Occurrence of virulence determinants in vibrio cholerae, vibrio mimicus, vibrio alginolyticus, and vibrio parahaemolyticus isolates from important water resources of Eastern Cape, South Africa
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Date
2023
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Journal ISSN
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Publisher
BioMed Central
Abstract
Background: Virulence determinants are crucial to the risk assessment of pathogens in an environment. This study
investigated the presence of eleven key virulence-associated genes in Vibrio cholerae (n=111) and Vibrio mimicus
(n=22) and eight virulence determinants in Vibrio alginolyticus (n=65) and Vibrio parahaemolyticus (n=17) isolated
from six important water resources in Eastern Cape, South Africa, using PCR techniques. The multiple virulence gene
indexes (MVGI) for sampling sites and isolates as well as hotspots for potential vibriosis outbreaks among sampling
sites were determined statistically based on the comparison of MVGI.
Result: The PCR assay showed that all the V. cholerae isolates belong to non-O1/non-O139 serogroups. Of the isolates,
Vibrio Cholera (84%), V. mimicus (73%), V. alginolyticus (91%) and V. parahaemolyticus (100%) isolates harboured at least
one of the virulence-associated genes investigated. The virulence gene combinations detected in isolates varied at
sampling site and across sites. Typical virulence-associated determinants of V. cholerae were detected in V. mimicus
while that of V. parahaemolyticus were detected in V. alginolyticus. The isolates with the highest MVGI were recovered
from three estuaries (Sunday river, Swartkopps river, buffalo river) and a freshwater resource (Lashinton river). The
cumulative MVGI for V. cholerae, V. mimicus, V. alginolyticus and V. parahaemolyticus isolates were 0.34, 0.20, 0.45, and
0.40 respectively. The targeted Vibrio spp. in increasing order of the public health risk posed in our study areas based
on the MVGI is V. alginolyticus>V. parahaemolyticus>V. cholerae>V. mimicus. Five (sites SR, PA5, PA6, EL4 and EL6)
out of the seventeen sampling sites were detected as the hotspots for potential cholera-like infection and vibriosis
outbreaks.
Conclusions: Our findings suggest that humans having contact with water resources in our study areas are
exposed to potential public health risks owing to the detection of virulent determinants in human pathogenic Vibrio
spp. recovered from the water resources. The study affirms the relevancy of environmental Vibrio species to the
Description
Keywords
Vibrio species, Virulence genes, Freshwater, Vibriosis, Multiple virulence gene index, Cholera-vibriosis hotspot determination
Citation
Abioye et al. BMC Microbiology (2023) 23:316 https://doi.org/10.1186/s12866-023-03060-z