Phylogenetic Distribution of Virulence Genes Among ESBL-producing Uropathogenic Escherichia coli Isolated from Long-term Hospitalized Patients.

OBJECTIVES

The present study was aimed to investigate the antibiotic resistance, virulence potential and phylogenetic grouping of ESBL-producing uropathogenic Escherichia coli (EP-UPEC) isolated from long-term hospitalized patients.

MATERIALS AND

METHODS

EP-UPEC isolates from September 2013 to June 2014 at a tertiary care hospital of China were screened for ESBL-production by the double disk diffusion test. Isolates with ESBL-phenotype were further characterized by antibiotic resistance testing, PCR of different ESBL and virulence genes, and phylogenetic grouping.

RESULTS

One hundred and twenty EP-UPEC were isolated from long-term hospitalized patients. All EP-UPEC isolates were resistant to Ampicillin, Cefazolin, Cefuroxime, Cefotaxime, Cefoperazone and Ceftriaxone, and the majority of EP-UPEC isolates were resistant to Piperacillin (82.5%), Ciprofloxacin (81.2%), Trimethoprim-Sulfamethoxazole (72.5%). The isolates showed the highest sensitivity against Imipenem (98.4%), Piperacillin/tazobactam (96.7%), Cefoperazone/sulbactam (91.7%), Amikacin (90.8%) and Cefepime (75.8%). Nine different ESBL genotype patterns were observed and CTX-M type was the most prevalent ESBL genotype (42.5%, 51/120). Majority of EP-UPEC isolates possess more than one ESBL genes. EP-UPEC isolates belonged mainly to phylogenetic group B2(36.7%) and D(35.0%). The prevalence of traT, ompT, iss, PAI, afa, fimH and papC were 75.8%, 63.3%, 63.3%, 60.8%, 40.8%, 19.2% and 6.7%, respectively. The number of virulence genes (VGs) detected was significantly higher in group B2 than in group A (ANOVA, p<0.001), group B1(ANOVA, p= 0.012) and D (ANOVA, p<0.001).

CONCLUSIONS

EP-UPEC strains showed multidrug resistance and co-resistance to other non β-lactam antibiotics. CTX-M was the most prevalent ESBL genotype and majority of EP-UPEC strains more than one ESBL genes. EP-UPEC strains belonged mainly to phylogenetic group B2 and D, and most of the virulence genes were more prevalent in group B2.