TABLE 3.
Organisms identified in outbreaks and their reservoirsa
| Organism (type of infection often associated with outbreak) | Common reservoir(s) | Reservoir(s)/site(s) associated with outbreaks | Method of detection | Description |
|---|---|---|---|---|
| Aspergillus spp. (blood, lower respiratory tract) | Air, dust, mold | Building renovation or construction sites, ventilation systems, dust-generating activities | P,b micro cultures; E,b air sampling, surface samples | Often pathogenic in immunocompromised populations |
| Staphylococcus aureus (surgical site, blood) | Human skin, anterior nares, upper respiratory tract, perirectal area, throat | Nasal/skin carriage in health care workers, increased nurse-to-patient ratios | P,b micro cultures; E,b settle plates, hand cultures | Usually associated with SSI; PFGE can be helpful to determine whether point source or technical; point source may suggest carrier and would require nare cultures |
| Staphylococcus species (coagulase negative) (blood) | Human skin | i.v. fluids, instrumentation, contaminated hands of health care workers, implanted devices | P,b micro cultures; E,b not known to be useful | Pathogenic in immunocompromised hosts and premature infants; commonly a contaminant |
| Salmonella species (GI tract infections) | Gastrointestinal and biliary tract | Contaminated food, dairy, eggs/poultry; contaminated blood products | P,b stool, blood cultures; E, not known to be useful | Not normal flora; cross-contamination reported |
| Streptococcus pyogenes (group A streptococcus) (deep wounds or intra-abdominal abscess) | Upper respiratory tract, perianal area (rectum and vagina) | Carriage among health care workers | P,b wound, stool cultures; E,b settle plates | Not commonly normal flora; threshold for investigation, 1 case |
| Enterococcus faecalis and E. faecium (enterococcus or group D streptococcus) (neonatal sepsis, cystitis, bacteremia) | Vaginal/perianal area, colon | Neonates/surgical patients | P,b stool, vaginal cultures; E, not known to be useful | |
| Pseudomonas cepacia and other Pseudomonas speciesc (blood) | Skin | Water, contaminated solutions and skin disinfectants, contaminated equipment | P, micro cultures, stool; E,b cultures of potentially implicated items | Associated with disinfectants (especially those containing iodine), water, solutions |
| Pseudomonas pickettiic (blood) | Skin | Water, skin disinfectants, sterile water | P,b micro cultures, stool; E,b cultures of potentially implicated items | Deliberate contamination of sterile fluids has been reported |
| Stenotrophomonas maltophilia (blood) | Skin | Water, contaminated anticoagulant, and other solutions | P,b micro cultures, stool; E,b cultures of potentially implicated items | Cross-contamination reported |
| Pseudomonas aeruginosa (burns, wounds, urinary tract, pneumonia) | Gastrointestinal tract | Ventilators, whirlpools, sitz baths, solutions (mouthwash), any other water sources | P,b micro cultures, stool; E,b cultures of potentially implicated items | Can be normal flora |
| Escherichia coli (epidemic diarrhea, wounds, urinary tract, neonatal sepsis or meningitis) | Colon | Equipment or fluids contaminated with organisms from lower GI tract | P,b micro cultures, stool; E,b cultures of potentially implicated items | Very common normal flora |
| Klebsiella pneumoniae (urinary tract, pneumonia) | Colon, nose, mouth, skin | Urinary catheters, hand lotions, contaminated fluids, ventilators, eczema | P,b micro cultures; E,b cultures of potentially implicated items | Cross-contamination described |
| Enterobacter species (urinary tract, i.v.-associated bloodstream infections) | Colon | Contaminated i.v. fluids, TPN, hands/dermatitis | P,b micro cultures; E,b cultures of potentially implicated items | Intensive care units, reuse of calibrated pressure transducers |
| Acinetobacter species | Vaginal/perianal area/skin | Instrumentation, burns, surgery, respiratory equipment, gloves, parenteral nutrition, water | P,b micro cultures; E,b cultures of potentially implicated items | Immunocompromised population and patients in intensive care units at increased risk |
| Haemophilus influenzae (infant meningitis, conjunctivitis, respiratory tract infections) | Upper respiratory tract | Contaminated medications/ equipment, eye drops | P,b cultures of potentially implicated items, micro cultures; E,b cultures of potentially implicated items | Nontypeable species are most common |
| Candida species (blood, urinary tract) | Air, endogenous flora | Hands, oncholysis, devices | P,b micro cultures; E,b cultures of hands and nail beds | Immunocompromised population at increased risk |
| Hepatitis A virus | Gastrointestinal | Hands/foods, transfusion | P, serology; E, not known to be useful, testing of potentially implicated personnel | Cross-contamination described |
