Temporal evolution of Acinetobacter baumannii ST107 clone: conversion of blaOXA-143 into blaOXA-231 coupled with mobilization of ISAba1 upstream occAB1

Nine carbapenem-resistant Acinetobacter baumannii isolates carrying bla(OXA-231) and an ISAba1 upstream occAB1 were evaluated. They were clonally related and belonged to ST107. An OXA-143-producing A. baumannii ST107 strain (Ac-148) that did not possess ISAba1 upstream occAB1 was included in the analysis. Reduction in the expression of occAB1 and a 4-fold increase of carbapenem MICs were observed for all isolates, except for the Ac-148 strain, probably due to the presence of ISAba1 upstream occAB1 but in the same transcriptional orientation. We reported an A. baumannii ST107 clone carrying bla(OXA-231) that acquired a mutation resulting into bla(OXA-143) and mobilized ISAba1 upstream occAB1. (C) 2018 Published by Elsevier Masson SAS on behalf of Institut Pasteur.