More about the Deformation of Our Language

<div><p>Background</p><p>Although tuberculosis is transmitted by the airborne route, direct information on the natural output of bacilli into air by source cases is very limited. We sought to address this through sampling of expelled aerosols in face masks that were subsequently analyzed for mycobacterial contamination.</p><p>Methods</p><p>In series 1, 17 smear microscopy positive patients wore standard surgical face masks once or twice for periods between 10 minutes and 5 hours; mycobacterial contamination was detected using a bacteriophage assay. In series 2, 19 patients with suspected tuberculosis were studied in Leicester UK and 10 patients with at least one positive smear were studied in The Gambia. These subjects wore one FFP30 mask modified to contain a gelatin filter for one hour; this was subsequently analyzed by the Xpert MTB/RIF system.</p><p>Results</p><p>In series 1, the bacteriophage assay detected live mycobacteria in 11/17 patients with wearing times between 10 and 120 minutes. Variation was seen in mask positivity and the level of contamination detected in multiple samples from the same patient. Two patients had non-tuberculous mycobacterial infections. In series 2, 13/20 patients with pulmonary tuberculosis produced positive masks and 0/9 patients with extrapulmonary or non-tuberculous diagnoses were mask positive. Overall, 65% of patients with confirmed pulmonary mycobacterial infection gave positive masks and this included 3/6 patients who received diagnostic bronchoalveolar lavages.</p><p>Conclusion</p><p>Mask sampling provides a simple means of assessing mycobacterial output in non-sputum expectorant. The approach shows potential for application to the study of airborne transmission and to diagnosis.</p></div

List of growth-attenuating genes with non-synonymous or frameshift mutations in <i>M. africanum</i>.

<p>List of growth-attenuating genes with non-synonymous or frameshift mutations in <i>M. africanum</i>.</p

<i>In vitro</i> growth curves from standardized inocula.

<p><i>M. tuberculosis</i> (solid line) and <i>M. africanum</i> (dashed line) were grown from standardized inocula in Bactec MGIT 960 and measured growth units (GU) are plotted versus time [days].</p

Status of putative <i>M.</i> africanum operons essential for intracellular survival.

<p>Seven operons were previously defined as essential for growth within the macrophage <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002220#pntd.0002220-Rengarajan1" target="_blank">[13]</a>. Genes that are identical to the wildtype <i>M. tuberculosis</i> H37Rv gene homologue are displayed with a solid border line and white background. Genes, with a non-synonymous mutation are displayed in blue with dashed lines. Genes with a frameshift mutation, are displayed with striped background.</p

Growth of <i>M. tuberculosis</i> complex isolates from sputum in The Gambia in two liquid culture systems.

*<p>Wilcoxon rank sum test comparing median time for <i>M. africanum</i> vs. <i>M. tuberculosis</i>.</p

Schematic overview of molecular transport mechanisms present in <i>M.</i> africanum.

<p>Genetic information of 132 genes encoding various families of membrane transporters was compared between the sequenced <i>M. africanum</i> strains and <i>M. tuberculosis</i> H37Rv. The analysis comprised both, transport mechanisms specific to nutrients and macromolecules (upper and lower figure). Genes that are identical to the wildtype <i>M. tuberculosis</i> H37Rv gene homologue are displayed with a solid border line and white background. Genes, with non-synonymous mutation are displayed in blue with dashed lines. Genes with a frameshift mutation, are displayed with striped background.</p

<b>GeneXpert ASSAY APPLIED TO FILTER INSERTS.</b>

<p>BAL =  bronchoalveolar lavage; LN =  lymph node aspirate, PA =  pleural aspirate, Sp =  sputum, SC =  scanty, ND =  Not done.</p>‡<p>UK Smear result from local diagnostic service, Gambia smear result from MRC lab. All Gambian patients had a prior smear-positive from their local health clinic.</p><p>*All patients diagnosed with extrapulmonary TB were sputum smear- and culture-negative.</p>†<p>Mask collected day 5 of TB treatment.</p

Schematic of mask processing for phage assay.

<p>See text for abbreviations.</p

<b>SERIES 1, PHAGE ASSAYS ON SURGICAL MASKS.</b>

<p>ND =  not done; U =  not recorded.</p><p>*<i>M. kansasii</i> isolated.</p>†<p><i>M. avium</i>isolated.</p>‡<p>Patients 1–9 - RB assay; 10–17 – OM assay.</p>¶<p>Pre-chemotherapy samples.</p

Maximum likelihood phylogeny of <i>Mtb</i> isolated from patients with active pulmonary TB.

<p>Branches are coloured by lineage and tips are coloured by the sub-clades within the lineages. A star marks almost identical genomes (<3 SNVs difference) isolated from different patients. Adjacent data links strains to patient metadata: MDR and pre-XDR status, treatment status, HIV status, sex and recruitment site and date of sample reception.</p