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

Background: 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.Methods: 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.Results: 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.Conclusions: 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

Clonal Expansion of Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis, Japan

Strain clustering suggests community transmission plays a critical role in incidence

Prospective multicentre accuracy evaluation of the FUJIFILM SILVAMP TB LAM Test for the diagnosis of tuberculosis in people living with HIV demonstrates lot-to-lot variability

There is an urgent need for rapid, non-sputum point-of-care diagnostics to detect tuberculosis. This prospective trial in seven high tuberculosis burden countries evaluated the diagnostic accuracy of the point-of-care urine-based lipoarabinomannan assay FUJIFILM SILVAMP TB LAM (FujiLAM) among inpatients and outpatients living with HIV. Diagnostic performance of FujiLAM was assessed against a mycobacterial reference standard (sputum culture, blood culture, and Xpert Ultra from urine and sputum at enrollment, and additional sputum culture ≤7 days from enrollment), an extended mycobacterial reference standard (eMRS), and a composite reference standard including clinical evaluation. Of 1637 participants considered for the analysis, 296 (18%) were tuberculosis positive by eMRS. Median age was 40 years, median CD4 cell count was 369 cells/ul, and 52% were female. Overall FujiLAM sensitivity was 54·4% (95% CI: 48·7-60·0), overall specificity was 85·2% (83·2-87·0) against eMRS. Sensitivity and specificity estimates varied between sites, ranging from 26·5% (95% CI: 17·4%-38·0%) to 73·2% (60·4%-83·0%), and 75·0 (65·0%-82·9%) to 96·5 (92·1%-98·5%), respectively. Post-hoc exploratory analysis identified significant variability in the performance of the six FujiLAM lots used in this study. Lot variability limited interpretation of FujiLAM test performance. Although results with the current version of FujiLAM are too variable for clinical decision-making, the lipoarabinomannan biomarker still holds promise for tuberculosis diagnostics

Structome Analysis of Virulent <i>Mycobacterium tuberculosis</i>, Which Survives with Only 700 Ribosomes per 0.1 fl of Cytoplasm

<div><p>We previously reported the exquisite preservation of the ultrastructures of virulent <i>Mycobacterium tuberculosis</i> cells processed through cryofixation and rapid freeze substitution. Here, we report the “structome” analysis (i.e., the quantitative three-dimensional structural analysis of a whole cell at the electron microscopic level) of virulent <i>M. tuberculosis</i> using serial ultrathin sections prepared after cryofixation and rapid freeze substitution and analyzed by transmission electron microscopy. Five <i>M. tuberculosis</i> cells, which were contained in the serial ultrathin cross sections encompassing from one end to the other, were cut into 24, 36, 69, 55, and 63 serial ultrathin sections, respectively. On average, the cells were 2.71 ± 1.05 μm in length, and the average diameter of the cell was 0.345 ± 0.029 μm. The outer membrane and plasma membrane surface areas were 3.04 ± 1.33 μm² and 2.67 ± 1.19 μm², respectively. The cell, outer membrane, periplasm, plasma membrane, and cytoplasm volumes were 0.293 ± 0.113 fl (= μm³), 0.006 ± 0.003 fl, 0.060 ± 0.021 fl, 0.019 ± 0.008 fl, and 0.210 ± 0.091 fl, respectively. The average total ribosome number was 1,672 ± 568, and the ribosome density was 716.5 ± 171.4/0.1 fl. This is the first report of a structome analysis of <i>M. tuberculosis</i> cells prepared as serial ultrathin sections following cryofixation and rapid freeze substitution and examined by transmission electron microscopy. These data are based on the direct measurement and enumeration of exquisitely preserved single-cell structures in transmission electron microscopy images rather than calculations or assumptions from indirect biochemical or molecular biological data. In addition, these data may explain the slow growth of <i>M. tuberculosis</i> and enhance understanding of the structural properties related to the expression of antigenicity, acid-fastness, and the mechanism of drug resistance, particularly in regard to the ratio of target to drug concentrations.</p></div

Three-dimensional profiles of <i>M</i>. <i>tuberculosis</i> cells.

<p>Three-dimensional profiles of <i>M</i>. <i>tuberculosis</i> cells.</p

Multiple mutations of Mycobacterium intracellulare subsp. chimaera causing false-negative reaction to the transcription-reverse transcription concerted method for pathogen detection

Objectives: To report an isolate of Mycobacterium intracellulare subsp. chimaera with multiple mutations in 16S ribosomal RNA (rRNA) gene, resulting in the false-negative reaction to the transcription-reverse transcription concerted (TRC) method for Mycobacterium avium-intracellulare complex. Methods: We used TRC, polymerase chain reaction (PCR), and Matrix-assisted laser desorption/ionization Time-of-Flight/Mass Spectrometry (MALDI-TOF/MS) methods to identify a clinical isolate in 2021. Due to the discordant results between TRC and PCR or MALDI-TOF MS methods, 16S rRNA sequencing, whole-genome shotgun (WGS) sequencing, and average nucleotide identity (ANI) analysis were employed to identify the isolate. Results: A mycobacterial isolate from a sputum sample gave negative results for the detection of Mycobacterium tuberculosis complex or M. avium-intracellulare complex by the TRC method. However, the isolate was identified as M. intracellulare by both PCR method and MALDI-TOF MS method. WGS sequencing of 16S rRNA genome revealed eight substitution mutations and one insertion mutation within the region, which could hamper the correct reaction to TRC method. Subsequent ANI analysis between the isolate and various species of nontuberculosis mycobacteria revealed that the isolate could be identified as M. intracellulare subsp. chimaera. Conclusion: Rare mutations within the 16S rRNA genome resulted in the false-negative identification of Mycobacterium chimaera by the TRC method. WGS sequencing and ANI analysis was necessary to identify the isolate

One- and two-dimensional properties of five <i>M</i>. <i>tuberculosis</i> cells obtained from serial ultrathin section TEM examination.

<p>The size of each schema correlates with the cell’s relative width and length. The diameter, length, aspect ratio, outer membrane (OM) surface area, and plasma membrane (PM) surface area of each of five cells are indicated.</p

TEM images of five cross-sectioned <i>M</i>. <i>tuberculosis</i> cells.

<p>Cells were cut in the middle. The outer membrane (OM), periplasm (asterisk), plasma membrane (PM), and ribosomes (R) are visible as shown in the bottom right panel (enlarged image of cell 3). The cytoplasm of cell 2 appeared to have degraded, as evidenced by its dark color and fewer ribosomes. Cell 3 can be seen to the upper left of cell 2. Bar: 100 nm.</p

Pie graphs showing the volumes of the cell compartments for each of the five <i>M</i>. <i>tuberculosis</i> cells examined.

<p>The size of each pie correlates with the cell’s relative volume. The whole-cell volume, proportion of the volumes of the cell compartments, total number of ribosomes, and ribosome density for each of five cells are indicated.</p

One-dimensional profiles of <i>M</i>. <i>tuberculosis</i> cells.

<p>One-dimensional profiles of <i>M</i>. <i>tuberculosis</i> cells.</p