Virulence, Resistance, and Genomic Fingerprint Traits ofVibrio choleraeIsolated from 12 Species of Aquatic Products in Shanghai, China

Abstract

Vibrio cholerae is a waterborne bacterium and can cause epidemic cholera disease worldwide. Continuous monitoring of V. cholerae contamination in aquatic products is imperative for assuring food safety. In this study, we determined virulence, antimicrobial susceptibility, heavy metal tolerance, and genomic fingerprints of 370 V. cholerae isolates recovered from 12 species of commonly consumed aquatic products collected from July to September of 2018 in Shanghai, China. Among the species, Leiocassis longirostris, Ictalurus punetaus, Ophiocephalus argus Cantor, and Pelteobagrus fulvidraco were for the first time detected for V. cholerae. Toxin genes ctxAB, tcpA, ace, and zot were absent from all the V. cholerae isolates. However, high occurrence of virulence-associated genes was detected, such as hapA (82.7%), hlyA (81.4%), rtxCABD (81.4%, 24.3%, 80.3%, and 80.8%, respectively), and tlh (80.5%). Approximately 62.2% of the 370 V. cholerae isolates exhibited resistance to streptomycin, followed by ampicillin (60.3%), rifampicin (53.8%), trimethoprim (38.4%), and sulfamethoxazole-trimethoprim (37.0%). Moreover, *57.6% of the isolates showed multidrug resistant phenotypes with 57 resistance profiles, which was significantly different among the 12 species (multiple antimicrobial resistance index, p < 0.001). Meanwhile, high incidence of tolerance to heavy metals Hg 2+ (69.5%), Ni 2+ (32.4%), and Cd 2+ (30.8%) was observed among the isolates. The enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR)-based fingerprinting profiles classified the 370 V. cholerae isolates into 239 different ERIC-genotypes, which demonstrated diverse genomic variation among the isolates. Overall, the results in this study meet the increasing need of food safety risk assessment of aquatic products.

First Experimental Evidence for the Presence of Potentially Toxic Vibrio cholerae in Snails, and Virulence, Cross-Resistance and Genetic Diversity of the Bacterium in 36 Species of Aquatic Food Animals

“…The hapA gene encodes a hemagglutinin protease secreted by V. cholera through the type II secretion system that functions in V. cholerae interactions with aquatic hosts [ 7 , 33 ]. Studies have reported that most V. cholerae strains carry the hap gene irrespective of their source (i.e., clinical or environmental) [ 6 , 9 , 34 ], consistent with our present results. RTX is essential for the cytotoxic activity of V. cholerae O1 El Tor strain upon Hep-2 cells in vitro [ 35 , 36 ].…”

“…Serratore et al reported that 28 batches of edible snails ( Nassarius mutabilis and Bolinus brandaris ) in the Adriatic Sea were negative for E. coli , Vibro vulnificus , and V. cholerae contamination [ 22 ]. In this study, our results also provided additional evidence to demonstrate high detection frequencies of V. cholerae in fish species such as A. nobilis , C. auratus , and P. pekinensis , consistent with results of our prior research [ 6 , 9 ].…”

“…Fu et al examined 370 V. cholerae isolates from twelve species of aquatic products including nine species of fish, one species of crustacean and two species of shellfish. They found that none of the isolates carried the ctxAB , tcpA, ace, or zot genes [ 9 ]. In this study, our results indicated that the ctxAB genes were absent from all the V. cholerae isolates tested, consistent with results in previous reports.…”

“…Virulence-associated genes that contribute to its pathogenicity include those encoding zonula occludens toxin ( zot ), accessory cholera enterotoxin ( ace ), RTX toxin ( rtxCABD ), El Tor hemolysin ( hlyA ), hemagglutinin protease ( hapA ), thermolabile hemolysin ( tlh ), mannose-sensitive hemagglutination pili ( mshA ), and putative type IV pilus ( pilA ) [ 6 ]. V. cholerae is frequently isolated from aquatic products including fish, shellfish, and crustaceans [ 6 , 7 , 8 , 9 ]. China is the largest producer, consumer, and exporter of aquatic products in the world, accounting for about 60% (64,803,600 tons) of the global total in 2019 (National Bureau of Statistics, , accessed on 17 February 2021).…”

“…Nevertheless, the available literature in this field is rare. Recently, we analyzed V. cholerae isolates recovered from 12 species of aquatic products sampled in Shanghai in 2017 and 2018, and found high incidence of tolerance of the isolates to Hg, Ni, Cd, Zn, and/or Pb [ 6 , 9 ].…”