In vitro antimicrobial susceptibility of strains of Rhodococcus equi by standard diffusion disk test and a modified method, by the addition dimethyl sulphoxide (5%), was evaluated. Increase in sensitivity of R. equi using modified method was observed in aminoglycosides group (kanamycin, amikacin, streptomycin) and cloramphenicol, while erythromycin and ß-lactam derivates (penicillin G, cephalosporins, amoxicillin, oxacillin) showed a reduction in sensitivity to the agent.
Rhodococcus equi; antimicrobial susceptibility test; dimethyl sulphoxide; pneumonia in foals
