Specimen Dilution Improves Sensitivity of the Amplified Mycobacterium tuberculosis Direct Test for Smear Microscopy-Positive Respiratory Specimens

• Published in: Journal of Clinical Microbiology 2008-01, Vol.46 (1), p.314-316
• Main Authors: Guerra, Renata L, Baker, James F, Alborz, Roya, Armstrong, Derek T, Kiehlbauch, Julia A, Conde, Marcus B, Dorman, Susan E, Hooper, Nancy M
• Format: Article
• Language: English
• Subjects: Bacteriology; Biological and medical sciences; Body Fluids - microbiology; Fundamental and applied biological sciences. Psychology; Humans; Microbiology; Microscopy; Miscellaneous; Molecular Diagnostic Techniques - methods; Mycobacteriology and Aerobic Actinomycetes; Mycobacterium tuberculosis; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - isolation & purification; Predictive Value of Tests; Sensitivity and Specificity; Tuberculosis - diagnosis
• ISSN: 0095-1137; 1098-660X; 1098-5530
• DOI: 10.1128/JCM.01313-07

Specimen dilution has been proposed as a strategy to minimize amplified Mycobacterium tuberculosis direct (MTD) test inhibition (N. Pollock, J. Westerling, and A. Sloutsky, Am. J. Clin. Pathol. 126:142-147, 2006; A. Sloutsky, L. L. Han, and B. G. Werner, J. Clin. Microbiol. 42:1547-1551, 2004). We evaluated the impact of respiratory specimen dilution on MTD test accuracy in a public health laboratory. The difference in MTD test sensitivity between the dilution and conventional methods was 15.9% (P = 0.001) for smear microscopy-positive specimens and -3.6% (P = 0.38) for smear microscopy-negative specimens.