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Year : 2020  |  Volume : 37  |  Issue : 6  |  Page : 495-500  

Nontuberculous mycobacteria: A report of eighteen cases from a tertiary care center in India

1 Department of Medicine, All India Institute of Medical Sciences, New Delhi, India
2 Department of Radio-Diagnosis, All India Institute of Medical Sciences, New Delhi, India

Date of Submission11-Aug-2020
Date of Acceptance30-Sep-2019
Date of Web Publication30-Oct-2020

Correspondence Address:
Dr. Manish Soneja
Department of Medicine, All India Institute of Medical Sciences, New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/lungindia.lungindia_365_19

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Context: Nontuberculous mycobacteria (NTM) are ubiquitous mycobacteria present in environment and generally affect patients with either structural lung disease or immunosuppression and commonly involve lungs, lymph node, or skin. Materials and Methods: Between July 2016 and February 2019, 18 cases of NTM were diagnosed and their relevant clinical, diagnostic, and treatment details were recorded after taking informed consent. Results: We report 18 cases of NTM involving lungs (n = 11), skin and soft tissue (n = 3), joint (n = 2), genitourinary (n = 1), and central nervous system (n = 1). History of immunosuppression was present in two patients, whereas history of some form of intervention was seen in six patients. Mycobacterium fortuitum group (n = 5) was the most commonly isolated organism, followed by Mycobacterium avium complex (n = 4), Mycobacterium abscessus (n = 3), Mycobacterium kansasii (n = 2), and Mycobacterium chelonae (n = 1). In two patients, M. chelonae and M. abscessus were isolated in succession. Of these 18 patients, clinical response was present in 15 of the patients. Diagnosis and treatment of NTM in resource limited settings is extremely challenging. Conclusion: Most of the patients with NTM are misdiagnosed and are treated as tuberculosis in India, sometimes with a multidrug resistance regimen, which results in significant morbidity and mortality. We present these cases to shed some light on the epidemiology of NTM in this part of India.

Keywords: Mycobacterium abscessus, Mycobacterium avium complex, Mycobacterium chelonae, Mycobacterium fortuitum, Mycobacterium kansasii

How to cite this article:
Gupta N, Mittal A, Niyas VK, Banerjee S, Ray Y, Kodan P, Malla S, Khot W, Fazal F, Singh BK, Jorwal P, Nischal N, Soneja M, Wig N. Nontuberculous mycobacteria: A report of eighteen cases from a tertiary care center in India. Lung India 2020;37:495-500

How to cite this URL:
Gupta N, Mittal A, Niyas VK, Banerjee S, Ray Y, Kodan P, Malla S, Khot W, Fazal F, Singh BK, Jorwal P, Nischal N, Soneja M, Wig N. Nontuberculous mycobacteria: A report of eighteen cases from a tertiary care center in India. Lung India [serial online] 2020 [cited 2021 Jun 19];37:495-500. Available from: https://www.lungindia.com/text.asp?2020/37/6/495/299658

   Introduction Top

Nontuberculous mycobacteria (NTM) encompass all mycobacteria (more than 140 species), except the members of Mycobacteriumtuberculosis complex and Mycobacteriumleprae.[1] NTM is ubiquitously present in the environment, most notably in water supplies. Their presence in tap water is attributed to their natural resistance to commonly used water disinfectants.[2] Because of this, routine exposure to NTM, most notably in the form of airborne particles, is extremely common. Considering the rarity of clinically significant NTM infection, it is safe to assume that certain risk factors are important for an individual to get an NTM infection. Two most important risk factors that are described in published literature are structural lung disease (cystic fibrosis, chronic obstructive pulmonary tuberculosis, past history of tuberculosis, etc.) and immunosuppression (HIV, transplantation, primary immunodeficiency, etc.).[3] Four common sites of NTM involvement are known: pulmonary, lymph node, skin, and bones/joints. Central nervous system including eye and ear involvement is considerably rare. The most common syndrome due to NTM is chronic pulmonary involvement followed by lymphadenitis. Cutaneous and bone NTM usually follow an invasive procedure and are a result of surgical site infection due to contaminated instruments. Disseminated NTM is usually described in immunosuppressed patients such as HIV/AIDS. NTM are classically classified based on the duration they take to grow on subculture on solid media into slow growers (>7 days) and rapid growers (<7 days).[1] The most important clinically relevant slow growers include Mycobacteriumavium complex (MAC), Mycobacteriumkansasii, MycobacteriumMarinum, and MycobacteriumUlcerans, whereas the most important clinically relevant rapid growers include Mycobacteriumabscessus complex (MABC), Mycobacteriumfortuitum complex, and Mycobacteriumchelonae. There are very few reports of large series of clinical cases with follow-up from the Indian subcontinent. We report a series of eighteen cases of nontubercular mycobacteria to shed some light on the epidemiology of NTM infections in India.

