Highly clonal carbapenem-resistant Acinetobacter baumannii isolates from a Peruvian hospital

Acinetobacter baumannii is an opportunistic pathogen of great clinical concern, showing high levels of resistance to several antimicrobials, including carbapenems. This study aimed to characterize carbapenem-resistant A. baumannii recovered from a tertiary care hospital (Lima, Peru) in January–February 2021 (during the coronavirus disease 2019 pandemic). Antimicrobial susceptibility was determined by VITEK-2, and the presence of carbapenem-resistance genes by PCR. All 40 A. baumannii isolates were extensively drug-resistant, showing full resistance to all antibiotics tested except ampicillin/sulbactam (95% of resistance) and colistin (10%). The bla_OXA-24-like gene was detected in 90% of isolates, and the remaining 10% isolates harbored the bla_OXA-23-like gene. Pulsed-field gel electrophoresis classified isolates into three different pulsotypes, grouping 8, 2, and 30 isolates, respectively. Additionally, whole-genome sequencing of two isolates of the main pulsotype revealed that they belonged to ST2 and ST2724 (international clone II) and harbored the bla_TEM-1, bla_OXA-66, bla_OXA-72, and bla_ADC-30 β-lactamase genes; mutations in gyrA and parC, aminoglycoside, tetracycline, and sulfonamide resistance genes; and a class 1 integron (In439) containing aac(6′)-Ib′, catB8, and aadA1 located inside the AbGRI3 genomic resistance island. These findings highlight the presence of highly resistant and clonally related ST2 of A. baumannii and their relationship with genomes of ST2 of South America.