Antibacterial activity of coumermycin alone and in combination with other antibiotics.

Coumermycin has been shown to inhibit Staphylococcus aureus and Staphylococcus epidermidis strains that are susceptible and those that are resistant to methicillin at concentrations less than or equal to 0.05 micrograms/ml. Listeria monocytogenes and Corynebacterium spp. resistant to cephalosporins were inhibited by less than or equal to 1.6 micrograms of coumermycin ml, and streptococcal species, with the exception of Streptococcus faecalis, were inhibited by 0.1 micrograms/ml. Cross-resistance with beta-lactams or aminoglycosides was not found. Coumermycin acted synergistically with ofloxacin, norfloxacin, and enoxacin against S. aureus but did not show synergy when combined with nafcillin, vancomycin, or rifampin. Coumermycin did not inhibit members of the family Enterobacteriaceae or Pseudomonas aeruginosa.