title: Antimicrobial resistance of streptococci isolated from mastitic bovine milk samples in Korea.
abstract: The aim of this study was to determine the antimicrobial resistance of streptococci isolated from mastitic bovine milk samples. A total of 178 isolates belonging to 6 different Streptococcus species were examined: S. uberis (n = 99), S. bovis (n = 30), S. oralis (n = 24), S. salivarius (n = 13), S. intermedius (n = 7), and S. agalactiae (n = 5). Only 8.9% (16/178) of the isolates were susceptible to all antimicrobial agents tested in this study, and S. agalactiae and S. intermedius isolates were all resistant to at least 1 antimicrobial agent tested. Overall, the most frequently observed resistance was to tetracycline (61.2%), followed by lincomycin (43.2%), gentamycin (35.3%), oxacillin (34.3%), and erythromycin (28.6%). Cephalothin and penicillin were the only antimicrobial agents to which most of the streptococci (>or=92%) were susceptible. Wide differences in the prevalence of resistance are apparent among the individual species: S. salivarius displayed exceptionally high resistance to cephalothin (23.0%) and oxacillin (76.9%) and S. agalactiae (20%) and S. intermedius (14.2%) to penicillin. Streptococcus salivarius and S. agalactiae were all susceptible to erythromycin, but others showed various rates of resistance ranging from 12.5% to 42.8%. Resistance to 3 or more of 7 antimicrobial agents was observed in all species (37.6%, 67/178).
authors.affiliation: Bacteriology and Parasitology Division, National Veterinary Research and Quarantine Service, 480, Anyang 6-dong, Anyang, Gyeonggi-do 430-824, Republic of Korea. namhm@nvrqs.go.kr
authors.forename: Hyang-Mi
authors.initials: HM
authors.lastname: Nam
authors.forename: Suk-Kyung
authors.initials: SK
authors.lastname: Lim
authors.forename: Hyun-Mi
authors.initials: HM
authors.lastname: Kang
authors.forename: Jae-Myoung
authors.initials: JM
authors.lastname: Kim
authors.forename: Jin-San
authors.initials: JS
authors.lastname: Moon
authors.forename: Keum-Chan
authors.initials: KC
authors.lastname: Jang
authors.forename: Yi-Seok
authors.initials: YS
authors.lastname: Joo
authors.forename: Mun-Il
authors.initials: MI
authors.lastname: Kang
authors.forename: Suk-Chan
authors.initials: SC
authors.lastname: Jung
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000502:physiology*; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D005839:Gentamicins / Q000494:pharmacology; D007723:Korea; D007774:Lactation / Q000502:physiology*; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D010068:Oxacillin / Q000494:pharmacology; D013291:Streptococcus / Q000187:drug effects / Q000302:isolation & purification*; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D004917:Erythromycin; D013752:Tetracycline; D010068:Oxacillin