Molecular typing of fluoroquinolone resistant Escherichia coli isolates from patients undergoing prostate biopsy

Escherichia coli (E. coli) is one of the most important infectious agents in patients undergoing prostate biopsy. It belongs to a large family of gram-negative rods, Enterobacteriaceae. This family includes members of the normal flora of the intestine that are only occasionally pathogenic. Recent considerations of rectal colonization with fluoroquinolone-resistant E. coli shows the need to change strategy of treatment of infection in patients undergoing prostate biopsy. Therefore, the purpose of this study was to determine molecular typing of fluoroquinolone resistant (FQR) E. coli rectal isolates and associated infections in patients undergoing prostate biopsy. In this prospective cohort study, rectal swabs were collected from 158 male patients before prostate biopsy at the Urology Research Center of Sina Hospital, Tehran, Iran, from March 2015 to February 2016. The FQR organisms were isolated using selective media, and antibiotic susceptibility pattern was determined for following antibiotics, ampicillin, levofloxacin, cotrimoxazole, amoxicillin-clavulanate, cefazolin, ceftazidime, cefepime, gentamicin, piperacillin-tazobactam, nitrofurantoin, amikacin, fosfomycin, imipenem. In general, phylogenetic background, prevalence of E. coli sequence type 131 (ST131) and its subclones (H30 and H30-Rx ST131) were compared in two groups of FQR E. coli rectal colonization and clinical isolates. In total, 73 patients had a positive rectal culture for FQR gram-negative bacteria, the most prevalent isolate of which was E. coli. Phylogenetic group B2 was most predominant, followed by A, E, C and D, B1 and F. The antibiotic susceptibility patterns for the FQR organisms showed high levels of resistance to ampicillin and trimethoprim-sulfamethoxazole, while the resistance to amikacin, fosfomycin and imipenem remained very low. In general, antibiotic resistance to several antibiotic was mainly detected in group B2 and with ST131 genotype. Despite the increase in infections among patients colonized with strains of E. coli ST131, its frequency was almost statistically significant between colonized and infected groups. The ST131 pathogen has a high prevalence in rectal colonization and post prostate biopsy infections, which showed widespread resistance to common antibiotics.