1. Slide repository module 5
Diagnosis of NTM-LD
Slide repository module 5
NP-EU

2. Eradication or disease management3 Potential misdiagnosis phase
The patient journey is typically long and difficult before diagnosis Only a few are diagnosed correctly from the outset1
Pulmonary symptoms worsen over time
Eradication or disease management3
Primary care doctor
Seek out physician
Potential misdiagnosis phase
Treatment initiation
Misdiagnosis
Bronchitis2
COPD2
Treatment initiation
Diagnosis correction
Symptom persistence
Asthma2
Referral to expert centre3
Prolonged misdiagnosis phase due to non-specific symptoms similar to underlying disease may lead to late diagnosis and delayed treatment.
Tuberculosis2
COPD, chronic obstructive pulmonary disease. 1. Mirsaeidi M, et al. Int J Infect Dis 2013; 17:e1000-4; 2. Infectious disease advisor - Rapidly Growing Nontuberculous Mycobacteria Accessed March, 2018; available at 3. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

3. Diagnosis

4. Symptoms of NTM-LD are frequently non-specific
Weight loss
General malaise
Haemoptysis
Chronic, recurrent cough
Fatigue
Chest pain
Fever
Dyspnoea
Sputum production
= All patients
= variable symptoms
Physical symptoms are more common in advanced disease. Assessment is often difficult, as the symptoms overlap with those of the underlying lung diseases (e.g. COPD, bronchiectasis)
COPD, chronic obstructive pulmonary disease; NTM-LD, non-tuberculous mycobacterial lung disease. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

5. Sputum, bronchial wash or lung biopsy* Exclusion of other diagnoses
Diagnostic criteria: Clinical, radiographic, and microbiologic criteria must be met to make a diagnosis of NTM-LD
Pulmonary symptoms
Sputum, bronchial wash or lung biopsy*
Exclusion of other diagnoses
Clinical criteria ?
Microbiological criteria
Positive culture required
Radiographic criteria
Chest radiograph:
HRCT:
multifocal bronchiectasis, multiple nodules
Nodular and cavitary opacities
*Bronchial wash only used when sputum samples are unavailable. HRCT, high resolution computed tomography; NTM-LD, non-tuberculous mycobacterial lung disease. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

6. Diagnosis of NTM-LD
ATS diagnostic criteria
Symptoms correlate with NTM-LD
Radiological findings compatible with NTM-LD (nodular/bronchiectatic or fibrocavitary)
At least two of three positive early-morning sputum samples over the course of a week
The NTM species should be identified by molecular methods
ATS, American Thoracic Society; NTM, non-tuberculous mycobacteria; NTM-LD, non-tuberculous mycobacterial lung disease. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

7. Diagnostic criteria for NTM-LD1,2
Radiological criteria1
Nodular or cavitary structures on chest radiograph or
Multifocal bronchiectasis with multiple small nodules on the HRCT scan
and
Exclusion of other causes
Microbiological criteria1,2
Three positive sputum cultures1,2 or
Positive culture from bronchoalveolar lavage1,2
Transbronchial/other lung biopsy with mycobacterial histopathological features and positive culture or biopsy with mycobacterial, histopathological features and ≥ 1 positive culture from sputum/ bronchoalveolar lavage1,2
Clinical criteria1
Bronchopulmonary symptoms
and
Exclusion of other lung diseases
Bronchoalveolar lavage is only appropriate when patients cannot produce sputum samples, or their specimens do not grow mycobacteria2
HRCT, high resolution computed tomography; NTM-LD, non-tuberculous mycobacterial lung disease. 1. Griffith DE, et al. Am J Crit Care Med 2007; 175: ; 2. van Ingen J. Clin Chest Med 2015; 36:43-54.

8. Radiographic criteria
Nodular or cavitary opacities on chest radiograph
Or multifocal bronchiectasis with multiple small nodules on HRCT scan
Fibrocavitary disease1
Chest HRCT indicated for evaluation
Nodular/bronchiectatic disease1
Chest HRCT indicated for evaluation
HRCT should also be used during treatment follow-up2
HRCT, high resolution computed tomography. 1. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175: ; 2. personal communication by scientific committee.