| Hepatitis B virus | Blood | Blood and secretions, transfusions, improperly cleaned equipment | P, serology, PCR; E, not known to be useful, testing of potentially implicated personnel | Patients on dialysis, patients in psychiatric units, contaminated devices |
| Hepatitis C virus | Blood | Blood and secretions, transfusions, improperly cleaned equipment, multidose vials | P, serology, PCR; E, not known to be useful, testing of potentially implicated personnel | Patients on dialysis, patients in psychiatric units, contaminated devices, multidose vials |
| Mycobacterium tuberculosis (respiratory) | Lungs | Airborne, improperly cleaned equipment | P,b micro cultures; E,b not known to be useful, cultures of potentially implicated personnel | Health care transmission suggests poor infection control |
| Atypical mycobacteria (Mycobacterium avium, M. gordonae) | Lungs, skin | Contaminated water, improperly cleaned and sterilized equipment | P,b micro cultures; E,b cultures of potentially implicated items | Associated with pseudo-outbreaks, reuse of improperly cleaned dialyzers, contaminated ice machines and other equipment |
| Campylobacter fetus | Gastrointestinal | Food | P,b micro cultures; E,b cultures of potentially implicated items/personnel | Neonatal intensive care unit patients at risk |
| Legionella pneumophila and other species | Water | Potable water, air-conditioning units, cooling towers, construction | P,b micro cultures; E,b cultures of potentially implicated items/personnel | Can be associated with intense scrutiny by the media |
| Streptococcus viridans (blood, skin) | Skin | Colonized health care workers, eczema | P,b micro cultures; E,b cultures of potentially implicated items/personnel | |
| Achromobacter xylosoxidans (blood) | Water | Contaminated water | P,b micro cultures; E,b cultures of potentially implicated items | Immunocompromised patients and those on dialysis, reuse of pressure transducers |
| E. coli O157:H7 and other hemorrhagic species (diarrhea and hemorrhagic colitis) | Gastrointestinal tract of animals | Contaminated water, and foods (meat, salads) | P,b micro cultures; E,b cultures of potentially implicated items | HUS and TTP are sequelae; high mortality among elderly and extremely young; cross-contamination described |
| Herpesvirus infection (skin, pneumonia) | Secretions and lesions | Patients and health care workers | P,b Tzanck prep and viral cultures, PCR, immunofluorescence staining, or serology; E,b not known to be useful | Outbreaks reported when patients shed or with lesions in health care workers |
| Varicella infections (disseminated or localized infection) | Secretions and skin lesions | Poor ventilation | P,b Tzanck prep and viral cultures, PCR, immunofluorescence staining or serology; E,b not known to be useful | Children and immunocompromised patients at risk, poor ventilation or poor infection control practices |
| Adenovirus (EKC) | Oral pharyngeal secretions | Equipment (tonometers) and health care workers | P,b viral cultures, PCR; E,b not known to be useful | Ophthalmologic patients, NICU patients, immunocompromised patients |
| Norovirus | Stool | Patients, health care personnel, and visitors, environment | P, stool EM, PCR; E, not known to be useful | Dramatic spread in any health care population; shedding can persist for days |
| Serratia marcescens (urinary tract, bloodstream) | Gastrointestinal and urinary tracts | Solutions, inhalation therapy equipment, disinfectants, plasma, EDTA collection tubes, air-conditioning vents, improperly cleaned equipment | P,b micro cultures; E,b cultures of potentially implicated items | Cross-contamination well described; reuse of calibrated pressure transducers |
| Listeria monocytogenes (bloodstream and central nervous system infections) | Food | Contaminated foods | P,b micro cultures; E,b cultures of potentially implicated items | Immunocompromised and mother-infant pairs at highest risk |
| Vancomycin-resistant Enterococcus | Gastrointestinal tract | Hands of health care workers, contaminated equipment and environment | P,b micro cultures; E,b cultures of potentially implicated items | Cross-contamination well described; immunocompromised patients and those in intensive care units at highest risk |
| Polymicrobial infections | Depends on setting | Contaminated i.v. solutions or medications | P,b micro cultures; E,b cultures of potentially implicated items | Suggests technical problems, increased nurse-to-patient ratios |
| Yersinia enterocolitica | Gastrointestinal tract | Packed red blood cells | P,b micro cultures; E,b cultures of potentially implicated items |
a
P, in patients; E, in the environment; micro, microbiological; PFGE, pulsed-field gel electrophoresis; i.v., intravenous; GI, gastrointestinal; TPN, total parenteral nutrition; HUS, hemolytic-uremic syndrome; TTP, thrombotic thrombocytopenic purpura; EKC, epidemic keratoconjunctivitis; NICU, neonatal ICU; EM, electron microscopy.
b
Molecular typing available.
c
Some species are now Burkholderia species.