Cartridge-based Nucleic Acid Amplification Test Research Articles

Combined modalities for the rapid diagnosis of patients with suspected tuberculous lymphadenitis: A cross-sectional study.

In settings with high burden of extrapulmonary tuberculosis, the use of various diagnostic modalities can result in superior and quick diagnosis leading to prompt initiation of treatment. This study assessed the diagnostic performance of the fine-needle aspiration cytology (FNAC), Ziehl-Neelsen (ZN) stain, fluorescence microscopy (FM) and cartridge-based nucleic acid amplification test (CBNAAT) in patients with suspected tuberculous lymphadenitis (TBLN). This cross-sectional studyodes, who underwent FNAC. The FNAC samples were subjected to cytomorphological examinati involved 255 patients clinically suspected of TBLN with palpable lymph non, ZN stain, FM and CBNAAT. The diagnostic performance of each modality was compared with CBNAAT, and combined performance was determined. The diagnostic performance of CBNAAT was determined by comparing it with composite reference standard. Of 255 patients, 148 (58.04%) showed features of TBLN on FNAC. The presence of epithelioid cell granulomas with caseous necrosis (67.57%) was the predominant cytomorphological pattern. On ZN stain, FM and CBNAAT, 31 (20.95%), 63 (42.57%) and 100 (67.57%) patients were found to be positive for TBLN, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of CBNAAT was 58.59%, 91.83%, 92% and 58.06%, respectively. Finally, the combination of ZN stain, FM and CBNAAT led to the detection of 88.51% patients with TBLN. Combined use of ZN stain, FM and CBNAAT leads to superior and swift diagnosis of patients with clinically suspected TBLN.

Etiology of Acute Encephalitis Syndrome in Adults in a Tertiary Care Center in Eastern Uttar Pradesh

Seasonal outbreaks of acute encephalitis syndrome (AES) with high case fatality rates have been commonly reported among adults in India. With an increase in Japanese encephalitis virus (JEV) vaccination, the etiology of AES is also changing. However, most studies on AES in India have focused only on children and on JEV. This study was conducted in the Department of Medicine, Institute of Medical Sciences, Banaras Hindu University between 2020 and 2022 to determine the etiology of AES in adults. Blood and cerebrospinal fluid (CSF) were collected from patients 18 years or older with fever and altered sensorium for ≤15 days. We did IgM ELISA for dengue, chikungunya, West Nile virus, scrub typhus, leptospirosis from serum, CSF-IgM for JEV, and CSF–polymerase chain reaction for herpes simplex virus 1 and 2, varicella-zoster virus, enterovirus, and cartridge-based nucleic acid amplification test (CBNAAT) for tuberculous meningitis (TBM). The most common cause of AES identified in our study was TBM (16.7%), followed by leptospirosis (15.1%) and scrub typhus (11.9%). The high occurrence of TBM in our study highlights the importance of CSF-CBNAAT for all AES patients. As leptospirosis and scrub typhus are easily treatable, early detection and treatment of these infections should be recommended.

UNSEEN TUBERCULOSIS: STUDY AMONG INPATIENTS OF A TERTIARY CARE HOSPITAL OF NORTH KARNATAKA

Objective: Tuberculosis (TB) remains a significant global health challenge, particularly in high-burden countries like India. However, high proportion of people never diagnosed or treated. Delayed diagnosis poses a significant threat to hospital inpatients, health-care workers, and medical trainees. Hence, systematic screening of high-risk groups, including hospital inpatients, has been recommended as a strategy to identify TB. Using signs and symptoms as an independent screening tool remains a global challenge for its relatively low accuracy. However, it could still be of value when it was used in a specific target population like inpatients of hospital. Hence, this study is aimed to determine the proportion of presumptive and active TB cases among inpatients. Methods: A hospital-based cross-sectional study was conducted among inpatients above 18 years of age admitted in non-emergency wards admitted during March to April 2023 at ESIC Hospital in Kalaburagi. A pre-existing TB diagnosis and patients admitted to critical care units were excluded. The convenient sampling method was used to recruit participants. Data were collected through using a pre-designed, semi-structured questionnaire. The patients who presented with one of the four symptoms for screening had undergone investigations such as cartridge-based nucleic acid amplification test, chest X-ray, and sputum microscopy to confirm the diagnosis, and the findings were recorded as proportion. Results: Out of 1363 inpatients, 35 (2.5%) patients had classified as presumptive TB case. Out of 35, 3 (8.57%) were found to be actual TB cases. All patients who had positive results for TB were young patients and belonged to low socioeconomic class. Two of three were rifampicin-sensitive TB cases. Conclusion: Timely screening of the patient’s is of utmost importance to avoid further spread of TB infection among inpatients. The higher prevalence of actual TB cases in younger adults needs further exploration.

