1. Introduction
Cholera is a water borne disease that not only continues to be a major public health problem in most of the developing countries but also is re-emerging in many places of the world from where it disappeared long ago [1]. Cholera, which is caused primarily by Vibrio cholerae strains belonging to the serogroup O1 and O139, is transmitted by the faecal–oral route. The dose for infection of V. cholerae is generally higher than that for other pathogens because of its poor acid tolerance in the stomach [2]. After its passage through the hostile environment of the stomach, surviving bacteria colonise the small intestine and produce cholera toxin leading to severe dehydration and shock in most of the cases. About half of the affected individuals would die without adequate and appropriate rehydration therapy [3]. Although oral rehydration remains the primary line of treatment, antibiotics are often used as an adjunct therapy as they shorten the duration of the disease. The emergence of multiple drug resistant strains of V. cholerae is thus a cause for global concern [4] and [5] and is prompting the exploration for alternative ways of treatment.