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Toxigenicity & drug sensitivity of Vibrio mimicus isolated from patients with diarrhoea
1Department of Microbiology, Post Graduate Institute of Basic Medical Sciences, University of Madras.
Abstract:
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.
Insights
Vibrio mimicus strains were isolated from patients with acute diarrhea and found to produce toxins and virulence factors. Some strains showed drug resistance, highlighting the need for V. mimicus screening in diarrheal illness diagnosis.
Area of Science:
- Microbiology
- Bacteriology
- Infectious Diseases
Background:
- Vibrio mimicus is an emerging pathogen causing diarrheal diseases.
- Understanding its virulence factors is crucial for diagnosing and treating infections.
Purpose of the Study:
- To characterize toxin production and virulence factors of V. mimicus strains isolated from patients.
- To assess the antimicrobial resistance patterns of these strains.
Main Methods:
- Isolation and pure culture of V. mimicus from 720 fecal specimens.
- In vitro and in vivo assays to determine toxin types (labile, stable, vascular permeability factor, cytotoxic factor).
- Sereny's test for invasiveness and antimicrobial susceptibility testing.
Main Results:
- 18 V. mimicus strains were isolated.
- 15 strains produced labile toxin, 2 produced stable toxin.
- 15 strains exhibited vascular permeability factor; none were invasive.
- All strains produced a cytotoxic factor.
- 22% of strains were multidrug-resistant.
Conclusions:
- V. mimicus possesses significant virulence factors including toxins and exhibits antimicrobial resistance.
- Continuous screening and identification of V. mimicus are essential for diagnosing acute diarrhea.