| In order to analyze the pathogenicity and drug resistance risk assessment of Apostichopus japonicus in Fujian province, the pathogen isolation, identification and pathogenicity analysis were carried out in 4 cases of Apostichopus japonicus in the Xiapu sea area in 2023. The antibiotic sensitivity and drug resistance risk assessment of corresponding bacterial pathogens were further carried out. In this study, a total of 4 dominant strains of 2335FTBA, 231124FTBA, 231210FTBA and 231214FTBA were isolated from the skin tissues of 4 outbreaks of the syndrome in the waters of Makang, Leijiang and Tanyu in Xiapu. Four strains of bacteria were identified as Vibrio atlanticus, Vibrio neocaledonicus and Vibrio atypicus by morphological analysis, 16S rDNA sequencing, physiological and biochemical characteristics analysis and phylogenetic tree construction. Artificial infection showed that these four dominant strains were pathogenic to skin ulcer syndrome of Apostichopus japonicus. Their half-lethal concentrations (LC50) were 6.19×105 CFU/mL, 6.19×104 CFU/mL, 9.21×104 CFU/mL and 1.09×105 CFU/mL, respectively, showing strong pathogenicity. he results of drug sensitivity test showed that the multiple antibiotic resistance index (MARI) of the four strains were 0.35, 0.76, 0.62 and 0.59, respectively, indicating a high risk of antibiotic exposure. Combined with the relevant national drug management regulations and drug sensitivity test results, antibiotics containing doxycycline and flufenicol can be used for the treatment of corresponding diseases. The results of drug resistance gene detection of the 4 dominant strains showed that all the 4 dominant strains carried qnrA, qnrS and cmle3 genes, but did not carry floR genes. Except chloramphenicol resistance genes cmle3 and floR genes, other resistance genes carried the same drug resistance phenotype, indicating that the resistance genes had a strong correlation with the resistance phenotype. The relevant results can provide scientific basis for the analysis of pathogen diversity and disease prevention and control of Apostichopus japonicus. |
