The scent of Mycobacterium tuberculosis

doi:10.1016/j.tube.2009.04.003

Tuberculosis

Volume 89, Issue 4, July 2009, Pages 263-266

https://doi.org/10.1016/j.tube.2009.04.003 Get rights and content

Summary

Recent figures show that tuberculosis (TB) is advancing and killing more than two million people annually, yet no breakthrough in rapid diagnostics is in sight. Volatile metabolites of Mycobacterium tuberculosis (MTB) may provide just that. It is well established that MTB produces nicotinic acid in vitro. We have converted the free acid into methyl nicotinate and detected statistically significant differences in the breath of smear positive patients compared with healthy (smear negative) subjects.

Introduction

Tuberculosis (TB) remains a major global public health threat and causes two million deaths per year worldwide. In order to fight TB the World Health Organisation and other non-profit organisations are in need of rapid, sensitive, specific, inexpensive, and non-invasive diagnostic tools.¹ Microscopy of acid-alcohol fast stained sputum samples has been used for more than 100 years and remains the mainstay of TB diagnosis, particularly in low income, high TB burden countries. An alternative diagnostic strategy is the detection of species-specific volatile metabolites that can be measured non-invasively in breath samples.

From four volatile compounds previously identified from Mycobacterium tuberculosis cultures,² we selected methyl nicotinate for validation in vivo.

Nicotinic acid is known to play an important role in oxidation reduction reactions in mycobacterial metabolism as it is produced in sufficient quantities to form the basis of the niacin test used to differentiate M. tuberculosis from other mycobacterial species.3, 4, 5 Early evidence for a possible diagnostic value of nicotinic acid in vivo was published in 1953. The study investigated nicotinic acid blood levels in tuberculosis sufferers. It was found that the “total nicotinic acid values of tuberculous patients was distinctively higher than those of normal subjects”.⁶

Nicotinic acid is very polar and poorly volatile. We were not able to detect it in breath in its acid form. In contrast methyl nicotinate was detectable after in situ derivatization on the SPME fiber providing a suitable analytical marker. In this proof of concept study breath samples from smear positive TB patients were analyzed for the presence of methyl nicotinate and compared to breath of healthy controls.

This short communication is a logical continuation of in vitro work published here previously.²

Section snippets

Subjects

Participants were Melanesian adults recruited at Modilon Hospital, Madang, Papua New Guinea and studied prospectively. All had symptoms or signs suggestive of clinical tuberculosis, a chest radiograph with findings typical of pulmonary tuberculosis and acid fast staining bacilli seen on microscopy of sputa. Medical treatment had not yet started. A recent drug and dietary history was taken using a standardised questionnaire. Ingestion or intake of the following was specifically sought: betel

Results

The levels of methyl nicotinate after derivatization in breath samples of smear positive TB patients compared with age and sex matched controls are illustrated in Figure 1. The difference between both groups is of statistical significance (P = 0.0030; unpaired t-test).

Patient information, ZN scores and non-quantitative methyl nicotinate counts are presented in Table 1.

There was no difference between methyl nicotinate levels in patients with low (scanty or 1+) versus high (2+; 3+) ZN scores (p =

Discussion

This pilot study was designed in order to establish the proof of principle. We have shown that levels of methyl nicotinate (after derivatization) are higher in smear positive tuberculosis patients than non-smoking healthy controls. The primary objective was to determine whether our analytical technique is sufficiently sensitive to be used as a human diagnostic tool, and whether it could discriminate between clearly infected individuals and healthy controls. The results demonstrate that this

Acknowledgement

The authors wish to thank Ekkehard Unger for his inspiration. The excellent team of research nurses from PNGIMR at Modilon Hospital, Madang, Papua New Guinea made patient recruitment possible. We gratefully acknowledge the technical equipment provided by Phenomenex, New Zealand and Varian Inc., Melbourne, Australia.

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The scent of Mycobacterium tuberculosis
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Nicotinic acid biosynthesis by Mycobacterium tuberculosis
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There are more references available in the full text version of this article.

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Tuberculosis

Summary

Introduction

Section snippets

Subjects

Results

Discussion

Acknowledgement

References (10)

Tuberculosis

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J Infect Dis

Nicotinic acid biosynthesis by Mycobacterium tuberculosis

J Bacteriol

Biosynthesis of nicotinic acid by Mycobacterium tuberculosis

J Bacteriol

Niacin test for mycobacteria: a comparative study of two methods

Ind J Tub

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Methyl nicotinate biomarker of tuberculosis voltammetrically detected on cobalt nanoparticle-dispersed reduced graphene oxide-based carbon film in blood

Diagnosis of tuberculosis through breath test: A systematic review

The application of metabolomics toward pulmonary tuberculosis research

DiagnosticsThe scent of Mycobacterium tuberculosis – Part II breath

Summary

Introduction

Section snippets

Subjects

Results

Discussion

Acknowledgement

Tuberculosis

Facing the crisis: improving the diagnosis of tuberculosis in the HIV era

J Infect Dis

Nicotinic acid biosynthesis by Mycobacterium tuberculosis

J Bacteriol

Biosynthesis of nicotinic acid by Mycobacterium tuberculosis

J Bacteriol

Niacin test for mycobacteria: a comparative study of two methods

Ind J Tub

Diagnostics
The scent of Mycobacterium tuberculosis – Part II breath