11 - Non-tuberculous mycobacteria

Summary

Introduction

Non-tuberculous mycobacteria (NTM) are unique from the amount of controversy generated over nomenclature, classification, exact role in disease and appropriate treatments. The archetype of mycobacterial disease – tuberculosis – has been recognised since neolithic times; Villemin in 1865 demonstrated its infectious aetiology 27 years prior to the discovery of the tubercle bacillus by Koch. There has never been any doubt that the isolation of Mycobacterium tuberculosis from any body secretion/tissue is synonymous with disease. Following the description of Mycobacterium avium by Nocard and Roux in 1887, the occasional finding of other mycobacterial species from clinical specimens had been largely dismissed as contamination for many years despite reports of apparent clinical disease. Obsession with the requirement that the organism should produce disease in guinea pigs in order to be considered significant undoubtedly contributed to under-diagnosis of disease due to NTM, until Timpe and Runyon in 1954 drew attention to disease caused by NTM. Since then there has been increasing recognition that NTM can produce significant human disease, both before and during the AIDS pandemic. This is reflected in, for example, the increase in notifications of NTM to the Communicable Disease Surveillance Centre and the reporting of cases of apparent pulmonary tuberculosis due to NTM. There are a number of controversial areas in the field of non-tuberculous mycobacteriology including nomenclature, differentiation between diagnosis of disease and colonisation and drug regimens including the relationship of in vitro/in vivo drug activities.