Cartridge-Based Nucleic Acid Amplification Test Compared to Fine Needle Aspiration Cytology in Suspected Cases of Tubercular Lymphadenitis (the Indian Experience)

INTRODUCTION: Diagnosis of tubercular lymphadenitis is daunting as there are varied clinical presentations and no single confirmatory gold standard test. Cartridge-based nucleic acid amplification test (CBNAAT) of the lymph node is a rapid molecular diagnostic test for simultaneously detecting tuberculosis (TB) and rifampicin resistance. AIM: To evaluate the performance of the CBNAAT test for detecting M. tuberculosis in lymph node specimens compared to fine needle aspiration cytology (FNAC). MATERIALS AND METHODS: The study was conducted in a rural tertiary care hospital in central India. A total of 180 patients clinically suspected of tubercular lymphadenitis were included. The male-to-female ratio was 1:1.3. The average age was 33.3 years. The age group 21–40 years had the highest number of cases. The most common complaints among the patients were fever (29.4%), followed by loss of appetite (9.5%), weight loss (9.5%), and cough (6.6%). However, most patients presented to the hospital with only lymphadenopathy (44.4%). The most common site involved was the anterior cervical lymph node (78.8%), followed by the axillary group (10.5%), submandibular (2.8%), inguinal (2.8%), supraclavicular (2.2%), submental (1.7%) and infraclavicular (1.1%) group of lymph nodes. The patients were subjected to both FNAC and CBNAAT testing. Results were reported as positive or negative for M. tuberculosis as CBNAAT gives a semiquantitative estimate of the concentration of bacilli. Rifampicin resistance results were reported as detected or not detected. RESULTS: Cytological examination of the lymph node aspirates revealed that most were tubercular lymphadenitis cases. Cytomorphological analysis of the cases of tubercular lymphadenitis revealed Type 6 (tubercular abscess) as the predominant pattern. CBNAAT testing detected 26 cases of M. tuberculosis and three cases of rifampicin resistance. The study reported a specificity of 92.92% and low sensitivity of 26.86% of combined FNAC and CBNAAT is much higher compared to only CBNAAT. CONCLUSION: CBNAAT, along with FNAC, is a valuable addition in first-line investigations of tubercular lymphadenitis to make a timely diagnosis.

Usefulness of RSV rapid diagnostic tests in hospitalised children

Introduction and objective: Respiratory syncytial virus is a major cause of lower respiratory tract infections, particularly in children under two years of age. Diagnostic methods include rapid antigen diagnostic tests, which have shown high specificity and variable sensitivity. The aims of this study were to verify the performance of these tests in hospitalised children, and to identify factors influencing the results. Materials and methods: The study enrolled children under two years old who were tested for respiratory syncytial virus using both rapid antigen diagnostic test and a cartridge-based nucleic acid amplification test. The sensitivity, specificity, and positive and negative predictive values of the tests were calculated. The influence of symptoms and fever duration, socioeconomic conditions, presence of siblings, and feeding method were analysed. Results: A total of 164 patients aged 10 days to 24 months (median 2.5 months) were included. Sensitivity reached 75% (95% confidence interval: 67.3–81.7%), specificity – 100% (73.5–100%), positive predictive value – 100%, and negative predictive value – 24% (19.3–29.4%). Lower sensitivity was associated with longer duration of signs/symptoms, with the lowest value obtained in the group with 6–7 days of signs/symptoms – 47.4% (24.5–71.1%), which differed from the 2–3 days group (p = 0.005) and the 4–5 days group (p = 0.016). No association was found between sensitivity and patient age, socioeconomic conditions, presence of siblings, clinical course including fever, or feeding method. None of these factors affected specificity, positive or negative predictive value. Conclusions: The reliability of the rapid antigen diagnostic tests in cases of positive results appears to be high, though negative results should be interpreted with caution. Prolonged duration of signs/symptoms before testing might reduce the level of sensitivity.

Evaluation of Diagnostic Methods and Rifampicin Resistance in Pulmonary Tuberculosis: A Hospital-Based Study.

