We aim to describe the antimicrobial resistance pattern and the genetic basis of carbapenem non-susceptible A. baumanii isolates in Romania, a country where multi drug resistant A. baumanii is widespread.. High Prevalence of ST502 carrying an OXA-24 carbapenemase in Carbapenem-non susceptible Acinetobacter baumannii calcoaceticus complex isolates in Romania

Acinetobacter baumanii can cause difficult to treat infections because it can acquire extensive antimicrobial resistance mechanisms. We aim to describe the antimicrobial resistance pattern and the genetic basis of carbapenem non-susceptible A. baumanii isolates in Romania, a country where multi drug resistant A. baumanii is widespread. We collected 110 consecutive meropenem non-susceptible A. baumanii isolates from 110 patients (35% female, mean age of 64 (SD 15)) between May 2015 and August 2017 from a large tertiary center in Romania. Representative isolates from AFLP groups underwent whole genome sequencing. All isolates were resistant to piperacillin/ tazobactam, ceftazidime, and ciprofloxacin, 89.0% to gentamicin, 82.7% to trimethoprim/ sulfamethoxazole. In contrast, 78.2% and 99.1% were susceptible to tobramycin and colistin, respectively. The blaOXA-24 was detected in 79.1%, and the blaOXA-23 in 20.9% of the isolates. In one isolate, blaOXA-23 was co-present with blaOXA-24. ST502 was the most common ST type, and was exclusively associated with blaOXA-24. High prevalence of ST502 associated with blaOXA-24 in the region where carbapenem non-susceptible A.baumanii is endemic was found. In these isolates, tobramycin and colistin might be the remained therapeutic options. Regarding A. baumannii surveillance, due to the differences in aminoglycoside resistance and substrate specificity, surveillance data should not grouped gentamicin, tobramycin and amikacin together.