LABORATORY ERRORS FOR IDENTIFICATION OF THE ESCHERICHIA COLI STRAINS OF THE SEROLOGICAL GROUPS O6 AND O25 AS ACUTE INTESTINAL INFECTIONS

Were studied the genes encoding the virulence factors of 221 strains: E. coli O6:H1 (194) and E. coli O25:H4 (27), isolated in 2014-2018 from stool samples of children and adults examined according to epidemic indications. Molecular methods included PCR with hybridization-fluorescence and electrophoresis detection of amplified products. The strains did not have virulence genes for diarrheagenic E. coli (DEC) pathogroups EPEC, ETEC, EIEC, EHEC, EAggEC, and belonged to the phylogenetic group B2. They contained from four to eight genes encoding virulence factors of ExPEC: E. coli O6:H1 - pap (68,6%), sfa (87,6%), fimH (96,4%), hly (62,4%), cnf (74,7%), iutA (97,9%), fyuA (95,9%), chu (100%); E. coli O25:H4 - pap (66,7%), afa (22,2%), fimH (100%), hly (44,4%), cnf (44,4%), iutA (100%) , fyuA (100%), chu (100%). The antimicrobial susceptibility testing to 6 classes of antimicrobials (beta-lactams, fluoroquinolones, aminoglycosides, nitrofurantoin, sulfanilamide, trimethoprim / sulfamethoxazole) according the EUCAST. 60,3% of E. coli O6:H1 were sensitive to antibiotics, E. coli O25:H4 remained sensitive to carbapenems and nitrofurans. Extended-spectrum cephalosporins resistance was due to the production ESBL (CTX-M). The 57,1% resistant strains of E. coli O6:H1 and 100% of E. coli O25:H4 strains belonged to the MDR phenotype. The XDR phenotype had one in five MDR strains of E. coli O6:H1 and E. coli O25:H4. All strains of E. coli O25:H4 belonged to ST131. Given the important role of E. coli in human pathology, detection of virulence genes should be performed to confirm the etiological significance of the isolated strain.