A 10-year survey of antimicrobial susceptibility of Streptococcus suis isolates from swine in Japan

A number of 689 Streptococcus suis isolates collected nationwide from diseased and healthy pigs from 1987 to 1996 were surveyed for antibiotic susceptibilities to 11 drugs. No isolates resistant to amoxicillin, chloramphenicol, and sulfamethoxazole/ trimethoprim were found. Isolates were highly susceptible to penicillins (penicillin GC, ampicillin, and amoxicillin) except cloxacillin. They were not susceptible to tetracycline, streptomycin, and kanamaycin (MIC90 50 mug/ml, greater than or equal to 100 mug/ml, and greater than or equal to 100 mug/ml, respectively). Multiple-resistant isolates (greater than or equal to3 antimicrobial agents) were found in 20.3% of all isolates tested.