Identification of VIM and IMP genes and metallo-betalactamaseenzymes in Escherichia coli isolates by molecularand phenotypic methods in shahrekord educational hospitals

Background and aims: Among urine pathogens, Escherichia coli (E. coli) causes ۸۰% of urinary tract infections (UTIs). Due to the destructive nature of penicillins, cephalosporins and carbapenems (except for monobactam such as aztreonam) and carbapenemase enzymes have created many problems for treating infectious diseases. Therefore, this study aimed to investigate the phenotypic and molecular characterization of metallo-beta-lactamase (MBL) genes produced by E. coli isolates in an educational hospital during ۲۰۱۶-۲۰۱۷.Methods: This cross-sectional study investigated ۸۰ UTI samples affected by E. coli. In addition, antibiotic susceptibility was evaluated by disk diffusion and E-test methods for two antibiotics of meropenem and imipenem. Phenotypic tests containing modified Hodge test, ethylenediaminetetraacetic acid (EDTA) disk synergy test, and AmpC Disk were performed to identify MBLenzyme-producing strains. Finally, the frequency of Verona integron-encoded metallo-β-lactamase (VIM) and imipenemase (IMP) genes was determined by polymerase chain reaction (PCR). Results: Among ۸۰ E. coli samples, ۲۱ (۲۶.۲۵%) isolates were resistant to meropenem and imipenem as detected by the disk-diffusion method and E-test. Further, phenotypic tests including modified Hodge test, EDS test, and AmpC disk test showed the positivity of ۱۵ (۱۸.۷۵%), ۱۵ (۱۸.۷۵%), and ۸ (۱۰%) isolates, respectively (P < ۰.۰۰۱). Eventually, polymerase chain reaction (PCR) test results for the VIM gene showed ۱۹(۲۳.۷۵%) positive isolates of E. coli, but the IMP gene was observed in none of the isolates (P < ۰.۰۰۱).Conclusion: In general, the emergence of E. coli producing MBL enzymes is a serious threat among clinical infections. The findings of this study indicated the presence of E. coli producing MBL. These enzymes can degrade carbapenems antibiotics, the last class current treatment of multiple drug-resistance infections.

Keywords:

Escherichia coli , Drug resistance , VIM , IMP