Characterization of Escherichia coli clinical isolates causing urinary tract infections in the community of Chilpancingo, Mexico

Escherichia coli is the main cause of urinary tract infections (UTI) in ambulatory patients, especially strains belonging to the B2 phylogenetic group and ST131 clonal group. Antibiotic treatment is usually administered empirically; however, it is not always effective due to bacterial multidrug resistance and the production of extended spectrum beta-lactamases (ESBLs). The aim of this study was to characterize E. coli clinical isolates from patients with UTI in a community of the State of Guerrero, Mexico. From January to August 2014, 134 clinical isolates of E. coli were recovered. Strain identification and antibiotic susceptibility were performed using the Vitek automated system. Phylogenetic and O25b-ST13 groups were determined by multiple PCR. Identification of the bla(CTX)-(M), bla(TEM), and bla(SHV) genes was performed by conventional PCR. We found that over 50% of the isolates were resistant to betalactams and quinolones, while 0 to 33% were resistant to aminoglycosides and nitrofurans, and 56.49% of the strains were ESBL producers. B2 phylogenetic group was the most predominant (43%) compared to the other groups. The prevalence of bla genes was: bla(CTX-M) 64.3%, bla(SHV) 41.4%, and bla(TEM) 54.3%. These results show a high percentage (55%) of multidrug-resistant strains isolated from UTI patients from the community in the city of Chilpancingo, Guerrero, Mexico.