Rickettsia Hund. Ewingii.while all are transmitted by tick bites, the specific tick may vary depending on the specific species of. Tetracycline or doxycycline is the antibiotic of choice for ehrlichiosis, and rocky mountain spotted fever though treatment needs to begin as early and swiftly as possible for a better response and may need to be continued through several weeks.
Infectious agents of rickettsial infections. Rickettsia rickettsii, the etiologic agent of rocky mountain spotted fever (rmsf), is a small (0.3 to 0.7 μm × 1.0 to 2.0 μm), tickborne, coccobacillus that resides and multiplies in the cytosol and occasionally in the nucleus of infected cells. Rickettsii is the causative agent of rocky mountain spotted fever.