Isolation, phenotypic and genotypic characterization of Escherichia coli from the bloodstream samples in Riyadh, Saudi Arabia

Abstract Bacteraemia is an international thread caused by extra-intestinal pathogenic Escherichia coli (ExPEC). Recently, the antimicrobial resistance of ExPEC has increased substantially, and this is attributed to the dissemination of E. coli ST131 clone. The present study explored the antimicrobial susceptibility patterns, extended spectrum β-lactamase (ESBL) carriage, virulence capacity and the prevalence of ST131 clone in Riyadh, Saudi Arabia.Thirty-oneE. coli blood isolates, collected between January 2018 and March 2018. The antimicrobial susceptibility patterns, extended spectrum β-lactamase (ESBL) carriage andvirulence factors were determined for all isolates. The prevalence of ST131 clone was determined based on the PCR assays. Twenty-eight (90.3%) of all tested isolates were resistant to ampicillin, while only 1 isolate (3.2%) showed resistance to imipenem. Sixteen (51.6%) of the all isolates were ESBL producers, with CTX-M-15 being the predominant ESBL type. The virulence potential was higher among ESBL-producing isolates. Overall, seventeen (54.8%) isolates belonged to the ST131 clone. ST131 isolates were associated with increased antibiotic resistance; ESBL carriage and virulence capacity compared to non ST131isolates.This study reported the high levels of antimicrobial resistance and ESBL carriage among ExPEC blood isolates. It is concluded that the prevalence of ST131 clone among E. coli blood population locally, and found high virulence potential and antimicrobial resistance levels among ST131 isolates. These might drive ST131 success as a major cause of bacteraemia worldwide.