Pseudo-outbreak of Pseudomonas aeruginosa and Serratia marcescens related to bronchoscopes.
OBJECTIVE
To investigate an apparent outbreak involving simultaneous isolation of Pseudomonas aeruginosa and Serratia marcescens from bronchoalveolar lavage (BAL) samples.


METHODS
Retrospective and prospective cohort studies using chart review, environmental sampling, and ribotyping of all available isolates. Cleaning and disinfection procedures for the bronchoscopes were also evaluated.


METHODS
A 380-bed private hospital in São Paulo, Brazil


METHODS
Forty-one patients who underwent bronchoscopic procedures between December 1994 and October 1996 and from whom P. aeruginosa and S. marcescens were concomitantly isolated. Bronchoscopes and related items were microbiologically assessed.


RESULTS
P. aeruginosa and S. marcescens were simultaneously isolated from BAL samples 12.6% of the time (41 of 324) during the epidemic period versus 1.8% of the time (1 of 54) in the pre-epidemic period (P = .035). Ribotyping revealed two strains of P. aeruginosa and one of S. marcescens that were isolated from BAL samples of patients with no signs of respiratory tract infection, suggesting a pseudo-outbreak. Evaluation of bronchoscope disinfection revealed that inappropriate methods were being used. Implementation of simple control measures resulted in a significant decrease in simultaneous isolation of these species.


CONCLUSIONS
Prevention of pseudo-outbreaks requires meticulous use of preventive measures for infection-prone medical procedures.
Silva
Cláudia V
CV
Infection Control Service, Hospital Israelita Albert Einstein, São Paulo, Brazil.
Magalhães
Vanda D
VD
Pereira
Crésio R
CR
Kawagoe
Julia Y
JY
Ikura
Chizue
C
Ganc
Arnaldo J
AJ
D001938:Brazil / Q000453:epidemiology; D018893:Bronchoalveolar Lavage; D020680:Bronchoscopes / Q000382:microbiology*; D001999:Bronchoscopy / Q000009:adverse effects*; D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000209:etiology*; D004196:Disease Outbreaks; D004203:Disinfection / Q000379:methods; D004866:Equipment Contamination; D017743:Equipment Reuse; D016304:Hospitals, Private; D006801:Humans; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000635:transmission*; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification* / Q000472:pathogenicity; D012189:Retrospective Studies; D021521:Ribotyping; D016868:Serratia Infections / Q000635:transmission*; D012706:Serratia marcescens / Q000302:isolation & purification* / Q000472:pathogenicity