[Study on the carbapenemase genotype and molecular epidemiology of Acinetobacter baumannii]

To investigate antibiotic resistance, clonal relatedness and carbapenemase genotype among carbapenem-resistant Acinetobacter baumannii collected from 3 comprehensive hospitals in Ningbo city, Zhejiang province.

28 strains of carbapenem resistant Acinetobacter baumannii were collected from Ningbo Li Hui-li Hospital, Ningbo Li Hui-li Hospital, Ningbo First Hospital, and N ingbo Second Hospital. The minimum inhibitory concentrations (MIC) of these strains were examined by agar dilution and E-test method. Homology of these isolates was analyzed by pulse-field gel electrophoresis (PFGE) and Genotype of carbapenemases were analyzed by PCR and verified by DNA sequencing.

28 strains of Acinetobacter baumanii were highly resistant to all of the antibiotics except polymyxin E. They were classified into 4 clones based on PFGE pattern. Clone A and B had been spreading widely. All of the 28 strains produced carbapenemases which were confirmed as OXA-23 by PCR and sequencing. Metallo-beta-lactamase was not detected in any of the isolates.

All of t hecarbapenem-resistant Acinetobacter baumannii collected from Ningbo were producing OXA-23 carbapenemase, suggesting that the transmission of clones had occurred in the 3 hospitals.