Sensitivity of Polymerase Chain Reaction Assay for Rickettsia tsutsugamushi in Patients' Blood Samples

Abstract

We developed a nested

Comparison of Conventional, Nested, and Real-Time Quantitative PCR for Diagnosis of Scrub Typhus

“…PCR assays have been widely used for rapid identification of fastidious organisms or rickettsiae that are difficult to cultivate. Murai et al (13) have reported that C-PCR requires 20 ng of DNA for detection. As N-PCR requires only 200 pg of DNA, N-PCR is 100 times more sensitive than C-PCR.…”

“…Since these serologic tests have low sensitivities in the early stage of scrub typhus due to insufficient production of antibodies, frequent follow-up tests are needed (2). Detection of specific O. tsutsugamushi genes has been used for the rapid diagnosis of scrub typhus, and nested PCR (N-PCR) is widely used to improve the sensitivity of conventional PCR (C-PCR) (3,4,13). In addition, real-time quantitative PCR (Q-PCR) targeting a specific gene permits the diagnosis of scrub typhus within 2 h and has high sensitivity and specificity (5).…”

Effects of Antibiotic Treatment on the Results of Nested PCRs for Scrub Typhus

“…Scrub typhus has also been diagnosed by PCR for O. tsutsugamushi-specific genes, and this has been shown to be of considerable use in the early diagnosis of scrub typhus (4,5,7). However, its potential disadvantages include false positivity due to DNA contamination and a decline in sensitivity following antibiotic administration.…”

“…It can be diagnosed by isolating O. tsutsugamushi from patients' blood during the febrile stage or by measuring antibody titers against O. tsutsugamushi during the acute and convalescent stages (5). However, it takes several weeks to isolate O. tsutsugamushi from cultured cells or infected rats (7,9), and the sensitivity of isolation is reported to be only 46.7% (6). Scrub typhus can be diagnosed on the basis of a fourfold or greater increase in antibody titer using the passive hemagglutination assay, indirect immunofluorescentantibody assay (IFA), indirect immunoperoxidase assay, or enzyme-linked immunosorbent assay (2,5).…”

Transfiguration of Rickettsial Diseases: Tsutsugamushi Disease and Spotted Fever Group Rickettsiosis in Japan.

“…Furuya et al reported a PCR method to detect R. tsutsugamushi DNA from blood clots of patients (6). Murai et al reported a nested PCR method to detect it from peripheral blood mononuclear cell samples of patients (7). The PCR method will be useful for rapid and specific diagnosis of tsutsugamushi disease in the early acute stage.…”