Toxigenicity & drug sensitivity of Vibrio mimicus isolated from patients with diarrhoea.

In a total of 720 faecal specimens from patients with secretory diarrhoea, vomiting, dehydration, gastroenteritis, cholera and cholera like illnesses, 18 strains of V. mimicus were isolated as pure culture. These were characterized for various toxin types and virulence factors using conventional in vitro and in vivo assays. Labile and stable toxins were elaborated by 15 and 2 strains respectively by ligated rabbit ileal loop (RIL) and suckling mouse assays. While 15 of the whole cell culture elaborated labile toxin, only 7 strains produced the same when culture filtrate was tested in RIL assay. Culture filtrates of 15 strains exhibited vascular permeability factor (PF) on adult rabbit skin, none of the strains were invasive as indicated by Sereny's test. Culture supernatants of all strains produced a cytotoxic factor to Vero and Chinese hamster ovary cells. Four of the 18 strains (22%) were resistant to multiple drugs (a combination of 3 or more drugs). The results emphasize the significance of continuous screening and identification of V. mimicus and to include in the differential diagnosis of patients with acute diarrhoea.

A retrospective analysis of the Madras epidemic of non-01 Vibrio cholerae new serogroup 0139 Bengal.

During the recent epidemic of cholera in Madras from October-December 1992, a total of 11,100 patients with acute secretory diarrhoea have been admitted to the Communicable Diseases Hospital, Madras, when compared to a total of 2,440 patients admitted during the pre-epidemic period studied between January - September 1992. A novel strain of non-01 V. cholerae was found to be the most predominant agent during the epidemic period. A representative sample of 84 non-01 strains isolated during the epidemic period were confirmed as V. cholerae non-01 and newly designated as serogroup 0139 at National Institute of Cholera and Enteric Diseases, Calcutta. All 84 strains of non-01 were found to elaborate cholera toxin (CT). Fourteen strains were also confirmed as serogroup 0139 from our non-01 stock recovered during the pre-epidemic period. Of the 17,540 patients admitted during the post epidemic period, studied from January 1993 - June 1994, 3.8 and 37.8 per cent patients were infected by 01 and non-01 serogroup 0139 respectively. The new serogroup 0139 continued to be the predominant isolate even during the post epidemic period.