High resistance to tetracycline and ciprofloxacin in bacteria isolated from poultry farms in Ibadan, Nigeria
Introduction: Resistance to ciprofloxacin and tetracycline is increasing in the food chain especially in E. coli strains and more worrisome will be occurrence of extended-spectrum beta-lactamase (ESBL) producers among ciprofloxacin- and tetracycline-resistant isolates. This study was undertaken to investigate the occurrence and mechanism of ciprofloxacin-, tetracycline- and ESBL-resistant bacteria in poultry in Ibadan, Nigeria.
Methodology: Bacteria were isolated from poultry feces in two farms in Ibadan and identified by MALDI-TOF. Antibiotic susceptibility patterns of the isolates were determined by disc diffusion and Minimum Inhibitory Concentration (MIC) using Vitek-2 apparatus. Four tetracycline genes and six plasmids mediated quinolone resistance genes (PMQR) were investigated by PCR. Whole genome sequencing was done for strains that were ESBL producers.
Results: Bacterial strains (≥ 105 cfu/mL) were counted on ciprofloxacin and tetracycline supplemented plates. 106 bacteria from 14 different species were identified with high resistance to quinolones, tetracycline and trimethoprim. 49% of the strains were E. coli with 90% resistance for nalidixic acid, moxifloxacin (94%), ciprofloxacin (88%) levofloxacin (78%) and tetracycline (77%). The genes tetA, tetB, qnrB, qnrS and qepA were detected with 37%, 4%, 35%, 4% and 2% prevalence in E. coli respectively. Three ESBL-producing E. coli of the sequence type ST-6359 were found and harboured blaCTX-M-15 located in the chromosome, at the same insertion site. All the ESBL producers harboured mutations in gyrA (S83L/D87N/D678E) and parC (S80I).
Conclusion: The observed high quinolones and tetracycline resistance with ESBL producers in this study calls for caution in the use of these antibiotics in poultry feeds.
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