Evaluation of the role of efflux pumps in multidrug-resistantEscherichia coli ST۱۳۱ isolated from blood samples in hospitalizedpatients in Tehran, Iran

Background and Aim : Nowadays antibiotic resistance is one of the biggest concerns for humanbeings. In this regard, group ST۱۳۱ E.coli isolates were repeatedly associated with fluoroquinoloneresistance and the most virulent strains belonging to phylogroup B۲. Among different mechanismsof antibiotic resistance, the role of genetically-encoded efflux pumps such as acrAB-TolC, Mdfa,Mdtb in MDR resistance should be considered in these bacteria.Methods : In this cross-sectional study, ۱۲۴ blood samples were collected from hospitalizedpatients in different wards of the two educational hospitals during ۲۰۲۰. To confirm that theisolated bacteria is E.coli several biochemical tests have been done. To understand the antibioticresistance pattern, antibiogram tests were performed according to the Kirby-Bauer methodaccording to the CLSI guideline. In the next step, E.coli ST۱۳۱ was recognized phylogenetically,and the role of efflux pumps was investigated in them.Results : The distribution of different strains in hospital wards shows that the most prevalent ofboth E. coli sequence type was related to the emergency department. In this study, the highestantibiotic resistance was to nalidixic acid and ampicillin (۷۸.۲%). On the other hand, the highestsensitivity was to tigecycline, ertapenem, and imipenem. According to the combined disc method,۵۷ isolates were identified as ESBL-producing strains. Among these, ۲۹ isolates belonged tophylogenetic group B۲. In the meantime, ۲۰ isolates were finally identified as type ۱۳۱ sequencesby PCR method.Conclusion : Improper use of over-the-counter antibiotics causes irrecoverable damages to humanhealth. This may cause the advent of multi-drug resistant (MDR) phenotypes by several mutations.Our study mentioned the improving role of efflux pumps and the increase of quinolone resistancein E.coli ST۱۳۱. New implementations of drug treatment by using alternative drugs combiningwith efflux pump inhibitors can be beneficial against these infections.

Keywords:

Efflux pump , multidrug resistance (MDR) , Fluoroquinolone , Escherichia coli ST۱۳۱