OXA-23 and OXA-40 producing carbapenem-resistant Acinetobacter baumannii in Central Illinois

We reviewed susceptibility of 840 A. baumannii complex isolates at two academic medical centers and explored their mechanism of carbapenem resistance. Carbapenem resistance rates among A. baumannii increased from 2 μg/mL). Phenotypic screening showed carbapenemase production in 50 isolates, but none was positive for MBL. Among carbapenem non-susceptible isolates, the CHDL (group D carbapenemase) encoding genes blaOXA-23 (52%) and blaOXA-40 (28%) were the most frequent genes. In conclusion, carbapenem resistance rates in A. baumannii peaked in 2011 and have since declined in our region. Carbapenem resistance among A. baumannii was primarily associated with production of acquired CHDLs including OXA-23 and OXA-40. •Carbapenem resistance A. baumannii (CRAB) peaked in 2011 and declined thereafter.•Group D carbapenemase (CHDL) production was the most common mechanism of resistance.•blaOXA-23 and blaOXA-40 genes are most common genes among our CRABs.