Multi-antibiotics resistance phenotype of pathogenic Vibrio parahaemolyticus isolated from acute hepatopancreatic necrosis disease in Litopenaeus vannamei farmed in the Mekong Delta

Vibrio parahaemolyticus is a significant causal agent of acute hepatopancreatic necrosis disease (AHPND), with huge production losses of white leg shrimp, Litopenaeus vannamei, cultivated globally, including aquaculture farms in the Mekong Delta of Vietnam. Controlling this disease is critical because of the worldwide expansion of antimicrobial-resistant V. parahaemolyticus isolates. The purpose of this study was to determine the frequency of multi-antibiotic resistance (MAR) in V. parahaemolyticus isolated from AHPND white leg shrimp extensively cultivated in Bac Lieu Province (Mekong Delta). Based on biochemical tests and toxR-PCR positive detections, 34 V. parahaemolyticus isolates were identified. Antibiotic susceptibility examination revealed that most of the isolates were phenotypically multidrug resistant, including resistance to ceftazidime (100%) and amoxicillin (97.06%), followed by colistin (74%) and erythromycin (65%). These isolates were highly sensitive to doxycycline (94%), followed by florfenicol (74%) and flumequine (71%). There were 27 distinct MAR phenotypes detected among 34 isolates, with 14.71% of the isolates exhibiting the antibiotic profile AMO-CEF-CEP-COL-ERY, followed by 11.76% for each of the profiles AMO-CEP-TET-COL and AMO-CEP-COL. In particular, 25 isolates (75%) were resistant to at least 5 (of the 12) antibiotics tested. A hierarchical clustering analysis of antibiotic-resistant V. parahaemolyticus isolates indicated cross-transmission across farms and its ability to survive in aquatic environments for extended periods (over 3 months). Our findings support the hypothesis that the variety of MARPs in V. parahaemolyticus is the result of human activities. Environmentally friendly therapy strategies should be used for the prophylaxis and treatment of V. parahaemolyticus infection.