Multidrug- and Extensively Drug-Resistant Acinetobacter baumannii in a Tertiary Hospital from Brazil: The Importance of Carbapenemase Encoding Genes and Epidemic Clonal Complexes in a 10-Year Study

This study aimed to characterize the main mechanisms of acquired antimicrobial resistance of 103 multidrug-resistant Acinetobacter baumannii isolated from bloodstream from 2006 to 2016 from a hospital in Londrina, Brazil. All 103 isolates were identified as A. baumannii by amplification of the bla OXA-51-like and rpo B genes. Mortality was observed in the majority (81.6%) of the patients. High non-susceptibility rates (100.0–10.7%) were obtained for the evaluated antimicrobials, including colistin, polymyxin B, and tigecycline, and most isolates were classified as extensively drug-resistant (78.6%). Carbapenemase production was observed in 92.2% of the isolates. All carbapenem-resistant isolates showed a carbapenem-hydrolyzing class D β-lactamase being either bla OXA-23-like (97.9%) or bla OXA-143-like (2.1%). None of the isolates had the genes bla OXA-24-like , bla OXA-58-like , bla OXA-48 , bla KPC , bla NDM , bla SPM-1 , bla SIM-1 , bla VIM , bla IMP , bla GIM , bla GES , mcr -1, qnr A, qnr B, qnr C, qnr S, and qnr Vc. As a genetic context of the bla OXA-23-like gene, Tn 2006 was predominated (86.0%), and Tn 2008 was less frequent (12.9%). Isolates harboring the bla OXA-143-like gene showed the bla OXA-253-like variant. A polyclonal profile was observed among the A. baumannii isolates. The presence of the international clonal complexes CC113/79, CC109/1, CC110/25, and CC103/15 was detected, with prevalence of CC113/79 (38.8%). This study provides essential information to understand the antimicrobial resistance patterns of A. baumannii and can be used to strengthen infection control measures in our hospital. Also, the study reinforces the urgent need to develop stewardship programs to avoid the spread and potential outbreaks by this pathogen.