Bacteriophage-Based Tests for the Detection of \u3cem\u3eMycobacterium tuberculosis\u3c/em\u3e in Clinical Specimens: A Systematic Review and Meta-analysis

Background: Sputum microscopy, the most important conventional test for tuberculosis, is specific in settings with high burden of tuberculosis and low prevalence of non tuberculous mycobacteria. However, the test lacks sensitivity. Although bacteriophage-based tests for tuberculosis have shown promising results, their overall accuracy has not been systematically evaluated. Methods: We did a systematic review and meta-analysis of published studies to evaluate the accuracy of phage-based tests for the direct detection of M. tuberculosis in clinical specimens. To identify studies, we searched Medline, EMBASE, Web of science and BIOSIS, and contacted authors, experts and test manufacturers. Thirteen studies, all based on phage amplification method, met our inclusion criteria. Overall accuracy was evaluated using forest plots, summary receiver operating (SROC) curves, and subgroup analyses. Results: The data suggest that phage-based assays have high specificity (range 0.83 to 1.00), but modest and variable sensitivity (range 0.21 to 0.88). The sensitivity ranged between 0.29 and 0.87 among smear-positive, and 0.13 to 0.78 among smear-negative specimens. The specificity ranged between 0.60 and 0.88 among smear-positive and 0.89 to 0.99 among smear-negative specimens. SROC analyses suggest that overall accuracy of phage-based assays is slightly higher than smear microscopy in direct head-to-head comparisons. Conclusion: Phage-based assays have high specificity but lower and variable sensitivity. Their performance characteristics are similar to sputum microscopy. Phage assays cannot replace conventional diagnostic tests such as microscopy and culture at this time. Further research is required to identify methods that can enhance the sensitivity of phage-based assays without compromising the high specificity

Use of Recommended Laboratory Testing Methods Among Patients with Tuberculosis in California

This study assessed the extent to which laboratory methods recommended by the Centers for Disease Control and Prevention were used in tuberculosis testing of patients in California in 1998. While recommended methods were used for most patients, there was room for improvement by hospital and independent non-health maintenance organization laboratories

A \u3cem\u3eMycobacterium ulcerans\u3c/em\u3e Toxin, Mycolactone, Causes Apoptosis in Guinea Pig Ulcers and Tissue Culture Cells

Mycobacterium ulcerans is the causative agent of Buruli ulcer, a tropical ulcerative skin disease. One of the most intriguing aspects of this disease is the presence of extensive tissue damage in the absence of an acute inflammatory response. We recently purified and characterized a macrolide toxin, mycolactone, from M. ulcerans. Injection of this molecule into guinea pig skin reproduced cell death and lack of acute inflammatory response similar to that seen following the injection of viable bacteria. We also showed that mycolactone causes a cytopathic effect on mouse fibroblast L929 cells that is characterized by cytoskeletal rearrangements and growth arrest within 48 h. However, these results could not account for the extensive cell death which occurs in Buruli ulcer. The results presented here demonstrate that L929 and J774 mouse macrophage cells die via apoptosis after 3 to 5 days of exposure to mycolactone. Treatment of cells with a pan-caspase inhibitor can inhibit mycolactone-induced apoptosis. We demonstrate that injection of mycolactone into guinea pig skin results in cell death via apoptosis and that the extent of apoptosis increases as the lesion progresses. These results may help to explain why tissue damage in Buruli ulcer is not accompanied by an acute inflammatory response

Host Restriction Phenotypes of \u3cem\u3eSalmonella typhi\u3c/em\u3e and \u3cem\u3eSalmonella gallinarum\u3c/em\u3e

Salmonella typhi and Salmonella gallinarum phenotypes correlated with mouse host restriction have been identified by using in vitro and in vivo systems. S. typhi is capable of entering the murine intestinal epithelium via M cells, as is Salmonella typhimurium, which causes systemic infection in the mouse. But, unlike S. typhimurium, S. typhi does not destroy the epithelium and is cleared from the Peyer’s patches soon after M-cell entry. S. gallinarum appears to be incapable of entering the murine Peyer’s patch epithelium. Our in vitro evidence suggests that S. gallinarum is taken up in murine phagocytic cells by a mechanism different from that of S. typhimurium. S. typhimurium is taken up at a higher frequency and is maintained at higher viable counts throughout a 24-h time course in a murine macrophage-like cell line than are S. gallinarum and S. typhi

Field Assessment of a Model Tuberculosis Outbreak Response Plan for Low-Incidence Areas

