Endemic Acinetobacter anitratus in a surgical intensive care unit: mechanical ventilators as reservoir.

Colonization and infection with an endemic multiresistant strain of Acinetobacter calcoaceticus variety anitratus had been observed in the surgical intensive care unit of a university hospital since 1982. An outbreak of infection with this endemic, multiresistant Acinetobacter anitratus strain occurred between January and September, 1984. After initial attempts at identification of environmental reservoirs had been unsuccessful, risk factors for the acquisition of Acinetobacter anitratus were investigated by comparing the epidemiological characteristics of patients who became colonized or infected with those of control patients without colonization. The results of this case-control study and of the ensuing specific cultures indicated that ventilators in use in the unit were the reservoirs of Acinetobacter anitratus, resulting in frequent nosocomial respiratory tract infections. After modification of the mechanical ventilators, colonization and infection rates with Acinetobacter anitratus decreased. Since January 1985, no new cases of colonization or infection with this endemic strain of Acinetobacter anitratus have been recorded.