molecular analysis of fosfomycin resistance among escherichia coliisolates from urinary tract infections in kidney transplant patientsduring 2019 - 2020

Background: this study aimed to estimate the prevalence of fosfomycin resistance and the frequency of extended-spectrumbeta-lactamase (esbl) production in escherichia coli isolates from three kidney transplant patients (ktps) in tehran.methods: sixty clinical isolates of uropathogenic e. coli were collected from three kidney transplant centers in tehran between apriland may 2019. antimicrobial susceptibility testing (ast), minimum inhibitory concentration (mic) of fosfomycin, and screeningfor esbl production were conducted following the protocols established by the clinical and laboratory standards institute (clsi).the presence of the blatem, blashv, blactx-m, fosa3, and fosc2 genes was evaluated using polymerase chain reaction (pcr) andsequencing. additionally, mutations in the mura, glpt, uhpt, and cya genes were assessed. the activity of the carbohydratephosphate transporter was measured using the real-time pcr assay.results: according to the ast results, ampicillin showed the highest resistance rate (86%), while ertapenem and doripenemexhibited complete susceptibility (100%). according to the e-test, 1.6% of e. coli isolates were resistant to fosfomycin. furthermore,33.4% of e. coli isolates in ktps were esbl producers, with the most frequent occurrence of the blatem gene (55%). additionally,mutations were identified in the mura, uhpt, and glpt genes of resistant samples. no plasmid genes for fosa3 and fosc2 weredetected. the expression of the uhpt gene increased 32-fold in a susceptible isolate, as determined by qpcr.conclusions: the high resistance of e. coli isolates from urinary tract infections (utis) of ktps to -lactam antibiotics remainsa significant clinical challenge. however, no correlation was found between esbl production and resistance to fosfomycin. theresistance rate to fosfomycin was low, and the primary cause of resistance was mutations in chromosomal genes.