DIAGNOSIS OF INFECTIONS WITH SHIGA-LIKE TOXIN-PRODUCING ESCHERICHIA-COLI BY USE OF ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR SHIGA-LIKE TOXINSON CULTURED STOOL SAMPLES

Shiga-like toxin-producing (SLT) Escherichia coil, particularly those belonging to serogroup O157, are responsible for haemorrhagic colitis, haemolytic uraemic syndrome and some cases of gastro-enteritis. The r apid and reliable diagnosis of all these infections is necessary for c orrect patient management and for epidemiological reasons, but is rare ly possible with present methods. We compared the efficacy of two meth ods, (i) the culture of faeces in broth that contained mitomycin C. fo llowed by enzyme-linked immunosorbent assay (ELISA) for SLTs, and (ii) the culture of faeces on sorbitol MacConkey agar (SMA), in the detect ion of infections caused by SLT-producing E. coil. SLT-producing E. co il O157 strains were isolated on SMA from 42 of 475 faecal samples, bu t SLTs were detected by ELISA in culture supernates or lysates of 54 o f 475 samples. SLT-producing E. coli strains were isolated subsequentl y from 11 of 12 ELISA-positive, SMA culture-negative samples by a colo ny blot technique. In four cases, SLT-producing E. coil of serogroups other than O157 were isolated and in seven cases E. coli O157 was isol ated in small numbers. The ELISA is a rapid and sensitive technique fo r the diagnosis of SLT-producing E. coil infection, especially where l ow numbers of the organism are present in faeces and when the infectio n is caused by a serogroup other than O157.