title: Optimizing Mycobacterial Culture in Smear-Negative, Human Immunodeficiency Virus-Infected Tuberculosis Cases.
abstract: BACKGROUND
  Tuberculosis (TB) is a significant public health problem and the diagnosis in human immunodeficiency virus (HIV)-infected individuals is challenging. The use of mycobacterial culture remains an important complementary tool and optimizing it has important benefits. We sought to determine the effect of an increase in the number of specimens evaluated, addition of nutritional supplementation to the culture medium, sputum appearance and volume on diagnostic yield and time to detection of pulmonary TB among smear-negative, HIV-infected adults.
  
  
  METHODS
  In this prospective study conducted at the Tshwane District Hospital and Academic TB Laboratory, Pretoria, South Africa we collected three sputum specimens an hour apart from presumptive TB cases at an antiretroviral treatment site. We analysed specimens from 236 patients. Specimen appearance and volume were recorded. All specimens were processed for culture using both standard and supplemented media.
  
  
  RESULTS
  A single specimen identified 79% of PTB cases using standard media; the second and third specimens added 12.5% and 8.3% respectively. Media supplementation, sputum appearance and specimen volume had no effect on culture yield or contamination rates. The mean time to detection was reduced from 19.8 days in standard cultures to 11.8 days in nutrient supplemented cultures (p = 0.002). For every 1 ml increase in sputum volume, time to detection was decreased by a factor of 0.797 (p = 0.011).
  
  
  CONCLUSIONS
  Use of an inexpensive culture supplement substantially reduced time to detection and could contribute to reducing treatment delay among HIV-infected cases.
authors.affiliation: Department of Medical Microbiology, Faculty of Health Science, University of Pretoria, Pretoria, South Africa.|Centre for Tuberculosis, National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: N A
authors.initials: NA
authors.lastname: Ismail
authors.affiliation: Centre for Tuberculosis, National Institute for Communicable Diseases, Johannesburg, South Africa.|Department of Medical Microbiology, University of Free State, Bloemfontein, South Africa.
authors.forename: H M
authors.initials: HM
authors.lastname: Said
authors.affiliation: TB/HIV Directorate, Gauteng Department of Health, Johannesburg, South Africa.
authors.forename: Z
authors.initials: Z
authors.lastname: Pinini
authors.affiliation: Centre for Tuberculosis, National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: S V
authors.initials: SV
authors.lastname: Omar
authors.affiliation: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Stellenbosch University, Cape Town, South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Beyers
authors.affiliation: Desmond Tutu TB Centre, Department of Paediatrics and Child Health, Stellenbosch University, Cape Town, South Africa.
authors.forename: P
authors.initials: P
authors.lastname: Naidoo
mesh_terms: D000328:Adult; D003470:Culture Media / Q000737:chemistry; D046508:Culture Techniques / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D008297:Male; D009169:Mycobacterium tuberculosis / Q000254:growth & development* / Q000302:isolation & purification / Q000502:physiology*; D013183:Sputum / Q000382:microbiology; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000150:complications* / Q000175:diagnosis* / Q000821:virology
chemical_list: D003470:Culture Media