   Materials and Methods Top

Between July 2016 and February 2019, 18 cases of NTM were diagnosed based on available diagnostic criteria.[4] Clinical features, radiological features, method of microbiological diagnosis, treatment details, and outcome were recorded after taking informing consent. Microbiological diagnosis was established in our accredited laboratory in 15 of the patients. Ziehl–Neelsen (ZN) staining was done on the direct specimen followed by liquid culture on mycobacterium growth indicator tube (Becton Dickinson, Sparks, MD). This contains a liquid broth (modified Middlebrook 7H9) in conjunction with a fluorescence quenching-based oxygen sensor that detects mycobacterial growth. Line probe assay in the name of GenoType® mycobacterium common mycobacteria/additional species assay (Hain Lifescience, Nehren, Germany) was done on the positive cultures.[5] Diagnosis of NTM was established in an outside laboratory in three patients due to logistic reasons. Two patients were diagnosed by matrix-assisted laser desorption and ionization time of flight-mass spectrophotometry (MALDITOF-MS) and one patient was diagnosed by sequencing [Table 1].
Table 1: Demography, clinical features, diagnosis, treatment, and response of patients with nontuberculous mycobacteria

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   Results Top

Of the 18 cases of NTM, 11 were male. The mean age was 41 ± 17 years. The state-wise distribution was as follows: Delhi (n = 8), Bihar (n = 2), Haryana (n = 2), Uttar Pradesh (n = 2), Madhya Pradesh (n = 2), West Bengal (n = 1), and Jammu and Kashmir (n = 1). The localization of NTM was as follows: pulmonary (n = 11), skin and soft tissue (n = 3), joint (n = 2), genitourinary (n = 1), and central nervous system (n = 1). The median duration of illness at presentation was 15 months (5.25–27 months). History of immunosuppression was present in two patients (HIV-1 and idiopathic CD4 lymphocytopenia-1). Six patients had a history of surgical intervention [Table 1]. All of these patients had rapidly growing mycobacteria as the causative agent. Constitutional symptoms such as fever, loss of appetite, and loss of weight were present in 13 patients [Table 1]. All except three patients had a history of receipt of conventional four-drug antitubercular therapy (ATT) for tuberculosis. The median duration of conventional ATT received before diagnosis was 6 months (5–30 months) [Table 1].

Of the 18 patients with culture positivity, culture isolates were speciated in 17 patients. Of the 17 patients, the same mycobacteria were cultured on multiple occasions in 15 patients. The organisms isolated on culture were M.fortuitum group (n = 5), MAC (n = 4), M.abscessus (n = 3), M.kansasii (n = 2), and M.chelonae (n = 1). In two patients, two different species were detected at different times in the course of illness. Both the patients had M.chelonae and M.abscessus in succession [Table 1]. Most patients were on a total of four drugs at a time (n = 9), followed by three drugs (n = 7), five drugs (n = 2), and six drugs (n = 1). The mean number of drugs was 3.8 ± 0.9. Most commonly used drugs in the regimens included clarithromycin (n = 11), amikacin (n = 9), ethambutol (n = 9), rifampicin (n = 6), linezolid (n = 5), levofloxacin (n = 5), doxycycline (n = 4), rifabutin (n = 4), streptomycin (n = 4), imipenem (n = 3), azithromycin (n = 3), isoniazid (n = 2), moxifloxacin (n = 1), and pyrazinamide (n = 1). Of these 18 patients, two died and one was lost to follow-up. Clinical response was present in the rest of the patients [Table 1]. Those patients with clinical response were on specific therapy for an average duration of 13.7 ± 6.5 months.

   Discussion Top

Most reports from India are laboratory data of culture isolates [Table 2].[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16] Because NTM are commonly known to colonize or contaminate nonsterile specimens, mere isolation does not establish disease and these reports although informative may not be the true representation of the epidemiology of NTM in India. Diagnosis of NTM infection, therefore, requires relevant clinical background. On the other hand, because the clinical features and radiological findings are often so nonspecific, microbiological diagnosis becomes mandatory to make a diagnosis of NTM.
Table 2: Nontuberculous mycobateria studies from India

