Skip to main content

Main menu

  • Home
  • Current issue
  • ERJ Early View
  • Past issues
  • Authors/reviewers
    • Instructions for authors
    • Submit a manuscript
    • Open access
    • COVID-19 submission information
    • Peer reviewer login
  • Alerts
  • Podcasts
  • Subscriptions
  • ERS Publications
    • European Respiratory Journal
    • ERJ Open Research
    • European Respiratory Review
    • Breathe
    • ERS Books
    • ERS publications home

User menu

  • Log in
  • Subscribe
  • Contact Us
  • My Cart

Search

  • Advanced search
  • ERS Publications
    • European Respiratory Journal
    • ERJ Open Research
    • European Respiratory Review
    • Breathe
    • ERS Books
    • ERS publications home

Login

European Respiratory Society

Advanced Search

  • Home
  • Current issue
  • ERJ Early View
  • Past issues
  • Authors/reviewers
    • Instructions for authors
    • Submit a manuscript
    • Open access
    • COVID-19 submission information
    • Peer reviewer login
  • Alerts
  • Podcasts
  • Subscriptions

Serial sputum induction in nontuberculous mycobacterial pulmonary disease

Michael R. Holt, Shannon H. Kasperbauer, Charles L. Daley
European Respiratory Journal 2020 55: 1902196; DOI: 10.1183/13993003.02196-2019
Michael R. Holt
1Division of Mycobacterial and Respiratory Infections, Dept of Medicine, National Jewish Health, Denver, CO, USA
2Dept of Medicine, University of Colorado Denver, Aurora, CO, USA
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • ORCID record for Michael R. Holt
  • For correspondence: michaelrholt@outlook.com
Shannon H. Kasperbauer
1Division of Mycobacterial and Respiratory Infections, Dept of Medicine, National Jewish Health, Denver, CO, USA
2Dept of Medicine, University of Colorado Denver, Aurora, CO, USA
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Charles L. Daley
1Division of Mycobacterial and Respiratory Infections, Dept of Medicine, National Jewish Health, Denver, CO, USA
2Dept of Medicine, University of Colorado Denver, Aurora, CO, USA
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • Info & Metrics
  • PDF
Loading

Abstract

Incremental detection yields of serial induced sputum samples support collection of three samples for detection of nontuberculous mycobacteria. In addition, higher colony counts on solid media are associated with markers of disease severity. http://bit.ly/2Tn14Qa

To the Editor:

The recommended procedure for diagnosis of nontuberculous mycobacterial pulmonary disease (NTM-PD) is collection of three sputum samples on separate days [1]. Sputum induction is suggested for patients unable to expectorate spontaneously. These recommendations align with evidence-based guidelines for pulmonary tuberculosis (TB) [2] but literature supporting their applicability to NTM-PD is lacking. In addition, the clinical utility of colony counts on solid media requires clarification. Early changes in semiquantitative colony counts are predictive of clinical and radiological improvement and treatment success [3] but the relationships of colony count with disease markers, such as smear status, have not been reported.

Standard evaluation of patients in the Division of Mycobacterial and Respiratory Infections at National Jewish Health (NJH) in Denver, CO, USA, includes three sputum inductions, generally by administration of nebulised 3–10% hypertonic saline via Aerobika oscillating positive expiratory pressure device. One spontaneously expectorated sputum sample is usually requested pre-admission. Microbiological analysis includes smear examination, culture in Mycobacteria Growth Indicator Tube (MGIT) and on Löwenstein-Jensen (LJ) slant and agar plate, and quantitation of colonies on solid media. The present study constituted a retrospective audit of this evaluation protocol with the following goals: 1) describe the yield of serial induced sputum samples for NTM and variation of yield with induction methodology; 2) compare the yield of induced and spontaneously expectorated samples; and 3) elucidate the relationship between colony count and smear status.

Diagnostic yield per sputum sample, as reported in the TB literature, translates imperfectly to NTM-PD. Whereas TB is defined by a single positive culture, NTM-PD diagnosis requires at least two positive sputum cultures with appropriate clinical and radiological findings [1]. Furthermore, patients at referral institutions commonly present with a history of positive cultures and isolation of multiple species. We therefore studied “detection yield”, defined as culture of any potentially pathogenic NTM.