Background Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, predominantly affecting the lungs (pulmonary TB) and is a significant public health challenge in India. The study aims to analyze demographic, radiological, and clinical subgroups of pulmonary TB cases, examine the relationship between smear acid-fast bacillus (AFB examination) and cartridge-based nucleic acid amplification test (CBNAAT), evaluate CBNAAT sensitivity for Mycobacterium tuberculosis (MTB) in new and previously treated patients, and determine the proportion of rifampicin resistance. Methods This hospital-based prospective study was conducted among patients diagnosed with pulmonary TB at the Respiratory Medicine Department of a Government Hospital over 16 months (August 2019 to December 2020). The study included 150 diagnosed TB cases (new and previously treated). Data collection encompassed demographic details, clinical symptoms, comorbidities, radiological findings (chest X-ray), and microbiological results (smear AFB examination, CBNAAT). Sputum samples were subjected to Ziehl-Neelsen staining and CBNAAT for MTB detection and rifampicin resistance testing. Statistical analysis was performed using IBM SPSS Statistics version 21.0 (IBM Corp., Armonk, NY, USA). Results Of the 150 patients, 69.3% were male, and 48% were aged 21-40 years. The majority had a BMI of 18.5-24.9 kg/m² (50%) and resided in urban areas (63.3%). Common symptoms included cough (95.3%), fever (80%), and weight loss (74%). Cavitary lesions on chest X-ray were observed in 84% of patients. Smear microscopy detected MTB in 72.7% of cases, while CBNAAT detected MTB in 94% of cases. CBNAAT sensitivity for smear-positive and smear-negative samples was 93.97% and 94.12%, respectively. Rifampicin resistance was found in 3% of new cases and 6% of previously treated cases. The sensitivity of smear microscopy was 77.33%, and the sensitivity of CBNAAT was 94%. Conclusion The study underscores the high burden of pulmonary TB and the utility of CBNAAT in detecting MTB and rifampicin resistance, particularly in smear-negative samples. The findings highlight the necessity of universal drug susceptibility testing (DST) for effective TB management and the importance of addressing drug resistance to improve treatment outcomes.

Prevalence of Co-infection of Culture-Proven Bacterial Pathogens in Microbiologically Confirmed Pulmonary Tuberculosis Patients From a Tertiary Care Center.

Tuberculosis (TB) is a chronic condition that weakens the immune system, causes structural changes in the lungs, and can lead to infections by other bacterial pathogens. Very few studies have been done to understand the magnitude of co-infection with other bacterial pathogens, so this study was conducted to understand the co-infection pattern and burden. A total of 174 microbiologically confirmed pulmonary TB patients' samples, identified by cartridge-based nucleic acid amplification test, were further tested for other bacterial pathogens by culture over a period of five months from May 2023 to September 2023. The isolates' identification and drug susceptibility were performed using the VITEK 2 system (bioMérieux, Marcy-l'Étoile, France). Of the 174 pulmonary samples tested, 19 samples grew a significant amount of other bacterial pathogens, making the prevalence 10.91% (19/174). Among the pulmonary samples tested, 54.59% were sputum, 38.5% were bronchoalveolar lavage, and 6.89% were endotracheal aspirate. Additionally, 70.11% of the patients tested were in the age group of 19-60 years. Of the patients who had co-infection, 94.73% (18/19) were male. The most common bacterial infection was caused by Pseudomonas aeruginosa, which was identified in 36.84% of the co-infection cases (7/19). This was followed by Acinetobacter baumannii in 31.57% (6/19), Klebsiella pneumoniae in 26.31% (5/19), and Stenotrophomonas maltophilia in 5.28% (1/19). Acinetobacter baumannii and Klebsiella pneumoniae showed high drug resistance, ranging from 60% to 100% against various groups of drugs tested. None of the patient samples with co-infection showed rifampicin resistance. Among all the samples with co-infection, the majority (42.10%, or 8/19) had a high load of Mycobacterium tuberculosis complex detected by CBNAAT Ultra (Cepheid, Sunnyvale, California). Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae are unusual pathogens causing infection in community patients and are known to cause illness in hospitalized patients. These organisms' resistance was also similar to the resistance shown by hospital-acquired infections. Thisindicates that bacterial co-infection in pulmonary TB patients will be similar to the pattern of hospital-acquired infections. The high prevalence of bacterial co-infections (10.91%) in patients with pulmonary TB poses a significant challenge as these bacterial pathogens are not susceptible to anti-tubercular drugs. Therefore, comprehensive screening for other bacterial infections in all pulmonary TB patients is crucial for effective treatment and outcomes.

