The role of the genetic elements bla oxa and IS Aba 1 in the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in carbapenem resistance in the hospital setting

Abstract

Introduction: Members of the Acinetobacter genus are key pathogens that cause healthcare-associated infections, and they tend to spread and develop new antibiotic resistance mechanisms. Oxacillinases are primarily responsible for resistance to carbapenem antibiotics. Higher rates of carbapenem hydrolysis might be ascribed to insertion sequences, such as the ISAba1 sequence, near bla OXA genes. The present study examined the occurrence of the genetic elements bla OXA and ISAba1 and their relationship with susceptibility to carbapenems in clinical isolates of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. Methods: Isolates identifi ed over 6 consecutive years in a general hospital in Joinville, Southern Brazil, were evaluated. The investigation of 5 families of genes encoding oxacillinases and the ISAba1 sequence location relative to bla OXA genes was conducted using polymerase chain reaction. Results: All isolates presented the bla OXA-51-like gene (n = 78), and 91% tested positive for the bla OXA-23-like gene (n = 71). The presence of ISAba1 was exclusively detected in isolates carrying the bla OXA-23-like gene. All isolates in which ISAba1 was found upstream of the bla OXA-23-like gene (n = 69) showed resistance to carbapenems, whereas the only isolate in which ISAba1 was not located near the bla OXA-23-like gene was susceptible to carbapenems. The ISAba1 sequence position of another bla OXA-23-like -positive isolate was inconclusive. The isolates exclusively carrying the bla OXA-51-like gene (n = 7) showed susceptibility to carbapenems. Conclusions: The presence of the ISAba1 sequence upstream of the bla OXA-23-like gene was strongly associated with carbapenem resistance in isolates of the A. calcoaceticus-A. baumannii complex in the hospital center studied.

Study of genetic diversity, biofilm formation, and detection of Carbapenemase, MBL, ESBL, and tetracycline resistance genes in multidrug-resistant Acinetobacter baumannii isolated from burn wound infections in Iran

“…Isolates were initially identified using the API 20 NE kit (bioMérieux, Marcy-l’Etoile, France) and then confirmed as A. baumannii by PCR/sequencing for the intrinsic bla OXA-51-like gene described previously [10]. According to the Clinical Laboratory Standards Institute (CLSI), following quality control strains were used as reference strains: A. baumannii ATCC 19606, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC, 25922.…”

“…There are few studies conducted in Iran on coexistence of different antibiotic resistance mechanisms with the ability to form biofilms in multidrug-resistant Acinetobacter baumannii isolated from burn wound infections, and there is relatively few information on diversity of these strains. Nowadays, understanding molecular characteristics of various antibiotic resistance mechanisms along with molecular epidemiology analysis in regions with high prevalence rates of MDR A. baumannii infection plays an essential role in developing therapeutic strategies and controlling MDR-AB outbreaks, both in community and hospitals [1, 7, 10]. Among molecular typing methods, Pulsed-Field Gel Electrophoresis (PFGE) is usually considered gold standard for epidemiological typing of A. baumannii [6].…”

Molecular docking, dynamics and free energy analyses of Acinetobacter baumannii OXA class enzymes with carbapenems investigating their hydrolytic mechanisms

“…The production of Ambler class D β-lactamases, also known as oxacillinases, is considered to be the paradigm of resistance to carbapenems in A. baumannii strains [6]. The β-lactamases hydrolyze beta-lactam antibiotics such as penicillin, which binds to the penicillin-binding proteins (PBP), inactivating the peptidoglycan transpeptidases and blocking the formation of peptide cross-linking of the sugar chains, resulting in weakened cell wall biosynthesis [7–9].…”

Multidrug Resistance (MDR) and Collateral Sensitivity in Bacteria, with Special Attention to Genetic and Evolutionary Aspects and to the Perspectives of Antimicrobial Peptides—A Review

“…A novel, epidemic, serine class-A type enzyme (KPC) is behind carbapenem resistance. It is encoded by the Bla (Oxa) gene family [ 161 , 162 , 163 , 164 , 165 ]. KPC exhibits powerful activity against all types of Beta-lactam molecules [ 166 , 167 , 168 ].…”