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Volume 21, Number 3—March 2015
Letter

Role of Race/Ethnicity in Pulmonary Nontuberculous Mycobacterial Disease

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To the Editor: We read with interest the study of gender and age in nontuberculous mycobacterial (NTM) lung disease case-patients in Taiwan (1). NTM lung disease is relatively uncommon; however, the exact prevalence of NTM lung disease and causative organisms are largely unknown in many regions of the United States because the disease is not reportable. A recent study using Medicare claims data in the United States showed that the annual prevalence of NTM lung disease increased from 20 cases/100,000 persons in 1997 to 47 cases/100,000 persons in 2007 (2). The study also showed that Hawaii had the highest period prevalence of cases (396 cases/100,000 persons), which was at least partially attributed to the large Asian/Pacific Islander population (2). During June–December 2011, we conducted a cross-sectional study to evaluate the epidemiologic and clinical significance of NTM isolated from patients in Honolulu, Hawaii; the patients had suspected pulmonary tuberculosis (TB) and were in airborne isolation at a university-affiliated, tertiary-care hospital.

NTM cases were defined according to the 2007 criteria of the American Thoracic Society/Infectious Diseases Society of America (3). The process required to establish a diagnosis of NTM lung disease is sometimes lengthy; thus, patients who did not initially meet the disease criteria but who had cultures positive for NTM were reviewed again 1 year after the original data were collected to see if follow-up microbiological and radiographic studies would confirm the presence of NTM lung disease. Descriptive statistics were used to describe categorical and continuous variables. During June–December 2011, a total of 113 patients with suspected pulmonary TB were placed into isolation at the tertiary-care hospital. Of these patients, 85 (75.2%) were men and 28 (24.8%) were women; the median age was 59.8 ± 17 years. Eighteen (15.9%) patients were white, 92 (81.4%) were Asian/Pacific Islander, and 1 (0.9%) was African American; for 2 (1.8%) patients, race/ethnicity was classified as not specified/other.

Of the 113 isolated patients, 21 (18.6%) were positive for mycobacteria. Of these 21 patients, 14 (66.7%) were men and 7 (33.3%) were women; the median age was 64.3 ± 17.3 years. Three (14.3%) of these patients were white, and 18 (85.7%) were Asian/Pacific Islander. Mycobacterium tuberculosis and NTM were identified in samples from 3 (14.3%) and 18 (85.7%) of the 21 patients, respectively. Of the 18 patients with NTM-positive samples, 4 (22.2%) had definite NTM lung disease (all of these patients were Asian/Pacific Islander); 2 (11.1%) had probable NTM lung disease; and 12 (66.7%) had possible NTM lung disease. M. chelonae (identified by DNA sequencing) was the causative agent for most of the definite cases (n = 3, 75%), and the largest proportion of possible cases was caused by M. avian complex bacteria (n = 5, 41.7%).

Our finding that 22.2% (4/18) of the patients in Honolulu with NTM-positive clinical samples during June–December 2011 received a definite diagnosis of NTM lung disease is slightly higher than but consistent with reports from other regions, which show that 9.8%–17.0% of such patients receive a definite NTM disease diagnosis (4,5). For unclear reasons, the number of NTM disease cases appears to be highest in Asian/Pacific Islander populations. Determining the reason(s) for this discrepancy should be the subject of future research efforts.

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Benjamin S. ThomasComments to Author  and Koh Okamoto

Author affiliations: Washington University School of Medicine, St. Louis, Missouri, USA (B.S. Thomas); Rush University Medical Center, Chicago, Illinois, USA (K. Okamoto)

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References

  1. Chien  JY, Lai  CC, Sheng  WH, Yu  CJ, Hsueh  PR. Pulmonary infection and colonization with nontuberculous mycobacteria, Taiwan, 2000–2012. Emerg Infect Dis. 2014;20:13825. DOIPubMed
  2. Adjemian  J, Olivier  KN, Seitz  AE, Holland  SM, Prevots  DR. Prevalence of nontuberculous mycobacterial lung disease in U.S. Medicare beneficiaries. Am J Respir Crit Care Med. 2012;185:8816. DOIPubMed
  3. Griffith  DE, Aksamit  T, Brown-Elliott  BA, Catanzaro  A, Daley  C, Gordin  F, An official ATS/IDSA statement: diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases [cited 2014 Aug 1]. http://www.thoracic.org/statements/resources/mtpi/nontuberculous-mycobacterial-diseases.pdf
  4. Koh  WJ, Kwon  OJ, Jeon  K, Kim  TS, Lee  KS, Park  YK, Clinical significance of nontuberculous mycobacteria isolated from respiratory specimens in Korea. Chest. 2006;129:3418. DOIPubMed
  5. Braun  E, Sprecher  H, Davidson  S, Kassis  I. Epidemiology and clinical significance of non-tuberculous mycobacteria isolated from pulmonary specimens. Int J Tuberc Lung Dis. 2013;17:969. DOIPubMed

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Cite This Article

DOI: 10.3201/eid2103.141369

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Table of Contents – Volume 21, Number 3—March 2015

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Benjamin S. Thomas, Washington University School of Medicine, Division of Infectious Diseases, 660 S Euclid Ave, Campus Box 8051, St. Louis, MO 63110, USA

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Page created: February 18, 2015
Page updated: February 18, 2015
Page reviewed: February 18, 2015
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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