Nahid Hosseinzadeh-sohi - Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Shahin Najar-Peerayeh - Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Bita Bakhshi - Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran

Background and Aim : Gastrointestinal colonization of ESBL-producing bacteria is a worldwide concern nowadays, especially among high-risk patients. This study aimed to assess the prevalence of fecal carriage of extended-spectrum B-lactamase (ESBL)-producing Escherichia coli in dialysis patients.Methods : From January ۲۰۱۸ to May ۲۰۱۹, ۱۵۰ fecal samples were collected in the dialyze ward of a hospital in Tehran. Fecal samples were diluted in saline and cultured on MacConkey agar plates including cefotaxime(۳۰μg) and ceftazidime(۳۰μ) disks. Colonies growing in the inhibition zone of each disk were screened for the presence of ESBLs. Antibiotic susceptibility testing was done by the disk diffusion method. PCR was used for detecting the presence of blaCTX-M-۱, blaTEM, and blaSHV genes.Results : The total prevalence of ESBLs carriage was ۵۰% (۷۵/۱۵۰). The most frequent gene was blaCTX-M-۱ (۸۱.۴%). Seventeen isolates co-harbored blaCTX-M-۱ and blaTEM, one isolates co-harbored blaTEM and blaSHV and two isolates co-harbored blaCTX-M-۱, blaTEM and blaSHV. Fifty-three isolates carried a single gene, including blaCTX-M-۱ in ۴۳ isolates, blaTEM in ۶ isolates, and blaSHV in ۴ isolates. ۷ isolates did not harbor any of the ۳ genes. The highest rates of resistance belonged to cefalotin (۹۸.۹%), cefotaxime (۹۴.۷%), aztreonam (۸۳.۱%), ceftazidime (۷۸.۹%). The lowest rates were seen for fosfomycin (۳.۱۵%), meropenem and imipenem (۱.۰۵%). ۹۶.۸% of isolates were multidrug-resistant.Conclusion : These results demonstrate highly carriage rate of ESBLs in dialysis patients. Therefore, active surveillance will be useful for reducing the transmission of antimicrobial-resistant bacteria and preventing infection.

Escherichia coli, ESBLs, Intestinal carriage, CTX-M-۱