9. Radiographic criteria: Nodular/bronchiectatic form
Characteristic pulmonary infiltrates in “tree-in-bud” pattern1,2
Bilateral small nodules in the lungs1,2
Cylindrical bronchiectasis often affects the right middle lobe and the lingual middle and lower lung fields2
In later stages cavities may also develop1
HRCT image courtesy of W. Hoefsloot. HRCT, high resolution computed tomography. 1. Weiss CH, Glassroth J. Expert Rev Respir Med 2012; 6: ; quiz 3; 2. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

10. Radiographic criteria: Fibrocavitary form
Radiological features are similar to tuberculosis1
Areas of increasing opacity and cavitation2
Usually the upper lobes of the lung are affected2
Frequent apical pleural thickening and fibrosis with volume loss and bronchiectasis visible2
Differences to tuberculosis:1
Thin-walled cavities with less surrounding parenchymal opacity
Less bronchogenic, but more related spread of the disease
Increased involvement of the pleura in the affected areas of the lungs
HRCT image courtesy of W. Hoefsloot. HRCT, high resolution computed tomography. 1. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175: ; 2. Bonaiti G, et al. Biomed Res Int 2015; 2015:

11. Radiographic criteria: Hypersensitivity-like pneumonitis
X-rays or chest CT scans are always abnormal
Most of them show diffuse nodular infiltration
Ground-glass opacities and mosaic patterns are commonly seen on HRCT scans
HRCT image courtesy of W. Hoefsloot. CT, computed tomography; HRCT, high resolution computed tomography. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

12. Microbiologic criteria: Culture of NTM essential for diagnosis
DIAGNOSIS REQUIRES:
Sputum:
Positive NTM culture at least 2 of 3 early morning samples collected on different days
Lung biopsy:
Mycobacterial histopathologic features and positive NTM culture
Bronchial wash/lavage:
Positive NTM culture from  1 sample* OR OR OR
Combination of samples
Mycobacterial histopathologic features on lung biopsy and  1 NTM culture-positive sputum or bronchial wash sample
*Only applicable if sputum samples cannot be obtained. NTM, non-tuberculous mycobacteria. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

13. Potential for contamination of samples
Environmental contamination must be avoided during sample collection
Bronchial washes are less likely to be contaminated than expectorated sputum samples
If culture reveals NTM that are environmental contaminants or infrequently encountered, expert guidance regarding clinical significance is necessary !
NTM, non-tuberculous mycobacteria. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

14. Drug susceptibility testing in NTM
Grouping/species
First choice
Alternatives
MAC
Broth macrodilution in 12B medium
Broth microdilution in CAMH
M. kansasii
Macrodilution, agar proportion
Other SGM
Broth microdilution in CAMH*
No recommendation
Fastidious species
M. marinum
Macrodilution, agar dilution
Rapid growers
Not established
Macrolide susceptibility in MAC and rapid-growing species can be tested by analysing mutations in the 23S rRNA and erm genes
Aminoglycoside resistance can be tested by analysing the 16S rRNA gene in MAC and M. abscessus
*M. xenopi grows poorly in this medium. CAMH, cation-adjusted Mueller-Hinton broth; MAC, Mycobacterium avium complex; rRNA, ribosomal ribonucleic acid; SGM, slow-growing mycobacteria. van Ingen J, et al. Drug Resist Update 2012; 15:

15. Species-level identification of NTM is clinically important
Genotypic testing
Commercially available nucleic acid hybridization probes1
PRA1
DNA sequence analysis1
Rapid, high sensitivity and specificity; not available for all NTM species1
Rapid and accurate2
Based on analysis of hsp65, rpoB, and 16S-23S rRNA sequences3
Species identification is vital to determining the course of treatment and, in the case of recurrent infection, whether it is new or due to a relapse1
It is important to identify NTM-LD caused by M. abscessus1
Presently no reliable or dependable antibiotic regimen to produce a cure for M. abscessus lung disease1
Sudden onset, rapidly progressive disease can occur in association with gastroesophageal diseases and CF1
CF, cystic fibrosis; MAC, Mycobacterium avium complex; NTM, non-tuberculous mycobacteria; NTM-LD, non-tuberculous mycobacterial lung disease; PRA, polymerase chain reaction restriction endonuclease assay; rRNA, ribosomal ribonucleic acid. 1. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175: ; 2. Verma AK, et al. Can J Microbiol. 2015; 61: 293-6; 3. Jang M-A, et al. J Clin Microbiol. 2014; 52: 1207–1212; 4.

