An outbreak of multidrug-resistant Pseudomonas aeruginosa associated with increased risk of patient death in an intensive care unit.
OBJECTIVE
To investigate an outbreak of multidrug-resistant Pseudomonas aeruginosa in an intensive care unit (ICU).


METHODS
Epidemiologic investigation, environmental assessment, and ambidirectional cohort study.


METHODS
A secondary-care university hospital with a 10-bed ICU.


METHODS
All patients admitted to the ICU receiving ventilator treatment from December 1, 1999, to September 1, 2000.


RESULTS
An outbreak in an ICU with multidrug-resistant isolates of P aeruginosa belonging to one amplified fragment-length polymorphism (AFLP)-defined genetic cluster was identified, characterized, and cleared. Molecular typing of bacterial isolates with AFLP made it possible to identify the outbreak and make rational decisions during the outbreak period. The outbreak included 19 patients during the study period. Infection with bacterial isolates belonging to the AFLP cluster was associated with reduced survival (odds ratio, 5.26; 95% confidence interval, 1.14 to 24.26). Enhanced barrier and hygiene precautions, cohorting of patients, and altered antibiotic policy were not sufficient to eliminate the outbreak. At the end of the study period (in July), there was a change in the outbreak pattern from long (December to June) to short (July) incubation times before colonization and from primarily tracheal colonization (December to June) to primarily gastric or enteral July) colonization. In this period, the bacterium was also isolated from water taps.


CONCLUSIONS
Complete elimination of the outbreak was achieved after weekly pasteurization of the water taps of the ICU and use of sterile water as a solvent in the gastric tubes.
Institute of Clinical Epidemiology and Molecular Biology, Akershus University Hospital, University of Oslo, Norway.
Geir
G
Bukholm
Tone
T
Tannaes
Anne Britt Bye
AB
Kjelsberg
Nils
N
Smith-Erichsen
D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D003428:Cross Infection / Q000401:mortality* / Q000517:prevention & control; D004196:Disease Outbreaks / Q000517:prevention & control*; D024901:Drug Resistance, Multiple, Bacterial; D017052:Hospital Mortality; D006801:Humans; D017053:Infection Control / Q000379:methods; D007362:Intensive Care Units; D016015:Logistic Models; D009664:Norway / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods; D011552:Pseudomonas Infections / Q000401:mortality* / Q000517:prevention & control; D012307:Risk Factors; D014871:Water Microbiology