appendix A. List of Organisms for Antimicrobial Resistance3
Please note that mapping of standardized terminology (SNOMED) are provided upon
request to the NHSN CDA Team at [email protected]. Testing methods should follow
most recent CLSI guidance as appropriate.
Organism
Acinetobacter
(All Acinetobacter species
noted in the IDM/pathogen
tab shall be reported as
Acinetobacter spp.)

Candida albicans
Candida glabrata

January 2016

Specimen Type
Blood, Urine, Lower
Respiratory, CSF

Antimicrobial Agents
Amikacin
Ampicillin-sulbactam
Cefepime
Cefotaxime
Ceftazidime
Ceftriaxone
Ciprofloxacin
Doxcycline
Gentamicin
Imipenem with Cilastatin
Levofloxacin
Meropenem
Minocycline
Piperacillin
Piperacillin-tazobactam
Tetracycline
Ticarcillin-clavulanate
Tobramycin
Trimethoprim-sulfamethoxazole
Additional Agents for Urine None
Blood, Urine, CSF
Anidulafungin
Note: Lower respiratory will Caspofungin
not be collected for Candida Fluconazole
spp.
Flucytosine
Itraconazole
Micafungin
Posaconazole
Voriconazole
Additional Agents for Urine None

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Antimicrobial Use and Resistance Module
AUR

Organism
Citrobacter freundii
Enterobacter

Specimen Type
Blood, Urine, Lower
Respiratory, CSF

(All Enterobacter species
noted in the IDM/pathogen
tab shall be reported as
Enterobacter spp.)

Escherichia coli
Klebsiella oxytoca
Klebsiella pneumoniae
Morganella morganii
Proteus mirabilis
Serratia marcescens

Additional Agents for Urine

January 2016

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Antimicrobial Agents
Amikacin
Amoxicillin-clavulanic acid
Ampicillin
Ampicillin-sulbactam
Aztreonam
Cefazolin
Cefepime
Cefotaxime
Cefoxitin
Ceftazidime
Ceftriaxone
Cefuroxime
Chloramphenicol
Ciprofloxacin
Doripenem
Ertapenem
Gentamicin
Imipenem with Cilastatin
Levofloxacin
Meropenem
Piperacillin
Piperacillin-tazobactam
Tetracycline
Ticarcillin-clavulanic acid
Trimethoprim-sulfamethoxazole
Tobramycin
Cephalothin
Lomefloxacin
Nitrofurantoin
Norfloxacin
Ofloxacin
Sulfisoxazole
Trimethoprim

Antimicrobial Use and Resistance Module
AUR

Organism
Enterococcus faecalis
Enterococcus faecium
Enterococcus spp. (when
not otherwise specified)
(excluding E. faecalis, E.
faecium, and other
identified species)

Specimen Type
Blood, Urine, Lower
Respiratory, CSF

Additional Agents for Urine
Note: Exclude Gentamicin
and Streptomycin

Pseudomonas aeruginosa

Blood, Urine, Lower
Respiratory, CSF

Additional Agents for Urine

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Antimicrobial Agents
Ampicillin
Daptomycin
Gentamicin
Linezolid
Penicillina
Quinupristin/dalfopristin
Rifampin
Streptomycin
Vancomycin
Note: For Gentamicin and
Streptomycin only:
Synergistic = Susceptible
Non-synergistic = Resistant
Ciprofloxacin
Levofloxacin
Nitrofurantoin
Norfloxacin
Tetracycline
Amikacin
Aztreonam
Cefepime
Ceftazidime
Ciprofloxacin
Gentamicin
Imipenem with Cilastatin
Levofloxacin
Meropenem
Piperacillin
Piperacillin-tazobactam
Ticarcillin
Tobramycin
Lomefloxacin
Norfloxacin
Ofloxacin

Antimicrobial Use and Resistance Module
AUR

Organism
Staphylococcus aureus

Specimen Type
Blood, Urine, Lower
Respiratory, CSF

Additional Agents for Urine

Stenotrophomonas
maltophilia

Blood, Urine, Lower
Respiratory, CSF

Additional Agents for Urine

January 2016

11-35

Antimicrobial Agents
Azithromycin
Cefoxitin
Chloramphenicol
Ciprofloxacin
Clarithromycin
Clindamycin
Daptomycin
Doxycycline
Erythromycin
Gentamicin
Levofloxacin
Linezolid
Minocycline
Moxifloxacin
Ofloxacin
Oxacillin or Nafcillinb
Penicillina
Quinupristin-dalfoprisin
Rifampin
Telithromycin
Tetracycline
Trimethoprim-sulfamethoxazole
Vancomycin
Lomefloxacin
Nitrofurantoin
Norfloxacin
Sulfisoxazole
Trimethoprim
Ceftazidime
Chloramphenicol
Levofloxacin
Minocycline
Ticarcillin-clavulanate
Trimethoprim-sulfamethoxazole
None

