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EID Journal Home > Volume 16, Number 10–October 2010
Volume 16, Number 10–October 2010
MEDSCAPE CME ACTIVITY
Changing Epidemiology of Pulmonary Nontuberculous Mycobacteria Infections

Medscape, LLC is pleased to provide online continuing medical education (CME) for this journal article, allowing clinicians the opportunity to earn CME credit. This activity has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Medscape, LLC and Emerging Infectious Diseases. Medscape, LLC is accredited by the ACCME to provide continuing medical education for physicians. Medscape, LLC designates this educational activity for a maximum of 0.5 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity. All other clinicians completing this activity will be issued a certificate of participation. To participate in this journal CME activity: (1) review the learning objectives and author disclosures; (2) study the education content; (3) take the post-test and/or complete the evaluation at www.medscapecme.com/journal/eid; (4) view/print certificate.


Learning Objectives

Upon completion of this activity, participants will be able to:

* Identify the prevalence and epidemiology of nontuberculous mycobacteria (NTM) infection and traditional risk factors and presentation of pulmonary NTM infection.
* Construct an appropriate diagnostic strategy for patients with suspected NTM.

Medscape CME Editor

Beverly D. Merritt, Technical Writer/Editor, Emerging Infectious Diseases. Disclosure: Beverly D. Merritt has disclosed no relevant financial relationships.

Medscape CME Author

Desiree Lie, MD, MSED, Clinical Professor of Family Medicine, Director of Research and Faculty Development, University of California, Irvine at Orange, California.

Disclosures: Désirée Lie, MD, MSEd, has disclosed the following relevant financial relationship: served as a nonproduct speaker for: "Topics in Health" for Merck Speaker Services.

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Changing Epidemiology of NTM Infections | CDC EID



EID Journal Home > Volume 16, Number 10–October 2010
Volume 16, Number 10–October 2010
Research
Changing Epidemiology of Pulmonary Nontuberculous Mycobacteria Infections

Rachel M. Thomson Comments to Author, on behalf of the NTM working group at the Queensland TB Control Centre and Queensland Mycobacterial Reference Laboratory
Author affiliation: Queensland Tuberculosis Control Centre, Brisbane, Queensland, Australia

Suggested citation for this article

Abstract
Nontuberculous mycobacteria (NTM) disease is a notifiable condition in Queensland, Australia. Mycobacterial isolates that require species identification are forwarded to the Queensland Mycobacterial Reference Laboratory, providing a central opportunity to capture statewide data on the epidemiology of NTM disease. We compared isolates obtained in 1999 and 2005 and used data from the Queensland notification scheme to report the clinical relevance of these isolates. The incidence of notified cases of clinically significant pulmonary disease rose from 2.2 (1999) to 3.2 (2005) per 100,000 population. The pattern of disease has changed from predominantly cavitary disease in middle-aged men who smoke to fibronodular disease in elderly women. Mycobacterium intracellulare is the main pathogen associated with the increase in isolates speciated in Queensland.

Worldwide, pulmonary disease caused by nontuberculous mycobacteria (NTM) appears to be increasing (1–4), yet accurate data to support this assumption are difficult to produce. Patients traditionally described are middle-aged men with underlying chronic lung disease, such as chronic obstructive pulmonary disease, who have upper lobe cavity formation and nodules of various sizes. An increasing number of patients have nodules, bronchiolitis, and bronchiectasis involving the middle lobe and lingula. These patients are more commonly female nonsmokers and have no preexisting lung disease (5,6).

NTM disease is not a reportable condition in most countries because no evidence of human-to-human transmission exists; therefore, it is not considered a public health concern. However, the organisms are ubiquitous in the environment, and substantial evidence shows that the environmental niche for Mycobacterium intracellulare (the most common pulmonary pathogen) is in biofilms lining suburban water pipes. Many NTM pathogens have been isolated from drinking water (7). Some clinicians believe the condition should be classified as an environmental health concern, similar to that caused by Legionella spp.

Globally, geographic variability in environmental exposure and prevalence of NTM disease is significant (8). Without detailed clinical information, differentiating between contamination of specimens, colonization/infection, and disease is difficult; laboratory reports of isolates do not always reflect the true incidence of disease. To determine if disease is present, sputum specimens and often a bronchoscopic sample of a patient’s lower respiratory tract must be collected. In addition, computed tomography scanning and clinical appointments with primary care providers and specialists are needed. Because this investigative process is costly to the healthcare system and the patient, accurate epidemiologic data on this condition should be of interest to public health experts.

Studies of avian versus human Mantoux testing in schoolchildren have shown that exposure to NTM organisms is common in Queensland (9–11). Therefore, since the introduction of TB control services, disease caused by NTM in Queensland has been notifiable. This practice has been continued primarily to avoid confounding of smear-positive cases with TB. The notification process provides a unique opportunity to study the clinical significance of isolates positive for NTM and the features such as age and sex, symptoms, underlying conditions, and radiology results of patients with disease, avoiding the inherent bias that occurs in case series that are reported by tertiary and quaternary referral centers. The incidence of clinically reported cases of pulmonary disease caused by M. avium complex (MAC) in Queensland has been increasing (1985, 0.63/100,000 population; 1994, 1.21/100,000; and 1999, 2.2/100,000). In 2005, the Queensland Tuberculosis Control Centre (QTBCC) revised the notification process to ensure collection of meaningful clinical data and follow-up of clinically significant NTM cases.


Suggested Citation for this Article

Thomson RM. Changing epidemiology of pulmonary nontuberculous mycobacteria infections. Emerg Infect Dis [serial on the Internet]. 2010 Oct [date cited]. http://www.cdc.gov/EID/content/16/10/1576.htm

DOI: 10.3201/eid1610.091201