Inclusion criteria were age >18 years, induction of three sputum samples with hypertonic saline during hospital admission, and culture of NTM other than M. gordonae from at least one of these samples. Electronic medical records for subjects identified by a search of the NJH Research Database were reviewed in reverse chronological order to apply the inclusion criteria and extract data. In total, 416 records were reviewed to obtain an a priori-defined sample of 200 patients, who were admitted between November 2016 and October 2018. Statistical analysis was performed in R, version 3.5.1. Continuous variables were compared with permutation analysis and proportions with Fisher's exact test.

Studied patients included 178 (89%) females and were of mean age 66 (95% CI 65–67) years and mean BMI 21.8 (95% CI 21.3–22.3) kg·m−2. Cough was reported by 152 (76%) subjects and haemoptysis within the preceding 6 months by 34 (17%). Reported computed tomography pulmonary findings included bronchiectasis in 188 (94%) patients, nodules in 161 (80%) and cavities in 51 (26%). NTM had previously been cultured from at least two sputum samples or at least one bronchoscopic fluid sample in 195 (98%) patients. 57 (28%) patients were receiving anti-NTM antibiotics at the time of admission and a further 61 (30%) had previously been treated.

Induced sputum samples were collected over a median 3 (range 3–10) days. At least two samples were culture-positive in 156 (78%) cases, 93% having repeated isolation of the same species. Mycobacterium avium complex and M. abscessus were isolated from 154 (77%) and 53 (27%) patients, respectively. More than one species was isolated in 27 (14%) patients.

The proportion of positive cultures differed with induced sputum number (p=0.03) and was lowest for third inductions (table 1). Bronchodilator pre-treatment and airway clearance device use were documented more frequently for first inductions, whereas administered hypertonic saline concentrations did not differ. Binary logistic regression analysis, including patient identifier as a random effects term, identified only sputum number as having a statistically significant influence on the likelihood of culture positivity (linear term OR 0.69, 95% CI 0.48–1.0; p=0.048). This diminishing likelihood of culture positivity with successive sputum inductions possibly reflects interventions initiated during admission, such as aggressive airway clearance. Absence of a statistically significant effect of saline concentration is consistent with a meta-analysis of sputum induction for TB diagnosis [4], although a weakness of the present study is paucity of patients receiving concentrations under 7%. In addition, it is possible that unrecorded bronchodilator pre-treatment or airway clearance device use confounded the lack of observed effect of these interventions.

View this table:
  • View inline
  • View popup
TABLE 1

Serial induced sputum sampling methodologies and results

Incremental detection yields for the first, second and third induced samples were 80%, 14% and 6%, respectively (table 1). These results align closely with diagnostic yields of serial smears and sputum cultures for TB [5–7]. Cumulative detection yield of the second sample from patients with pulmonary cavitation was 100%. In contrast, there was a trend towards detection yields being less efficient in patients using inhaled corticosteroids, potentially representing an effect of the medication or underlying pulmonary disease. Detection yields did not vary with treatment status (likely reflecting referral bias toward treatment-refractory patients), forced expiratory volume in 1 s, haemoptysis or serum C-reactive protein (CRP) level. Additional comorbid diagnoses were not specifically studied due to marked predominance of bronchiectasis and diagnostic uncertainty inherent in the retrospective study design.

Pre-admission spontaneously expectorated samples were submitted by 93 patients whose treatment status did not change between collection of pre-admission and first induced samples, a median interval of 42 (range 5–185) days. The rates of culture positivity were similar between pre-admission and first induced samples (81% versus 78%; p=0.86) and there was concordance of positive/negative results in 67 (72%) cases. Species identification concurred in 55 of 61 (90%) cases with concordant positive results. Similarity of detection yields between spontaneously expectorated and induced samples was also reported in a prospective study of diagnostic yields for TB in patients who were able to expectorate spontaneously and were not pre-screened by previous negative sputum smear/culture [8].

Colony counts for culture-positive samples were recorded from agar plate culture reports or designated as zero for growth only in MGIT and/or on LJ slant. Colony counts of 29 smear-positive samples were statistically significantly greater than 436 smear-negative samples (median 200 (interquartile range (IQR) 100–200) versus median 17 (IQR 2–100); p<0.01). The optimal cut-point for predicting smear positivity on receiver operating characteristic curve analysis was 100 colonies (sensitivity 79%, specificity 73%, area under the curve 0.79). Patients with colony counts ≥100 on at least one culture exhibited greater serum CRP concentrations (1.5, 95% CI 1.0–2.3, versus 0.6, 95% CI 0.5–0.8 mg·dL−1; p<0.001) and frequencies of pulmonary cavitation (27/72, 38% versus 24/128, 19%; p<0.01) than those without. Smear positivity in NTM-PD is associated with reduced treatment response, cavitation and increased disease progression and mortality [9–11]. Further evaluation of the clinical significance of colony counts and their utility for treatment decision-making, especially in smear-negative patients, is warranted.

