ISOLATION AND CHARACTERIZATION OF VIBRIO SPECIES FROM FISH AND FISH POND WATER
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Date
2022-03
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
The consumption of raw, improperly cooked or cross-contaminated fish and fish
products by Vibrio spp. can cause foodborne diseases. The present study was
undertaken to characterize Vibrio species of fish and fish pond water origin based on
cultural isolation. It was also aimed to determine the major antibiotic resistant
genotypes and virulence genes of Vibrio species of worldwide public health importance.
A total of 300 samples comprising fish and fish pond water samples were analyzed for
presence of Vibrio spp. viz., V. parahaemolyticus, V. alginolyticus, V. cholerae and V.
vulnificus. Overall prevalence of genus Vibrio was found to be 55% (165/300). Out of 165
Vibrio isolates, m-PCR revealed 28 (16.9%) to be V. parahaemolyticus, 17(10.3%) to be
V. alginolyticus and 15 (9.09%) to be V. cholerae and 11 (6.66%) to be V. vulnficus.
Out of 131 positive Vibrio spp. in fish, highest prevalance was found in Catla catla (54.28%) followed by Labeo rohita (53.75%), Channa striata (48.38%) and other fishes (37.20%). Virulence genes are major indicators to pathogenicity of these microorganisms.
Virulence genes ctxAB, tcp, rfbO1, zot were not detected in any of the V. cholerae
isolates. Out of 28 V. parahaemolyticus isolates, virulence genes trh and tdh were
detected in 21.42% and 10.71% of isolates, respectively. Out of 17 V. alginolyticus
isolates, one (5.88%) isolate was carrying tdh gene. Out of 11 V. vulnificus isolates, cps
allele 2 and vcgE were detected in 27.27% and 18.18% respectively and 18.18% of
isolates were positive for both cps allelle 2 and vcg E.
Antibiogram profiling of 71 isolates revealed a major fraction of the Vibrio
isolates to be resistant towards ampicillin (100%) followed by amoxicillin/clavulanic
acid (91.54%) and erythromycin (52.11%). ESBL production was confirmed in 15
Vibrio spp. isolates by both phenotypic and molecular methods and blaTEM was the
predominant gene in 14 isolates and blaOXA gene was detected in only one isolate.
A greater degree of heterogeneity was observed among 71 Vibrio isolates of
different species from different sources as revealed by presence of 70 genotypes and 71
genotypes by ERIC and REP-PCR analysis, respectively. Twenty seven different V.
parahaemolyticus, 17 V. alginolyticus, 15 V. cholerae and 11 V. vulnificus subtypes
were differentiated by ERIC-PCR, whereas 28 different V. parahaemolyticus, 17 V.
alginolyticus, 15 V. cholerae and 11 V. vulnificus subtypes by REP- PCR. Genotyping
of Vibrio species by ERIC- PCR and REP- PCR was found to be highly significant
since discriminatory power >0.9 is considered highly significant (0.9974 for ERIC PCR and 1 for REP-PCR. Cluster analysis also revealed a great degree of homogeneity and heterogeneity among different isolates recovered from different sources and
indicating that there is a chance of cross-contamination particularly in the fish markets
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