Molecular epidemiology of Acinetobacter baumannii in different hospitals in Tripoli, Lebanon using bla(OXA-51-like) sequence based typing

BACKGROUND: A. baumannii has emerged as an important nosocomial pathogen with an outstanding ability to acquire multidrug resistant mechanisms. In this study, we investigate the molecular epidemiology and carbapenem resistance mechanisms of A. baumannii in Tripoli, Northern Lebanon. METHODS: One hundred sixteen non-duplicate isolates isolated between 2011 and 2013 in different hospitals in Tripoli, Lebanon from Lebanese patients and wounded Syrian patients during Syrian war were studied. Antibiotic susceptibility testing was determined by agar disc diffusion and Etest. Carbapenemase-encoding genes were investigated by PCR. All isolates were typed by bla(OXA-51-like) sequence based typing (SBT) and 57 isolates were also analysed by MLST using Pasteur’s scheme followed by eBURST analysis. RESULTS: Of the 116 isolates, 70 (60 %) showed a carbapenem resistance phenotype. The bla(OXA-23) with an upstream insertion of ISAba1 was the major carbapenem resistance mechanism and detected in 65 isolates. Five isolates, including four from wounded Syrian patients and one from a Lebanese patient, were positive for bla(NDM-1). bla(OXA-51-like) SBT revealed the presence of 14 variants, where bla(OXA-66) was the most common and present in 73 isolates, followed by bla(OXA-69) in 20 isolates. MLST analysis identified 17 sequence types (ST) and showed a concordance with bla(OXA-51-like) SBT. Each clonal complex (CC) had a specific bla(OXA-51-like) sequence such as CC2, which harboured bla(OXA-66) variant, and CC1 harbouring bla(OXA-69) variant. NDM-1 producing isolates belonged to ST85 (4 Syrian isolates) and ST25 (1 Lebanese isolate). CONCLUSIONS: Our results showed a successful predominance of international clone 2 with a widespread occurrence of OXA-23 carbapenemase in Lebanese hospitals. These findings emphasise the urgent need of effective measures to control the spread of A. baumannii in this country.