VIRULENCE MARKERS OF ESCHERICHIA COLI O1 STRAINS

Aim. To detect virulence genes in clinical isolates of Escherichia coli O1 using polymerase chain reaction (PCR). Materials and methods. One hundred and twenty strains of E.coli O1 strains isolated from faeces of patients with acute diarrhea (n=45) and healthy persons (n=75) were studied. PCR with primers for rfb and fliC genes, which control synthesis of O- and H-antigens respectively, was used. Fourteen virulence genes (pap, aaf, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, st, and aer) were detected by PCR primers. K1-antigen was determined by Pastorex Meningo B/E.coli O1 kit (Bio-Rad). Results. rfb gene controlling O-antigen synthesis in serogroup O1 as well as fliC gene controlling synthesis of H7 and K1 antigens were detected in all strains. Thus all E.coli strains had antigenic structure O1:K1:H-:F7. Virulence genes aaf1, sfa, afa, eaeA, bfpA, ial, hly, cnf, stx1, stx2, lt, and st were not detected. All strains owned pap and aer genes regardless of the presence of acute diarrhea symptoms. Conclusion. It was shown that E.coli O1:K1:H-:F7 strains do not have virulence genes which are characteristic for diarrhea-causing Escherichia. In accordance with the presence of pap and aer genes they could be attributed to uropathogenic Escherichia (UPEC) or avianpathogenic Escherichia (APEC). It is necessary to detect virulence factors in order to determine E.coli as a cause of intestinal infection.

PCR, pathogenicity genes