|Year : 2021 | Volume
| Issue : 3 | Page : 122-123
Mycobacterium genavense Causing Lung Abscess in an Immunocompetent Individual
Ria Lawrence, R Narasimhan
Department of Respiratory Medicine, Apollo Main Hospital, Chennai, Tamil Nadu, India
|Date of Submission||27-Dec-2021|
|Date of Decision||25-Feb-2022|
|Date of Acceptance||04-Mar-2022|
|Date of Web Publication||12-May-2022|
Department of Respiratory Medicine, Apollo Main Hospital, Greams Lane, Chennai - 600 006, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Mycobacterium genavense is a rare nontuberculous mycobacterium, known to cause serious infections in HIV-infected patients and immunocompromised individuals. The diagnosis of M. genavense is challenging because of its slow-growing nature in the routine acid-fast culture methods. Here, we present the case of lung abscess caused by M. genavense in an immunocompetent individual.
Keywords: Lung abscess, lung cavity in immunocompetent individuals, lung cavity, Mycobacterium genavense, nontuberculous mycobacteria, nontuberculous mycobacteria lung abscess, nontuberculous mycobacteria
|How to cite this article:|
Lawrence R, Narasimhan R. Mycobacterium genavense Causing Lung Abscess in an Immunocompetent Individual. J Assoc Pulmonologist Tamilnadu 2021;4:122-3
|How to cite this URL:|
Lawrence R, Narasimhan R. Mycobacterium genavense Causing Lung Abscess in an Immunocompetent Individual. J Assoc Pulmonologist Tamilnadu [serial online] 2021 [cited 2022 May 16];4:122-3. Available from: http://www.japt.com/text.asp?2021/4/3/122/345087
| Introduction|| |
NTM are known to cause insidious and severe disseminated infections in immunocompromised patients. M. genavense is a slow growing species has emerged as an important NTM among AIDS patients, causing up to 15% of all NTM infections. Mycobacterium genavense has unusual fastidious growth requirements and shows poor and variable growth in vitro.
| Case Report|| |
A 54-year-old female, a known asthmatic on regular inhaled bronchodilators, with no other comorbidities, has been reported with complaints of fever and productive cough for 2 weeks. She was not on oral steroids. On examination, she was febrile, saturating well at room air; on auscultation, she had left side crackles. Blood investigation revealed leukocytosis. Chest X-ray [Figure 1] revealed left lower lobe cavity. A high-resolution computed tomography (CT) scan of the thorax was done [Figure 2], which showed left lower lobe abscess and right lower lobe consolidation. Bronchoscopy was performed, and bronchial wash was sent for microbiological analysis. Bronchial wash sent Gram stain, acid-fast staining, and cartridge-based nucleic acid amplification test for Mycobacterium tuberculosis was negative. She was started on empirical antibiotics. She did not improved on antibiotics and continued to be symptomatic; on follow-up, we found that the acid-fast bacilli culture showed Mycobacterium genavense. It would have been ideal to do repeat three specimens for culture before diagnosing, but since the clinical condition warranted and in consultation with the microbiologist, we started her on treatment with anti tubercular treatment (ATT). She was started on a modified antitubercular regimen with clarithromycin, rifabutin, and amikacin. She improved clinically and is in regular follow-up. [Figure 3] shows the chest X-ray and CT chest after treatment.
|Figure 1: Chest X-ray posteroanterior view showing left lower lobe cavity|
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|Figure 2: Computed tomography chest plain showing left lower lobe cavity with right lower lobe consolidation|
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| Discussion|| |
Nontuberculous mycobacteria (NTM) are ubiquitous organisms responsible for opportunistic infections with a broad-spectrum of virulence. NTM lung disease can present as varied forms from bronchiectasis, fibrocavitary, or nodular lesions. Acid-fast bacilli staining cannot be used to differentiate between M. tuberculosis and NTM. Either a nucleic acid amplification test or culture of the organism is needed to confirm the diagnosis. The culture method is the gold standard for confirmation of NTM and is required for the identification of the species and drug susceptibility test. The most common NTM species characterized was Mycobacterium kansasii followed by Mycobacterium chelonae, Mycobacterium xenopi, Mycobacterium scrofulaceum, Mycobacterium avium, Mycobacterium asiaticum, and Mycobacterium fortuitum.
M. fortuitum (27.4%) and Mycobacterium abscessus (14.4%) were the most frequently isolated NTM species from extrapulmonary samples in India. So far, there a very few cases reports on M. genavense causing disease in an immunocompetent host.
M. genavense is a ubiquitous NTM. It is a slowly growing, fastidious mycobacterium that has been found in tap water, animals (birds, rabbits, cats, ferrets, and rabbits), and the intestinal tract of healthy humans. M. genavense is a fastidious NTM that needs liquid media, acid pH, higher than usual temperature (45°C), mycobactin J as a supplement, and at least 3 months of incubation to grow.
It was initially found in HIV-infected patients causing serious infections. It is also known to cause infections in non-HIV patients who are immunocompromised, such as solid-organ transplant recipients and patients on chemotherapy. The diagnosis of M. genavense infection is clinically challenging because of the difficulties in routinely culturing the organism and the absence of specific symptoms, even in fatal infections. Therefore, diagnosing M. genavense infection in patients without known evidence of immunodeficiency is particularly difficult. M. genavense should be envisaged in patients with mycobacterial pulmonary disease and digestive involvement or negative mycobacterial culture lasting for more than 1 month. The high effectiveness of clarithromycin and rifabutin has been demonstrated in a murine model. Multidrug therapies, including clarithromycin, are recommended. Even with appropriate treatment, clinical evolution is long before the resolution of symptoms, and patients have to be treated for at least 12–24 months. In our case, the patient was started on empirical antibiotics for lung abscess treatment. On further follow-up, acid-fast bacillus culture showed M. genavense. After which, she was started on clarithromycin, amikacin, and rifabutin. She has improved clinically and is on regular follow-up.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his 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
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]