Virulence-associated genes and antibiotic resistance patterns of Vibrio spp. isolated from cultured marine fishes in Malaysia

Nurliyana Mohamad,Ina Salwany Md Yasin,Nor Amalina Zulkiply,Muskhazli Mustafa,Mohd Zamri Saad,Mohammad Noor Azmai Amal,Nurrul Shaqinah Nasruddin

doi:10.1186/s12917-019-1907-8

Nurliyana Mohamad, Ina Salwany Md Yasin + Show 5 more

Open Access

https://doi.org/10.1186/s12917-019-1907-8

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Abstract

BackgroundVibriosis is an important bacterial disease of cultured marine fishes worldwide. However, information on the virulence and antibiotic resistance of Vibrio spp. isolated from fish are scarce. This study investigates the distribution of virulence associated genes and antibiotic resistance patterns of Vibrio spp. isolated from cage-cultured marine fishes in Malaysia.ResultsA total of 63 Vibrio spp. isolated from 62 cultured marine fishes in various geographical regions in Peninsular Malaysia were analysed. Forty-two of the isolates (66.7%) were positive for all chiA, luxR and vhpA, the virulence genes produced by pathogenic V. harveyi. A total of 62 Vibrio isolates (98%) had tlh gene of V. parahaemolyticus, while flaC gene of V. anguillarum was detected in 43 of isolates (68%). Other virulence genes, including tdh, trh, hlyA and toxRvc were absent from any of the isolates. Multiple antibiotic resistance (MAR) was exhibited in all strains of Harveyi clade, particularly against ampicillin, penicillin, polypeptides, cephems and streptomycin. The MAR index ranged between 0.06 and 0.56, and 75% of the isolates have MAR index of higher than 0.20. Host species and geographical origin showed no correlation with the presence of virulence genes and the antibiotic resistance patterns of Vibrio spp.ConclusionsThe study indicates that majority of Vibrio spp. isolated from cultured marine fishes possess virulence genes, but were not associated with human pathogen. However, the antibiotics resistance is a real concern and warrants ongoing surveillance. These findings represent an updated knowledge on the risk of Vibrio spp. to human health, and also provides valuable insight on alternative approaches to combat vibriosis in cultured fish.

Highlights

Vibriosis is an important bacterial disease of cultured marine fishes worldwide
This study described the presence of virulence-associated genes and antibiotic resistance patterns of Vibrio spp. within the Harveyi clade, which were isolated from various aquaculture areas in Peninsular Malaysia
Only two out of six virulence genes were detected in other Vibrio spp. tested in this study

Summary

Introduction

Information on the virulence and antibiotic resistance of Vibrio spp. isolated from fish are scarce. This study investigates the distribution of virulence associated genes and antibiotic resistance patterns of Vibrio spp. isolated from cagecultured marine fishes in Malaysia. Vibrio spp. that have been associated with diseases in animals and human often possess virulence factors, which are not available or present in the environmental Vibrio [1]. Since Vibrio possesses highly plastic genome, the probability of horizontal transfer of the virulence genes between pathogenic and environmental Vibrio is high. This contributes to the increased number of pathogenic Vibrio strains in aquatic environment [2]. Virulence of several pathogenic Vibrio has been attributed to quorum-sensing, the bacterial cell to cell communication [12]

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