Enterotoxigenicity screening of viable environmental Vibrio cholerae strains from rainwater pools in a university campus in Chennai, South India

Abstract

Background: Vibrio spp., being primarily inhabitants of the aquatic environment, pose a severe health threat to humans. This problem is escalated in developing countries where water-logging after rainfall is very common. Therefore, screening of environmental water samples for the presence of clinically important species of Vibrio becomes essential. Methods: This study was conducted for a period of 1 y. Water samples were collected every month from 4 locations where water pools formed after rains, on the campus of a university in Chennai, South India. The water samples were monitored for Vibrio species, and characterized isolates were screened for enterotoxigenicity. Results: Thirty isolates of Vibrio cholerae belonging to a variety of serogroups and 11 strains of Vibrio species other than cholerae were isolated from the rainwater pools. On polymerase chain reaction (PCR) screening, while all the strains were positive for the ompW gene, none tested positive for the ctxA gene. Conclusions: Though all the environmental isolates of V. cholerae were non-epidemic, 4 isolates demonstrated enterotoxigenicity by rabbit ileal loop method and antibiotic resistance to drugs. This is of concern and underscores the importance of screening environmental specimens and improving civic infrastructure to prevent prolonged water-logging in developing countries.

Keywords::

• Cholera
• Vibrio
• Vibrio cholerae
• enterotoxin

Acknowledgements

The authors cordially thank the students and staff of the Department of Microbiology, Dr A.L.M. Postgraduate Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai for their continuous support and cooperation.

Declaration of interest: No conflict of interest.