title: Lack of effect of dexamethasone on growth of Orientia tsutsugamushi Gilliam in mouse L929 cells.
abstract: OBJECTIVE
  Previous studies and our own clinical experience suggest that concurrent corticosteroid treatment for severe rickettsial disease with multiorgan failure may improve the clinical course or reduce mortality. However, the use of corticosteroids as adjunctive treatment for rickettsial diseases is controversial. We attempted to determine the influences of corticosteroid on the growth of Orientia tsutsugamushi in vitro to justify and evaluate the clinical applicability of corticosteroid in rickettsial disease.
  
  
  METHODS
  L929 cells were infected with Orientia tsutsugamushi Gilliam. Dexamethasone was added to the cells at final concentrations of 10¹ and 10⁷ pg/mL. Cultures were incubated at 35°C and processed for flow cytometry on the 6th day after addition of dexamethasone.
  
  
  RESULTS
  Observation on the 6th day after treatment with dexamethasone in infected cultures revealed that there was no difference in fluorescence intensity among the treatment wells. Treatment of the cells with dexamethasone at concentrations of 10¹ and 10⁷ pg/mL showed no influence on the growth of Orientia tsutsugamushi.
  
  
  CONCLUSIONS
  Our results to show that isolated corticosteroid does not enhance the replication of Orientia tsutsugamushi in vitro. Concurrent use of anti-inflammatory or immunosuppressive doses of corticosteroids in conjunction with antibiotics may not have detrimental effects on the course of scrub typhus.
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, 250 Seongsan-ro, Seodaemun-gu, Seoul 120-752, Korea.
authors.forename: Chang Oh
authors.initials: CO
authors.lastname: Kim
authors.forename: Ae Jung
authors.initials: AJ
authors.lastname: Huh
authors.forename: Joon Sup
authors.initials: JS
authors.lastname: Yeom
authors.forename: Kkot Sil
authors.initials: KS
authors.lastname: Lee
authors.forename: Bum Sik
authors.initials: BS
authors.lastname: Chin
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Han
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Jeong
authors.forename: Jun Yong
authors.initials: JY
authors.lastname: Choi
authors.forename: Young Goo
authors.initials: YG
authors.lastname: Song
authors.forename: June Myung
authors.initials: JM
authors.lastname: Kim
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D005434:Flow Cytometry; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D012285:Orientia tsutsugamushi / Q000187:drug effects* / Q000254:growth & development; D012612:Scrub Typhus / Q000188:drug therapy / Q000382:microbiology
chemical_list: D003907:Dexamethasone; D007371:Interferon-gamma