Role of GeneXpert in the diagnosis of extrapulmonary tuberculosis.

The World Health Organization endorsed the cartridge-based nucleic acid amplification test Xpert MTB/RIF (GXP) for the diagnosis of tuberculosis (TB). Studies about GXP efficiency in extrapulmonary TB (EPTB) are scarce. Hence, we decided to study the role of GXP in EPTB. This prospective observational study, conducted in the pulmonary medicine department of a tertiary care hospital after ethics committee permission, recruited 200 EPTB patients. The diagnosis of TB was achieved with the help of clinico-radiological correlation with microbiological test positivity. Acid-fast bacilli (AFB) culture was treated as the comparative gold standard. Patients who had no or incomplete data were excluded from the study. Data was analyzed to calculate the sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of TB and the detection of rifampicin resistance. The majority of cases were women (126 patients: 63%). The mean age was 23.71 years. On GXP, 130 (65%) had detected mycobacterium tuberculosis (MTB), and 70 (35%) did not. Adding AFB culture data, 168 (81.5%) showed microbiological evidence of TB, and 32 (18.5%) were negative. On the drug susceptibility test, 131 cases were rifampicin-sensitive, 32 were rifampicin-resistant TB, and in 5 cases, data was unavailable. The most common extrapulmonary site of involvement was the lymph node, with 94 patients (47%). The most common lymph node involved was the cervical lymph node, with 70 patients (74.5%). The sensitivity, specificity, positive predictive value, and negative predictive value of GXP in EPTB collectively were 76.68%, 86.48%, 96%, and 45.7%, respectively. GXP is useful for the rapid detection of EPTB and the identification of rifampicin resistance, especially in a high-prevalence country like India.

Granulomatosis with polyangiitis masquerading as disseminated tuberculosis in presence of bilateral lung cavities and hemorrhagic infarct

Lung cavitations with constitutional symptoms are usually associated with pulmonary tuberculosis due to its high prevalence and are the most common infectious cause in India. Granulomatosis with polyangiitis (GPA) with the systemic pulmonary disease will have different radiological presentations such as nodule, mass, and consolidation with or without cavitation. In this case report, we have reported a 40-year-old female presented with cough, fever, and weight loss of 6 months duration with chest imaging suggestive of bilateral cavitary lung disease. She was labeled as a case of disseminated tuberculosis due to involvement of the central nervous system and empirically treated with anti-tuberculosis treatment (ATT) without microbiological evidence of tuberculosis in smear and cartridge-based nucleic acid amplification tests. The absence of clinical response and radiological worsening to empirical ATT gives a clue for an alternate diagnosis. Bronchoscopy workup documented Aspergillus colonization and vasculitis workup in the presence of cavitary lung disease documented abnormally raised proteinase 3 anti-neutrophil cytoplasmic antibodies titers. She was treated with a combination of systemic methylprednisolone and azathioprine with voriconazole. Her clinical response was observed in 4 weeks and radiological response with complete radiological clearance of pulmonary cavitations was documented after 6 months of treatment. We recommend prompt workup and ruling out GPA in all cases with pulmonary cavitations with negative microbiological workup and no empirical ATT should be given in the era of rapid microbiological tests with good sensitivity and specificity.

Insights into changing patterns of extrapulmonary tuberculosis in North India

PurposeTuberculosis is one of the dreadful infections and India contributes to substantial burden of TB cases globally. Though majority of cases are pulmonary, extra-pulmonary tuberculosis (EPTB) share significant burden, more in HIV-positive persons. Despite the striking burden, very few studies have been conducted in India and present study was undertaken to determine trends of EPTB at our tertiary care centre. MethodsThis was a retrospective study conducted over a period of 4 years 3 months. Diagnosis of EPTB was based on suspected clinical features, with positive micobiological evidence with cartridge based nucleic acid amplification test (CBNAAT) with/without microscopy. ResultsA total of 10,560 samples (pulmonary and extra-pulmonary) were received during the study period, of which 3972 were extrapulmonary. Of these, a total of 18% were noted to be positive for EPTB. Trend of positivity revealed highest burden in 2018 and a decline was noted over the years, however, rise in cases was noted in 2022. Pleural, meningitis, musculoskeletal, peritoneal and pericardial TB was more common in males, while lymphadenitis was more common in females (p value: <0.0001). Pleural TB (31%) was the most common presentation, followed by lymphadenitis. A gradual decline in lymphadenitis was noted with significantly increasing trend only for musculoskeletal TB. Rifampicin resistance was detected in 7.45% of positive samples, of which the maximum rate of resistance was noted in lymph node aspirates (11.11%), followed by musculoskeletal and pleural samples. ConclusionThe present study showed a gradual decline in positivity of EPTB cases over the years. Younger productive age group with more propensity to transmit infection was the most commonly affected, with pleural TB as the most common presentation. Rare presentations of EPTB also contributed major share. Higher rates of resistance underline requisite to strengthen ongoing programs, to achieve the End TB strategy by 2025.

