Molecular characterization of carbapenem resistant Acinetobacter baumannii and investigation of genetic diversity between local and international clones

The emergence of Carbapenem-resistant Acinetobacter baumannii is a threat to modern medicine and has been recognised globally. Epidemic clones of A. baumannii are associated with hospital epidemics throughout the world causing serious ramifications. There are number of molecular typing techniques used for molecular characterisation, however, due to lack of resources molecular epidemiology remains unfledged in developing countries. In this study a total number of 205 carbapenem-resistant Acinetobacter species were collected and compared with European Clone I, II and III. PCR for and bla_OXA-51-like was performed for confirmation and multiplex PCR was performed for bla_OXA-23-like, bla_OXA-24-like and bla_OXA-58-like genes. Isolates harbouring carbapenemases were selected for molecular typing using PFGE, RAPD-PCR and REP-PCR and discriminatory index was performed. The cost of all molecular typing methods was calculated. The bla_OXA-51-like gene was present in 188 (91.7%), and within these 188 isolates; bla_OXA-23-like 36(19%), bla_OXA-24-like 62(33%), 30(16%) carried bla_OXA-58-like genes. PFGE typing revealed 13 clusters and 15 unique types, RAPD-PCR, 11 clusters and 23 unique types and REP-PCR, 8 clusters and no unique types. With 80% similarity cut-off value, 11 isolates were similar to EU clone I, 5 isolates were similar to EU II and 3 isolates were similar to EU III. Cost of molecular methods was compared between PFGE, RAPD-PCR and REP-PCR. PFGE was found to have high discriminatory power and RAPD-PCR was economical.