Epidemiological Cut-off Values Generated for Disc Diffusion Data from Photobacterium damselae

Abstract

In this study, epidemiological cut-off values were estimated for 44 Photobacterium damselae isolates, since clinical breakpoints have not been established for this pathogenic bacterium. The susceptibility of the isolates to 10 antibiotics was evaluated using internationally standardized disc diffusion protocols. Normalized resistance interpretation was used to generate statistically valid epidemiological cut-off values for the susceptibility data. There were not enough strains exhibiting full sensitivity to ampicillin and amoxicillin to allow analysis of these antibiotics. Because there were only a marginally sufficient number of strains exhibiting full sensitivity to oxytetracycline, the cut-off value generated provided only a provisional estimate. The valid wild-type cut-off values were <13, 13, 9, 22, 25, 27, and 28 mm for gentamicin, cephalexin, erythromycin, oxolinic acid, flumequine, florfenicol, and sulfamethoxazole/ trimethoprim, respectively. The application of these cut-off values should greatly facilitate the rational selection of antibiotics for use in commercial fish farms.

Serotype distribution and antibiogram of Streptococcus parauberis isolated from fish in South Korea

“…This study aimed to track the trends of the antibiotic-resistance patterns of S. parauberis isolated between 1999 and 2021, along with serotyping. In fact, we used 31 whole-genome sequencing of S. parauberis, including nine genomes sequenced in our laboratory, and compared our results with as relevant many references showing antimicrobial susceptibility and serotypes of the pathogen as possible ( 4 , 7 , 8 , 10 , 16 – 18 , 21 , 22 , 29 , 30 ) to overcome the limited numbers of strains ( n = 103) used. We found profound diversity in terms of antibiotic resistance in S. parauberis through the establishment of ECVs for 10 antimicrobial agents based on disk diffusion test data using 103 isolates ( Fig.…”

“…Therefore, the ECV should not be used as a predictor of clinical success but as epidemiological surveillance tool for bacterial antimicrobial resistance ( 20 ). Although we previously established ECVs for S. parauberis based on disk diffusion data using 75 isolates ( 21 ), serotyping and the detection of ARGs were not performed. This study used a total of 103 isolates, including recently isolated strains.…”