Efficacy of cartridge-based nucleic acid amplification test (CBNAAT) in comparison with line probe assay and liquid culture in the evaluation of tubercular lymph node abscess.

Tuberculosis (TB) remains the number one cause of adult deaths by a curable infectious disease. Mycobacterium tuberculosis bacilli (MTB) is the most common causative organism isolated from mycobacterial lymphadenitis. Accurate and speedy diagnosis is required, especially in paucibacillary extrapulmonary TB. In this study, we compared the efficacy of CBNAAT with line probe assay and liquid culture in the evaluation of tubercular lymph node abscesses. This is a hospital-based observational cross-sectional study conducted at Gandhi Medical College and Hospital, Secunderabad, TS, in patients who presented with lymph node abscesses over a period of 18 months after obtaining clearance from the ethics committee and obtaining informed consent. Each sample was evaluated and analyzed in association with the clinical findings, AFB staining, CBNAAT, LPA, and AFB culture, and the results were compared. Fifty patients with TB lymph node abscess diagnosed through FNAC were included in the present study. AFB smear was positive in 29 samples, CBNAAT was positive in 43 samples, LPA was positive in 44 samples, and liquid culture was positive in 39 samples. CBNAAT could detect TB in 16 smear-negative cases, 10 liquid culture-negative cases, and one LPA-negative case. In our study, CBNAAT was more effective in diagnosing TB lymph node abscess than AFB smear. No significant results were obtained when comparing CBNAAT with LPA and liquid culture. This study demonstrates excellent diagnostic accuracy of the Xpert MTB/RIF test in patients with tuberculous lymphadenitis, with a sensitivity of 86%, specificity of 83.33%, negative predictive value of 95.56%, and positive predictive value of 58.82%. Thus, it can be a rule in testing for lymph node TB. These efforts will contribute to the attainment of the TB elimination goal.

Tuberculous Otitis Media: A Mysterious Ailment

Abstract: Introduction: Tuberculous otitis media (TOM) is an infrequent ailment. As an uncommon form of extra-pulmonary Tuberculosis, it is often underestimated, leading to a delay in diagnosis and start of appropriate treatment. Case Series: We describe 3 cases of TOM diagnosed and treated in our institute. The typical presentation was prolonged ear discharge not responding to culture sensitive antibiotics, hard of hearing, perforation of tympanic membrane, pale whitish granulation tissue. Pure Tone Audiogram (PTA) done to evaluate the hearing loss. The granulation tissue from all the patients sent for Histopathology examination (HPE) and Cartridge Based Nucleic Acid Amplification Test (CBNAAT) examination. CBNAAT results were positive in all three patients. HPE reported as chronic inflammatory pathology. PTA revealed sensorineural hearing loss in 2 patients and conductive hearing loss in 1 patient. Treatment with regular ATT 4FDC (Anti Tubercular Treatment- Four Drug Combination) regimen was started as per weight band for 6 months. Each of them was on follow up and symptomatically improving. Discussion: TOM requires recognition in refractory chronic otitis media. Early diagnosis and intervention are essential to prevent complications and optimise outcomes. The delay in initiating therapy may lead to complications such as facial nerve palsy. This case series aims to highlight the clinical presentation, effective diagnostic modalities and treatment of tuberculous otitis media and stresses the importance of awareness among otorhinolaryngologists regarding TOM and its timely management.

