NHSN Key Terms, Acronyms, and Definitions
Long-term Care Facility Component
January 2024
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1. 80% Rule: A principle used to determine which location label to select when different types of
service are provided on a single unit. A location label selected for a given unit should describe
the service provided to the majority (~80%) of residents housed there in the previous year. See
CDC Location for additional details.
2. Annual Facility Survey: Completed at the beginning of each calendar year to describe the facility
characteristics and practices for the previous calendar year. For example, in 2024, facilities will
complete the 2023 Annual Facility Survey to document facility characteristics and practices
during the 2023 calendar year.
3. Antibody Test: May be referred to as serological test, blood test, serology test. May be useful in
detecting a past infection.
4. Antigen Test: Diagnostic test. May be referred to as a rapid diagnostic test. May be useful in
detecting an active infection.
5. ASC/AST: Active Surveillance Cultures or Testing. For purposes of NHSN surveillance; Active
Surveillance Culture/Testing (ASC/AST) refers to testing that is intended to identify the
presence/carriage of microorganisms for the purpose of instituting or discontinuing isolation
precautions (for example, nasal swab for MRSA, rectal swab for VRE), or monitoring for
eradication of a carrier state. ASC/AST does NOT include identification of microorganisms with
cultures or tests performed for diagnosis and treatment purposes (for example, specimens
collected from sterile body sites including blood specimens). Also see Surveillance Cultures.
6. Assisted Living Facility (AL or ALF): These facilities provide help with activities of daily living (for
example, taking medicine, using eye drops, getting to appointments, and preparing meals).
Residents often live in their own room or apartment within a building or group of buildings.
7. BSI: Bloodstream Infection. The LTCF Component does not have a protocol for reporting BSIs.
However, when reporting a UTI using the NHSN UTI protocol, users will mark “Yes” to
“Secondary Bloodstream Infection” if the resident has a microorganism reported in a urine
culture and has the same microorganism reported from a blood culture.
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NHSN Key Terms, Acronyms, and Definitions
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8. CAUTI: Catheter-associated Urinary Tract Infection. Referred to as CA-SUTI (catheter associated
symptomatic urinary tract infection) in the LTCF protocol. See LTCF UTI Event protocol.
9. CCN: CMS Certification Number (CCN). May also be referred to as Medicare Provider Number.
10. CDC Location: A CDC-defined designation given to a resident care area housing residents who
have similar disease conditions or who are receiving care for similar medical specialties. Each
facility location that is monitored is “mapped” to one CDC Location. The specific CDC Location
label is determined by the type of resident cared for in that area according to the 80% Rule. That
is, if 80% of residents are of a certain type (for example, individuals requiring restorative care
following recent hospitalization) then that area is designated as that type of location (in this
case, a LTCF Skilled Nursing/Short Term Rehabilitation unit). For detailed instructions on how to
map locations, see “Instructions for Mapping Patient Care Locations in NHSN” in the Locations
and Descriptions chapter.
11. CDI: Clostridioides difficile infection. Previously referred to as Clostridium difficile infection.
Frequently referred to as C. diff or C. difficile. See LabID Event protocol.
12. Catheter Days: A daily count of the number of residents in the LTCF with an indwelling urinary
(Foley) catheter. To calculate catheter days, for each day of the month, at the same time each day,
record the number of residents who have an indwelling urinary (Foley) catheter. At the end of the
month, sum the daily counts and enter the total into the NHSN. See LTCF UTI Event protocol.
13. CSV: Comma separated values. A plain text file (contains only numbers and letters) that contains
a list of data that can be easily exchanged between different applications by importing to and
exporting from.
14. Dashboard: The LTCF dashboard provides users with a high-level summary overview of reported
infections and prevented process measure data in the facility through graphs and tables. The
LTCF dashboard can be found on the NHSN homepage.
15. Date of Event: The date of event is defined as the date when the first clinical evidence
(signs/symptoms) of the UTI appeared or the date the specimen used to make or confirm the
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NHSN Key Terms, Acronyms, and Definitions
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diagnosis was collected, whichever comes first. This definition does not apply to LabID event. See
Event Date in LabID Event protocol.
16. Device-associated Infection: A healthcare-associated Infection (HAI) in a resident with a device
(for example, indwelling urinary catheter) if the device was in place for >2 calendar days on the
date of event and was also in place on the date of event or the day before. If the device was in
place for >2 calendar days and then removed, the date of event must be the day of
discontinuation or the next day to be device associated.
17. Dysuria: The sensation of pain, burning, or discomfort on urination.
18. Event Contributed to Death: The event either directly caused death or exacerbated an existing
disease condition, which then led to death.
