Detection of antibiotics resistance and distribution of resistance genes in Vibrio parahaemolyticus from cultured shrimp

We used agar dilution method to detect the resistance of 36 strains of Vibrio parahaemolyticus to 16 drugs. And used PCR amplication and DNA sequencing to detect the antimicrobial resistance to quinolones (qnrA, qnrB, qnrS, qnrVC), phenicols (cat, optrA, floR, cfr), tetracyclines (tetA, tetB, tetM), sulfonamides (sul1, sul2, sul3), aminoglycosides (strA, strB, aadA, aacA), rifampicin (arr), β-lactams (carB) and macrolides (erm). The results indicate that the isolates exhibited high resistance to ampicillin (88.9%) and sulfamethoxazole (SMZ, 66.7%), all susceptible to neomycin sulfate, gentamicin, ceftriaxone and meropenem. In general, multi-drug resistance (MDR) was highly prevalent (61.1%), and one isolate was resistant to six antimicrobials. Furthermore, 72.2% and 58.3% of the isolates were primarily mediated by qnrVC and strB, respectively; and the macrolides and rifamycin resistant genes were not detected in all the isolates. Obvious mismatch was found between the antimicrobial resistance phenotypes and genotypes, revealing the complexity of resistance to V. parahaemolyticus.