Diagnostic accuracy of cartridge-based nucleic acid amplification test and resistance pattern in new and previously treated tuberculosis cases: A prospective observational study

Background: Diagnostic methods, particularly sputum microscopy, are the standard method for diagnosing tuberculosis (TB) in many settings. The emergence of cartridge-based nucleic acid amplification test (CBNAAT) as a newer diagnostic tool for TB has shown promising results. CBNAAT is a rapid molecular test that detects the genetic material of Mycobacterium tuberculosis (MTB), the bacterium causing TB, in sputum samples. It offers higher sensitivity and faster results compared to sputum microscopy. Aim: The study aimed to 1) compare the diagnostic accuracy of CBNAAT in detecting smear-positive and smear-negative pulmonary TB cases, and 2) compare rifampicin resistance prevalence between newly diagnosed and previously treated pulmonary TB patients. Methodology: A hospital-based prospective study was conducted in the Respiratory Medicine Department of Guru Gobind Singh Government Hospital, Jamnagar, on PTB patients from August 2019 to December 2020. Data were collected through a self-structured questionnaire that included detailed clinical history, radiological, biochemical, and microbiological investigations. Descriptive statistical analyses were performed to present data as percentages and frequencies. Diagnostic accuracy analysis was conducted. A P-value &lt;0.05 was considered significant. Results: Out of 150 cases, 104 (69.3 %) were male, while 46 (30.7%) were female. Sixty-one percent of new and 86% of previously treated cases were male, whereas 39% of new and 14% of previously treated cases were female. The sensitivity of sputum smear microscopy is 77.33% in cases of PTB, whereas sputum CBNAAT detected 94% of cases of PTB. The sensitivity of CBNAAT for MTB detection in smear microscopy–positive samples was 93.97%, whereas the sensitivity in smear microscopy–negative samples was 94.12%. Regarding rifampicin resistance, the prevalence was lower in newly diagnosed (3/100) compared to previously treated patients with rifampicin-resistant PTB (3/50). Conclusion: These findings suggest that CBNAAT can be a valuable tool for the detection of TB, particularly in cases where sputum smear microscopy results are negative. However, further research is needed to validate these results and evaluate the clinical implications of using CBNAAT in routine TB diagnostics.

Mycobacterium welchii Vaccine Granuloma – A Cautionary Tale

Background: Mycobacterium welchii (Mycobacterium w) vaccine was one of the many strategies used to both treat and prevent coronavirus disease 2019 (COVID-19) infection. We report the results of a retrospective analysis of 15 cases with vaccine-site granulomas after administration of prophylactic Mycobacterium w vaccine as part of a trial for COVID-19 and our experience in managing those cases. Methods: This was a retrospective analysis of 15 patients with vaccine-site granulomas who were given the vaccine as a prophylactic measure as part of a trial with informed consent. Results: The mean average age of cases was 37 and the male-to-female ratio was 1:0.87. All of the patients developed erythematous tender nodules over the injection sites within a month of receiving the inoculations. Mycobacterial cultures and cartridge-based nucleic acid amplification tests yielded negative results. Skin biopsy revealed granulomatous dermatitis with acid-fast bacilli positivity. A diagnosis of noninfective granulomatous dermatitis was made. Treatment started with analgesics and anti-inflammatory agents. Systemic antibiotics were required in 9/15 patients. Patients are being followed up with no reported recurrence till date. Conclusion: The possibility of injection-site granuloma should be taken into the risk–benefit analysis for the administration of Mycobacterium w vaccine and the patients should be counseled as such. Patients with persistent ulceration respond to combinations of doxycycline, ofloxacin, and clarithromycin.

Comparison of Xpert MTB RIF (G4) With Xpert MTB (Ultra) in Diagnosis of Mycobacterium Tuberculosis in Clinical Samples

