Prevalence of ST131 Clone Producing Both ESBL CTX-M-15 and AAC(6')Ib-cr Among Ciprofloxacin-Resistant Escherichia coli Isolates from Yemen

Abstract

Objective: The aim of this study was to characterize the O25b/ST131 clone in ciprofloxacin-resistant Escherichia coli isolates from Yemen. Materials and Methods: A total of 41 ciprofloxacin-resistant E. coli strains were collected from clinical samples of inpatients and outpatients from Sana'a (Yemen) from January to December 2013. Antimicrobial susceptibility testing, polymerase chain reaction amplification, and sequencing were used for detection of plasmid-mediated quinolone resistance determinants, extended-spectrum beta-lactamases genes and mutations in the quinolone resistance-determining regions of the target genes gyrA and parC. Genetic relatedness of E. coli isolates was determined by pulsed-field gel electrophoresis (PFGE). O25b/ST131 clone detection was performed using polymerase chain reaction of O25b rfb and allele 3 of the pabB gene and by a multilocus sequence typing. Results: All E. coli isolates contained the aac(6')Ib-cr gene associated with bla_CTX-M-15 and qnrS genes in 63.4% and 12.2%, respectively. A rate of 36.6% (15/41) of O25b/ST131 E. coli isolates were identified belonging to the H30-Rx subclone producing both CTX-M-15 and Aac(6')Ib-cr enzymes and carrying two substitutions in GyrA (Ser83Leu/Asp87Asn) and two substitutions in ParC (Ser80Ile/Glu84Val). Most of them were uropathogenic unrelated E. coli isolates recovered from outpatients. Conclusion: This is the first report of a high prevalence of E. coli O25b/ST131 from Yemen.

Keywords: Aac(6′)Ib-cr; CTX-M-15; E. coli,; O25b-ST131; Yemen.