HAI Pathogens and Antimicrobial Resistance Report 2018-2021

Technical Resources

Acronym Description
ACH Acute care hospital
AR Antimicrobial resistance
AST Antimicrobial susceptibility test
CAUTI Catheter-associated urinary tract infection
CDC Centers for Disease Control and Prevention
CLABSI Central line-associated bloodstream infection
CMS Centers for Medicare and Medicaid Services
CNS Coagulase-negative staphylococci
DA Device-associated
ESC Extended-spectrum cephalosporin
HAI Healthcare-associated infection
ICU Intensive care unit
IRF Inpatient rehabilitation facility
LCBI Laboratory-confirmed bloodstream infection
LTACH Long-term acute care hospital
MBI Mucosal barrier injury
NHSN National Healthcare Safety Network
NICU Neonatal intensive care unit. Includes locations identified in NHSN as Level II/III, Level III, and Level IV NICUs [PDF – 677 KB]
PVAP Possible ventilator-associated pneumonia
SSI Surgical site infection
VAE Ventilator-associated event
Term Description
Hospital Wards Includes non-ICU, non-oncology adult patient locations within acute care hospitals including step-down units, mixed acuity units, and specialty care areas.
Inpatient Rehabilitation Facility (IRF) Unless otherwise noted, this term includes free-standing IRFs and CMS-certified inpatient rehabilitation units located within hospitals.
Klebsiella aerogenes (formerly Enterobacter aerogenes) Klebsiella aerogenes (formerly Enterobacter aerogenes) is classed in the Enterobacter group in 2018-2019 and the Klebsiella group in 2020-2021.
Other Candida Combines Candida identified to the species level (excluding C. albicans and C. glabrata), and Candida for which the species was not reported.
Other Enterococcus Combines enterococci identifies to the species level (excluding E. faecalis and E. faecium) and enterococci for which the species was not reported.
Pediatric Wards Includes non-ICU, non-oncology pediatric patient locations within acute care hospitals such as step-down units, mixed acuity units, and specialty care areas.
Selected Klebsiella spp. Includes K. oxytoca and K. pneumoniae; for 2020-2021 data, this group also includes K. aerogenes.
Surgical Category Abdominal—Appendix surgery, bile duct, liver, or pancreatic surgery, liver transplant, gallbladder surgery, colon surgery, gastric surgery, herniorrhaphy, small bowel surgery, spleen surgery, exploratory laparotomy, and rectal surgery.

Breast—Breast surgery.

Cardiac—Cardiac surgery, heart transplant, coronary artery bypass graft with chest incision with or without donor incision, pacemaker surgery, and thoracic surgery.

Kidney—Kidney surgery and kidney transplant.

Neck—Neck surgery, and thyroid and/or parathyroid surgery.

Neurosurgical—Craniotomy and ventricular shunt.

Ob/Gyn–Cesarean section, abdominal hysterectomy, ovarian surgery, and vaginal hysterectomy.

Orthopedic—Open reduction of fracture, hip prosthesis, knee prosthesis, limb amputation, spinal fusion/refusion, and laminectomy.

Prostate—Prostate surgery.

Vascular—Abdominal aortic aneurysm repair, shunt for dialysis, carotid endarterectomy, and peripheral vascular bypass surgery.

SSI Type Deep Incisional—Involves deep soft tissues of the incision (for example, fascial and muscle layers).

Organ/Space—Involves any part of the body deeper than the fascial/muscle layers that is opened or manipulated during the operative procedure.

Superficial Incisional—Involves only the skin and subcutaneous tissue of the incision.

Full definitions of these terms are available in the NHSN Protocol [PDF – 6.9 MB]

Phenotype Definitions
Phenotype Definitions
Phenotype Name Phenotype Definition
Carbapenem-non-susceptible (NS) Acinetobacter spp. Acinetobacter species (spp.) with a result of intermediate (I) or resistant (R) to imipenem, meropenem, or doripenem
Carbapenem-resistant Enterobacterales (CRE) E.coli, selected Klebsiella spp.*, and Enterobacter species with a result of resistant (R) to at least one of the following drugs: imipenem, meropenem, doripenem, ertapenem, imipenem/relebactam, or meropenem/vaborbactam
Cefepime-non-susceptible (NS) Enterobacter spp. Enterobacter+ spp. with a result of intermediate/susceptible-dose dependent (I/S-DD) or resistant (R) to cefepime
Extended-spectrum cephalosporin-NS Enterobacterales E.coli, Klebsiella pneumoniae, and Klebsiella oxytoca with a result of intermediate (I), intermediate/susceptible-dose dependent (I/S-DD, cefepime only), or resistant (R) to at least one of the following drugs:


cefepime, cefotaxime, ceftazidime, ceftriaxone, ceftazidime/avibactam, or ceftolozane/tazobactam

Meth/ox/cefox-resistant Staphylococcus aureus (MRSA) Staphylococcus aureus with a result of resistant (R) to methicillin, oxacillin, or cefoxitin
Multidrug-resistant (MDR) Pseudomonas aeruginosa Pseudomonas aeruginosa with a result of intermediate (I) or resistant (R) to at least one drug in at least three antimicrobial classes:

a.   Extended-spectrum cephalosporins (cefepime, ceftazidime, ceftazidime/avibactam, or ceftolozane/tazobactam) 

b.   Fluoroquinolones (ciprofloxacin or levofloxacin)

c.   Carbapenems (imipenem, meropenem, or doripenem)

d.   Aminoglycosides (amikacin, gentamicin, or tobramycin)

e.   Piperacillin/tazobactam

Vancomycin-resistant Enterococcus faecalis (VRE) Enterococcus faecalis with a result of resistant (R) to vancomycin
Vancomycin-resistant Enterococcus faecium (VRE) Enterococcus faecium with a result of resistant (R) to vancomycin


* Included K. oxytoca and K. pneumoniae; for 2020-2021 data, this group also included K. aerogenes, formerly known as Enterobacter aerogenes.

+ Included all species of Enterobacter. Data from 2018-2019 included E. aerogenes.