Background: For a regional project in four low-incidence states, we designed a customizable tuberculosis outbreak response plan. Prior to dissemination of the plan, a tuberculosis outbreak occurred, presenting an opportunity to perform a field assessment of the plan. The purpose of the assessment was to ensure that the plan included essential elements to help public health professionals recognize and respond to outbreaks. Methods: We designed a semi-structured questionnaire and interviewed all key stakeholders involved in the response. We used common themes to assess validity of and identify gaps in the plan. A subset of participants provided structured feedback on the plan. Results: We interviewed 11 public health and six community stakeholders. The assessment demonstrated that (1) almost all of the main response activities were reflected in the plan; (2) the plan added value by providing a definition of a tuberculosis outbreak and guidelines for communication and evaluation. These were areas that lacked written protocols during the actual outbreak response; and (3) basic education about tuberculosis and the interpretation and use of genotyping data were important needs. Stakeholders also suggested adding to the plan questions for evaluation and a section for specific steps to take when an outbreak is suspected. Conclusion: An interactive field assessment of a programmatic tool revealed the value of a systematic outbreak response plan with a standard definition of a tuberculosis outbreak, guidelines for communication and evaluation, and response steps. The assessment highlighted the importance of education and training for tuberculosis in low-incidence areas

When Tuberculosis Comes Back: Who Develops Recurrent Tuberculosis in California?

Recurrent tuberculosis suggests potentially modifiable gaps in tuberculosis treatment and control activities. The frequency of late recurrences following treatment completion has not been well-studied. We determined the frequency of, and risk factors associated with, tuberculosis that recurs at least one year after completion of anti-tuberculosis therapy in California.The study population included culture-positive, pulmonary tuberculosis patients reported to the California tuberculosis case registry from 1993 to 2007 who completed anti-tuberculosis therapy. A person with late recurrent tuberculosis was defined as an individual that appeared in the registry more than once, determined by match on name and date-of-birth, with at least one year between treatment completion of the first episode and treatment initiation of the second episode.Among 23,517 tuberculosis patients, 148 (0.63%) had a late recurrence. Independent risk factors for recurrence included: infection with a pyrazinamide mono-resistant isolate (adjusted hazard ratio, 2.93; p = 0.019); initiation of an isoniazid- and rifampin-only treatment regimen (adjusted hazard ratio, 2.55; p = 0.0412); sputum smear-positive disease (adjusted hazard ratio, 1.96; p = 0.0003); human immunodeficiency virus infection (adjusted hazard ratio, 1.81; p = 0.0149); and birth in the United States (adjusted hazard ratio, 1.88; p = 0.0002). Infection with an isoniazid mono-resistant isolate was protective (adjusted hazard ratio, 0.25; p = 0.0171).The low frequency of late recurrent tuberculosis in California suggests that local TB control programs are largely successful at preventing this adverse outcome. Nonetheless, we identified subpopulations at increased risk of late tuberculosis recurrence that may benefit from additional medical or public health interventions

Isolation and Expression of a Gene Cluster Responsible for Biosynthesis of the Glycopeptidolipid Antigens of \u3cem\u3eMicobacterium avium\u3c/em\u3e

Bacteria within the Mycobacterium avium complex are prominent in the environment and are a source of serious disseminated infections in patients with AIDS. Serovars of the M. avium complex are distinguished from all other mycobacteria and from one another by the presence of highly antigenic glycolipids, the glycopeptidolipids, on their surfaces. A genomic library of DNA from serovar 2 of the M. avium complex was constructed in the Escherichia coli-Mycobacterium shuttle cosmid, pYUB18, and used to clone and express in Mycobacterium smegmatis the genes responsible for the biosynthesis of the oligosaccharide segment of the M. avium serovar 2-specific glycopeptidolipid. The responsible gene cluster was mapped to a 22- to 27-kb functional region of the M. avium genome. The recombinant glycolipid was also isolated by high-pressure liquid chromatography and chemically characterized, by gas chromatography-mass spectrometry and fast atom bombardment-mass spectrometry, to demonstrate that the lipopeptide core originated in M. smegmatis, whereas the oligosaccharide segment arose from the cloned M. avium genes. This first-time demonstration of the cloning and expression, in a nonpathogenic mycobacterium, of the genes encoding complex cell wall glycoconjugates from a pathogenic mycobacterium presents a new approach for studying the role of such products in disease processes

Use of In Vivo Complementation in \u3cem\u3eMycobacterium tuberculosis\u3c/em\u3e to Identify a Genomic Fragment Associated with Virulence

