Insertion sequences and sequence types profile of clinical isolates of carbapenem-resistant A. baumannii collected across India over four year period

Objectives: Acinetobacter baumannii emerged as a major nosocomial pathogen responsible for infections. In this study, we report the molecular characterization, association of insertion sequences and sequence types of clinical isolates of carbapenem resistant A. baumannii. Materials and Methods: A total of 763 non-duplicate isolates of A. baumannii received from 8 centres across India during January 2014 to December 2017 were studied. Susceptibility testing was done by Kirby-Bauer method. PCR was performed for detection of extended spectrum beta-lactamases, metallo beta-lactamases, oxacillinases and ISAba1. Mapping PCR was performed to identify the position of ISAba1 with respect to bla(OXA-23) like and bla(OXA-51) like gene. MLST was performed to identify the sequence type. Whole genome sequencing was done to decipher the genetic arrangement of ISAba1 with bla(OXA-23) like and with bla(OXA-51) like. Results: All the isolates were resistant to imipenem and meropenem. bla(OXA-23) like was the predominant carbapenemase. All isolates were positive for ISAba1. The common sequence types were ST848, ST451 and ST1305 which belongs to International clone II. Whole genome sequencing showed considerable variation in the insertion site location. Conclusions: In conclusion, high prevalence of bla(OXA-23) like in A. baumannii and its association with ISAba1 and sequence types belonging to IC-II facilitates the successful dissemination of these extremely drug resistant strains. (C) 2019 Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).