Isolation of Orientia tsutsugamushi from Patients in Shikoku and Finding of a Strain Which Grows Preferentially at Low Temperatures

Abstract

Three strains of Orientia tsutsugamushi were isolated from patients in Anan City, Tokushima Prefecture. The strains were identified as Karp type by analyses of reactivities with type-specific monoclonal antibodies. One strain, Okazaki, was isolated in L cells cultivated at 31C, but not in cells at 36C or in mice. This strain showed better growth at 31C than 36C. This is the first report of an O. tsutsugamushi strain which grows preferentially at low temperatures.