A case of isolated pulmonary Mycobacterium avium complex infection in an immunocompetent host

Sivanthi Sapna Rajendran; Gayathri Anur Ramakrishnan

doi:10.4103/japt.japt_39_22

CASE REPORT

Year : 2023 | Volume : 6 | Issue : 2 | Page : 69-71

A case of isolated pulmonary Mycobacterium avium complex infection in an immunocompetent host

Sivanthi Sapna Rajendran, Gayathri Anur Ramakrishnan
Department of Respiratory Medicine, Apollo Hospitals, Chennai, Tamil Nadu, India

Date of Submission	23-Dec-2022
Date of Decision	05-May-2023
Date of Acceptance	11-May-2023
Date of Web Publication	13-Jul-2023

Correspondence Address:
Dr. Sivanthi Sapna Rajendran
No. 8, 4A, J D Jayithri Flats, P T Rajan Salai, KK Nagar, Chennai - 600 078, Tamil Nadu
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/japt.japt_39_22

Abstract

A 48-year-old male presented with complaints of occasional dry cough and sneezing for the past 4 months and high-resolution computed tomography chest done showed tree in bud and patchy nodular opacities in the right upper lobe and right middle lobe. He underwent bronchoscopy and bronchoalveolar lavage Gene X-pert Mycobacterium Tuberculosis (MTB) was not detected, but cytology showed granulomas and hence he was started on empirical antituberculous therapy (Isoniazid, Rifampicin, Pyrazinamide and Ethambutol (HRZE) regimen). His acid-fast bacilli C/S reports during follow-up showed growth of Mycobacterium Avium complex (MAC). Drug sensitivity testing was done and then he was started on oral rifampicin, ethambutol, and azithromycin and this regimen was continued for the next 6 months.

Keywords: Mycobacterium avium complex, Mycobacterium intracellulare, nontuberculous mycobacteria

How to cite this article:
Rajendran SS, Ramakrishnan GA. A case of isolated pulmonary Mycobacterium avium complex infection in an immunocompetent host. J Assoc Pulmonologist Tamilnadu 2023;6:69-71

How to cite this URL:
Rajendran SS, Ramakrishnan GA. A case of isolated pulmonary Mycobacterium avium complex infection in an immunocompetent host. J Assoc Pulmonologist Tamilnadu [serial online] 2023 [cited 2023 Sep 30];6:69-71. Available from: https://www.japt.in//text.asp?2023/6/2/69/381420

Introduction

Mycobacteria other than tuberculosis (TB) known as “atypical and nontuberculous mycobacteria” (NTM) are ubiquitous and mostly saprophytes (free-living bacterium found in water, soil and dust),^[1] but some pathogens cause variety of diseases especially in immunocompromised patients. Among them, Mycobacterium avium complex (MAC) infection most commonly occurs in patients with preexisting lung diseases like chronic obstructive pulmonary disease, fibronodular bronchiectasis, and cavitary lung disease (prior pulmonary TB infection and pneumoconioses, especially silicosis).^[2] Lung diseases due to MAC and other NTM including Mycobacterium intracellulare, Mycobacterium kansasii, Mycobacterium malmoense, Mycobacterium abscessus, and Mycobacterium xenopi also occurs in immunocompromised patients.^[3] They are opportunistic free-living organisms that cause disease if host defenses are impaired.^[2] This is a case of MAC infection in an immunocompetent patient without an underlying structural lung disease.

Case Report

A 48-year-old male presented with complaints of occasional dry cough and sneezing of 4-month duration. High-resolution computed tomography (CT) chest [Figure 1], [Figure 2], [Figure 3] done showed tree in bud and patchy nodular opacities in the right upper lobe and right middle lobe. HIV Elisa test done was negative. To rule out underlying immunocompromised status, vasculitis workup was done which turned out to be negative. Bronchoscopy was done and bronchoalveolar lavage (BAL) samples sent for acid-fast bacilli (AFB) smear was negative, Gene X-pert MTB was not detected, but cytology showed granuloma lesions. Hence, he was started on empirical anti-tuberculous therapy-HRZE regimen and advised to follow-up with AFB C/S reports. BAL AFB culture later showed growth of M. intracellulare (MAC). Drug sensitivity testing was done and he was started on oral rifampicin, ethambutol, and azithromycin and this regimen was continued for next 6 months. The patient became AFB culture negative later and got symptomatically better. During follow-up visits, no relapse is seen.

