Transformation mediated transfer of Extended Spectrum Beta lactamases (ESBLs) and Sul 1 genes obtained from trimethoprim-sulfamethoxazole resistant (TSR) Escherichia coli and Pseudomonas aeruginosa clinical isolates

Background: Plasmid mediated Multi-Drug Resistant (MDR) Sul and ESBL resistance genes are major threats due to their ability to be transferred horizontally in any environment. In this study, the prevalence of Sul1 gene and ESBL genes (blaCTX-M, blaTEM or blaSHV) in E. coli and P. aeruginosa and their capacity to transfer resistance through transformation were determined. Methods: Ninety-two TSR isolates belonging to E. coli and P. aeruginosa species were obtained from clinical samples such as urine, wound and blood from patients in 3 government hospitals in Delta State, Nigeria. Resistance to antimicrobial agents was determined by disc diffusion methods. PCR amplification was performed on extracted plasmid DNAs for the detection of ESBL and Sul1 genes using specific primers. Extracted plasmid DNAs of ESBL producing and Sul1 positive isolates were used as donors in a CaCl2 competent E. coli K-12 recipient cell via transformation experiment. Results: All 92 TSR isolates were MDR with a vast majority of resistant patterns associated with the cephalosporins, amoxicillin-clavulanic acid and the fluoroquinolones. Sul1 gene and ESBL genotypes were produced in 29.3% and 58.7% isolates, respectively. E. coli was a more prevalent ESBL producer (75.9%) than P. aeruginosa (24.1%) and the blaCTX-M was the most prevalent gene (30.4%). Conclusion: Twenty-three isolates transferred several antibiotic resistances, Sul1 gene and ESBL genotypes by transformation, thereby indicating a high potential for dissemination of resistance markers in hospitals. These findings are of health concern because of the rise in antimicrobial resistance associated with ESBL isolates.