Antimicrobial Use and Resistance Module
AUR

Organism
Specimen Type
Streptococcus pneumoniae Blood, Urine, Lower
Respiratory, CSF

Group B Streptococcus

Additional Agents for Urine
Blood, Urine, Lower
Respiratory, CSF

Additional Agents for Urine

January 2016

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Antimicrobial Agents
Amoxicillin
Amoxicillin-clavulanic acid
Azithromycin
Cefepime
Cefotaxime (meningitis or nonmeningitis breakpoint)c
Ceftriaxone (meningitis or nonmeningitis breakpoint)c
Cefuroxime
Chloramphenicol
Clindamycin
Ertapenem
Erythromycin
Gemifloxacin
Imipenem with Cilastatin
Levofloxacin
Linezolid
Meropenem
Moxifloxacin
Ofloxacin
Penicillina (meningitis or nonmeningitis breakpoint)c
Penicillin Va (oral breakpoint)
Rifampin
Telithromycin
Tetracycline
Trimethoprim-sulfamethoxazole
Vancomycin
None
Ampicillin
Cefazolin
Cefotaxime
Cefoxitin
Ciprofloxacin
Clindamycin
Daptomycin
Erythromycin
Levofloxacin
Linezolid
Penicillina
Tetracycline
Vancomycin
None

Antimicrobial Use and Resistance Module
AUR

a

If the LIS does not differentiate between Penicillin G and Penicillin V, list susceptibility
results under Penicillin G and indicate that Penicillin V was not tested (N).
b
For Staphylococcus aureus susceptibility testing, if the LIS tests Nafcillin instead of
Oxacillin, report Nafcillin susceptibility results as Oxacillin.
c
If the LIS produces meningitis and non-meningitis breakpoint results, rely on the
specimen source to determine which susceptibility results to report. If the specimen source
is CSF report the meningitis breakpoint susceptibility. If the specimen source is blood,
urine, or lower respiratory report the non-meningitis breakpoint susceptibility.

January 2016

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Antimicrobial Use and Resistance Module
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Appendix B. SNOMED Codes to Identify Eligible Specimen Types
Please note that mapping of standardized terminology for specimen type are provided upon
request to the NHSN CDA Team at [email protected].

Specimen
Type
Blood
Urine
Cerebral
Spinal Fluid
Lower
Respiratory
Specimens

January 2016

Description
Blood specimen (specimen)
Urinary specimen (specimen)
Cerebrospinal fluid sample (specimen)
coughed sputum specimen (specimen)
specimen from trachea (specimen)
specimen from lung obtained by bronchial washing procedure
(specimen)
specimen from lung obtained by biopsy (specimen)
specimen from lung obtained by fiberoptic bronchoscopic
biopsy (specimen)
upper respiratory fluid specimen obtained by tracheal aspiration
(specimen)
tissue specimen from bronchus (specimen)
tissue specimen from trachea (specimen)
bronchial fluid sample (specimen)
sputum specimen obtained by aspiration (specimen)
sputum specimen obtained by aspiration from trachea
(specimen)
sputum specimen obtained by sputum induction (specimen)
sputum specimen obtained from sputum suction trap (specimen)
lower respiratory tissue sample (specimen)
lower respiratory fluid sample (specimen)
transbronchial lung biopsy sample (specimen)
bronchial biopsy sample (specimen)
bronchial brushings sample (specimen)
tissue specimen from lung (specimen)
specimen obtained by bronchial aspiration (specimen)
specimen obtained by bronchioloalveolar lavage procedure
(specimen)
specimen from trachea obtained by aspiration (specimen)
specimen obtained by bronchial trap (specimen)
bronchial fluid specimen obtained from bronchial trap
(specimen)
sputum specimen (specimen)
specimen from bronchus (specimen)

11-38

SNOMED
CT Code
119297000
122575003
258450006
119335007
119390000
122609004
122610009
122611008
122877000
128158009
128173005
258446004
258608003
258609006
258610001
258611002
309170008
309171007
309173005
309174004
309176002
399492000
441903006
441917002
445447003
446838005
447345009
119334006
119391001

Antimicrobial Use and Resistance Module
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Specimen
Type

Description
specimen from lung (specimen)
lower respiratory sample (specimen)
bronchoalveolar lavage fluid sample (specimen)
tracheal biopsy sample (specimen)

