Infectious Disease Compendium

Actinomyces

Microbiology

Gram positive branching rods; includes A. israelii as the most common but includes A. cardiffensis, A. europaeus, A. funkei, A. gerencseriae, A. graevenitzii, A. houstonensis, A. lingnae, A. meyeri,A. naeslundii/viscosus complex, A. neuii, A. odontolyticus, A. radingae, A. turicensis, Arcanobacterium (Actinomyces) bernardiae, Arcanobacterium (Actinomyces) pyogenes. Infections are more often than not polymicrobial.

Epidemiologic Risks

Part of the human GI tract, often disease occurs with poor dentition (lumpy jaw), aspiration (most commonly), and trauma (abdominal/uterine infections).

Syndromes

Lumpy jaw, empyema, lung abscess, abdominal and uterine infections (esp with IUD) as well as the odd other organ infection. These infections are indolent and often present like a malignancy.

If you are concerned about lumpy jay, make pathologist does the proper histopathology: "Twelve serial sections for each case were cut from the paraffin blocks, individually collected on positively charged slides to obtain good section-to-slide adhesion, and stained with hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS). Histopathological examination of the serial sections allowed the identification of bacterial colonies consistent with actinomycetes in 22 cases (32 %). The proposed histopathological examination allowed the retrospective diagnosis of cervical actinomycosis in one-third of clinical specimens that remained misdiagnosed following traditional H&E examination (PubMed)."

It may have an improtant role in bisphosphonate-related osteonecrosis of the jaw (PubMed) and be a manifesation of chronic granulomatous disease (PubMed).

May be  be a cause of mastitis (breast infection) (PubMed).

Treatment

Penicillin, doxycycline, erythromycin, clindamycin. Therapy often is needed for 6 months to a year, but can be oral. The end point is cure. What a concept.

Notes

It causes the so called sulfur granules (which are masses of the organism, not sulfur) and the organism likes to track through, rather than along, tissue planes, so it tends to pop out in unexpected places. On exam, lumpy jaw really does feel like balsa wood.