Correlation of Rickettsial Titers, Circulating Endotoxin, and Clinical Features in Rocky Mountain Spotted Fever

Efficacy of chloramphenicol, enrofloxacin, and tetracycline for treatment of experimental Rocky Mountain spotted fever in dogs

“…In previous experimental studies with dogs, rickettsemia was detected by tissue culture isolation as early as the first 24 to 48 h of fever, and detectable levels of rickettsemia decrease with defervescence (2,4,8). Rickettsiae can be successfully isolated from the blood of febrile human patients if cultures are initiated within the first 36 h of treatment with tetracycline or 48 h with chloramphenicol (8,17,19). In the guinea pig model, defervescence occurred after 4 days of tetracycline treatment, but rickettsial organisms could not be found in tissues by immunofluorescent staining after 72 h (33).…”

Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis — United States

“…PCR amplification of DNA extracted from whole blood specimens collected during the acute stage of illness is particularly useful for confirming E. chaffeensis, A. phagocytophilum, E. ewingii, and EML agent infections because of the tropism of these pathogens for circulating cells. PCR detection of R. rickettsii in whole blood is possible but less sensitive because low numbers of rickettsiae typically circulate in the blood in the absence of advanced disease (16,269,290). Tissue specimens are a more useful source of SFG rickettsial DNA than acute blood samples (8).…”

“…For patients with a rash or eschar, immunohistochemical staining of a skin punch biopsy is a useful diagnostic technique for SFG rickettsioses (296)(297)(298). Immunostaining of skin biopsy specimens is 100% specific and 70% sensitive in diagnosing RMSF (290,299). Sensitivities might be higher for tests using eschars than for those using rash lesions (269) because of the higher concentration of organisms in eschars compared with rash lesions.…”

Laboratory diagnosis of rickettsioses: current approaches to diagnosis of old and new rickettsial diseases

“…Samples can be tested fresh (69,82,126,170,171,185) or after formalin fixation and paraffin embedment (47,48,92,169,175). Biopsy specimens of the skin with a rash around the lesion, preferably petechial lesions, and tache noire specimens are the most common samples used (47,82,92,126,170,171,185). In animals or patients with fatal cases of infection, bacteria are detectable at autopsy in the tissues of numerous organs such as the liver, spleen, kidney, heart, meningeal membranes, or skin (48,69).…”