A total of 145 Escherichia coli strains causing pyelonephritis in children were investigated for the prevalence of genes encoding the following virulence factors (VFs): P fimbria (67.6 %), S fimbria (53.8 %), AFA adhesins (2.8 %), cytotoxic necrotizing factor 1 (37.9 %), α-hemolysin (41.4 %), and aerobactin (71.7 %). One hundred and thirty-six (93.8 %) isolates harbored at least one of the virulence genes detected in the present study. Statistically significant co-occurrent presence of two VF genes was found for α-hly-cnf1, α-hly-sfa, cnf1-sfa (p<0.001), and α-hly-pap (p=0.001). Twenty-six profiles of VF genes were detected in this study. The combinations of aer-pap and aer-pap-sfa-α-hly-cnf1 were presented with the highest frequency-both of them in 28 isolates (19.3 %). All E. coli strains included in the study were susceptible to meropenem, amikacin, and tobramycin; the highest frequency resistance was found toward ampicillin (43.4 %), piperacillin (31.7 %), tetracycline (15.9 %), and trimethoprim/sulfamethoxazole (11.7 %). The resistance to the other tested antimicrobial drugs did not exceed 3 % incidence. Overall, 55.9 % strains were susceptible to all tested anti-infective agents. Antimicrobial resistance of E. coli strains toward trimethoprim/sulfamethoxazole statistically significantly correlated with the presence of α-hly (p<0.001), sfa (p<0.01), and cnf1 (p<0.05).

Institute of Microbiology Faculty of Medicine Comenius University and University Hospital Bratislava Sasinkova 4 811 08 Bratislava Slovak Republic

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