16. NTM-LD and TB must be differentiated
It is important to differentiate between pulmonary TB and NTM-LD1
Treatment is different for the two diseases1*
Cystic fibrosis
Symptoms, radiography or smear microscopy are not sufficient to differentiate between TB & NTM-LD1
Molecular methods are the methods of choice for identifying NTM1
*Approved first line TB drugs: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol, Streptomycin2. NTM, non-tuberculous mycobacteria; NTM-LD, non-tuberculous mycobacterial lung disease; TB, tuberculosis. 1. Kwon YS, Koh W-J. Tuberc Respir Dis 2014; 77: 1-5; 2. WHO, Treatment of Tuberculosis: Guidelines, 4th edition, Geneva; 2010.

17. Pulmonary TB and NTM-LD: Comparison of radiographic findings
Plain chest radiography
HRCT TB
Poorly defined nodules, linear opacities and cavities1
Focal or patchy heterogeneous consolidation1
Centrilobular nodules1
Tree-in-bud lesions1
Patchy or lobular consolidations1
Cavities1
NTM-LD
Fibrocavitary NTM-LD
Thin-walled cavities with less surrounding parenchymal opacity than TB2
Less bronchogenic but more contiguous spread of disease than TB2
More marked involvement of pleura over involved areas of lungs than TB2
Nodular/bronchiectatic NTM-LD
Bilateral multifocal bronchiectasis and bronchiolitis1,2
Clusters of small (< 5 mm) nodules2
Considerable overlap with appearance of TB1
There is considerable overlap in the radiographic manifestations of pulmonary TB and NTM-LD, and radiographic find­ings alone cannot be used to differentiate the two diseases1
HRCT, high resolution computed tomography; NTM-LD, non-tuberculous mycobacterial lung disease; TB, tuberculosis. 1. Kwon YS, Koh W-J. Tuberc Respir Dis 2014; 77: 1-5; 2. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

18. Adequate numbers of respiratory specimens should be collected
Colonisation
Colonisation without infection has not been proven, and suspected cases may represent indolent or slowly progressive infection
Guideline-based criteria should be used to determine the clinical significance of any NTM identified
Adequate numbers of respiratory specimens should be collected
Individuals with NTM-positive sputum but no disease symptoms should be monitored closely and expert opinion sought
NTM, non-tuberculous mycobacteria. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:

19. Summary
Relatively few patients with NTM are diagnosed correctly at the outset1
Diagnostic symptoms are non specific and can be mistaken for other conditions2
Several diagnostic criteria have to be met in order to diagnose a case of NTM-LD2,3
Nodular or cavitary structures on chest radiograph, or multifocal bronchiectasis with multiple small nodules by HRCT scan2
Three positive sputum cultures, or positive cultures from biopsy or bronchoalveolar lavage; 2,3 care must be taken that these are not contaminated2
Bronchopulmonary symptoms2
Other causes of disease should be excluded2
It is important to differentiate between NTM species and to rule out TB as a possible cause,2,4 and this can be achieved using molecular techniques and identification of key radiographic findings2,5
Colonisation without infection is unproven and is likely to represent indolent or slowly progressing infection2
HRCT, high resolution computed tomography; NTM, non-tuberculous mycobacteria; NTM-LD, non-tuberculous mycobacterial lung disease; TB, tuberculosis. 1. Mirsaeidi M, et al. Int J Infect Dis 2013; 17:e1000-4; 2. Griffith DE, et al. Am J Respir Crit Care Med 2007; 175:367-41; 3. van Ingen J. Clin Chest Med 2015; 36:43-54; 4. Kwon YS, Koh W-J. Tuberc Respir Dis 2014; 77: 1-5; 5. Jang M-A, et al. J Clin Microbiol. 2014; 52: 1207–1212.

20. Glossary
Agar proportion Involves testing bacterial susceptibility to antibiotics by growing colonies on agar plates with different concentrations of antibiotic
Bronchoalveolar lavage a medical procedure in which a bronchoscope is passed through the mouth or nose into the lungs and fluid is squirted into a small part of the lung and then collected for examination, typically performed to diagnose lung disease
Broth macrodilution Involves testing bacterial susceptibility to antibiotics by bacterial cells in suspension in volumes of 1 ml or greater
Broth microdilution Involves testing bacterial susceptibility to antibiotics by bacterial cells in suspension in a microtiter plate format
Fastidious NTM Species with very specific growth requirements
NTM, non-tuberculous mycobacteria.