Molecular Detection of Tetracycline Resistance Genes in Escherichia coli Isolated from Urine Samples in Michael Okpara University of Agriculture Clinic, Umudike

Abstract

Background: Antimicrobial resistance among urinary Escherichia coli isolates can reduce the effectiveness of commonly used antibacterial agents. Aims: This study examined antibiotic susceptibility and the presence of tetracycline-resistance genes in E. coli recovered from urine samples at Michael Okpara University of Agriculture, Umudike, Nigeria. Methods: One hundred midstream urine samples were examined using cultural, morphological and biochemical methods. Six presumptive E. coli isolates were subjected to disc-diffusion susceptibility testing against ampicillin, ceftazidime, ciprofloxacin, gentamicin, amoxicillin–clavulanate, tetracycline and cefuroxime. Three tetracycline-resistant isolates were selected for 16S rRNA gene analysis and polymerase chain reaction screening for tetA and tetB. Results: Six E. coli isolates were recovered, representing 6.0% of the samples examined. Three of the six isolates were resistant to tetracycline. Resistance to ampicillin, ciprofloxacin and amoxicillin–clavulanate was detected in two isolates each, while one isolate each was resistant to ceftazidime, gentamicin and cefuroxime. The three isolates selected for molecular analysis produced 16S rRNA amplicons. Among these three isolates, one carried both tetA and tetB, corresponding to 33.3% of the molecularly screened isolates and 16.7% of all six E. coli isolates. Conclusion: Tetracycline resistance and associated efflux-mediated resistance genes were detected among a small number of urinary E. coli isolates. Larger studies using complete clinical data, validated molecular controls and broader resistance-gene panels are required to determine the local epidemiological significance of these findings.