Role of Extended Spectrum Beta Lactamases in Cephalosporin and Carbapenem Resistance in Escherichia coli from Inpatients and Outpatients in Nigeria

Abstract

Introduction: Antimicrobial resistance requires global coordinated action with a view to addressing its rising threat. Prevalence of antimicrobial resistance has been increasing worldwide in both developed and developing countries. Whilst cephalosporin and carbapenem resistance is a problem in Escherichia coli in Nigeria, there is a paucity of information regarding the mechanisms of resistance underpinning this in prevalence and types of extended spectrum in clinical E. coli. Aim: To detect and characterise Extended Spectrum β Lactamases (ESBL) in clinical E. coli from inpatients and outpatients in Nigeria. Materials and Methods: A total of 104 E. coli were obtained from 498 non-duplicate clinical specimens from Northern Nigeria between November 2017 and November 2018. Antibiotic susceptibility of third generation cephalosporin including other important antibiotics and phenotypic detection of ESBL of the isolates were determined. Genotypic detection of ESBL and randomly amplified polymorphic DNA to determine clonality were used to further characterise 44 E. coli isolates selected based on their phenotypes and clinical specimens. The data were analysed with the aid of statistical package for social sciences (IBM SPSS), version 21.0 and were reported in frequency tables and in percentages. Results: Majority of the E. coli isolates showed no clonal relationships. More than half of E. coli were resistant to third generation cephalosporin class of antibiotics. There was no difference between MIC50 and MIC90 values for the majority isolates for most drugs where MICs ≥256 µg/mL were the norm except for carbapenems with low level resistance. In total, 44/104 (42.3%) E. coli were ESBL producers. blaCTX-M was the dominant ESBLs seen in 75% (33/44) of isolates, of these blaCTX-M-15 variant was most common and seen in 72.7% (24/33) of isolates followed by blaVEB, 21/44 (47.7%) and blaPER 6/44 (13.6%). No AmpC or carbapenemase genes were identified. Conclusion: E. coli isolates from Northern Nigeria are highly multi-drug resistant with only carbapenems of common therapeutic drug classes retaining significant activity. Betalactam resistance is largely underpinned by carriage of CTX-M15 and carbapenem resistance is likely to be a result of ESBL carriage with other mechanisms.

Keywords

• antibiotics
• bacteria
• infections
• resistance genes