Diagnostic accuracy of tongue swab testing on two automated tuberculosis diagnostic platforms, Cepheid Xpert MTB/RIF Ultra and Molbio Truenat MTB Ultima.

Tongue dorsum swabbing is a potential alternative to sputum collection for tuberculosis (TB) testing. Previous studies showed that Cepheid Xpert MTB/RIF Ultra (Xpert Ultra) can detect Mycobacterium tuberculosis DNA on tongue swabs stored in buffer, with 72% sensitivity and 100% specificity relative to a sputum microbiological reference standard (sputum MRS). The present study evaluated a more convenient sample collection protocol (dry swab storage), combined with streamlined sample processing protocols, for evaluating two commercial TB diagnostic tests: Xpert Ultra and Molbio Truenat MTB Ultima (MTB Ultima). Copan FLOQSwabs were self-collected or collected by study workers from 321 participants in Western Cape, South Africa. All participants had symptoms suggestive of TB, and 245 of them had sputum MRS-confirmed TB (by sputum MGIT culture and/or Xpert Ultra). One tongue swab per participant was tested on Xpert Ultra, and another tongue swab was tested with MTB Ultima. Xpert Ultra was 75.5% sensitive and 100% specific relative to sputum MRS, similar to previous methods that used swabs stored in buffer. MTB Ultima was 71.6% sensitive and 96.9% specific relative to sputum MRS. When sample lysates that were false-negative or invalid by MTB Ultima were frozen, thawed, and re-tested, MTB Ultima sensitivity rose to 79.1%. Both tests were more sensitive with swabs from participants with higher sputum Xpert Ultra semi-quantitative results. Although additional development could improve diagnostic accuracy, these results further support tongue swabs as easy-to-collect samples for TB testing. IMPORTANCE: Tongue dorsum swabbing is a promising alternative to sputum collection for tuberculosis (TB) testing. Our results lend further support for tongue swabs as exceptionally easy-to-collect samples for high-throughput TB testing.

Tongue swab testing on two automated tuberculosis diagnostic platforms, Cepheid Xpert® MTB/RIF Ultra and Molbio Truenat® MTB Ultima.

Tongue dorsum swabbing is a potential alternative to sputum collection for tuberculosis (TB) testing. Previous studies showed that Cepheid Xpert® MTB/RIF Ultra (Xpert Ultra) can detect Mycobacterium tuberculosis (MTB) DNA in tongue swabs stored in buffer, with 72% sensitivity and 100% specificity relative to a sputum microbiological reference standard (sputum MRS). The present study evaluated a more convenient sample collection protocol (dry swab storage), combined with streamlined sample processing protocols, for side-by-side analysis using two commercial TB diagnostic tests: Xpert Ultra and Molbio Truenat® MTB Ultima (MTB Ultima). Copan FLOQSwabs were self-collected, or collected by study workers, from 321 participants in Western Cape, South Africa. All participants had symptoms suggestive of TB, and 245 of them had sputum MRS-confirmed TB (by sputum culture and/or Xpert Ultra). One tongue swab per participant was tested on Xpert Ultra and another tongue swab was tested with MTB Ultima. Xpert Ultra was 75.4% sensitive and 100% specific, and MTB Ultima was 71.6% sensitive and 96.9% specific, relative to sputum MRS. When sample lysates that were false-negative by MTB Ultima were frozen, thawed, and re-tested, MTB Ultima sensitivity rose to 79.1%. Both tests were more sensitive with swabs from participants with higher sputum Xpert semi-quantitative results. The protocol for Xpert Ultra enabled fast and easy testing of dry-stored swabs with no loss of accuracy relative to previous methods. MTB Ultima testing of dry-stored swabs exhibited comparable performance to Xpert Ultra. These results further support tongue swabs as easy-to-collect samples for high-throughput TB testing.

Complementary Nonsputum Diagnostic Testing for Tuberculosis in People with HIV Using Oral Swab PCR and Urine Lipoarabinomannan Detection.

