Eradication of Rickettsia tsutsugamushi from patients' blood by chemotherapy, as assessed by the polymerase chain reaction.

The presence of Rickettsia tsutsugamushi DNA in peripheral blood mononuclear cells of eight patients with tsutsugamushi disease was determined by the polymerase chain reaction during antibiotic treatment with minocycline or doxycycline. Rickettsia tsutsugamushi DNA was detectable in all samples from these patients collected the day before treatment began. After the initiation of chemotherapy, all samples tested positive on the third or fourth day, and one sample tested positive on the eighth day, showing a slow action of the drugs against the rickettsia within cells. Immune responses against R. tsutsugamushi also seemed to be important for eradication of the pathogens, as suggested by patients' high antibody titers.