19. Event Date: See date of event.
20. Fever: See vital signs.
21. HAI: Healthcare-associated Infection. An infection is considered a HAI if the date of event of the
NHSN site-specific infection criterion (for example, UTI) occurs on or after the 3
rd
calendar day of
current admission to the LTCF where day of current admission is calendar day 1. There must be no
evidence that the infection was present or incubating at the time of admission to the LTCF, unless
a change in pathogen or signs and symptoms strongly suggests the acquisition of a new infection.
Note: The HAI definition is not to be used in the LabID Event protocols.
22. HPS: Healthcare Personal Safety (HPS). May be used by LTCFs to report healthcare staff safety
events such as influenza vaccination. See Surveillance for Healthcare Personnel Vaccination home
page.
23. Hypotension: See vital signs.
24. Indwelling Urinary Catheter: A drainage tube that is inserted into the urinary bladder through the
urethra, is left in place, and is connected to a collection system; also called a Foley catheter.
Straight in-and-out catheters are not considered indwelling urinary catheters.
25. Infection Date: See date of event.
26. IP: Infection preventionist or infection prevention.
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27. ICPO: Infection control and prevention officer.
28. Incomplete Event Alert: Reported events that are missing required information. All incomplete
events must be resolved before event data are considered as complete and included in analyses
for the month.
29. Incomplete Summary Data Alert: Occurs when the monthly summary data submission is
incomplete for a given month. This often occurs when a monthly reporting plan is updated to
include an additional event(s) after summary data have been submitted or when the “Report No
Events” box has been left unchecked when at least one in-plan event was not reported.
Incomplete summary data alerts must be resolved before data are considered complete and
included in analyses for that month.
30. In-plan Surveillance: Facility has indicated in their monthly reporting plan that the NHSN
surveillance protocol(s) will be used, in its entirety, for that particular event. A monthly reporting
plan must be completed each month before a facility is able to enter event data into the NHSN
application. Out-of-plan surveillance options are not available in the LTCF Component.
31. LabID Event: Laboratory-identified event. See Laboratory-identified Multidrug-Resistant Organism
(MDRO) & Clostridium difficile Infection (CDI) Events for Long-term Care Facilities (LTCFs) module.
32. Location: The resident care area to which a resident is assigned while receiving care in facility.
33. Long-term Care Hospital (LTCH): A hospital in which extended medical and rehabilitative care is
provided to individuals with clinically complex problems, such as multiple acute or chronic
conditions, that need hospital-level care for relatively extended periods. Also referred to by the
NHSN as long-term acute care (LTAC).
34. Long-term Care Facility (LTCF): Facilities providing a spectrum of medical and non-medical
supports and services to frail or older adults unable to reside independently in the community.
The following LTCFs are able to use NHSN for surveillance (some or all modules): Nursing
Homes/Skilled Nursing Facilities (LTC:SKILLNURS); Intermediate Care Facilities for Individuals with
Intellectual Disabilities (LTC:ICF/IID); Assisted Living Facilities and Residential Care Facilities
(LTC:ASSIST); Psychiatric Residential Treatment Facility (LTC:PSYCH); Skilled Nursing Facility for
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State Veteran’s Homes (LTC:SVHSNF); and Assisted Living Facility for State Veteran’s Homes
(LTC:SVHALF).
35. MDRO: Multidrug resistant organism. See Laboratory-identified Multidrug-Resistant Organism
(MDRO) & Clostridium difficile Infection (CDI) Events for Long-term Care Facilities (LTCFs) module.
36. Missing Event Alert: Occurs when a module and event type is selected on the monthly reporting
plan, but no events were reported for that month and the monthly summary data submission is
either missing or does not indicate that in-plan events were not identified during the month
(referred to on the monthly summary page as “Report No Events”).
37. Missing Summary Data Alert: Occurs when a module and event type is selected on the monthly
reporting plan, but no summary/denominator was submitted for the month. Complete summary
data are required to be submitted before data are considered complete and included in analyses
for the month.
38. Molecular Test. Diagnostic test. May be referred to as viral test, RT-PCR test, LAMP test, nucleic
acid amplification test (NAAT), rapid molecular test. May be useful in detecting active infection.
39. MRP: Monthly reporting plan. The Monthly Reporting Plan informs the NHSN which modules and
events a facility will be tracking for the month. A facility must have a MRP for each month in
which the facility will perform surveillance in the NHSN.
40. NAAT: Nucleic acid amplification test. Allows the identification of pathogenic organisms by
detecting their DNA or RNA. Includes, but not limited to, Polymerase Chain Reaction (PCR) and
Real Time Polymerase Chain Reaction (RT-PCR).
