Aeromonas veronii Infection in Commercial Freshwater Fish: A Potential Threat to Public Health.

Tong Li,Bintong Yang,Wuwen Sun,Aidong Qian,Yuanhuan Kang,Sayed Haidar Abbas Raza,Guiqin Wang,Yufeng Sun,Chunfeng Wang,Xiaofeng Shan

doi:10.3390/ani10040608

Abstract

Simple SummaryAeromonas veronii is an important aquatic zoonotic agent. In this study, A. veronii was isolated from healthy fish, and the relationship between the pathogenicity and virulence genes of A. veronii was investigated by molecular identification. The aim of this study was to ensure the safety of freshwater products by evaluating the infection status in edible freshwater fish. Aeromonas veronii is an important pathogen causing freshwater fish sepsis and ulcer syndrome. An increasing number of cases have demonstrated its significance as an aquatic zoonotic agent. The purpose of this study was to ensure the safety of freshwater products by evaluating the infection status of edible freshwater fish. In this experiment, we isolated A. veronii from several species of apparently healthy freshwater fish, including Carassius auratus, Cyprinus carpio, Ctenopharyngodon idella, and Silurus asotus. A. veronii was identified through bacterial staining, culture characteristics, and 16S rDNA gene sequence. In addition, polymerase chain reaction (PCR) was used to investigate the distribution of seven major virulence genes, including aerolysin (aer: 88.51%), cytotoxic enterotoxin (act: 71.26%), serine proteinase (ser: 54.02%), adhesin (Aha: 40.23%), phospholipase (lip: 45.98%), nuclease (exu: 51.72%), and quorum sensing-controlled virulence factor (LuxS: 59.77%). In total, 496 strains of Aeromonas were isolated, including 87 strains of A. veronii. The isolates of A. veronii were Gram-negative, rod-shaped bacteria, and the colonies are yellow on Rimler-Shotts (RS) medium and showed greater than 99% homology with A. veronii ATCC35624 according to analyses of the 16S rDNA sequence. Nearly 50% of the A. veronii isolates carried at least four or more virulence genes, 25% of the isolates carried at least five types of virulence genes, and 59.77% isolates carried the LuxS gene, and the isolates carrying more virulence genes were found to be more virulent. These results are of great significance for further improving the food safety assessment of freshwater aquatic products.

Highlights

Aeromonas veronii is a Gram-negative, rod-shaped, and facultative anaerobic bacterium
The isolates of A. veronii showed greater than 99% homology with A. veronii ATCC35624(X60414.2) by analysis of the 16S rDNA sequence
We investigated the burden of A. veronii infection in commercially available fish, including Carassius auratus, Cyprinus carpio, Ctenopharyngodon idella, and Silurus asotus

Summary

Introduction

Aeromonas veronii is a Gram-negative, rod-shaped, and facultative anaerobic bacterium. There have been an increasing numbers of cases of large-scale A. veronii outbreaks. A. veronii can cause human infections, especially in elderly and children with low immunity, causing sepsis, gastroenteritis, and other diseases [5,6,7,8,9,10,11]. Recent reports suggest that individuals with healthy immune function can be infected [12,13]. The development of aquaculturehas been accompanied by an increased incidence of bacterial diseases. The abuse of antibiotics has led to the increased antibiotic resistance of Aeromonas, and the presence of antibiotic residues in aquatic products threatens human health [14]. Reports of infectious diarrhea and food poisoning caused by pathogenic bacteria have increased [15]

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