The susceptibility of isolates of Corynebacterium equi to antimicrobial drugs.

Fifty-one isolates of Corynebacterium equi recovered from pigs and horses belonging to two capsular serotypes were tested for susceptibility to antimicrobial agents. No clear differences were detected in sensitivity between isolates of different sources or serotypes. All isolates were sensitive to less than 0.25 micrograms/ml of erythromycin and gentamicin. The following minimum inhibitory concentrations (MICs) of antimicrobial agents were determined for greater than or equal to 90% of isolates: methicillin greater than 16 micrograms/ml, clindamycin 1-2 micrograms/ml, tobramycin less than or equal to 1 microgram/ml, cephalothin 8-64 micrograms/ml, kanamycin 2-8 micrograms/ml, amikacin less than or equal to 1-2 micrograms/ml, penicillin 2-greater than or equal to 4 micrograms/ml, ampicillin 2-8 micrograms/ml, trimethoprim-sulfa 4/76-32/608 micrograms/ml tetracycline 1-4 micrograms/ml and chloramphenicol 8-16 micrograms/ml.