Antibiotic Resistance and Genetic Profiles of Vibrio parahaemolyticus Isolated from Farmed Pacific White Shrimp ( Litopenaeus vannamei ) in Ningde Regions.

To better understand the antibiotic resistance, virulence genes, and some related drug-resistance genes of Vibrio parahaemolyticus in farmed pacific white shrimp ( Litopenaeus vanname i) in Ningde regions, Fujian province, we collected and isolated a total of 102 strains of V. parahaemolyticus from farmed pacific white shrimp in three different areas of Ningde in 2022. The Kirby-Bauer disk method was used to detect V. parahaemolyticus resistance to 22 antibiotics, and resistant genes (such as quinolones ( qnr VC136, qnr VC457, qnr A), tetracyclines ( tet A, tet M, tet B), sulfonamides ( sul I, sul II, sul III), aminoglycosides ( str A, str B), phenicols ( cat , optr A, flo R, cfr), β-lactams ( car B), and macrolides ( erm )) were detected by using PCR. The findings in this study revealed that V. parahaemolyticus was most resistant to sulfamoxazole, rifampicin, and erythromycin, with resistance rates of 56.9%, 36.3%, and 33.3%, respectively. Flufenicol, chloramphenicol, and ofloxacin susceptibility rates were 97.1%, 94.1%, and 92.2%, respectively. In all, 46% of the bacteria tested positive for multi-drug resistance. The virulence gene test revealed that all bacteria lacked the tdh and trh genes. Furthermore, 91.84% and 52.04% of the isolates were largely mediated by cat and sul II, respectively, with less than 5% resistance to aminoglycosides and macrolides. There was a clear mismatch between the antimicrobial resistance phenotypes and genotypes, indicating the complexities of V. parahaemolyticus resistance.