A patient presented with cough and evening rise of temperature since one month. Which among the following is the definitive diagnostic test for tuberculosis?
Gram's staining
Culture
Guinea-pig inoculation
Tuberculin testing
Definitive diagnosis depends on the isolation and identification of M. tuberculosis from a clinical specimen or the identification of specific sequences of DNA in a nucleic acid amplification test. Specimens may be inoculated onto egg- or agar-based medium (e.g., Lowenstein-Jensen or Middlebrook 7H10) and incubated at 37degC (under 5% CO2 for Middlebrook medium). Because most species of mycobacteria, including M. tuberculosis, grow slowly, 4-8 weeks may be required before growth is detected. Ref: Raviglione M.C., O'Brien R.J. (2012). Chapter 165. Tuberculosis. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.