Identification of Mycobacterium tuberculosis in sputum by direct inoculation of the BACTEC NAP vial

Charles E. Stager, James R. Davis, Salman H. Siddiqi

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3 Scopus citations


The Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis, and M. africanum) can be differentiated from mycobacteria other than M. tuberculosis (MOTT bacilli) with the BACTEC NAP test (Johnston Laboratories, Becton, Dickinson & Co., Towson, MD), by selectively inhibiting their growth with p-nitro-alpha-acetyl-amino-β-hydroxypropriophenone (NAP). The BACTEC NAP test is recommended for isolated mycobacterial cultures. In this report, a direct NAP test is performed by immediate inoculation of BACTEC NAP vials with processed sputum specimens that stain acid-fast positive. Seventy-six of 80 M. tuberculosis were correctly identified and all of the MOTT bacilli (nine M. avium complex and one M. kansasii) were correctly classified. The average time required for identification of M. tuberculosis with the direct BACTEC NAP test was 7.8 days compared to 36.5 days for the conventional method. The direct BACTEC NAP test described here is more convenient than the recommended indirect test, and it is an accurate and rapid method to differentiate the M. tuberculosis complex from MOTT bacilli.

Original languageEnglish (US)
Pages (from-to)67-73
Number of pages7
JournalDiagnostic Microbiology and Infectious Disease
Issue number2
StatePublished - Jan 1 1988

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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