Comparison of species distribution and antimicrobial susceptibility of aerobic actinomycetes from clinical specimens.

To compare the species distribution and antimicrobial susceptibility of aerobic actinomycetes, we evaluated 366 isolates referred to the Centers for Disease Control from October 1985 through February 1988. We used conventional biochemical tests to identify the various species. Four species accounted for 191 (52%) of aerobic actinomycete isolates: Nocardia asteroides (98 isolates), Actinomadura madurae (42 isolates), Streptomyces griseus (28 isolates), and Nocardia brasiliensis (23 isolates). Sputum and wounds were the most common sources. No isolate was resistant to amikacin, no N. brasiliensis isolate was resistant to sulfamethoxazole or trimethoprim-sulfamethoxazole, and no A. madurae isolate was resistant to ceftriaxone or imipenem. In summary, our findings show that unusual species of aerobic actinomycetes can cause infection, colonization, or both and that antimicrobial resistance varies markedly by species.