Testing for mycobacterial lipoarabinomannan (LAM) in urine is a practical but insensitive alternative to sputum testing to diagnose tuberculosis (TB) in people with HIV (PWH). Here, we evaluated urine LAM testing alongside PCR-based tests for Mycobacterium tuberculosis (MTB) DNA in tongue swabs. We hypothesized that the two nonsputum samples would deliver complementary, not redundant, results. The study included 131 South African patients of whom 64 (48.1%) were confirmed to have TB by GeneXpert MTB/RIF Ultra (Xpert Ultra) or culture analysis of sputum. A total of 120 patients (91.6%) were coinfected with HIV and 130 yielded a valid urine LAM result (Alere DETERMINE LAM Ag). Tongue swab samples were tested by IS6110-targeted qPCR with a quantification cycle (Cq) cutoff of 32. Relative to reference sputum testing (TB culture and Xpert Ultra), combined urine LAM and oral swab testing (either sample positive) was significantly more sensitive than either nonsputum sample alone (57% sensitivity for combined testing versus 35% and 39% sensitivity for urine LAM and tongue swabs; P = 0.01 and 0.04, respectively). Specificity of combined testing (neither sample positive) was 97%. On average, tongue swab-positive participants had higher sputum signal strength than urine-LAM positive participants, as measured by sputum Xpert Ultra Cq value (P = 0.037). A subset of tongue swabs (N = 18) was also tested by using Xpert Ultra, which reproduced true positive and true negative IS6110 qPCR results and resolved the two false-positive tongue swabs. With further development, tongue swabs and urine may feasibly serve as complementary nonsputum samples for diagnosis of TB in PWH.

Steady-State Pre-rRNA Analysis to Investigate the Functional Microbiome.

The gut microbiome is recognized as a critical regulator of human diseases. Constituents of the microbiota and their individual activities can affect a broad range of disease states related to autoimmunity, cancer, infection, metabolism, mental health, and toxicant exposure. A substantial number of microbiome species are not culturable, limiting their study in vitro. Sequencing methods have allowed quantification of the composition of the microbiome, but methods to characterize the physiological status of bacterial species remain limited. Ribosomal RNA precursors (pre-rRNAs) are species-specific intermediates in bacterial ribosomal synthesis, and their levels are highly responsive to environmental changes. Immediately before and during active growth, pre-rRNA levels are high, whereas in non-dividing cells, copy numbers are orders of magnitude lower. These dynamics are conserved in all bacterial species and occur exclusively in viable cells, allowing the specific characterization of living and functional bacteria in their native states. Pre-rRNA analysis has been shown to yield valuable real-time information on the physiology of individual bacterial species within complex samples, beyond what traditional qPCR and sequencing methods can offer. Herein, we describe a PCR-based protocol to interrogate and quantify the in situ growth status of bacterial species of interest within a complex microbiome. We also describe an in vitro protocol to characterize the pre-rRNA/growth relationship for a given bacterial species to provide greater context for values obtained from natural samples. Improved understanding of microbial physiological responses to exposures could reveal novel toxicological mechanisms, biomarkers, and potential treatments. © 2021 Wiley Periodicals LLC. Basic Protocol: Targeted steady-state pre-rRNA analysis Support Protocol: Characterization of pre-rRNA/growth relationship © 2021 by John Wiley & Sons, Inc.

Characterization of oral swab samples for diagnosis of pulmonary tuberculosis.

Oral swab analysis (OSA) has been shown to detect Mycobacterium tuberculosis (MTB) DNA in patients with pulmonary tuberculosis (TB). In previous analyses, qPCR testing of swab samples collected from tongue dorsa was up to 93% sensitive relative to sputum GeneXpert, when 2 swabs per patient were tested. The present study modified sample collection methods to increase sample biomass and characterized the viability of bacilli present in tongue swabs. A qPCR targeting conserved bacterial ribosomal rRNA gene (rDNA) sequences was used to quantify bacterial biomass in samples. There was no detectable reduction in total bacterial rDNA signal over the course of 10 rapidly repeated tongue samplings, indicating that swabs collect only a small portion of the biomass available for testing. Copan FLOQSwabs collected ~2-fold more biomass than Puritan PurFlock swabs, the best brand used previously (p = 0.006). FLOQSwabs were therefore evaluated in patients with possible TB in Uganda. A FLOQSwab was collected from each patient upon enrollment (Day 1) and, in a subset of sputum GeneXpert Ultra-positive patients, a second swab was collected on the following day (Day 2). Swabs were tested for MTB DNA by manual IS6110-targeted qPCR. Relative to sputum GeneXpert Ultra, single-swab sensitivity was 88% (44/50) on Day 1 and 94.4% (17/18) on Day 2. Specificity was 79.2% (42/53). Among an expanded sample of Ugandan patients, 62% (87/141) had colony-forming bacilli in their tongue dorsum swab samples. These findings will help guide further development of this promising TB screening method.