Resistance to Quinolones Family among Biofilm Producing Escherichia coli Strains Isolated from Patients with Urinary Tract Infection in Zahedan during 2017

Urinary tract infection (UTI) is one of the most common and serious bacterial infections in humans and uropathogenic Escherichia coli (UPEC) strains are responsible for more than 75% of all UTI worldwide. UPEC strains are able to form biofilm which enable them to show resistance to variety of antibiotics such as quinolones which enable them to persist within the urinary tract and serve as a reservoir for recurrent infections. In this study the patterns of quinolone resistance among UPEC strains isolated from patients with UTI in a hospital in Zahedan was determined.

In this study, a total of 81 E. coli isolates were collected from patients with UTI in a referral hospital in Zahedan. Isolates were cultured on MacConkey agar and eosin methylene blue (EMB) agar plates and identified using PCR assay by specific primers of tufA gene. The ability of E. coli strains to form biofilm was measured using qualitative Congo red agar (CRA) assay and susceptibility of strains to 5 antibiotics was determined by disk diffusion method according to the guideline of Clinical and Laboratory Standards Institute (CLSI).

All isolates were positive for tufA gene and confirmed as E. coli strains. Using qualitative CRA agar assay 7, 87 and 6% of strains were able to form rdar, bdar and pdar morphotypes, respectively and were selected as biofilm positive strains. In addition, 18 isolates showed susceptibility to all antibiotics, and 64% were resistant to ciprofloxacin. Moreover, 56, 50, 50 and 48% of strains showed resistance to nalidixic acid, levofloxacin, ofloxacin and norfloxacin, respectively. Moreover, 6 resistance patterns were identified among the strains in which pattern 6 (resistant to all antibiotics tested) was selected as the most prevalent type type in this study.

Results of this study revealed the high prevalence of quinolone resistant and biofilm producing UPEC strains among patients with UTI in the studied hospital in Zahedan.