Plasmid-mediated quinolone resistance genes transfer among enteric bacteria isolated from human and animal sources

• Main Authors: EHWARIEME Daniel Ayobola, WHILIKI Onoriadjeren Oscar, EJUKONEMU Francis Ejovwokoghene
• Format: Article
• Language: English
• Published: AIMS Press 2021-06-01
• Series: AIMS Microbiology
• Subjects: enteric bacteria; quinolones; gene transfer; minimum inhibitory concentration
• Online Access: https://www.aimspress.com/article/doi/10.3934/microbiol.2021013?viewType=HTML

This research investigates the transferability of plasmid-mediated quinolone resistance (PMQR) genes among enteric bacteria isolates in human and animal samples, as well as its implication on resistance of recipient cells. A total of 1,964 strains of five different enteric bacteria species (<i>Escherichia coli, Salmonella sp., Shigella sp., Klebsiella sp</i>. and <i>Aeromonas sp</i>.) were screened for plasmid-mediated quinolone resistance (PMQR) genes from a population of quinolone resistant (Q-r) isolates. Screening for PMQR isolates was achieved by plasmid curing using sub-lethal concentration of Sodium Dodecyl Sulphate and PMQR genes (<i>qnrA</i>, <i>qnrB</i>, <i>qnrS, Aac(6′)-Ib-cr</i>and <i>Qep A</i>) were detected by polymerase chain reaction (PCR). Conjugation and transformation experiments were attempted to ascertain transfer of genes from the Q-r isolates to a susceptible, standard recipient, <i>E. coli</i> J53-2. The minimum inhibitory concentration (MIC) was determined before and after gene transfer, using E-test strips. Results indicate that percentage resistance to the quinolones (Qs): Nalidixic acid, Ciprofloxacin, Pefloxacin and Ofloxacin determined by agar plate diffusion technique stood at 52.6, 47.3, 50.5, 70.6 and 46.0% for <i>Escherichia coli, Salmonella</i> sp., <i>Shigella</i>sp., <i>Klebsiella sp</i>. and <i>Aeromonas sp</i>. respectively. Analysis of variance indicated the occurrence of significant differences (F, 46.77–613.30; 0.00) in the resistance to each tested Qs. Generally, Human isolates showed greater resistance than Animal isolates (57.4 vs 47.2%). Investigation with specific primers indicated 11, 15, 7, 1 and 0 for <i>qnrA, qnrB, qnrS, qepA</i> and <i>Aac(6′)-Ib-cr</i> genes respectively, out of 1018 Q-r and 29 PMQR isolates. Gene transfer experiments indicated the transfer of all genes except <i>qepA</i> either by conjugation or transformation. The MIC of tested Qs on recipient bacterium before gene transfer greatly increased from 0.0625 to 0.25 µg/mL, after transfer. This study demonstrates that PMQR genes amongst enteric bacteria in the Niger delta of Nigeria were transferable and transfer conferred a higher Q- resistance on recipient bacterium.