In conclusion, incremental detection yields of serial induced sputum samples, observed in a cohort of patients with predominantly pre-existing diagnoses of NTM-PD, supported the practice of collecting three samples to detect NTM. Although the detection yields of single spontaneous and induced sputa were comparable, the present study did not compare serial collections and was unable to evaluate diagnostic utility of induction. Furthermore, the study design precluded determination of sensitivity of induced sputum culture for NTM. A threshold of 100 colonies on agar plate was modestly sensitive and specific for smear positivity and associated with greater serum CRP concentration and frequency of pulmonary cavitation. Limitations of the present study are its retrospective design and, due to being performed at a referral institution, potential for selection bias and limited generalisability. For example, collection of sputum samples on three successive days may be difficult in an outpatient setting. Prospective study of optimal induction methodology, detection yields and colony count correlates at the point of NTM-PD diagnosis is required.

Shareable PDF

Supplementary Material

This one-page PDF can be shared freely online.

Shareable PDF ERJ-02196-2019.Shareable

Acknowledgements

Thank you to Douglas C. Everett (Division of Biostatistics and Bioinformatics, National Jewish Health) for advice regarding the statistical analysis.

Footnotes

  • Conflict of interest: M.R. Holt has been an investigator in Insmed studies, outside the submitted work.

  • Conflict of interest: S.H. Kasperbauer reports personal fees for advisory board work and lectures from Insmed, outside the submitted work.

  • Conflict of interest: C.L. Daley has nothing to disclose.

  • Support statement: Data used for this study were downloaded from the National Jewish Health Research Database, supported by National Jewish Health.

  • Received November 13, 2019.
  • Accepted February 15, 2020.
  • Copyright ©ERS 2020
https://www.ersjournals.com/user-licence

References

  1. ↵
    1. Griffith DE,
    2. Aksamit T,
    3. Brown-Elliott BA, 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. doi:10.1164/rccm.200604-571ST
    OpenUrlCrossRefPubMedWeb of Science
  2. ↵
    1. Lewinsohn DM,
    2. Leonard MK,
    3. LoBue PA, et al.
    Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: diagnosis of tuberculosis in adults and children. Clin Infect Dis 2017; 64: e1–e33. doi:10.1093/cid/ciw694
    OpenUrlCrossRefPubMed
  3. ↵
    1. Griffith DE,
    2. Adjemian J,
    3. Brown-Elliott BA, et al.
    Semiquantitative culture analysis during therapy for Mycobacterium avium complex lung disease. Am J Respir Crit Care Med 2015; 192: 754–760. doi:10.1164/rccm.201503-0444OC
    OpenUrlCrossRef
  4. ↵
    1. Gonzalez-Angulo Y,
    2. Wiysonge CS,
    3. Geldenhuys H, et al.
    Sputum induction for the diagnosis of pulmonary tuberculosis: a systematic review and meta-analysis. Eur J Clin Microbiol Infect Dis 2012; 31: 1619–1630. doi:10.1007/s10096-011-1485-6
    OpenUrlCrossRefPubMed
  5. ↵
    1. Ipuge YA,
    2. Rieder HL,
    3. Enarson DA
    . The yield of acid-fast bacilli from serial smears in routine microscopy laboratories in rural Tanzania. Trans R Soc Trop Med Hyg 1996; 90: 258–261. doi:10.1016/S0035-9203(96)90239-4
    OpenUrlCrossRefPubMed
    1. Ssengooba W,
    2. Kiwanuka N,
    3. Kateete DP, et al.
    Incremental yield of serial sputum cultures for diagnosis of tuberculosis among HIV infected smear negative pulmonary TB suspects in Kampala, Uganda. PLoS One 2012; 7: e37650. doi:10.1371/journal.pone.0037650
    OpenUrlPubMed
  6. ↵
    1. Al Zahrani K,
    2. Al Jahdali H,
    3. Poirier L, et al.
    Yield of smear, culture and amplification tests from repeated sputum induction for the diagnosis of pulmonary tuberculosis. Int J Tuberc Lung Dis 2001; 5: 855–860.
    OpenUrlPubMedWeb of Science
  7. ↵
    1. Geldenhuys HD,
    2. Whitelaw A,
    3. Tameris MD, et al.
    A controlled trial of sputum induction and routine collection methods for TB diagnosis in a South African community. Eur J Clin Microbiol Infect Dis 2014; 33: 2259–2266. doi:10.1007/s10096-014-2198-4
    OpenUrlCrossRefPubMed
  8. ↵
    1. Tanaka E,
    2. Kimoto T,
    3. Tsuyuguchi K, et al.
    Effect of clarithromycin regimen for Mycobacterium avium complex pulmonary disease. Am J Respir Crit Care Med 1999; 160: 866–872. doi:10.1164/ajrccm.160.3.9811086
    OpenUrlCrossRefPubMedWeb of Science
    1. Lee G,
    2. Lee KS,
    3. Moon JW, et al.
    Nodular bronchiectatic Mycobacterium avium complex pulmonary disease. Natural course on serial computed tomographic scans. Ann Am Thorac Soc 2013; 10: 299–306. doi:10.1513/AnnalsATS.201303-062OC
    OpenUrlCrossRefPubMed
  9. ↵
    1. Fleshner M,
    2. Olivier KN,
    3. Shaw PA, et al.
    Mortality among patients with pulmonary non-tuberculous mycobacteria disease. Int J Tuberc Lung Dis 2016; 20: 582–587. doi:10.5588/ijtld.15.0807
    OpenUrlCrossRef
PreviousNext
Back to top
View this article with LENS
Vol 55 Issue 6 Table of Contents
European Respiratory Journal: 55 (6)
  • Table of Contents
  • Index by author
Email

