Expression of virulence and antimicrobial resistance genes among Escherichia coli clinical isolates from blood and stool samples

Objective: As major nosocomial pathogens, Escherichia coli isolates exhibit antibiotic resistance and also express adhesive structures and antibiotic resistance genes. The objective of this study was the comparison of virulence gene expression of extended-spectrum beta-lactamase (ESBL)-producing E. coli between blood and stool samples. Methods: In this study, 20 E. coli clinical isolates (10 ESBL-producers including 5 from blood, 5 from stool samples and 10 non-ESBL-producer strains) were included. The existence of fimA, kpsMII and cdt (adhesives and toxin), acr-ab (efflux-encoding) and bla CTX-M1 genes were confirmed by PCR. The quantitative real-time PCR was performed for evaluation of gene expression. Results: ESBL-producing E. coli isolates from stool samples could express fimA, kpsMII and cdt genes significantly higher than blood samples, whereas those isolates from blood samples significantly expressed the acr-ab (efflux-encoding) genes. In addition, the bla CTXM1 gene was expressed among isolates from stool samples significantly higher (P = 0.022) than those from blood samples according to the analysis of variance (ANOVA) test. In addition, among non-ESBL-producers, the expression of fimA, kpsMII and cdt genes was significantly lower than ESBL-producing isolates from blood samples, but not significantly different than those from stool samples. Moreover, the expression of acr-ab genes was significantly lower than those from stool samples. Conclusion: The results exhibited that the expression of virulence genes among clinical isolates of E. coli is not the same or similar in various conditions or from various clinical origins. Thus determining the profile of gene expression in each of clinical situations can be helpful in tracking the infectious pathogens. ESBL-producing strains possibly have regulatory factors for inducing higher virulence gene expression.