title: Patient and sample-related factors that effect the success of in vitro isolation of Orientia tsutsugamushi.
abstract: Orientia tsutsugamushi is the causative agent of scrub typhus infection, a major cause of human disease in rural areas of Southeast Asia. Twenty-six blood samples collected from patients with serologically proven scrub typhus during a six month period were sent to Bangkok (535 km from the clinical site) by road at ambient temperature (average daily temperature range: 27.1-29.1 degrees C) for attempted in vitro isolation in Vero cells. O. tsutsugamushi was isolated from 12 samples (sensitivity 46.7%) with the time to isolation ranging from 16 to 37 days [median 27 days, inter-quartile range (IQR) 22.5-33.5 days]. Patient factors such as days of fever and O. tsutsugamushi IgM antibody titer, transport factors such as transit time, and isolate genotype (Karp and Gilliam/Kawasaki) were assessed to determine their influence on the outcome of in vitro isolation. None of the factors significantly influenced the isolation outcome. This study demonstrates that O. tsutsugamushi can often be isolated in vitro from the blood of scrub typhus patients when transported at ambient tropical temperatures for many days.
authors.affiliation: Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors.forename: Rungnapa
authors.initials: R
authors.lastname: Luksameetanasan
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Blacksell
authors.forename: Thareerat
authors.initials: T
authors.lastname: Kalambaheti
authors.forename: Vanaporn
authors.initials: V
authors.lastname: Wuthiekanun
authors.forename: Wirongrong
authors.initials: W
authors.lastname: Chierakul
authors.forename: Sunee
authors.initials: S
authors.lastname: Chueasuwanchai
authors.forename: Apichat
authors.initials: A
authors.lastname: Apiwattanaporn
authors.forename: John
authors.initials: J
authors.lastname: Stenos
authors.forename: Stephen
authors.initials: S
authors.lastname: Graves
authors.forename: Sharon J
authors.initials: SJ
authors.lastname: Peacock
authors.forename: Nicholas P J
authors.initials: NP
authors.lastname: Day
mesh_terms: D000818:Animals; D006801:Humans; D066298:In Vitro Techniques; D012285:Orientia tsutsugamushi / Q000302:isolation & purification*; D012424:Rural Population; D012612:Scrub Typhus / Q000097:blood* / Q000175:diagnosis / Q000382:microbiology; D022603:Shiga Toxins / Q000097:blood; D013048:Specimen Handling / Q000379:methods*; D013696:Temperature; D013785:Thailand / Q000453:epidemiology; D013997:Time Factors
chemical_list: D022603:Shiga Toxins