Computerized complex typing of Escherichia coli strains from different clinical materials

A multivariate analysis of 3334 Escherichia coli strains originating from different clinical materials revealed that 50.2% of isolates belonged to the most common 12 (O1, O2, O4, O6, O7, O8, O15, O18, O45, O75, O78, O83) out of 133 serogroups. Haemolysin (Hly) production, mannose resistant haemagglutinating activity for human erythrocytes (MRHA) and colicinogenicity (Col) were recorded in 30, 30 and 36%, respectively. Antigens K1 and K5 were present in 11% and 6.6%, respectively. Association were found among certain serotypes and virulence markers (O1, H-, H7, K1, MRHA, Col; O2, H-, Kl, Col; O4, H-, H5, MRHA, Hly; O6, H-, H1, MRHA, Hly; O6, K5, MRHA, Col; O7, H-, H4, K1, MRHA, Col; O18ac, H7, K1, Col; O18ac, H-, K5, MRHA, Hly; O78, H-, Col (V-type); O83, H-, K1, Col). There were associations among clinical specimens, age of patients, nosocomial group of diseases, serogroups and virulence markers, too (cerebrospinal fluid-CSF-O7, O18ac, O45, O83-K1-newborn meningitis; O78-ColV-meningitis, sepsis, inflammations diseases of premature babies; CFS-O6, MRHA, Hly-adult-meningitis, sepsis, urinary tract infection-UTI-, pneumonia, other inflammatory diseases; blood-O2, O4, O6, O18ac, ONT, K5, MRHA, Hly-sepsis, UTI, hepatic diseases; urine-O1, O2, O4, O6, O18ac, O75, virulence markers fall to differ among upper and lower UTI; faeces-O1, O4, O6, O18ac, O78, virulence markers rare). Associations were also found among animal pathogenicity tests, specimens, serogroups and virulence factors: highly virulent group strains (i.e. LD50 below 10(6)) belonged to serogroups O2, O6, O18ac, possessed antigen K1 (less frequently the presence of MRHA, Hly, K5) and originated mainly from CSF. With mouse lung toxicity test correlations of serogroups (O4, O6, O18ac), antigen K5, MRHA, Hly and specimens (blood) were also shown. However, association was found between the lack of virulence factors and phage insensitivity and also between K5 positivity and sensitivity to phages 16, 17, there were no correlations between serogroups and phage patterns. On the basis of the above-described associations one can find correlations among virulence markers, serotype, and nosological group of diseases. Animal pathogenicity tests give additional data in understanding the pathomechanism of diseases. Correlations between phage patterns and serogroups reveal certain epidemiological relatedness and also virulence of strains.