Change of antibiotic resistance in Vibrio spp. during shrimp culture in Shanghai

The judicious application of antibiotics in shrimp aquaculture is vital for addressing bacterial infections, yet monitoring bacterial resistance during distinct aquaculture phases remains deficient. This study focused on tracking antibiotic resistance dynamics in Vibrio strains sourced from both shrimp and their breeding settings. Over a standard aquaculture period (day 0, 20, 40, 60, and 80), we isolated eighty-eight Vibrio cholerae and ninety Vibrio parahaemolyticus strains from water, sediment, and shrimp samples. All isolates underwent assessment for antibiotic resistance phenotype and genotype. Both Vibrio species demonstrated resistance to nine antimicrobials. Notably, Vibrio cholerae isolates exhibited resistance rates of up to 46.6% for cephazolin, 30.7% for streptomycin, and 11.4% for ampicillin. Conversely, V. parahaemolyticus isolates displayed pronounced resistance to ampicillin (100%), cephazolin (62.2%), and cefoxitin (36.7%). Moreover, we identified 38 anti-biotic resistance genes (ARGs) across all samples, with a higher prevalence observed in the water. Genetic di-versity and clonal origins of the Vibrio isolates were quantified using Multilocus Sequence Typing (MLST). New Sequence Types (STs) were predominant among V. cholerae (95.4% of 43 isolates) and V. parahaemolyticus (92.9% of 28 isolates). Predominantly, V. parahaemolyticus isolates formed two extensive clonal groups: CC1420 and CC744. As the shrimp cultivation period progressed, both the resistance development rate among isolates and the average ARG count within the same STs of Vibrios steadily increased. This study underscores the potential role of ARGs transmission in the aquaculture environment as a crucial conduit for Vibrio antibiotic resistance development. Insights gained contribute to understanding the dissemination and transmission of antibiotic resistance in aquaculture, aiding in devising strategies to curb antibiotic resistance in aquatic environments.