Summary, One hundred and sixty-eight strains of Escherichia coli were isolated from cases of pyelonephritis (24) and lower urinary tract infections (UTI) (144) from hospitalised and outpatient children up to 2 years old. These strains were investigated for the expression of P fimbriae (PF), mannose-resistant and mannose-sensitive haemagglutination, cell-surface hydrophobicity, serum resistance and the production of a-haemolysin (AH), colicins and aerobactin. PF, AH, aerobactin production and serum resistance were significantly more frequent amongst strains expressing mannose-resistant haemagglutination. PF and AH production was significantly more frequent in pyelonephritogenic strains than in lower UTI strains. Serotypes 0 6 and 0 1 12 were isolated most frequently and plasmids were found in the majority of strains tested.
A B S T R A C TIn total, 201 a-haemolytic Escherichia coli isolates from various clinical materials (urine samples and vaginal and rectal swabs) were examined by PCR for the presence of genes for the virulence factors a-haemolysin (hly), cytotoxic necrotising factor type 1 (cnf1), P-fimbriae (pap), S ⁄ F1C-fimbriae (sfa ⁄ foc), aerobactin (aer) and afimbrial adhesin (afaI). Among vaginal isolates, 96% were positive for cnf1, compared with 80% of urine strains (p 0.02) and 63% of rectal strains (p 0.0001). Similarly, sfa ⁄ focspecific DNA sequences were found in 97% of vaginal isolates compared with 75% of rectal strains (p 0.004). The afa1 and aer genes were associated more with rectal a-haemolytic E. coli strains than with extra-intestinal isolates. The results suggested that CNF1 and ⁄ or S ⁄ F1C-fimbriae contribute to colonisation and persistence of a-haemolytic E. coli strains in the vaginal environment.
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