41. NHSN: National Healthcare Safety Network.
42. NHSN Facility Administrator: A specific individual identified by a healthcare facility as the person
who will be managing the facility within the NHSN application. This person serves as the primary
point of contact for NHSN communication to the facility and is responsible for NHSN facility
enrollment, set-up, and adding and inactivating users. The NHSN facility administrator is often the
person who oversees infection prevention program activities and does not have to be the
organization’s facility administrator or part of executive leadership.
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NHSN Key Terms, Acronyms, and Definitions
Long-term Care Facility Component
43. Nursing Home (NH): A nursing facility providing primarily long-term maintenance and restorative
care for individuals needing support with their activities of daily living. A large percentage of
certified nursing homes in the U.S. provide a combination of long-term nursing care or restorative
services and skilled nursing services.
44. Org ID: Organization ID, also referred to as Facility ID. The unique identification number created
by NHSN, which is assigned to a facility at the time of enrollment.
45. PPE: Personal protective equipment. A source of protection against physical, chemical, and
biological hazards. Routes of exposure may include inhalation, dermal contact, ingestion, contact
through mucous membranes, or other methods. Examples of PPE includes respirators to protect
against aerosolized pathogens, (for example N95); goggles and face shields to protect eyes from
exposure to splashes and sprays; facemasks to protect the nose and mouth from exposure to
splashes, sprays, and respiratory secretions; protective clothing (for example, fluid resistant,
impermeable protective clothing such as gowns); and gloves to protect against exposure to
infectious materials or chemical exposures. This list is not exhaustive. For additional information,
please visit the National Institute for Occupational Safety and Health (NIOSH)
46. PSC: Patient Safety Component. Used by hospitals and other acute care and healthcare facilities
for infection reporting.
47. Resident Days: A daily count of the number of residents in a long-term care facility location
during a specific period of time. Calculate resident days for each day of the month, at the same
time each day, record the number of residents. When resident days are available from electronic
databases, these sources may be used only if the counts are not substantially different (+/- 5%)
from manually collected counts. At the end of the month sum the daily counts and enter the total
into NHSN.
48. SAMS: Secure Access Management Services. SAMS provides secure online access to and exchange
of information between CDC and healthcare facilities and public health partners. U.S. law requires
federal government agencies like CDC perform an identity check on each person before granting
access to non-public information.
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49. SARS-CoV-2: The virus that causes COVID-19.
50. Skilled Nursing Facility (SNF): A facility engaged primarily in providing skilled nursing care and
rehabilitation services for residents who require such care because of injury, disability, or illness.
A large percentage of SNFs are dually certified as both SNFs and nursing homes.
51. SAMS Grid Card: A grid card issued through Secure Access Management Services (SAMS) that
adds a layer of security when users access NHSN through a web-based portal to submit data to
CDC. Users will receive a SAMS grid card after successfully registering through SAMS.
52. Summary Data: Also referred to as denominator data that must be entered for each month a
facility is participating in NHSN reporting. Examples of denominator/summary data include total
resident days for the month, total admissions for the month, and total urinary catheter days, to
name a few. The required data depends on which module(s) a facility participated in during the
given month. Best practice is to complete denominator data by the end of the following month.
For example, denominator data for July should be submitted to NHSN by the end of August.
Timely and complete event and summary data submission ensures complete data are included in
analyses.
53. Surveillance Cultures: Those cultures reported as part of infection prevention and control
surveillance including, but not limited to perirectal cultures for vancomycin-resistant Enterococci
(VRE) and/or nasal swabs for methicillin-resistant Staphylococcus aureus (MRSA) surveillance.
Not for use in resident diagnosis. Also called active surveillance cultures or testing (ASC/AST).
Positive surveillance cultures do not contribute or preclude a resident from meeting NHSN HAI or
LabID event criteria. Also see Active Surveillance Culture/Testing (ASC/AST).
54. Temperature: See Vital Signs. The temperature value applied to meet surveillance criteria should
be the value documented in the medical record regardless of site tested (for example, tympanic,
oral, or axillary).
55. UTI: Urinary tract infection. See NHSN LTCF UTI protocol.
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56. Variable: A term used to describe an individual data collection object where it contains numeric
or character (text) information. The term can also be called “field” or “data element” and is
similar to the concept of a column in a spreadsheet.
57. Vital Signs: If a specific value for a vital sign is not stated in a CDC/NHSN HAI definition criterion
(for example, hypotension), the facility should use the vital sign parameters as stated in its
policies and procedures for clinical practices. For fever, which NHSN does have as a stated value,
use the temperature documented in the patient’s medical record (specifically, no conversion of
temperature based on route of collection).
