Molecular Characterization of Ciprofloxacin Resistant Escherichia coli from Ghana

Abstract

Aim: This study aimed to characterize ciprofloxacin-resistance genes in clinical Escherichia coli isolates obtained from a six-month antimicrobial resistance (AMR) surveillance from Ghana. Methods: Eighty-three of 440 archived E. coli isolates were confirmed by biochemical reactions and resistance profiles by the disc diffusion method. These isolates were cultured from urine (42), stool (23), vaginal swabs (12), wounds (5) and heart valve (1) during AMR surveillance. Minimum Inhibition Concentration (MIC) by E-test method was performed on all E. coli isolates that were resistant to ciprofloxacin by the disc diffusion method. Additionally, all isolates with reduced MIC to ciprofloxacin (>32 µg/ml) were selected for molecular assays.  Three chromosomal and nine plasmid-mediated resistance genes were screened in all Ciprofloxacin resistant E. coli (CRE) by polymerase chain reaction (PCR). Randomly selected amplified genes were commercially sequenced and analyzed. Results: In total, 47/83 (56.6%) E. coli isolates were resistant to ciprofloxacin and 29 (61.7%) had MIC values greater than 32 µg/ml. Chromosomal mediated genes (gyrA, gyrB and parC) were present in all 29 CRE isolates (100%). Distribution of the plasmid-mediated genes were as follows; qnrA 16/29 (55.1%), qnrB 16/29(55.1%), qnrC 22/29(75.8%), qnrS 26/29(89.6%), qepA 5/29(17.2%) and oqxB 19/29(65.5%). Genes encoding for altered aminoglycoside acetyltransferase [aac(6’)1bcr] were also present in all 29 CRE isolates. The majority (72.4%) of the CRE isolates had gyrA mutations at codons 83 and 87. In parC, the mutations were at codons 71 and 80. Five isolates had mutations at codon 56 and four each had mutations at positions 79 and 80. Conclusion: In this study, fluoroquinolone resistance genes were identified in all CRE isolates, mostly with putative mutations in the Quinolone Resistance Determining Region (QRDR). These chromosomal and plasmid-mediated genes may be widespread in Ghana and associated with CRE from the AMR surveillance. Although new mutations points were identified in parC, they may not be linked to the CRE.