|Year : 2022 | Volume
| Issue : 1 | Page : 10-13
Prevalence of Mycobacterium tuberculosis in patients suffering from chronic respiratory diseases in a tertiary care hospital using Gene Xpert as the diagnostic tool
Baishali Das1, Dina Raja2
1 Intermediate Reference Laboratory, Guwahati, Assam, India
2 Department of Microbiology, Gauhati Medical College and Hospital, Guwahati, Assam, India
|Date of Submission||01-Jun-2021|
|Date of Acceptance||29-Jul-2021|
|Date of Web Publication||18-Apr-2022|
Department of Microbiology, Gauhati Medical College and Hospital, Narakasur Hilltop, Bhangagarh, Guwahati 781032, Assam
Source of Support: None, Conflict of Interest: None
Background: Chronic respiratory diseases constitute a grave problem throughout the world and particularly in the middle- and low-income countries. The burden of these diseases leads to poor quality of life and disability of affected individuals leading to premature deaths and a great economic loss to their families and society. Tuberculosis remains one of the deadliest communicable diseases. Though culture is the gold standard for the diagnosis of tuberculosis, the long period of time required for a positive result leads to the transmission of the disease in the community. Objective: The study was conducted to study the prevalence of Mycobacterium tuberculosis in patients suffering from chronic respiratory diseases. Materials and Methods: Bronchoalveolar lavage fluid samples of patients with chronic respiratory diseases undergoing bronchoscopy were collected under aseptic conditions after obtaining approval from the Institutional Ethics Committee. Each sample was subjected to Ziehl Neelsen stain and Cartridge Based Nucleic Acid Amplification Test (CBNAAT) on Xpert MTB/RIF manufactured by Cepheid (Sunnyvale, CA). Results: Eighteen of 110 cases (16.36%) showed the presence of M. tuberculosis in the samples, of which rifampicin resistance was detected in 2 (11.11%) cases. Conclusions: M. tuberculosis remains a common underlying pathogen in the cases of chronic respiratory diseases.
Keywords: Chronic respiratory diseases, Gene Xpert, Mycobacterium tuberculosis
|How to cite this article:|
Das B, Raja D. Prevalence of Mycobacterium tuberculosis in patients suffering from chronic respiratory diseases in a tertiary care hospital using Gene Xpert as the diagnostic tool. Assam J Intern Med 2022;12:10-3
|How to cite this URL:|
Das B, Raja D. Prevalence of Mycobacterium tuberculosis in patients suffering from chronic respiratory diseases in a tertiary care hospital using Gene Xpert as the diagnostic tool. Assam J Intern Med [serial online] 2022 [cited 2022 May 21];12:10-3. Available from: http://www.ajimedicine.com/text.asp?2022/12/1/10/343427
| Introduction|| |
Chronic respiratory diseases comprise chronic diseases of the airways and other structures of the lungs. People of all ages suffer from chronic respiratory diseases all around the world and the most common etiologic agent of chronic lower respiratory tract infection is Mycobacterium tuberculosis.
According to the Global Tuberculosis Report 2019, the global burden of tuberculosis (TB) in 2018 was estimated to be 10 million cases of which 1.2 million deaths occurred due to TB in HIV-noninfected cases and 2,51,000 HIV-infected cases. The burden of TB is different in different countries ranging from less than 5–500 new cases per lakh per year. The global average of TB burden is 130 new cases per lakh per year. India has the highest burden of TB in the world where the global incidence of multidrug-resistant TB is half a million new cases of rifampicin-resistant TB where India comprises 27% of the global burden. Globally, the highest burden of TB is seen in men (>15 years of age) comprising 57% of all cases, 32% in women, and 11% in children in 2018. Currently, the entire world, especially the countries with a high burden of TB, is not seen to progress toward the End TB Strategy 2020 milestones. Between 2000 and 2018, the global average rate of decline of incidence rates was seen to be 1.6% per year and 2.0% between 2017 and 2018.
Cartridge Based Nucleic Acid Amplification Test (CBNAAT) takes less than 2 h to detect M. tuberculosis and rifampicin resistance by detecting the presence of a mutation in the 81 bp hotspot region of the rpo gene.
Hence, this study was conducted to determine the prevalence of M. tuberculosis in bronchoalveolar lavage (BAL) samples collected from patients of chronic respiratory diseases attending a tertiary care hospital in Northeast India and to determine the prevalence of cases of TB resistant to rifampicin.
| Materials and methods|| |
This study was a hospital-based prospective study. The study was carried out in a tertiary care hospital, involving 110 cases. The period of the study was for 1 year from June 2017 to May 2018. Approval from the Institutional Ethics Committee (IEC) was obtained. Informed consent was taken from the patients and clinical details were recorded in a predesigned proforma. Adult patients with chronic respiratory diseases and any case of hemoptysis undergoing bronchoscopy were included in the study. Samples containing blood or debris were rejected. The site to be lavaged was determined radiographically with the help of high-resolution computed tomography (HRCT) chest and the BAL fluid was recovered in 2–3 aliquots.