Figure 1: CT chest at level of carina showing tree in bud opacities in the right upper lobe. CT: Computed tomography

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Figure 2: CT chest showing patchy nodular opacities in the right middle lobe. CT: Computed tomography

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Figure 3: CT chest showing peripheral nodular opacities in the right middle lobe. CT: Computed tomography

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Discussion

The main route of transmission of MAC is through inhalation or ingestion and majority of these infections are extrapulmonary. Many patients present with nonspecific symptoms and laboratory workup reveals anemia, elevated alkaline phosphatase, and lactate dehydrogenase. Sputum specimens subjected to fluorochrome staining is preferred because it can be done more rapidly, and it is a more sensitive technique to identify mycobacteria than carbolfuchsin staining.^[4] Nucleic acid amplification techniques rapidly distinguish mycobacterium TB from NTM in both smear-positive and smear-negative respiratory specimens.^[4] Similar to suspected TB cases, all respiratory specimens should be cultured in both liquid and solid media.^[5] Traditional culture methods show detectable growth, with most slowly growing NTM only after 3–6 weeks on solid media, and after 1–2 weeks in liquid media.^[5]

Clinical and microbiologic criteria for diagnosis of nontuberculous mycobacterial pulmonary disease

Clinical: Pulmonary and systemic signs and symptoms such as cough, fatigue, weight loss, fever, and dyspnea
Radiologic: Nodular or cavitary opacities on chest radiograph, or a high-resolution CT scan that shows bronchiectasis with multiple small nodules
Appropriate exclusion of other diagnoses^[6]
Microbiologic:

Positive culture results from at least two separate expectorated sputum samples. If the results are nondiagnostic, consider repeat sputum AFB smears and cultures (or)
Positive culture results from at least one bronchial wash or lavage samples
Transbronchial or other lung biopsy with mycobacterial histologic features (granulomatous inflammation or AFB) and positive culture for NTM or biopsy showing mycobacterial histologic features (granulomatous inflammation or AFB) and one or more sputum or bronchial washings that are culture positive for NTM.

Drug susceptibility testing is only recommended for NTM isolates that are clinically significant.^[2] Treatment of MAC infection in an immunocompetent patient involves combination of a newer macrolide (azithromycin/clarithromycin), ethambutol, rifampicin/rifabutin with/without streptomycin.^[7] Therapy should be continued for at least 1 year till culture results revert to negative. In our case, with the above regimen, the patient became AFB culture negative and got symptomatically better.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1.	Falkinham JO 3^rd. Epidemiology of infection by nontuberculous mycobacteria. Clin Microbiol Rev 1996;9:177-215.
2.	Field SK, Cowie RL. Lung disease due to the more common nontuberculous mycobacteria. Chest 2006;129:1653-72.
3.	Thomsen VO, Andersen AB, Miörner H. Incidence and clinical significance of non-tuberculous mycobacteria isolated from clinical specimens during a 2-y nationwide survey. Scand J Infect Dis 2002;34:648-53.
4.	Woods GL. The mycobacteriology laboratory and new diagnostic techniques. Infect Dis Clin 2002;16:127-44.
5.	Henry MT, Inamdar L, O'Riordain D, Schweiger M, Watson JP. Nontuberculous mycobacteria in non-HIV patients: Epidemiology, treatment and response. Eur Respir J 2004;23:741-6.
6.	Daley CL, Iaccarino JM, Lange C, Cambau E, Wallace RJ Jr., Andrejak C, et al. Treatment of nontuberculous mycobacterial pulmonary disease: An official ATS/ERS/ESCMID/IDSA clinical practice guideline. Clin Infect Dis 2020;71:e1-36.
7.	Griffith DE. Treatment of Mycobacterium avium Complex (MAC). Semin Respir Crit Care Med 2018;39:351-61.