Drug resistance and virulence of uropathogenic Escherichia coli from Shanghai, China

Uropathogenic Escherichia coli (UPEC) is the major cause of urinary tract infections (UTIs). In the present study, 198 E. coli isolates from patients with UTIs in Shanghai in 2008 were examined by susceptibility testing, with an extremely high number (153/198) showing multidrug resistance (MDR). And, the expression of extended-spectrum β-lactamases (ESBLs) reached 48.5% (96/198). The resistance rates to penicillins, fluoroquinolone, folate pathway inhibitors and first- and second-generation cephalosporins were high. Molecular analyses showed that the CTX-M-9 group (70/96) was the most common CTX-M group among UPEC, followed by the CTX-M-1 group (27/96). Phylogenetic group D accounted for 42.4% (84/198) of the isolates, exhibiting the highest ESBLs (50/84) and MDR (75/84) rates. Virulence genes were present in a significantly high proportion in the phylogenetic group B2 isolates, except for the afaBC gene. The ESBL-producing strains analyzed by pulsed-field gel electrophoresis (PFGE) were clustered into six groups at a cutoff of 67%. Notably, the findings that afaBC was specific to phylogenetic group D and PFGE group I and was correlated with the CTX-M-9 group were different from a previous report. In conclusion, knowledge of antimicrobial resistance data and virulence factors may enable clinicians to tailor empirical antibiotic treatments for UTIs.