TABLE 2.

Epidemiologically significant pathogens^b

Pathogen	Risk factors for colonization and/or infection	Commonly associated infections	Impacta
HA-MRSA	Recent hospitalization, hemodialysis, diabetes mellitus, IVDU, surgery, AIDS	BSIs, pneumonia, SSI, endocarditis, skin and soft tissue infection, osteomyelitis	Increased cost, $6,916; increased LOS, 2 days; increased attributable mortality compared to MSSA, OR of 1.93
CA-MRSA	Contact with someone known to have CA-MRSA, IVDU, incarceration, MSM, participation in contact sports	BSIs, pneumonia, SSI, endocarditis, skin and soft tissue infection, osteomyelitis	Similar to those of HA-MRSA
VRE	Sharing a hospital room with patient colonized or infected with VRE, older age, duration of antibiotic use, increased no. of antibiotics used, urinary catheter	BSIs, CA-UTI, endocarditis, SSI	Increased cost, $33,000; increased LOS, 22 days; increased mortality, variable
Acinetobacter species	Residence in nursing home, residence in long-term care facility, hospitalization in the previous 3 mo, hospitalization ≥5 days, antibiotic use in the previous 3 mo, hemodialysis, home infusion therapy or wound care in the last 30 days, immunosuppression, family member with MDR pathogen	BSIs, VAP, HAP, SSI, CA-UTI	Increased cost, $50,000; increased LOS, 6-16 days; attributable mortality, 7-15%
Pseudomonas aeruginosa	Residence in nursing home, residence in long-term care facility, hospitalization in the previous 3 mo, hospitalization ≥5 days, antibiotic use in the previous 3 mo, hemodialysis, home infusion therapy or wound care in the last 30 days, immunosuppression, family member with MDR pathogen	BSIs, VAP, HAP, SSI, CA-UTI
ESBL-producing Enterobacteriaceae	Residence in nursing home, residence in long-term care facility, hospitalization in the previous 3 mo, hospitalization ≥5 days, antibiotic use in the previous 3 mo, hemodialysis, home infusion therapy or wound care in the last 30 days, immunosuppression, family member with MDR pathogen	BSIs, VAP, HAP, SSI, CA-UTI
Carbapenemase-producing Gram-negative organisms	Residence in nursing home, residence in long-term care facility, hospitalization in the previous 3 mo, hospitalization ≥5 days, antibiotic use in the previous 3 mo, hemodialysis, home infusion therapy or wound care in the last 30 days, immunosuppression, family member with MDR pathogen	BSIs, VAP, HAP, SSI, CA-UTI
Clostridium difficile	Antibiotic use, hospitalization	CDI, pseudomembranous colitis, toxic megacolon	Increased cost, $15,000; increased LOS, 3 days
Candida species	Intravascular catheter use, increased length of hospital stay, broad-spectrum antibiotic use, burns, ICU stay, parenteral nutrition, neutropenia	BSIs, SSI, disseminated candidiasis	Increased cost, $2-4 billion/yr
Aspergillus species	Immunosuppression, neutropenia, exposure to construction and renovation	Pulmonary aspergillosis, tracheobronchial aspergillosis, sinus disease, disseminated aspergillosis	Crude mortality, 45-80%
Nosocomially acquired respiratory viruses	Residence in long-term care facility, immunosuppression, extremes of age, contact with infected or unvaccinated health care worker	RSV, influenza virus, bronchiolitis	Increased cost, $3,860; increased LOS, 5 days
Nosocomially acquired gastrointestinal viruses	Older age, immunocompromised	Norovirus, rotavirus	Outbreak cost, $650,000

^aEstimated per infection unless otherwise stated.

^bHA-MRSA, health care-associated methicillin-resistant S. aureus; CA-MRSA, community-associated methicillin-resistant S. aureus; MSSA, methicillin-susceptible S. aureus; BSI, bloodstream infection; LOS, length of stay; IVDU, intravenous drug user; SSI, surgical-site infection; MSM, men who have sex with men; VRE, vancomycin-resistant Enterococcus; CA-UTI, catheter-associated urinary tract infection; VAP, ventilator-associated pneumonia; HAP, hospital-acquired pneumonia; ESBL, extended-spectrum beta-lactamase; MDR, multidrug resistant; CDI, Clostridium difficile infection; ICU, intensive care unit; RSV, respiratory syncytial virus.