Abstract Background: Tuberculosis (TB) continues to be a major cause of morbidity and mortality worldwide. The main strategy to fight the pandemic is the development of rapid, accurate diagnostic tests, which helps to reduce the time for initiation of therapy. In 2010, WHO recommended the use of Xpert Mycobacterium tuberculosis/rifampicin (MTB/RIF) (G4), which is a cartridge-based semi-automated nucleic acid amplification test (NAAT) as a primary test with an aim to improve the detection of MTB. Later on, to improve the diagnostic efficacy, the new and improved cartridges called Xpert Ultra were introduced in 2017. Materials and Methods: One thousand and sixty-nine clinical samples were utilized for the study for microscopy, culture, and NAATs (Xpert MTB/RIF G4 and Ultra). The samples were randomly allocated. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated while assuming trace results as positive and negative in two separate scenarios. Results: The sensitivity of Xpert MTB/RIF Ultra cartridge was higher (100%) than Xpert MTB/RIF G4 cartridge (95.23%) and the specificity of Ultra cartridge was lower (71.79%) when compared to G4 cartridge (91.63%). However, the specificity of Xpert Ultra cartridge improved by reclassifying the “trace” interpretation as negative (89.1%). The NPV was 100% and 99.09% for Xpert Ultra cartridge and the Xpert G4 cartridge, respectively, and did not change by reclassifying the “trace” interpretation as negative. In contrast, the PPV varied greatly between the two tests, 26.66% for Xpert Ultra cartridge and 66.66% for Xpert G4 cartridge. The PPV of Xpert Ultra cartridge was improved to 48.48% by including “trace” samples in the negative pool. Conclusion: Xpert Ultra and G4 shows good performance as a first line diagnostic test. Caution should be exercised when interpreting ‘trace’ results in a country like India without parallel confirmatory tests like microscopy and culture. Data is limited on this newly incorporated value assigned in the automated report. Conducting further studies on results interpreted as ‘trace’ will help in improving the guidelines and as well as utilisation of such tests.

Performance of CBNAAT on Pleural Biopsies Obtained by Semirigid Thoracoscopy for Diagnosis of Unexplained Pleural Effusion: A Prospective Study from North India.

Exudative pleural effusions are commonly encountered in clinical practice, but in about one-fourth of cases, etiology remains elusive after initial evaluation. Medical thoracoscopy with semirigid thoracoscope is a minimally invasive procedure with high diagnostic yield for diagnosing pleural diseases, especially these undiagnosed exudative pleural effusions. In tubercular endemic areas, often, these effusions turn out to be tubercular, but the diagnosis of tubercular pleural effusion is quite challenging due to the paucibacillary nature of the disease. Although culture is the gold standard, it is time-consuming. Cartridge-based nucleic acid amplification test (CBNAAT) is a novel rapid diagnostic test for tuberculosis (TB) and has been recommended as the initial diagnostic test in patients suspected of having extrapulmonary TB (EPTB). We conducted a prospective observational study of 50 patients with undiagnosed pleural effusion admitted to our tertiary care hospital. The primary aim of the study is to evaluate the diagnostic performance of CBNAAT on thoracoscopic guided pleural biopsy and compare it with conventional diagnostic techniques like histopathology and conventional culture. Of 50 undiagnosed pleural effusions, TB (50%) was the most common etiology. The overall diagnostic yield of semirigid thoracoscopy in this study was 74%. Our study showed that CBNAAT of pleural biopsies had a sensitivity of 36% only but a specificity of 100%. The sensitivity of CBNAAT was not far superior to the conventional culture. Tuberculosis (TB) is a common cause of undiagnosed pleural effusion in our set-up. CBNAAT testing of pleural biopsy, though, is a poor rule-out test for pleural TB, but it may aid in the early diagnosis of such patients.

Predictors for Concurrent Diabetes in Tuberculosis Patients. Perspectives from Two Mining Districts of Eastern Tribal State Jharkhand, in India.

Tuberculosis and diabetes both diseases are present in large numbers in the country and we are major contributors to both globally. With the objective to understand the various traits of patients having both tuberculosis and diabetes and to ascertain various possible predictors for such occurrence based on the public health database we carried out this study. We seek answers to questions like they have any effects? Are they having any additive role to play? One-year data from the NIKSHAY portal of both districts were analyzed to look for possible associations and other variable traits. Data were analyzed using standard methods to express data in frequency and percentage. Chi-square test was used to establish association, while step-wise approach was used to calculate univariate and multivariate logistic regression analysis for knowing various predictors. P-value of <0.05 was considered statistically significant. Concurrent diabetes in tuberculosis patients was close to 294 (6%) in the 4933 individuals. In total, 65.2% of the study population were male. Diagnosis of tuberculosis was made most of the time by chest X-ray (49.4%) followed by Microscopy ZN staining and cartridge-based nucleic acid amplification test (CBNAAT). Death was more among diabetics (4.4%) as compared to nondiabetics (3.5%). Diabetes is increasing in tuberculosis patients; improvement in data quality is needed. More research is required to reveal various other reasons that make tuberculosis patients more prone to develop diabetes.

