Orientia tsutsugamushi DNA load and genotypes in blood as a marker of severity

Genomic bacterial load associated with bacterial genotypes and clinical characteristics in patients with scrub typhus in Hainan Island, Southern China

“…developed for the detection and quantitative analysis of O. tsutsugamushi infection, in which 16S rRNA genes and the membrane protein 56-kDa and 47-kDa genes are the most widely used targets [15,16,26]. In this study, we developed a real-time PCR assay for the quantification of O. tsutsugamushi targeting the 56-kDa TSA gene of O. tsutsugamushi, and the assay showed good concordance with the nested PCR assay.…”

“…The median O. tsutsugamushi DNA load in this study was 3.11×10 3 copies/mL, ranging between 44 and 3.2×10 6 copies/mL. However, this load varies among studies; Singhsilarak et al reported a median number of 4.2×10 6 copies/mL (range, 1×10 6 -2.88 ×10 7 copies/mL) using real-time PCR targeting the 47 kDa gene in 7 patients with scrub typhus and positive RT-PCR, whereas Kim et al reported a median number of 7.8×10 4 copies/mL (range 3,960) in surviving patients, and a median number of 8.38×10 7 copies/mL (range 244,600) in 3 non-surviving patients using the same primers and probes [15,16]. Sonthayanon et al reported a median number of 284 copies/mL of O. tsutsugamushi DNA (range, 124-943 copies/mL) in 81 patients with positive quantitative RT-PCR results targeting 16 S rRNA [15].…”

“…Additionally, recent studies have investigated the relationship between O. tsutsugamushi genomic DNA load and clinical characteristics of scrub typhus. The results indicated that the patients with fatal disease had a significantly higher bacterial load than patients with non-fatal disease, and that duration of illness, presence of eschar, and hepatic enzyme levels were positively correlated with the O. tsutsugamushi DNA load [15,16] High genomic DNA load is a marker for the virulence of the pathogen and is associated with disease severity in bacterial infectious diseases. In severe sepsis, the genomic bacterial load has been proposed to be a useful marker for assessing severity, predicting prognosis, and monitoring clinical response [17].…”

“…Although studies have examined the relationship of DNA load and disease severity for surviving and non-surviving patients with scrub typhus, the association between DNA load and severity in surviving patients has not been investigated [15,16]. In this study, the O. tsutsugamushi genomic load in blood samples of patients with scrub typhus taken at the time of hospital admission was evaluated, and its association with disease severity, O. tsutsugamushi genotypes, and other clinical features was analyzed.…”

“…Although studies have examined the relationship of DNA load and disease severity for surviving and non-surviving patients with scrub typhus, the association between DNA load and severity in surviving patients has not been investigated [ 15 , 16 ]. In this study, the O .…”