Analysis of blaCHDL Genes and Insertion Sequences Related to Carbapenem Resistance in Acinetobacter baumannii Clinical Strains Isolated in Warsaw, Poland

Abstract

Acinetobacter baumannii is an important cause of nosocomial infections worldwide. The elucidation of the carbapenem resistance mechanisms of hospital strains is necessary for the effective treatment and prevention of resistance gene transmission. The main mechanism of carbapenem resistance in A. baumannii is carbapenemases, whose expressions are affected by the presence of insertion sequences (ISs) upstream of blaCHDL genes. In this study, 61 imipenem-nonsusceptible A. baumannii isolates were characterized using phenotypic (drug-susceptibility profile using CarbaAcineto NP) and molecular methods. Pulsed field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) methods were utilized for the genotyping. The majority of isolates (59/61) carried one of the following acquired blaCHDL genes: blaOXA-24-like (39/59), ISAba1-blaOXA-23-like (14/59) or ISAba3-blaOXA-58-like (6/59). Whole genome sequence analysis of 15 selected isolates identified the following intrinsic blaOXA-66 (OXA-51-like; n = 15) and acquired class D β-lactamases (CHDLs): ISAba1-blaOXA-23 (OXA-23-like; n = 7), ISAba3-blaOXA-58-ISAba3 (OXA-58-like; n = 2) and blaOXA-72 (OXA-24-like; n = 6). The isolates were classified into 21 pulsotypes using PFGE, and the representative 15 isolates were found to belong to sequence type ST2 of the Pasteur MLST scheme from the global IC2 clone. The Oxford MLST scheme revealed the diversity among these studied isolates, and identified five sequence types (ST195, ST208, ST208/ST1806, ST348 and ST425). CHDL-type carbapenemases and insertion elements upstream of the blaCHDL genes were found to be widespread among Polish A. baumannii clinical isolates, and this contributed to their carbapenem resistance.

The Prevalence of Virulence Factor Genes among Carbapenem-Non-Susceptible Acinetobacter baumannii Clinical Strains and Their Usefulness as Potential Molecular Biomarkers of Infection

“…The most prevalent mechanisms of carbapenem resistance among A. baumannii isolates are CHDLs, with OXA-23 occurring the most often among A. baumannii worldwide [ 30 , 31 ]. Meanwhile, the results of our study showed that in our region, OXA-40-positive isolates are dominant, which is consistent with other studies conducted in Poland [ 32 ]. In our study, no isolates were simultaneously positive for both tested bla OXA genes.…”

Ethynyl-substituted benzosiloxaboroles: the role of C(π)⋯B interactions in their crystal packing and use in Cu(i)-catalyzed 1,3-dipolar cycloaddition

“…Only 1c and 2c displayed weak activity against Gram-negative rods with MICs ranging from 200 to >400 mg L −1 (Table S2.2†). Considering that resistance of Gram-negative rods is frequently associated with efflux pump activity, 41 we also determined the MICs of newly compounds in the presence of efflux pump inhibitor, i.e. , phenylalanine-arginine-β-naphthylamide (PAβN).…”

Coming from the Wild: Multidrug Resistant Opportunistic Pathogens Presenting a Primary, Not Human-Linked, Environmental Habitat

“…Besides intrinsic and mutational acquired resistance, the members of this bacterial species have acquired several β-lactamases and other ARGs by HGT [ 139 ]. Among them, and in addition to the intrinsic OXA-type β-lactamase, other OXA derivatives have been found [ 140 ], frequently linked to insertion sequences (ISs) located upstream the genes encoding β-lactamases [ 141 ]. Indeed, the activity of ISs, capable of modifying the expression of genes involved in resistance when located in the right positions, seems to be also instrumental for the acquisition of the resistance phenotype [ 142 , 143 ].…”