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Impact of New American Thoracic Society Diagnostic Criteria on Management of Nontuberculous Mycobacterial Infection

We appreciate the comments by van Ingen and colleagues regarding proposed diagnostic criteria for nontuberculous mycobacterial (NTM) diseases in the recent American Thoracic Society/Infectious Diseases Society of America statement (1). There are more than 120 species of nontuberculous mycobacteria that manifest a wide spectrum of virulence, likely influenced by host susceptibility. Many NTM pathogens are encountered so rarely that there is not enough experience to estimate the predictive value of diagnostic criteria for those organisms. Additionally, some organisms, such as Mycobacterium gordonae, although frequently encountered, are so rarely human pathogens that diagnostic criteria have little pertinence to them. Overall, no single set of diagnostic criteria can be appropriate for all nontuberculous mycobacteria in every clinical circumstance.

The proposed diagnostic guidelines for NTM pulmonary disease represent a balance between underdiagnosis and progressive NTM disease, and overdiagnosis, with drug toxicity in uninfected patients. We agree that more patients will likely be diagnosed with NTM lung disease as a result of the new diagnostic criteria, but the slightly more lenient microbiologic diagnostic criteria are presented in a well-defined clinical context that makes the a priori likelihood of disease quite high. It is unknown how many of those same patients would have morbidity resulting from untreated NTM disease.

In the evaluation and treatment of patients with NTM disease (especially lung disease), it is impossible to eliminate the burden of clinical judgment residing with the managing clinician. We agree that, "More lenient criteria even increase the responsibility of physicians in the treatment decision." The clinician usually has the time to carefully weigh the diagnostic evidence and the risk/benefit balance of therapy for a specific patient, a topic that is discussed in the Mycobacterium avium complex (MAC) lung disease section of the current statement (1). This statement is deliberately structured not to artificially oversimplify the complicated aspects of NTM diseases, such as pulmonary disease diagnosis. Ambiguities about the decision to initiate therapy may lead to "more confusion" by the clinician, but those ambiguities are often unavoidable, and the confusion is acknowledgment of the complicated nature of the problem.

The diagnosis of disseminated lymphatic, skin, soft tissue, and bone diseases are discussed in the overview sections for those diseases and in the laboratory section. However, not all potential diagnostic contingencies are discussed, such as the recovery of nontuberculous mycobacteria from nonsterile, nonpulmonary sites in immunocompetent hosts. We agree that more data are needed in this area and that the isolation of nontuberculous mycobacteria in these circumstances is a stimulus to seek expert consultation.

David E. Griffith

University of Texas Health Center, Tyler, Tyler, Texas

On behalf of the ATS Mycobacterial Diseases Subcommittee

FOOTNOTES

Conflict of Interest Statement: The author has no financial relationship with a commercial entity that has an interest in the subject of this manuscript.

REFERENCES

1. Griffith DE, Aksamit T, Brown-Elliot BA, Catanzaro A, Daley C, Gordin F, Holland SM, Horsburgh R, Huitt G, Iademarco MF, et al. An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med 2007;175:367–416.[Free Full Text]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Griffith, D. E. Search for Related Content PubMed Articles by Griffith, D. E.