Prevalence, antibiotic susceptibility and serotyping of Streptococcus parauberis isolates from diseased marine fish. (10th August 2021)

• Record Type: Journal Article
• Authors: Woo, Soo Ji; Do, Mi Young; Jeong, Min Gyeong; Kim, Na Young; Kim, Myoung Sug
• Is Part Of: Aquaculture research. Volume 52:Number 12(2021)
• Page Start: 6525
• Page End: 6536
• Publication Date: 2021-08-10
• Subjects: antibiotic resistance -- serotyping -- Streptococcus parauberis; Aquaculture -- Periodicals; Fishery management -- Periodicals; 639.8
• DOI: 10.1111/are.15523
• Languages: English
• ISSNs: 1355-557X

Abstract

Abstract: Streptococcus parauberis is the main causative bacterial pathogen for streptococcosis in marine fish, causing a significant economic loss to the mariculture industry. In this study, we aimed to investigate the serotypes and antimicrobial susceptibilities of 83 S. parauberis isolates from diseased farmed fish ( Paralichthys olivaceus, Platichthys stellatus and Sebastes schlegelii ) in Korea. This study categorized the S. parauberis isolates based on PCR serotyping into serotype I (subtypes Ia and Ib/Ic) and serotype II. Serotype Ia was identified to be significantly more prevalent than serotypes Ib/Ic and II. An antimicrobial susceptibility analysis showed that all of the isolates were susceptible to amoxicillin/clavulanic acid. Overall, the isolates studied showed resistance to penicillin and ampicillin (1.2%), tetracycline (68.7%), oxytetracycline (72.3%), doxycycline (53.0%) and erythromycin (37.3%). Interestingly, we found that serotypes Ia and II showed higher degrees of tetracycline resistance than serotype Ib/Ic. The macrolide resistance gene erm (B) was present in 75.8% of the Ia isolates, whereas the mef (A) gene was not detected in any of the isolates. The tetracycline resistance genes tet (S) and tet (M) were detected in 95.2% and 60% of Ia and II isolates respectively. Moreover, β‐lactam antibiotic‐resistant Ia isolates contained a set of 11 mutations in PBP1A and PBP2X . Our study provides a valuable reference for surveillance of antimicrobial resistance and underscores the strict management of antibiotic use to prevent the emergence of resistant of S. parauberis serotypes.