ACTINOMYCES-PYOGENES - SUSCEPTIBILITY OF 103 CLINICAL ANIMAL ISOLATESTO 22 ANTIMICROBIAL AGENTS

Actinomyces pyogenes induces suppurative diseases in ruminants and man y other animal species. Most of the earlier antimicrobial susceptibili ty data has been obtained by disk diffusion techniques. Minimal inhibi tory concentrations (MIC) of 22 antibiotics for 103 strains of A pyoge nes of animal origin were determined by agar dilution test (Mueller-Hi nton agar supplemented with 5% sheep blood). All the strains were susc eptible to penicillin G, amoxicillin, methicillin, cephalothin, cefope razone, pristinamycin, kanamycin, gentamicin, spectinomycin, chloramph enicol, vancomycin, novobiocin and rifampin. Fifty-nine percent were r esistant to streptomycin, 67%. to tetracycline, doxycycline and minocy cline, 12%. to erythromycin, spiramycin and lincomycin. Most of the st rains resistant to macrolides and lincosamides exhibited a constitutiv e MLS(B)-like phenotype. In the cultural conditions used, it was not p ossible to determine accurate MIC of fucidic acid and pefloxacin.