|Year : 2022 | Volume
| Issue : 3 | Page : 158-161
A case series of Mycobacterium kansasii pulmonary infection in a tertiary care private hospital
Rohit Vashisht1, Senthur Nambi Panchatcharam2, Nandini Sethuraman3
1 Department of Internal Medicine, AFMC, Pune, Maharashtra, India
2 Department of Infectious Diseases, Apollo Hospitals, Chennai, Tamil Nadu, India
3 Department of Microbiology, Apollo Hospitals, Chennai, Tamil Nadu, India
|Date of Submission||20-Jun-2021|
|Date of Decision||12-Dec-2021|
|Date of Acceptance||13-Dec-2021|
|Date of Web Publication||01-Jul-2022|
Dr. Rohit Vashisht
Department of Internal Medicine, Infectious Disease Specialist, AFMC, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Mycobacterium kansasii is being increasingly recognized as an important pathogen mimicking clinically Mycobacterium tuberculosis (MTB). We describe here a series of cases due to M. kansasii lung disease from a tertiary care private hospital from South India. Methods: A retrospective chart review of patients diagnosed with M. kansasii pulmonary infection at a tertiary care referral center between January 2017 and April 2019 was conducted. Positive bronchoalveolar lavage (BAL) cultures were included in the study. Results: Seven patients with majority having underlying predisposing conditions presented with respiratory symptoms and radiological features resembling pulmonary tuberculosis. Smear acid fast bacillus (AFB) positivity was seen in 3 out of 7 cases. M. kansasii was isolated from bronchial culture in all of them with negative GeneXpert MTB reports. Five patients showed clinical improvement after starting treatment, while two were lost to follow up. Conclusion: M. kansasii should be suspected in AFB smear positive but GeneXpert MTB negative patients. Getting AFB cultures done is crucial in such patients to make an appropriate etiological diagnosis.
Keywords: Culture, kansasii, pulmonary
|How to cite this article:|
Vashisht R, Panchatcharam SN, Sethuraman N. A case series of Mycobacterium kansasii pulmonary infection in a tertiary care private hospital. J Mar Med Soc 2022;24, Suppl S1:158-61
| Introduction|| |
Mycobacterium kansasii is a slow-growing nontuberculous mycobacterium (NTM) which has been considered for long an important cause of pulmonary disease. It was first described by Buhler and Pollak in 1953. It has a characteristic photochromogenicity, based on which it can be easily identified. It produces a yellow pigment when exposed to light, due to deposition of beta-carotene crystals. The main reservoir of this organism is in tap water and the contamination is via the airway, mostly acquired through the aerosol or aspiration route. Little evidence for person-to-person transmission exists. Chronic pulmonary cavitary disease in the upper lobe is the most common presentation of M. kansasii infections, clinically resembling that of Mycobacterium tuberculosis (MTB)., It can occur in both immunocompetent and immunosuppressed patients. It is important to differentiate a true infection from a mere colonization of a particular sputum sample. Cultures are considered to be significant if positive in the case of two consecutive positive sputum samples or one positive bronchoscopy specimen. Here, we present a series of M. Kansasii pulmonary infections proven by Bronchoalveolar lavage (BAL) culture, encountered in a single tertiary care hospital.
| Methods|| |
We conducted a retrospective chart review of patients diagnosed with M. kansasii pulmonary infection at a tertiary care referral center between January 2017 and April 2019. The primary aim was to study the clinical profile of patients with pulmonary M. kansasii infection and highlight the importance of differentiating it from MTB complex. BAL samples were cultured in BACTEC mycobacterial growth indicator tube (MGIT) system and nontuberculous mycobacteria were identified by matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry (MALDI-TOF; VITEK-MS, bioMerieux, Marcy l'Etoile). Only proven cases with BAL positivity were included and single positive sputum cultures were excluded to rule out colonization.
