Multilocus sequence typing and molecular characterization of β-lactamase genes among Acinetobacter baumannii isolates in a burn center.

Acinetobacter baumannii (A. baumannii) is one of the leading pathogens in hospital infections. To characterize the epidemiology of A. baumannii in a burn ward, we collected all A. baumannii isolates though 18 months. Antibiotic susceptibility and antibiotic resistant genes were tested. Multilocus sequence typing (MLST) was further used to molecularly subtype these isolates. These isolates showed a severe multidrug resistant phenotype with 85% resistance to imipenem and meropenem. Along with the resistant phenotype, antibiotic resistant genes were widely found among these isolates. The prevalences of OXA23, AmpC, PER and VIM were 65.1%, 84%, 37.7% and 53%, respectively. Fifteen reported STs and sixteen novel STs were found in this study. ST368 (35%) was the dominant type, followed by ST195 (15%), ST191 (12%), ST369 (10%) and ST208 (10%). Majority (82.8%) of these isolates belong to clonal group 92, indicating the nosocomial spreading of A. baumannii. Further monitoring and control measures for A. baumannii spreading are necessary.