title: Specimens and culture media for the laboratory diagnosis of typhoid fever.
abstract: BACKGROUND
  Culture of S. Typhi is necessary for the definitive diagnosis of typhoid fever and provides isolates for antibiotic susceptibility testing and epidemiological studies. However, current methods are not fully optimised and sourcing culture media and bottles for culture media may be problematic.
  
  
  METHODS
  In two hospital laboratories in Viet Nam, comparisons of media for blood and stool culture were conducted. The effect of the volume of blood or stool on culture positivity rate was examined and direct plating of the blood buffy coat was trialed.
  
  
  RESULTS
  For 148 suspected typhoid fever cases, ox bile broth (58 positive) and brain-heart infusion broth containing saponin (63 positive), performed equally well. For 69 confirmed adult typhoid fever cases, large-volume (15 ml) blood culture gave the same sensitivity as 1 ml of bone marrow culture. For 44 confirmed typhoid fever cases, the direct plating of the buffy coat was positive in 28 cases. For 263 positive stool cultures, selenite F and selenite mannitol performed equally well and culturing 2 g rather than 1g increased the isolation rate by 10.5%.
  
  
  CONCLUSIONS
  For the diagnosis of typhoid fever by blood culture the medium should be a rich nutrient broth containing a lysing agent. In adults 1 ml bone marrow or 15 ml blood culture gave similar results. Where isolates are needed for susceptibility testing or epidemiological studies, but resources for culture are scarce, direct plating of the blood buffy coat can be used with a 50% fall in sensitivity compared to standard blood culture.
authors.affiliation: The Wellcome Trust Clinical Research Unit, Centre for Tropical Diseases, Ho Chi Minh City, Vietnam. jw5@sanger.ac.uk
authors.forename: John
authors.initials: J
authors.lastname: Wain
authors.forename: To Song
authors.initials: TS
authors.lastname: Diep
authors.forename: Phan Van Be
authors.initials: PV
authors.lastname: Bay
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Walsh
authors.forename: Ha
authors.initials: H
authors.lastname: Vinh
authors.forename: Nguyen M
authors.initials: NM
authors.lastname: Duong
authors.forename: Vo Anh
authors.initials: VA
authors.lastname: Ho
authors.forename: Tran T
authors.initials: TT
authors.lastname: Hien
authors.forename: Jeremy
authors.initials: J
authors.lastname: Farrar
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: White
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Parry
authors.forename: Nicholas P J
authors.initials: NP
authors.lastname: Day
mesh_terms: D000328:Adult; D001853:Bone Marrow / Q000382:microbiology*; D002648:Child; D019411:Clinical Laboratory Techniques; D003470:Culture Media / Q000737:chemistry*; D046508:Culture Techniques / Q000379:methods; D005243:Feces / Q000382:microbiology*; D006801:Humans; D007755:Laboratories, Hospital; D008353:Mannitol / Q000737:chemistry; D012485:Salmonella typhi / Q000302:isolation & purification; D012680:Sensitivity and Specificity; D018038:Sodium Selenite / Q000737:chemistry; D014435:Typhoid Fever / Q000097:blood / Q000175:diagnosis; D014744:Vietnam
chemical_list: D003470:Culture Media; D008353:Mannitol; D018038:Sodium Selenite