Introduction Nontuberculous mycobacterial (NTM) lung disease is a general term for a group of disorders characterized by exposure to specific bacterial germs known as mycobacteria. These germs are found in the water and soil and are common throughout the environment as a whole. They usually do not cause illness. The term ‘ nontuberculous ’ is used to differentiate these disorders from the mycobacterium that cause tuberculosis (i.e. mycobacterium tuberculosis complex).
Difference B/W NTM & MTB
Non- tuberculous mycobacteriae can cause various clinical syndromes : 1.NTM- pulmonary disease (90%) 2.Superficial lymphadenitis 3.Dissiminated disease in immunocompromised patients 4.Skin and soft tissue infections
Epidemiology Estimated annual prevalence of 6.2/100,000 in the EU5 and 24.9/100,000 in Japan in 2016, it is evident that NTM-PD has become a clinically significant infection in these countries They are not usually transmitted from person to person Source of infection is soil, water, food and animals ( environmental)
Causes of NTM-PD More than 120 species of mycobacteria have been identified that can cause disease in humans. The most common are Mycobacterium avium complex or MAC. MAC encompasses three mycobacterial species known as M. avium,M . intracellulare , and M. chimaera. Collectively, these species account for approximately half of all mycobacterial infections .
Risk Factors Destroyed lungs due to TB or other diseases like pneumoconiosis Trauma (direct infection from environs) Bronchiectasis (esp. middle lobe and lingula ) Chronic obstructive pulmonary disease Cystic fibrosis-CFTR gene polymorphism Primary ciliary dyskinesia Alpha 1 antitrypsin deficiency Lung cancer Thoracic skeletal abnormalities ( kyphoscoliosis ) Gastroesophageal reflux disease Pulmonary alveolar proteinosis
C linical phenotypes : There are two main Clinical phenotypes Classic(aka cavitary disease) and Non-classic(aka bronchiectic disease) : The classic form presents as cavitary disease in the upper zones of the lobes, with symptoms similar to tuberculosis but no hemoptysis . On imaging, there are nodules in all lobes, with a slight predilection for the apical and posterior segments. The nodules develop into cavities, as new nodules also occur
A 50-year-old male and COPD patient had a routine HRCT exam that showed small nodules in both lungs (arrows)
The patient returned with cough and malaise a year later. CT showed an increase in the size of the nodules as well as cavitation. Bronchial lavage produced acid-fast bacilli, later proved to be mycobacterium avium intracellulare
The Non-classic NTMB aka Nodular bronchiectic Disease : presents with chronic cough and as a bronchiectatic disease, with centrilobular nodules . Cavitation are rare in non-classic NTMB.
Symptoms Cough Fatigue Weight loss Shortness of breath (dyspnea) Coughing up blood (hemoptysis) Fever Night sweats
D iagnosis
Differential Diagnosis There are many conditions that are associated with the same nonspecific symptoms that can characterize NTM lung disease. Such conditions include bronchiectasis tuberculosis lung cancer aspergillosis fungal diseases such as blastomycosis , histoplasmosis , and coccidioidomycosis
Treatment .
Treatment
Prognosis 5 years Mortality after diagnosis was 25.0% and 44.9 % among patients with NTM without and with comorbidities, respectively