title: Quantitative culture of Mycobacterium tuberculosis from clinical sputum specimens and dilution endpoint of its detection by the Amplicor PCR assay.
abstract: The minimum number of Mycobacterium tuberculosis CFU detectable in clinical sputum specimens by the Amplicor PCR test was estimated by performing the test on duplicate samples of quantitatively cultured serial dilutions of sputum. Positive PCR test results were obtained for all samples that contained 42 CFU of M. tuberculosis. The detection limits of the PCR assay for decontaminated (N-acetyl-L-cysteine [NALC]-NaOH) and nondecontaminated (NALC only) specimens were equivalent, even though the number of CFU cultured from decontaminated samples was only 11 to 20% of the number cultured from nondecontaminated samples. Thus, the 42 CFU that could be detected in nondecontaminated specimens by the Amplicor PCR test correspond to the approximately 8 CFU (0.20 x 42) that could be recovered in culture after decontamination with NALC-NaOH.
authors.affiliation: Department of Laboratory Medicine, University of California, San Francisco General Hospital 94110, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Yajko
authors.forename: C
authors.initials: C
authors.lastname: Wagner
authors.forename: V J
authors.initials: VJ
authors.lastname: Tevere
authors.forename: T
authors.initials: T
authors.lastname: Kocagöz
authors.forename: W K
authors.initials: WK
authors.lastname: Hadley
authors.forename: H F
authors.initials: HF
authors.lastname: Chambers
mesh_terms: D001431:Bacteriological Techniques / Q000706:statistics & numerical data; D015169:Colony Count, Microbial / Q000379:methods / Q000706:statistics & numerical data; D003470:Culture Media; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005069:Evaluation Studies as Topic; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D012972:Sodium Hydroxide; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D012972:Sodium Hydroxide