Novel molecular tools and genetic methods were developed to isolate genomic fragments of Mycobacterium tuberculosis that may be associated with virulence. We sought to restore virulence, a characteristic of M. tuberculosis that is correlated with growth rate in mouse spleen and lung tissue, to the avirulent strain H37Ra by complementation. A representative library of the virulent M. tuberculosis strain H37Rv was constructed and transformed into H37Ra. Enrichment for individual faster-growing recombinants was achieved by passage of pools of H37Ra transformants harboring the H37Rv library through mice. A molecular strategy was devised to isolate and clone the H37Rv genomic DNA fragment ivg, which conferred a more rapid in vivo growth rate to H37Ra

Traffic-Related Air Pollution and All-Cause Mortality during Tuberculosis Treatment in California.

BackgroundAmbient air pollution and tuberculosis (TB) have an impact on public health worldwide, yet associations between the two remain uncertain.ObjectiveWe determined the impact of residential traffic on mortality during treatment of active TB.MethodsFrom 2000-2012, we enrolled 32,875 patients in California with active TB and followed them throughout treatment. We obtained patient data from the California Tuberculosis Registry and calculated traffic volumes and traffic densities in 100- to 400-m radius buffers around residential addresses. We used Cox models to determine mortality hazard ratios, controlling for demographic, socioeconomic, and clinical potential confounders. We categorized traffic exposures as quintiles and determined trends using Wald tests.ResultsParticipants contributed 22,576 person-years at risk. There were 2,305 deaths during treatment for a crude mortality rate of 1,021 deaths per 10,000 person-years. Traffic volumes and traffic densities in all buffers around patient residences were associated with increased mortality during TB treatment, although the findings were not statistically significant in all buffers. As the buffer size decreased, fifth-quintile mortality hazards increased, and trends across quintiles of traffic exposure became more statistically significant. Increasing quintiles of nearest-road traffic volumes in the 100-m buffer were associated with 3%, 14%, 19%, and 28% increased risk of death during TB treatment [first quintile, referent; second quintile hazard ratio (HR)=1.03 [95% confidence interval (CI): 0.86, 1.25]; third quintile HR=1.14 (95% CI: 0.95, 1.37); fourth quintile HR=1.19 (95% CI: 0.99, 1.43); fifth quintile HR=1.28 (95% CI: 1.07, 1.53), respectively; p-trend=0.002].ConclusionsResidential proximity to road traffic volumes and traffic density were associated with increased all-cause mortality in patients undergoing treatment for active tuberculosis even after adjusting for multiple demographic, socioeconomic, and clinical factors, suggesting that TB patients are susceptible to the adverse health effects of traffic-related air pollution. https://doi.org/10.1289/EHP1699

Bacteriophage- based tests for the detection of Mycobacterium tuberculosis in clinical specimens: a systematic review and meta- analysis

BACKGROUND: Sputum microscopy, the most important conventional test for tuberculosis, is specific in settings with high burden of tuberculosis and low prevalence of non tuberculous mycobacteria. However, the test lacks sensitivity. Although bacteriophage-based tests for tuberculosis have shown promising results, their overall accuracy has not been systematically evaluated. METHODS: We did a systematic review and meta-analysis of published studies to evaluate the accuracy of phage-based tests for the direct detection of M. tuberculosis in clinical specimens. To identify studies, we searched Medline, EMBASE, Web of science and BIOSIS, and contacted authors, experts and test manufacturers. Thirteen studies, all based on phage amplification method, met our inclusion criteria. Overall accuracy was evaluated using forest plots, summary receiver operating (SROC) curves, and subgroup analyses. RESULTS: The data suggest that phage-based assays have high specificity (range 0.83 to 1.00), but modest and variable sensitivity (range 0.21 to 0.88). The sensitivity ranged between 0.29 and 0.87 among smear-positive, and 0.13 to 0.78 among smear-negative specimens. The specificity ranged between 0.60 and 0.88 among smear-positive and 0.89 to 0.99 among smear-negative specimens. SROC analyses suggest that overall accuracy of phage-based assays is slightly higher than smear microscopy in direct head-to-head comparisons. CONCLUSION: Phage-based assays have high specificity but lower and variable sensitivity. Their performance characteristics are similar to sputum microscopy. Phage assays cannot replace conventional diagnostic tests such as microscopy and culture at this time. Further research is required to identify methods that can enhance the sensitivity of phage-based assays without compromising the high specificity