Detection of QnrS Genes in E. coli from Clinical Isolates in Bayelsa State, Nigeria

Abstract

Escherichia coli (E. coli), is a Gram-negative rod known to be a member of the normal flora of both humans and animals. E. coli belong to the family of Enterobacteriaceae. It is characterized by its oxidase activity, motility, lactose, glucose and sucrose fermentation property. It grows well at a temperature of 37C and a pH of 6.0-7.0. Resistance occurs when an antibiotic is no longer effective in inhibiting the growth of and killing bacteria. Quinolone are a group of synthetic wide-spectrum antibiotic that are used in the treatment of several infections caused by members of the Enterobacteriaceae especially E. coli. Quinolone resistance gene, such as qnrA, qnrB and qnrS are the three main classes of qnr determinants which have been identified in several members of Enterobacteriaceae family such as E. coli and K. pneumonia. Plasmid-mediated quinolone resistance is mediated by the genes (qnr)encoding proteins that belong to the pentapeptied repeat family and protect DNA gyrase and topoisomerase IV against quinolone compounds this study was to detect the presence of qnrS gene in E. coli from clinical isolates using standard microbiology methods. These methods were based on macroscopic and microscopic characteristics, biochemical testing, API 20E, antimicrobial susceptibility testing with Gentamycin, Cefuroxime, Augmentin, septrin, Streptomycin, Ceporex, Nalidixic acid, Ciprofloxacin, Ofloxacin, Nitrofurantoin, and Meropenem and Polymerase chain Reaction (PCR) technique. A total fifty (50) clinical isolates were collected from Niger University Teaching Hospital, Okolobiri. These isolates were from urine, blood, stool, sputum, wound swab and High vaginal swab from both males and females. Out of the 50 isolates, 18(36%) were from males while 32(64%) were from females. Of the 50 isolates from these samples 15(30%) was K. Pneumonia, 11(22%) P. aeruginosa, 8(16%) C. freudii, 9(18%) E. coli and 7(14%) P. mirabilis. Out of the 50 isolates,9(18%) E. coli were recovered and subjected to PCR amplification using specific primers after extraction of DNA from the isolates, 8(88.8%) were positive to qnrS gene. Susceptibility rates of E. coli to antibiotics was highest in Cefuroxime and Augmentin 9(100%), Gentamycin and Ofloxacin 5(55.56%) and Ciprofloxacin 1(11.11%) respectively. In conclusion, this study reveals a high prevalence of qnrS gene among E. coli from clinical isolates from NDUTH, Okolobiri. Therefore, more studies should be done for early detection of resistance quinolone gene that could help in early diagnosis and modification of quinolone with a wider spectrum of activity and improve treatment.