Biotyping, ribotyping and esterase electrophoresis as epidemiological tools for Acinetobacter baumannii

Abstract An epidemiological survey was carried out over a one-week period to assess the spread of Acinetobacter baumannii in a medical intensive care unit. Fifty strains were isolated from patients colonized or infected by the organism and from a hospital environment. These strains belonged to biotypes 9 or 18. The rRNA gene restriction patterns (using Eco RI and Pvu ll as restriction endonucleases) and the esterase electrophoretic profiles were determined on 31 strains, using as comparison strain isolates from another intensive care unit of our hospital and from two other French hospitals. Four Eco RI ribotypes, four Pvu ll ribotypes and six esterase profiles were identified. All biotype 9 strains isolated in our hospital presented the same ribotype after Eco RI digestion, the same ribotype after Pvu ll digestion and the same zymotype. The same observation was made on most of the biotype 18 strains. Biotyping is an appropriate method for screening of strains, and ribotyping and esterase electrophoresis could be used as additional methods to delineate outbreaks of nosocomial infections caused by A. baumannii .