January 2016

11-39

SNOMED
CT Code
127458004
258606004
258607008
309169007

Antimicrobial Use and Resistance Module
AUR

Appendix C. Isolate Based Report Variables
NAME

DESCRIPTION OF FIELD

Facility ID

NHSN-assigned facility ID number

Patient ID

Alphanumeric patient ID assigned by the
hospital and may consist of any combination
of numbers and/or letters. This should be an
ID that remains the same for the patient across
all visits and admissions.
The date of the patient’s birth including
month, day, and year.
M (Male), F (Female), O (Other) to indicate
the gender of the patient.
Date patient was admitted to the inpatient
facility including month, day, and year.
Date the specimen was collected including
month, day, and year.
Specimen source from which the isolate was
recovered (e.g. urine, lower respiratory,
blood, CSF).
Patient care area where patient was located
when the laboratory specimen was collected.
Use patient location obtained from
administrative data system (ADT).
Isolate identifier unique for each isolate
within laboratory.
Organism identified from specimen collected
(Appendix A).

Date of Birth
Gender
Date admitted to
facility
Specimen
collection date
Specimen
source
Location

Isolate identifier
Organism

Antimicrobiala

PBP2aagglutination
PCR mec-gene
E-test sign
E-test
value/units of
measure
Interpretation of
E-test

January 2016

Antimicrobial(s) tested for susceptibility
(Appendix A will define agents by organism
and specimen source)
Result for PBP2a-agglutination (only if SA)
Pos/Neg/Unk
Result for PCR mec-gene (only if SA)
Pos/Neg/Unk
E-test signb
E-test (Value in micrograms/liter). Use '.' as
decimal delimiter, e.g. 0.25
Interpretation result of the E-test susceptibility
test performed

11-40

CODE
VALUE LIST
NHSN

LEVEL OF
REQUIREMENT
Required
Required

Required
Required
Required
Required
SNOMED

Required

CDC Location
Codes

Required

Required
SNOMED

Required

RxNorm

Required

Conditional (for
Staph aureus)
Conditional (for
Staph aureus)
Optionally
Required
Optionally
Required
Required

Antimicrobial Use and Resistance Module
AUR

NAME

DESCRIPTION OF FIELD

MIC sign

MIC signb

MIC value/units
of measure
Interpretation of
MIC test
Zone sign

MIC (Value in micrograms/liter). Use '.' as
decimal delimiter, e.g. 0.25
Interpretation result of the MIC susceptibility
test performed
Zone signb

Zone value/units
of measure
Interpretation of
Zone test
Final
Interpretation
result

Zone value in millimeters
Interpretation result of the zone susceptibility
test performed
Final interpretation result of all different
susceptibility tests performed

CODE
VALUE LIST

LEVEL OF
REQUIREMENT
Optionally
Required
Optionally
Required
Required
Optionally
Required
Optionally
Required
Required
Required

a

At this time, the R1 Norm Implementation Guide uses RxNorm codes to report
antimicrobials for the AR Option. NHSN plans to move to antimicrobial/test expressed as
LOINC codes in a future version of the Implementation Guide used for the AR Option.
b

Refer to the HL7 Implementation Guide for specifics on how to code these values in the
CDA report.
Note: While many of these specific test results (i.e., E-test, MIC, Zone) are required to be
included in the CDA report, facilities unable to electronically obtain these results may still
participate by using ‘Unknown’ or ‘Not Tested’. Facilities should not employ manual
means of data collection.

January 2016

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Antimicrobial Use and Resistance Module
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Appendix D. Denominator Data Variables
DESCRIPTION OF FIELD

CODE
VALUE LIST

LEVEL OF
REQUIREMENT

NHSN

Required

Facility Wide Denominator
Facility ID

NHSN –assigned facility ID number

Location

FacWideIN

Required

Month

2-Digit month

Required

Year

4-Digit year

Required

Patient
Days

For facility wide inpatient locations enter the total
number of patient days collected at the same time
each day combined for the month. All of the
facility’s inpatient locations with an overnight stay
should be included where denominators can be
accurately collected.
For facility wide inpatients, enter the total number
of admissions for all facility inpatient locations
combined for the month. All the facility’s inpatient
locations with an overnight stay should be included
where denominators can be accurately collected.

Required

Admission
Count

January 2016

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Required


File Typeapplication/pdf
File TitleAntimicrobial Use and Resistance (AUR) Option
SubjectThe explanation and analysis of a mechanism for facilities to report and analyze antimicrobial use and/or resistance as part of
AuthorCDC
File Modified2016-03-23
File Created2016-03-23

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