Antimicrobial susceptibility and genetic characteristics of Streptococcus uberis isolated from bovine mastitis milk

Lee, Gil; Kang, Hyun-Mi; Chung, Chung-il; Moon, Jin-San

Korean Journal of Veterinary Research 2007;47(1):33-41.

Gil Lee¹, Hyun-Mi Kang², Chung-il Chung¹, Jin-San Moon²

¹Department of Dairy Science, Konkuk University
²National Veterinary Research and Quarantine Service

젖소 유방염 유즙에서 분리한 Streptococcus uberis의 항생제 감수성 및 유전학적 특성

이길¹, 강현미², 정충일¹, 문진산²

¹건국대학교 낙농학과
²국립수의과학검역원

Abstract

Streptococcus spp. comprising Streptococcus (S.) uberis S. dysgalactiae strains is major causeof bovine mastitis from particularly well-managed or low somatic cell count herds that have successfullycontrolled contagious pathogens. In this study, antimicrobial susceptibility and genetic characteristics of S.uberis isolated from clinical or subclinical mastitis milk at 2003 were investigated. Eighty seven isolatesof Streptococus spp. were identified by the conventional biochemical methods. The antimicrobialsusceptibility by disk diffusion method was determined for 46 S. uberis, 11 S. bovis, 10 S. oralis, 6 S.uberis and 14 other Streptococcus spp.. Overall, the tested strains were susceptible to tetracycline (11.5%),amikacin (14.9%), streptomycin (16.1%), neomycin (26.4%), kanamycin (35.6%), gentamicin (65.2%),oxacillin (70.1%), ampicillin (75.9%), chloramphenicol (78.2%), and cephalothin (97.7%). Additionally, S.uberis strains were susceptible to pencillin G (97.8%), but resistant to erythromycin (76.0%) by minimalinhibitory concentration test. The multiple-drug resistance rate of isolated bacteria to 4 more thanamplification fingerprinting patterns amplifed with primer 8.6d showed that 3 to 8 number of distinguishableDNA fragments ranged from 180 bp to 1,20 bp. Thirty seven isolates of S. uberis strains were subtypedinto 8 distinct patterns. Each subtype revealed a typical pattern of antimicrobial susceptibilities. Thesefindings demonstrate that S. uberis isolates were mastitis pathogens of diverse serotypes, and oftenencountered the diverse resistant patterns.

Key Words: antimicrobial susceptibility, cow, mastitis, Streptococcus uberis