Genotypic Diversity and Characterization of Quinolone Resistant Determinants from Enterobacteriaceae in Yaoundé, Cameroon

Abstract

Background: Enterobacteriaceae causes many types of infections which are often treated with quinolones and fluoroquinolone (Q/FQ). The resistance mechanisms to Q/FQ are usually associated with mutations in the quinolone resistance determining region which alter the conformation of target amino acid residues within the protein and in the qnr genes. This study aimed at determining the antimicrobial resistant profile of a sample of Enterobacteriaceae from Cameroon and the genetic diversity in quinolone-resistant isolates in view of implementing a better management, treatment, control and prevention of the transmission of these resistant strains. Methods: Identification and antimicrobial susceptibility testing was done using VITEK 2. The detection of plamid-mediated quinolone resistance (PMQR) genes was carried out using the conventional PCR method. Sequencing was done using the Applied Biosystem 3500 genetic analyser. DNA fingerprint was obtained using Pulsed-Field Gel electrophoresis. Results: Among 440 Enterobacteriaceae, the most prevalent genera were: Escherichia 178/440 (39.5%); Klebsiella 148/440 (33.6%); Enterobacter 35/440 (8%); Pantoea 28/440 (6.4%); Proteus 14/440 (3.2%) Salmonella 13/440 (3%). Ampicillin resistance showed the highest prevalence with 371/440 (81%) and Imipenem the lowest resistance 9/440 (2.1%). The ciprofloxacin resistance rate was 161/440 (36.6%). The detected plasmid mediated quinolone resistance (PMQR) genes were: qnrA, 2/161 (1.2%); qnrB, 31/161 (19.3%); qnrS, 13/161 (8.1%): Aac (6')Ib-cr, 84/161 (52.2%) and qepA, 3/161 (1.9%). There were several mutations in the parC gene of Klebsiella leading to S80D and S80N substitutions. Two pairs of Klebsiella peumoniae strains were phenotypically and genotypically identical with 100% similarity in the dendrogramme. Conclusion: This study showed that quinolone resistance was high. The PMQR genes contributing to this resistance were diverse. This high PMQR indicates that there has been an unknown circulation of these genes in our community. To avoid the rapid dissemination of these PMQR genes continuous surveillance of antimicrobial resistance should be carried out not only in humans but also in animals to monitor the evolution of these genes.