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Pulmonary involvement is the most common NTM syndrome known worldwide. There are two major forms of pulmonary NTM: fibrocavitary and nodular bronchiectasis.[17] Of the 11 patients with pulmonary NTM in our series, eight patients had cavitary disease (bilateral – 3 and unilateral – 5), whereas the rest three had nodular/bronchiectatic pattern. All but one patient with pulmonary NTM in our series had a prior history of ATT intake due to presumed pulmonary tuberculosis. MAC is the most common etiology of pulmonary NTM and is also responsible for lymphadenitis and disseminated infection in patients with HIV. Mycobacterium avium complex includes M. avium, Mycobacterium intracellulare and several other species closely related to M. intracellulare like Mycobacterium chimaera, Mycobacterium indicus pranii, M. Marseillense, etc.[18] It is interesting to note that M.chimaera is reported to be less virulent than M.avium and M.intracellulare.M.kansasii is the second most common cause of lung disease worldwide and is usually believed to be a true pathogen in most cases.[19]

Rapid growers such as MABC (M.abscessus subsp. abscessus, M.abscessus subsp. Bolletii,andM.abscessus subsp. massiliense), M.fortuitum group (including Mycobacteriumsenegalense, Mycobacteriumsepticum, and Mycobacteriumbrisbanense), and M.chelonae are important causes of pulmonary infection and surgical site infection.[20] Rapid growers are commonly health care associated (prosthetic devices, postinjection abscesses, cosmetic, and laparoscopic procedures) because of their ubiquitous presence in water and ability to form biofilms.[11],[21],[22] History of procedure, prosthetic device, intramuscular injection, or road traffic accident was present in six of our patients.

The first step in the microbiological diagnosis of NTM is visualization of acid-fast bacilli in ZN stain. Subtle differences have been described to differentiate between M.tuberculosis and NTM on ZN stain, but conclusive diagnosis of NTM cannot be established on microscopy alone. Classically, the standard of diagnosis for NTM has been culture followed by biochemical identification, but due to the cumbersome nature of tests, most laboratories have moved on to molecular identification following culture. The most common molecular methods for speciation of NTM are 16SrRNA sequencing, line probe assay, and MALDITOF-MS.[5],[23]

Recommended treatment for MAC is a three-drug macrolide-based regimen with an aim to achieve at least 12 months of negative cultures in cases of pulmonary NTM. M.kansasii is usually responsive to treatment and requires a combination of rifampicin, isoniazid, and ethambutol. For rapid growers, combination therapy is recommended for a total of at least 4–6 months. Intravenous drugs should be a part of the initial combination until there is clinical improvement after which oral combination therapy can be used. The treatment of NTM is usually guided by the ATS/IDSA guidelines and the British thoracic guidelines, but the adherence to these guidelines is often difficult.[4],[24] Except for liposomal inhaled amikacin, which is not available in India, there are no other Food and Drug Administration-approved drugs for NTM.[25] Treatment of NTM is largely based on small observational studies and expert opinion. Furthermore, the speciation of NTM is often not available at the first go. More often than not, the diagnosis of NTM is usually based on the negativity of immunochromatography test that detects antigens specific for M.tuberculosis complex. The speciation if available is often delayed that results in administration of empiric treatment regimens. Furthermore, drug susceptibility of NTM is not available in most centers and it is difficult to predict response without susceptibility. This results in use of more drugs than recommended in absence of early response because of fear of nonsusceptibility. For this reason, most of our patients were on three to four drugs at a time. Microbiological cure is often very difficult to achieve, and therefore, duration of treatment in most cases has to be decided on a case-to-case basis. The average duration in our series was more than a year. The treatment outcome in NTM depends on the underlying host factors, organ involved, and the disease severity. In our series, history of immunosuppression was present in only two patients. The time of initiation and choice of treatment regimens also have considerable bearing on the outcomes. Favorable outcome of NTM infections varies with the definitions of cure used in different studies. In a systematic review, proportion of sputum culture conversion was around 61% for MAC (on triple drug regimen), 41% for M.abscessus, and 80% for M.kansasii.[26],[27] A favorable clinical outcome in terms of resolution of clinical symptoms was reported in 15 of 18 patients. In patients with pulmonary NTM, eight out of eleven patients showed culture conversion.

   Conclusion Top

India is highly endemic for tuberculosis, but the epidemiology of NTM in India is not well defined. Most of the patients with NTM are misdiagnosed and are treated as tuberculosis, sometimes with a multidrug resistance regimen, which results in significant morbidity and mortality. Diagnosis and treatment of NTM in resource-limited settings is extremely challenging. There is an urgent need for increased suspicion, better diagnostic facilities that provide drug-susceptibility testing, and newer evidence-informed treatment guidelines.

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  [Table 1], [Table 2]


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