Risk factors for an outbreak of multi-drug-resistant acinetobacter nosocomial pneumonia among intubated patients

Introduction: Acinetobacter baumanii is a Gram-negative coccobacillus that is normally a commensal pathogen but can be a nosocomial pathogen, An epidemiologic study was performed to investigate an outbreak of A baumanii that occurred in our medical intensive care unit (MICU) from March to September 1995, Methods: A case-control study was performed by retrospective chart review, comparing case patients to randomly selected patients who were mechanically ventilated in the MICU for at least 1 week during the outbreak. A case patient was defined as any patient with an Acinetobacter infection in which the epidemic strain was considered to be a pathogen, The epidemic strain,vas defined by its antibiogram, Case patients and control patients were compared for age, gender, underlying disease, acute physiology and chronic health evaluation III score, length of MICU stay, prior antibiotic use, presence of fewer, sepsis, type of pulmonary infiltrate, and outcome. Environmental and handwashing studies also were performed during the period of the outbreak, Molecular typing was performed on available bloodsteam isolates. Results: There were 15 cases of A baumanii nosocomial pneumonia, fifty percent were bacteremic; one chart was unavailable for review, Twenty-nine patients were identified as control patients, The mean age for case patients was 50 (range, 21 to 84). The mean duration of time from admission to the ICU to infection was 12.8 days (range, 4 to 40). Sepsis developed in 3546 of the case patients. Forty-three pet-cent of the case patients died during their hospitalization, with two of those deaths attributed to Acinetobacter infection, Univariate analysis showed that prior use of ceftazidime was associated with infection with Acinetobacter (11/14 case patients compared to 11/29 control patients; p < 0.01), Pulsed-held gel electrophoresis revealed two strains to be responsible for the outbreak, Hand washing was performed before patient contact by only 10% of health-care workers, and only 32% washed their hands after patient contact. Conclusion: The use of ceftazidime was associated with an increased risk of nosocomial pneumonia with resistant strains of Acinetobacter, Health-care workers need to improve compliance with hand-washing recommendations.