Two Consecutive Outbreaks ofStenotrophomonas Maltophilia (Xanthomonas Maltophilia)in an Intensive-care Unit Defined by Restriction Fragment-Length Polymorphism Typing

Abstract

AbstractObjective:To investigate and control consecutive outbreaks ofStenotrophomonas maltophiliainfections in intensive-care–unit (ICU) patients.Design:Epidemiological investigation; restriction fragment-length polymorphism typing by pulsed-field gel electrophoresis (PFGE) of genomic DNA of outbreak strains; institution of infection control measures to limit spread.Setting:The medical-surgical ICU in an 800-bed tertiary-care center in Calgary, Alberta, Canada.Results:S maltophiliawas recovered from 14 ICU patients (12 infected, 2 colonized) between February 1993 and February 1994. Ten of the 14 patient isolates and 1 environmental isolate were available for PFGE typing. Patient isolates from 6 of the first 10 patients were identical. Isolates from the next 3 of 4 patients and an isolate recovered from a ventilator being used by a patient not infected withS maltophiliaalso were identical, but different from the first 6. The ventilator isolate was temporally associated with the latter 4 patients.Conclusion:Molecular typing allowed us to determine that there were two separate consecutiveS maltophiliaoutbreaks rather than a single protracted outbreak. Recovery ofS maltophiliafrom patient ventilators and an in-line suction catheter suggests that the organism may have been spread by cross-contamination from contaminated equipment or from an environmental source.