Comparison of specificity and sensitivity of diagnostic methods for Enteromyxum leei and Enteromyxum fugu detected from cultured tiger puffer, Takifugu rubripes in Korea.

Enteromyxum leei and Enteromyxum fugu, which are myxosporean parasites, were first found in cultured tiger puffer Takifugu rubripes in Korea. We collected four tiger puffers that showed severe emaciation signs for our experiments. DNA sequencing was confirmed that the tiger puffers were coinfected with E. leei and E. fugu. Furthermore, similar amounts of E. leei and E. fugu were confirmed using real-time PCR in the intestine. To the best of our knowledge, there have been no reports of E. fugu infection in the olive flounder Paralichthys olivaceus. However, the diagnosis of inflowing water, discharged water and olive flounder samples using highly sensitive diagnostic methods confirmed the presence of E. fugu in water and fish samples from olive flounder farms near the tiger puffer farm. Therefore, the present study aimed to develop highly sensitive diagnostic methods such as real-time and two-step PCR for early diagnosis and follow-up of the emaciation disease and multiplex PCR for rapid diagnosis. The multiplex PCR method exhibited the same sensitivity as the one-step PCR method developed in this study, demonstrating its efficacy for rapid diagnosis. Therefore, the suggested methods can be utilized for the early diagnosis and rapid diagnosis of emaciation diseases and reduction of economic losses through rapid disease control.

Antibiotic Susceptibility of Bacterial Pathogens That Infect Olive Flounder (Paralichthys olivaceus) Cultivated in Korea.

Paralichthys olivaceus (olive flounder) is widely cultivated in Korea. However, data on the antibiotic susceptibility of bacterial pathogens that infect olive flounders in Korea are limited. The susceptibility of 84 strains of 3 pathogenic bacteria (Streptococcus spp., Vibrio spp., and Edwardsiella piscicida) to 18 antibiotics was tested using the minimum inhibitory concentration (MIC) panels, and the distribution of the MIC values for each species was confirmed. Among the panel antibiotics, nine commonly used antibiotics were selected, and the multiple antibiotic resistance (MAR) index and antibiotic resistance pattern were indicated using the disk diffusion method. It was confirmed that most of the isolates had a MAR index greater than 0.2, indicating a high-risk source. The distribution patterns of the MIC values and resistance pattern between gram-positive and gram-negative bacteria showed slightly different results. Ampicillin, erythromycin, and clindamycin were more effective against gram-positive bacteria than gram-negative bacteria. However, the MIC values of flumequine for gram-positive bacteria were higher than those of gram-negative bacteria. Through the distribution patterns of the MIC values and resistance patterns presented in this study, the need for monitoring the multidrug-resistant bacteria in aquaculture is emphasised.