Comparative Evaluation of Cartridge-based Nucleic Acid Amplification Test Smear Microscopy and Conventional Culture Techniques in Laboratory Diagnosis of Tuberculosis

Comparative Evaluation of Cartridge-based Nucleic Acid Amplification Test Smear Microscopy and Conventional Culture Techniques in Laboratory Diagnosis of Tuberculosis

Urinary lipoarabinomannan in individuals with sputum-negative pulmonary tuberculosis.

Tuberculosis (TB) is a major global cause of ill health. Sputum microscopy for confirmation of presumptive pulmonary TB (PTB) has a reportedly low sensitivity of 22-43 per cent for single smear and up to 60 per cent under optimal conditions. National TB Elimination Programme in India recommends the use of cartridge-based nucleic acid amplification test (CBNAAT) and culture for microbiological confirmation in presumptive PTB individuals with sputum smear negative test. The use of lateral flow urine lipoarabinomannan (LF-LAM) is usually recommended for the diagnosis of TB in HIV-positive individuals with low CD4 counts or those who are seriously ill. The objective of this study was to detect urinary LAM using cage nanotechnology that does not require a physiologic or immunologic consequence of HIV infection for LAM quantification in human urine in 50 HIV-seronegative sputum smear-negative PTB individuals. To study the diagnostic value of urinary LAM in sputum smear negative PTB individuals, a cage based nanotechnology ELISA technique was used for urinary LAM in three different groups of participants. Fifty smears negative PTB clinically diagnosed, 15 smear positive PTB and 15 post TB sequel individuals. Sputum was tested by smear, CBNAAT, and culture along with urine LAM before treatment. The results were interpreted by ROC curve in comparison to the standard tests like CBNAAT and culture. The mean urinary LAM value was 0.84 ng/ml in 37 culture-positive [Mycobacterium tuberculosis (M.tb)] and 0.49 ng/ml in 13 culture-negative (M.tb) smear-negative individuals with PTB, respectively. In 47 smear-negative PTB cases with microbiologically confirmed TB by CBNAAT, the mean urinary LAM was 0.76 ng/ml. The mean urinary LAM in post-TB sequel individuals was 0.47 ng/ml. As per the receiver operating characteristic curve, cut-off value of urinary LAM in individuals with smear-negative PTB microbiologically confirmed by: (i) CBNAAT was 0.695 ng/ml and (ii) culture was 0.615 ng/ml. The findings of this study suggest that individuals with smear-negative PTB and a urinary LAM value of >0.615 ng/ml were most likely to have microbiological confirmed TB while those with a LAM value <0.615 ng/ml >0.478 ng/ml are less likely and those with a value <0.478 ng/ml are unlikely to have microbiological confirmed TB.

A comparative study of accuracy between gene Xpert (cartridge-based nucleic acid amplification test) and line probe assay in retreatment cases of sputum-positive pulmonary tuberculosis

Abstract Background: Many studies have compared the efficacy of Gene Xpert (cartridge-based nucleic acid amplification test [CBNAAT]) and line probe assay (LPA) techniques; however, a systematic and meticulous comparison of these two techniques is lacking. Objective: To study the accuracy of GeneXpert Mycobacterium tuberculosis (MTB)/rifampicin (RIF) assay and LPA in the detection of MTB complex in smear-positive retreatment cases of pulmonary tuberculosis (TB). Materials and Methods: This diagnostic evaluation study was conducted on 300 retreatment cases of pulmonary TB. The patients who were receiving retreatment were identified by sputum for acid fast Bacilli by Ziehl–Neelsen staining method and were instructed to provide sputum samples for CBNAAT and LPA. These sputum samples were then processed for liquid culture as part of the routine diagnostic procedure. Results: Majority of the patients (52.3%) were of 31–45 years of age. Males (56%) were more than females (44%). Most of the cases were relapse (88%). Ninety-three percent were reactive on sputum culture. Seventy percent had RIF resistance on CBNAAT. Isoniazid and RIF resistance was seen in 69.7% on LPA. 23.3% were sensitive on LPA and 7% had isoniazid resistance. The sensitivity, specificity, positive predictive value, and negative predictive for CBNAAT as compared with LPA were 75%, 100%, 100%, and 22.2%, respectively. Conclusion: Both LPA and CBNAAT are equally effective in detecting MTB in the given sputum sample. However, LPA is preferred over can be very helpful as it can point out the Isoniazid (INH) and Rifampicin (RIF) resistant nature of the bacterium.