08.04 ID

08.04 ID [PDF link] bacterial & fungal infections: Rocky mountain spotted fever (Rickettsia rickettsii), Epidemic typhus (Rickettsia proazekii), Endemic typhus (Rickettsia typhi), Scrub typhus (Orienta tsutsugamushi), Typhus, Actinomyces spp, Nocardia spp, Candida spp, Cryptococcosis, Aspergillus spp (incl allergic bronchopulmonary aspergillosis), Mucormycosis, Histoplasmosis

More on Actinomyces spp

• Gram positive branching/filamentous anaerobic/microaerophilic bacteria

• Normally found in the mouth, colon and vagina. Can infect any part of the body. Infections typically are indolent and slowly progressive, and often mistaken for other disease processes such as cancer.

• Classic presentations include

  • Chronic disease processes that cross tissue boundaries (eg starting in the lungs, spreading contiguously to the chest wall) with mass-like features (often mistaken for cancer)

  • Development of sinus tracts

  • “Refractory or relapsing” infection – usually because not treated sufficiently; Actinomyces requires long treatment courses

• Treatment: IV benzylpenicillin for first 2-6 weeks, followed by PO penicillin/amoxicillin (may require treatment for 6-12 months). If pen-allergic, erythromycin, doxycycline, or clindamycin are proven alternatives.

• Xu Y, Shi J. Disseminated Actinomycosis. N Engl J Med 2018;379:1071–1071. https://doi.org/10.1056/NEJMicm1802090.

  • Lesions containing sulfur granules + filamentous bacteria seen with silver staining are characteristic of actinomycosis