Introducing a diagnostic test for Non-O157 verocytotoxin escherichia coli in stools of patients.

Abstract

Escherichia coli is a Gram-negative rod which belongs to the Enterobacteriaceae family. Several stains of this bacterium exist but the most predominant is the 0 157 serogroup. Recently, other serogroups have become important, since these can also cause several symptoms, which may vary from non-bloody diarrhoea, to diarrhoea with dysentery including mucus and leucocytes. Escherichia coli is a member of the normal flora of the gastrointestinal tract. It colonizes this tract within the first few hours of the newborn's life. This commensal can acquire virulence factors and turn into an Enteropathogenic Escherichia coli. This pathogenic organism can be attacked by a bacteriophage which will react with its DNA and turn it into a veroctytoxin-producing Escherichia coli (VTEC). In this state, this organism can cause several severe symptoms including the Haemolytic Uraemic Syndrome. In this study, all samples received in the laboratory, from the beginning of August, 2005 till the end of November of the same year were used for this purpose. These were tested against a polyvalent antiserum to detect specific Escherichia coli cell walls. All positive polyvalent strains were tested against six different serogroups to see under which group they fell. Then, all serogroups were subjected to a toxin test to detect whether any strain had reached the verocytotoxin-producing stage. Through all this testing it was determined that the most predominant serogroup was 0 26 and it was found mainly in the children's ward- Disneyland. All toxin tests carried out proved to be negative. This meant that no strain had become verocytotoxin-producing. This was somewhat expected, due to the fact that an average of 2 cases a year are found of the serogroup 0 157 VTEC, which is by far more commonly encountered than the other serogroups tested for in this dissertation.