| Results|| |
A total of 7 patients (3 males and 4 females) were found to have active M. kansasii infection. The mean age group was 40–60 years. Predisposing factors were identified in 6 out of 7 patients in the form of underlying lung diseases (chronic obstructive pulmonary disease [COPD], interstitial lung disease, and bronchiectasis) and immunosuppression. All presented with cough, fever, and breathlessness. Smear acid-fast bacillus (AFB) positivity was seen in 3 out of 7 cases, while GeneXpert MTB (Cepheid) was negative in all cases. Upper zone cavitary lesions were the predominant radiological finding in 5 cases. Five patients were started on treatment as per available drug susceptibility testing and have shown clinical improvement on later outpatient visits, while two were lost to follow-up [Table 1]. [Figure 1] and [Figure 2] show the pretreatment radiological findings and posttreatment status of one patient, while [Figure 3] and [Figure 4] represent it for another patient. During the study period, a total of 272 MGIT BAL cultures were positive for mycobacterial species. Out of this, 239 were MTB and 33 were NTM. Out of the 33 NTM, 7 cases turned out to be M. kansasii.
|Figure 1: Pretreatment chest X-ray of patient no. 2 showing cavities and nodules in the right upper zone|
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|Figure 2: Posttreatment chest X-ray of patient no. 2 showing resolution of lesions|
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|Figure 3: Pretreatment chest X-ray of patient no. 3 showing left upper zone cavitary lesion|
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|Figure 4: Posttreatment radiological status of patient no. 3 showing mild resolution|
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| Discussion|| |
M. kansasii infection is one of the most common causes of nontuberculous mycobacterial lung disease in the world. Jain et al. conducted a retrospective review of isolation rates of NTM in a tertiary center in Delhi and found that out of the 9 pulmonary NTM cases, 2 cases were M. kansasii (culture proven from 2 sputum specimens each). One had an underlying diabetes with no specific risk factor and the other was on steroids as a predisposing factor. Both were AFB stain positive and had pulmonary findings. In our study also, one female patient was on immunosuppression. All patients had BAL-proven M. kansasii with supporting clinical and radiological findings.
Padmapriyadarsini et al. also presented a case series of 9 cases of M. kansasii lung infection. All the cases were males in their study. All were sputum samples (smear positive) which were grown on Lowenstein–Jensen media and species identification later done by high-performance liquid chromatography technique. Our study had both males and females as cases. We did the cultures on liquid MGIT media with subsequent identification by newer MALDI-TOF technique. This mass spectrometry technique allows identification of organisms on the basis of unique spectral fingerprints produced by extracted proteins. In view of large number of species included in its database, it has shown its usefulness in being a reliable and accurate method in species-level identification of NTM and moreover gives faster results as compared to conventional culture-based techniques.
Maliwan and Zvetina did one of the largest retrospective studies (a 50 years' experience) of sputum samples of 302 patients of M. kansasii pulmonary infection and analyzed clinical features with follow-up. The average age found in that study was 50 years and all were males. Heavy smoking, COPD, alcoholism, diabetes, prior tuberculosis, and immunocompromised states were prevalent as underlying conditions in their study. The main symptoms were cough (84%), sputum production (80%), shortness of breath (32%), and chest pain (28%); 16% were asymptomatic. Right-sided, apical or subapical, thin-walled cavitary infiltrate was the characteristic radiological feature. In our study, the average age was about 45 years and there was no sex predilection. Underlying pulmonary comorbidities, prior immunosuppression, and past history of antitubercular therapy (in 5 out of 7 patients) for presumed tuberculosis were also found in our study as associated conditions. Our patients also showed a similar kind of symptomatology and radiological features. However, we preferred including patients based on BAL samples rather than on sputum samples to minimize the possibility of colonization.
Hence, this BAL-proven case series from India highlights an important and often forgotten infectious entity with emphasis on correctly identifying the mycobacterial species.
| Conclusion|| |
This study, to the best of our knowledge, is the largest BAL culture-proven case series from India on M. kansasii pulmonary infection. The disease mimics pulmonary tuberculosis and should be suspected in any patient with AFB smear-positive but GeneXpert MTB-negative pulmonary disease. Mycobacterial culture should be routinely requested, preferably on BAL samples, and MALDI-TOF should be utilized for identification when mycobacteria are grown. Treatment is different from that for M. tuberculosis and outcome is generally good.
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 initial s 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], [Figure 4]