Prevalence, pathogenic markers and antibiotic susceptibility of vibrio cholerae in sardines, water and phytoplankton in Lake Tanganyika, Tanzania

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Sokoine University of Agriculture


Cholera is an epidemic disease of major global and public health significance. A cholera outbreak in Kigoma region of Tanzania is reported to be endemic as it occurs almost every year. The aim of this study was to investigate the prevalence, pathogenic markers and antibiotic susceptibility of Vibrio cholerae in sardines, water and phytoplankton in Lake Tanganyika. A total of 120 samples from sardines, water and phytoplankton were collected from October, 2015 to February, 2016. Isolation of V. cholerae was carried out as per Tanzania Bureau Standards (2002). All isolates were subjected to PCR for confirmation by detecting the outer membrane protein (ompW). Virulence genes were detected using molecular methods by targeting cholera enterotoxin gene (ctx), the toxin co-regulated pilus gene (tcpA), the toxin regulatory protein (toxR) and the haemolysin gene (hlyA). Then, the isolates were tested for antibiotic susceptibility using antibiotic discs with Ampicillin, Chloramphenicol, Ciprofloxacin, Gentamycin, Amoxicillin and Tetracycline. The findings showed that, 9% (n = 66) of the sardines samples and 3% (n=30) of the water sample harboured V. cholerae O1. Vibrio cholerae was not detected and isolated in phytoplankton samples (n = 24). One Isolate from water samples harboured both toxR and hlyA, but not ctx and tcpA. Vibrio cholerae isolates were resistant to Ampicillin (83.33%), Amoxicillin (100%), Chloramphenicol (50%) and Tetracycline (100%). All of the isolates were susceptible to Gentamicin and Ciprofloxacin. Generally the study concludes that sardines and water are important reservoirs of V. cholerae. Regardless the absence of ctx and tcpA, monitoring for V. cholerae should be done as they pose threat to human health. Prevention and control regimes should take into considerations the type of antibiotics to be used based on the level of resistance observed in this study.


Masters Thesis


Pathogenic markers, Antibiotic susceptibility, Vibrio cholera, Sardines, Phytoplankton, Lake Tanganyika, Tanzania