Virulence and drug resistance of Aeromonas veronii isolated from shellfish

Aeromonas veronii (A. veronii) is one of the important zoonotic pathogens. The development of drug resistance and enrichment of resistant genes not only cause misery from bacterial diseases but also pose a threat to public health security. In this study, A. veronii was isolated and identified from 357 shellfish samples imported from 6 aquaculture bases in Jilin Province, China, and tested for virulence, tolerance and drug resistance genes. According to 16S rRNA and gyrB gene PCR result, 47 strains were identified as Aeromonas veronii. The distribution of 9 virulence factors including fla (55.3%), Alt (42.5%), Act (31.9%), Aer (31.9%), Lip (19.1%), gcaT (12.7%), ahyB (12.7%), ascV (10.6%) and Ast (8.5%) was determined exclusively in Aeromonas veronii. Nine virulence genes were detected in two isolates. In addition, the resistance rate of isolates to sulfamonomethoxine and florfenicol was 100%, while to tetracycline, aureomycin and doxycycline it was 34.0%（16/47）， 29.8%（14/47） and 25.5%（12/47） , respectively. Among all tested strains, thirty-five isolates were sensitive to enrofloxacin, and the majority of drug-resistant strains carried strA（95.7%） , strB （93.6%） , qnrA（40.4%） , qnrD（31.9%） , tetQ (31.9%） and tetK (29.8%) resistance genes. The results provide a basis for a risk assessment of the drug resistance of Aeromonas veronii.