Virulence characteristics and antibiotic susceptibility of vibrio cholera in low quality water, fish and vegetables in Morogoro, Tanzania

Abstract

Cholera, one of the world’s deadliest infectious diseases, remains rampant and frequent in Tanzaniaand thus thwartexisting control measures. The current study wasundertaken to evaluate the occurrence of toxigenic Vibrio cholerae in low quality water, fish and vegetables during the non-outbreak period in Morogoro, Tanzania. From October 2014 to February 2015, 60 wastewater samples, 60 fish samples from sewage stabilization ponds and 60 vegetable samples were collected. Samples were subjected to bacteriological analyses for identification of V. choleraeand confirmed by detection of the outer membrane protein (OmpW) by Polymerase Chain Reaction (PCR). The isolates were then tested for antibiotic susceptibility and forvirulence genes including, cholera enterotoxin gene (ctx), the toxin co-regulated pilus gene (tcpA), toxin regulatory protein (ToxR) and the haemolysin gene (hlyA). The proportion of contamination ofV. choleraein wastewater, vegetables and fish was 36.7%, 21.7% and 23.3% respectively.Two isolates from fish gills wereV. cholerae O1 and tested positive for ctx and tcpA.One of them contained in addition the hlyA gene while 5isolates from fish intestines tested positive for tcpA.The V. cholerae isolates displayed a strong resistance to Ampicillin and Amoxicillin followed by a moderate resistance to Tetracycline. However, they were susceptible to Gentamicin, Chloramphenicol and Ciprofloxacin.It is concluded that pathogenic, toxigenic and antibiotic resistant V. cholerae species are present and persist in aquatic environments and can be isolated even during the non-outbreak periods. This is of serious public health importance and one of the great challengestoCholera control programmes.