ISOLATION OF GRAM-POSITIVE RODS THAT RESEMBLE BUT ARE CLEARLY DISTINCT FROM ACTINOMYCES-PYOGENES FROM MIXED WOUND INFECTIONS

Beginning in 1990, gram-positive rods resembling Actinomyces pyogenes were found with increasing frequency in mixed cultures from various in fectious processes, most of them from patients with otitis, empyema, p ilonidal cysts, perianal abscesses, and decubitus ulcers. Ribotyping a nd hybridization showed that these gram-positive rods could be divided into five groups not related to known Actinomyces species. Biochemica l markers for reliable differentiation into these groups, however, cou ld not be found. Therefore, naming new species is not warranted unless parameters are discovered that allow identification without DNA hybri dization. These gram-positive rods have been isolated only in mixed cu ltures with anaerobes, Staphylococcus aureus, Streptococcus ''milleri, '' enterococci, and gram-negative rods. Their exact role in these poss ibly synergistic infections needs further investigation.