Antimicrobial resistance of streptococci isolated from mastitic bovine milk samples in Korea.
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).
Nam
Hyang-Mi
HM
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
Lim
Suk-Kyung
SK
Kang
Hyun-Mi
HM
Kim
Jae-Myoung
JM
Moon
Jin-San
JS
Jang
Keum-Chan
KC
Joo
Yi-Seok
YS
Kang
Mun-Il
MI
Jung
Suk-Chan
SC
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
D000900:Anti-Bacterial Agents; D005839:Gentamicins; D004917:Erythromycin; D013752:Tetracycline; D010068:Oxacillin