MLST analysis of multiple antimicrobial resistant Acinetobacter baumannii

Multi-locus sequencing typing (MLST) of Acinetobacter baumannii, isolated at Showa University Hospital, was performed between November 2010 and March 2011. A. baumannii was isolated from 15 patients. Among the 15 isolates, the STs of three isolates were able to be determined, ST76, ST92, and ST146, and belonged to Clonal Complex (CC) 92, the global epidemic clone among carbapenem resistant A. baumannii. The other 12 strains were not applicable to the MLST classification. The ST76 strain was resistant to carbapenems, aminoglycosides, and fluoroquinolones. The ST92 strain was resistant to aminoglycosides and fluoroquinolones. The ST146 strain was resistant to fluoroquinolones. The other 12 strains were susceptible to either of the drugs. Neither the metallo beta lactamase gene (IMP type or VIM2) nor the OXA23 gene was detected in carbapenem resistant A. baumannii. These results indicate that A. baumannii of CC92 has spread as the drug resistant strain in Japan. Monitoring A. baumannii using molecular epidemiology is necessary.