A smear was made from the sediment of the centrifuged BAL sample and it was subjected to Ziehl Neelsen stain according to the methods described by Duguid et al. Detection of a single AFB/100 fields was taken as positive for M. tuberculosis.
The falcon tube containing BAL was subjected to CBNAAT on Xpert MTB/RIF manufactured by Cepheid (Sunnyvale, California) as per the manufacturer’s instructions. Rifampicin resistance was evaluated along with the detection of M. tuberculosis in the same setting. Results were obtained in less than 2 h.,,
| Results|| |
A total of 110 patients were included during the study period. Most of the cases in this study were between the ages of 51–60 years (21.81%) followed by 21–30 years (20.9%). There were no cases below 10 years of age. The median age is 48.5 years [Table 1].
There were 71% men and 29% of women included in the study group. The male-to-female ratio was 2.5:1 (M:F).
Most of the patients in this study belonged to lower (61.81%) and lower middle (24.54%) socioeconomic status according to modified B.G. Prasad’s socioeconomic status classification, which is applicable to both urban and rural populations [Table 2].
The majority of the patients included in the study had bronchiectasis (20%) and non-resolving pneumonia (19.09%), followed by lung mass, pulmonary TB, interstitial lung disease, emphysema, bronchitis, and hilar mass, carinal mass, and sarcoidosis [Figure 1].
Of 110 smears examined for acid-fast bacilli, 9 (8.18%) were BALF smear positive for acid-fast bacilli and number of cases where M. tuberculosis was detected by CBNAAT was seen to be 18 (16.36%) [Table 3].
|Table 3: Prevalence of acid fast bacilli in direct smear and Mycobacterium tuberculosis detected by CBNAAT|
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Of a total of 18 cases of M. tuberculosis detected, 16 (88.88%) were sensitive and 2 (11.11%) were resistant to rifampicin.
| Discussion|| |
Chronic respiratory disase is a public health challenge across the world owing to the disability and economic burden associated with it. Moreover, India comprises the highest burden of TB, which is 27% of the global burden. Keeping this in mind, this study was conducted to study the prevalence of M. tuberculosis as an underlying cause of morbidity and mortality in the cases of chronic respiratory diseases.
This study showed that the median age of the cases suffering from pulmonary TB was 42.5 years, which was slightly higher than the median age of the patients suffering from pulmonary TB in the study by Revendran et al. (32 years). This difference in the median age could be due to the reason that prevalence of pulmonary TB is different in different geographical areas and different populations.
In this study, it was seen that of a total of 110 cases, there were 78 (71%) men and 32 (29%) women in the study group which was in concordance with the study by Bari et al., which included 60% men and 40% women. This study also showed that most of the cases belonged to the lower and lower middle socioeconomic scale according to modified B.G. Prasad’s socioeconomic status classification. In this study, the number of cases of chronic respiratory diseases where M. tuberculosis was detected by CBNAAT was found to be 18 (16.36%) which was in concordance with the studies by Theron et al. (19.4%) and Agrawal et al. (20.13%). However, higher percentages of M. tuberculosis were detected in some other studies by Revendran et al. (31%) and Avashia et al. (49.27%). This variation could be due to the difference in the geographic location where the studies were conducted as the burden of TB varies in different areas and populations.
Of the 18 (16.36%) cases of M. tuberculosis detected by CBNAAT, 9 (50%) were BAL fluid smear positive and 9 (50%) were BAL fluid smear negative, which correlated with the study by Tueller et al., which showed a 47% cases of BALF smear positive for AFB.
From this study, it can be concluded that in endemic areas, TB remains an underlying cause of morbidity and mortality in the cases of chronic respiratory disease in adults. Moreover, Gene Xpert being a highly sensitive tool in the diagnosis of multidrug-resistant TB can be used for early diagnosis of patients with high clinical suspicion of pulmonary TB. Moreover, it can also be used to identify a large number of cases of smear-negative pulmonary TB, which can help in reducing the morbidity and mortality in society. It simultaneously detects sensitivity to rifampicin and is especially helpful in multidrug-resistant cases and should be studied further.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
Obtained from the Institutional Ethics Committee (IEC) of Gauhati Medical College & Hospital, Guwahati.
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[Table 1], [Table 2], [Table 3]