Comparative evaluation of three immunochromatographic identification tests for culture confirmation of Mycobacterium tuberculosis complex

• Published in: BMC infectious diseases Vol. 14; no. 1; p. 54
• Main Authors: Chikamatsu, Kinuyo, Aono, Akio, Yamada, Hiroyuki, Sugamoto, Tetsuhiro, Kato, Tomoko, Kazumi, Yuko, Tamai, Kiyoko, Yanagisawa, Hideji, Mitarai, Satoshi
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 01-02-2014; BioMed Central
• Subjects: Bacterial Proteins - genetics; Bacterial Typing Techniques - methods; Care and treatment; Deoxyribonucleic acid; Diagnosis; DNA; Drug resistance; Genes; Humans; Immunochromatography - methods; Medical laboratories; Mutation; Mycobacterium tuberculosis; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - genetics; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Sensitivity and Specificity; Studies; Tuberculosis; Tuberculosis - diagnosis; Tuberculosis - microbiology; Japan
• ISSN: 1471-2334; 1471-2334
• DOI: 10.1186/1471-2334-14-54

The rapid identification of acid-fast bacilli recovered from patient specimens as Mycobacterium tuberculosis complex (MTC) is critically important for accurate diagnosis and treatment. A thin-layer immunochromatographic (TLC) assay using anti-MPB64 or anti-MPT64 monoclonal antibodies was developed to discriminate between MTC and non-tuberculosis mycobacteria (NTM). Capilia TB-Neo, which is the improved version of Capilia TB, is recently developed and needs to be evaluated.
Capilia TB-Neo was evaluated by using reference strains including 96 Mycobacterium species (4 MTC and 92 NTM) and 3 other bacterial genera, and clinical isolates (500 MTC and 90 NTM isolates). M. tuberculosis isolates tested negative by Capilia TB-Neo were sequenced for mpt64 gene.
Capilia TB-Neo showed 100% agreement to a subset of reference strains. Non-specific reaction to M. marinum was not observed. The sensitivity and specificity of Capilia TB-Neo to the clinical isolates were 99.4% (99.6% for M. tuberculosis, excluding M. bovis BCG) for clinical MTC isolates and 100% for NTM isolates tested, respectively. Two M. tuberculosis isolates tested negative by Capilia TB-Neo: one harbored a 63-bp deletion in the mpt64 gene and the other possessed a 3,659-bp deletion from Rv1977 to Rv1981c, a region including the entire mpt64 gene.
Capilia TB-Neo is a simple, rapid and highly sensitive test for identifying MTC, and showed better specificity than Capilia TB. However, Capilia TB-Neo still showed false-negative results with mpt64 mutations. The limitation should be recognized for clinical use.