Virulence, Phylogenetic Grouping, and Antimicrobial Resistance Traits of Extraintestinal Escherichia coli in Clinical Isolates From Northwest Mexico.

Escherichia coli is a highly diverse bacterial species that is canonically commensal; however, its genomic characteristics have enabled its evolution into pathogens capable of causing extraintestinal infections (ExPEC), which pose significant clinical challenges because of the variety of sites that can infect (mainly the urinary tract) and the multidrug resistance associated with these strains. The present study is aimed at characterizing ExPEC isolates recovered from the wards of a hospital in Sinaloa, Mexico, to establish their virulence and antimicrobial resistance profiles, as well as the phylogenetic group. Then, 200 Escherichia coli isolates and their antimicrobial susceptibility were confirmed by the VITEK-2 automated system. Virulence factor genes and phylogenetic grouping were performed through endpoint and multiplex PCRs. Then, 59% of the strains produced extended-spectrum β-lactamases (ESBLs), and 71.5% were classified as multidrug resistant (MDR), exhibiting high resistance rates to antibiotics such as amoxicillin, ampicillin, ciprofloxacin, and various cephalosporins. In this sense, 68.5% and 33% of the isolates were positive for the blaCTX-M1-8 and blaCTX-M9 genes, respectively, both associated with resistance to cefotaxime. Furthermore, 37% of the isolates harbored the blaOXA48 gene, which is linked to resistance to oxacillin-type β-lactams. Moreover, 143 (71.5%) of them were classified as MDR. Regarding virulence, the distribution of toxin genes such as hlyA and vat was 16.5% and 24.5%, respectively. Adhesins papC and fimA were found in 62% and 34%, respectively. Additionally, the iron acquisition systems and outer membrane proteins such as iutA (74%), fyuA (63%), iroN (10%), agn43 (82%), and kpsmTII (34.5%) were present in the isolates. Phylogenetic analysis showed a predominance of group B2 (46%), followed by groups A (13.5%) and E (10.5%). These findings highlight the complexity and challenges posed by ExPEC strains in terms of antimicrobial resistance and virulence relevant to public health in hospital settings.