Prevalence of VIM- and GIM-producing Acinetobacter baumannii from patients with severe urinary tract infection

Carbapenems are administered as the final drug of choice for treating complicated nosocomial infections caused by multidrug-resistant Acinetobacter baumannii strains. It is currently a worldwide issue that metallo-β-lactamases (MBLs) as carbapenem-hydrolyzing enzymes are one of the major drug resistance mechanisms. This investigation is thus aimed to assess the prevalence and characterize the MBL-producing strains of A. baumannii both by phenotypic assays and by genotypic characterization. A total of 73 isolates of A. baumannii were phenotypically and genotypically characterized from patients (N = 1,000) with severe urinary tract infection. Tested strains were subjected to double disc synergy testing (DDST) by Kirby-Bauer disc diffusion method with imipenem (IMP) and IMP/EDTA combination discs. Plasmid DNA was molecularly screened for MBL-encoding bla_IMP, bla_VIM, bla_GIM, and bla_NDM genes by PCR for the genetic relatedness of the MBL genes with carbapenem resistance. Carbapenem resistance profile showed 100%, 45%, and 49% non-susceptibility against imipenem, doripenem, and meropenem, respectively. Altogether 42.46% (n = 31) of the isolates showed MBL production upon double disc phenotypic test with IMP and IMP/EDTA discs. The bla_VIM and bla_GIM were detected in 34.24% (n = 25) and 16.43% (n = 12) of the isolates, respectively, while the co-occurrence of bla_VIM and bla_GIM was 2.73% among the isolates. DDST-positive isolates showed 21.19% and 9.58% strains positive for bla_VIM and bla_GIM, respectively, whereas 1.36% of the strains for both genes. None of the strains yielded bla_IMP and bla_NDM genes. The findings of this study showed prevalence of carbapenem resistance among A. baumannii from urine samples and the frequency of bla_VIM and bla_GIM.