Thank you for your interest in spreading the word on European Respiratory Society .

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Serial sputum induction in nontuberculous mycobacterial pulmonary disease
(Your Name) has sent you a message from European Respiratory Society
(Your Name) thought you would like to see the European Respiratory Society web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Print
Citation Tools
Serial sputum induction in nontuberculous mycobacterial pulmonary disease
Michael R. Holt, Shannon H. Kasperbauer, Charles L. Daley
European Respiratory Journal Jun 2020, 55 (6) 1902196; DOI: 10.1183/13993003.02196-2019

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero

Share
Serial sputum induction in nontuberculous mycobacterial pulmonary disease
Michael R. Holt, Shannon H. Kasperbauer, Charles L. Daley
European Respiratory Journal Jun 2020, 55 (6) 1902196; DOI: 10.1183/13993003.02196-2019
del.icio.us logo Digg logo Reddit logo Technorati logo Twitter logo CiteULike logo Connotea logo Facebook logo Google logo Mendeley logo
Full Text (PDF)

Jump To

  • Article
    • Abstract
    • Shareable PDF
    • Acknowledgements
    • Footnotes
    • References
  • Figures & Data
  • Info & Metrics
  • PDF
  • Tweet Widget
  • Facebook Like
  • Google Plus One

More in this TOC Section

Agora

  • Carbon footprint of respiratory treatments
  • ERS/ATS standards on lung function test interpretation: some limitations
  • Reply: ERS/ATS standards on lung function test interpretation: some limitations
Show more Agora

Research letters

  • Carbon footprint of respiratory treatments
  • Treatment outcomes of MDR-TB with chronic kidney/liver disease
  • Outcomes of cirrhotic patients with pre-capillary pulmonary hypertension
Show more Research letters

Related Articles

Navigate

  • Home
  • Current issue
  • Archive

About the ERJ

  • Journal information
  • Editorial board
  • Reviewers
  • Press
  • Permissions and reprints
  • Advertising

The European Respiratory Society

  • Society home
  • myERS
  • Privacy policy
  • Accessibility

ERS publications

  • European Respiratory Journal
  • ERJ Open Research
  • European Respiratory Review
  • Breathe
  • ERS books online
  • ERS Bookshop

Help

  • Feedback

For authors

  • Instructions for authors
  • Publication ethics and malpractice
  • Submit a manuscript

For readers

  • Alerts
  • Subjects
  • Podcasts
  • RSS

Subscriptions

  • Accessing the ERS publications

Contact us

European Respiratory Society
442 Glossop Road
Sheffield S10 2PX
United Kingdom
Tel: +44 114 2672860
Email: journals@ersnet.org

ISSN

Print ISSN:  0903-1936
Online ISSN: 1399-3003

Copyright © 2022 by the European Respiratory Society