Gastric specimens for diagnosing tuberculosis in adults unable to expectorate in Rawalpindi, Pakistan

Yield & accuracy of Gastric Lavage in non-expectorating adults with Suspected Pulmonary Tuberculosis

Objective

To determine the yield of Gastric lavage (GL) in non-expectorating adults with suspected Pulmonary Tuberculosis (PTB) and accuracy of GL-AFB smear with GL-GeneXpert (GXP) by taking AFB culture as gold standard.

Methods

Cross-sectional study on suspected PTB patients was done at Ojha Institute of Chest Diseases during period 16th July 2020 till 15th January 2021. Adult patients of either gender suspected to have PTB and not expectorating were included. GL was performed and sent for AFB smear, GXP and AFB culture. Odds ratio, sensitivity and specificity were calculated.

Results

After informed written consent, 206 patients, mean age was 38.17 ±17.30 years were inducted, including 89 (43.2%) males and 117 (56.8%) females. Gene Xpert, AFB smear & AFB culture were positive in 83(40%), 50 (24%) & 72 (35%) respectively in GL samples. Odds of PTB were 3.95 times higher among patients with ≤1 month of duration of symptoms (aOR 3.95, 95% CI 1.82-8.57, p-value 0.001), 6.24 times higher among patients with weight loss (aOR 6.24, 95% CI 3.03-12.84, p-value <0.001), and 4.22 times higher among patients with cavitation (aOR 4.22, 95% CI 1.99-8.93, p-value <0.001). GL-AFB smear showed sensitivity 63.89%, specificity 97.01%, positive predicted value 92%, negative predicted value 83.3%, and overall diagnostic accuracy 85.4%. Whereas GL-GXP showed sensitivity 94.4%, specificity 88.81%, positive predicted value 81.93%, negative predicted value 96.75%, and overall diagnostic accuracy 90.78%.

Conclusion

Yield of GL significant to detect PTB in suspected cases who are not expectorating. GL-GXP diagnostic accuracy and sensitivity is higher than GL-AFB smear.

Pulmonary Tuberculosis Presenting As Septic Shock in an Immunocompetent Patient: Revisiting an Old Disease With New Perspectives

Septic shock due to Mycobacterium tuberculosis (M. tuberculosis) in immunocompromised patients (particularly HIV) is a well-recognized clinical entity. However, tubercular sepsis in the immunocompetent is still underdiagnosed and under-discussed. Moreover, sepsis is usually associated with gram-negative and other gram-positive microorganisms that can cause similar pulmonary and disseminated disease and can further convolute the diagnosis. We herein discuss a case of an elderly female who presented with acute onset fever, cough, and altered talk from the last seven days. Her initial clinical and laboratory examination revealed features of lower respiratory tract infection with septic shock. She was started on broad-spectrum antibiotics based on severe community-acquired pneumonia management guidelines. Her blood and urine cultures were sterile. She did not respond to initial antibiotics. Furthermore, sputum production was not possible, which compelled us for gastric aspirate analysis, which came positive for cartridge-based nucleic acid amplification test (CBNAAT). In repeated blood cultures, M. tuberculosis was also isolated. She was started on antitubercular treatment; on the 12th day of antitubercular treatment, she developed acute respiratory distress and eventually succumbed to her illness on the 19th day of hospitalization. We highlighted the importance of early diagnosis and prompt antitubercular therapy in tubercular septic shock. We also discuss the possibility of tubercular-immune reconstitution inflammatory syndrome (IRIS) in such patients, which could be a contributing factor to mortality.

Efficacy of Xpert in tuberculosis diagnosis based on various specimens: a systematic review and meta-analysis

Objective

The GeneXpert MTB/RIF assay (Xpert) is a diagnostic tool that has been shown to significantly improve the accuracy of tuberculosis (TB) detection in clinical settings, with advanced sensitivity and specificity. Early detection of TB can be challenging, but Xpert has improved the efficacy of the diagnostic process. Nevertheless, the accuracy of Xpert varies according to different diagnostic specimens and TB infection sites. Therefore, the selection of adequate specimens is critical when using Xpert to identify suspected TB. As such, we have conducted a meta-analysis to evaluate the effectiveness of Xpert for diagnosis of different TB types using several specimens.

Methods

We conducted a comprehensive search of several electronic databases, including PubMed, Embase, the Cochrane Central Register of Controlled Trials, and the World Health Organization clinical trials registry center, covering studies published from Jan 2008 to July 2022. Data were extracted using an adapted version of the Checklist for Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modeling Studies. Where appropriate, meta-analysis was performed using random-effects models. The risk of bias and level of evidence was assessed using the Quality in Prognosis Studies tool and a modified version of the Grading of Recommendations Assessment, Development, and Evaluation. RStudio was utilized to analyze the results, employing the meta4diag, robvis, and metafor packages.

Results

After excluding duplicates, a total of 2163 studies were identified, and ultimately, 144 studies from 107 articles were included in the meta-analysis based on predetermined inclusion and exclusion criteria. Sensitivity, specificity and diagnostic accuracy were estimated for various specimens and TB types. In the case of pulmonary TB, Xpert using sputum (0.95 95%CI 0.91-0.98) and gastric juice (0.94 95%CI 0.84-0.99) demonstrated similarly high sensitivity, surpassing other specimen types. Additionally, Xpert exhibited high specificity for detecting TB across all specimen types. For bone and joint TB, Xpert, based on both biopsy and joint fluid specimens, demonstrated high accuracy in TB detection. Furthermore, Xpert effectively detected unclassified extrapulmonary TB and tuberculosis lymphadenitis. However, the Xpert accuracy was not satisfactory to distinguish TB meningitis, tuberculous pleuritis and unclassified TB.

Conclusions

Xpert has exhibited satisfactory diagnostic accuracy for most TB infections, but the efficacy of detection may vary depending on the specimens analyzed. Therefore, selecting appropriate specimens for Xpert analysis is essential, as using inadequate specimens can reduce the ability to distinguish TB.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=370111, identifier CRD42022370111.

High rate of successful treatment outcomes among childhood rifampicin/multidrug-resistant tuberculosis in Pakistan: a multicentre retrospective observational analysis

Background

There was a complete lack of information about the treatment outcomes of rifampicin/multidrug resistant (RR/MDR) childhood TB patients (age ≤ 14 years) from Pakistan, an MDR-TB 5th high burden country. Therefore, this study evaluated the socio-demographic characteristics, drug resistance pattern, treatment outcomes and factors associated with unsuccessful outcomes among childhood RR/MDR-TB patients in Pakistan.

Methods

This was a multicentre retrospective record review of all microbiologically confirmed childhood RR/MDR-TB patients (age ≤ 14 years) enrolled for treatment at seven units of programmatic management of drug-resistant TB (PMDT) in Pakistan. The baseline and follow-up information of enrolled participants from treatment initiation until the end of treatment were retrieved from electronic nominal recording and reporting system. World Health Organization (WHO) defined criterion was used for deciding treatment outcomes. The outcomes of “cured” and “treatment completed” were collectively grouped as successful, whereas “death”, “treatment failure” and “lost to follow-up” were grouped together as unsuccessful outcomes. Multivariable binary logistic regression analysis was used to find factors associated with unsuccessful outcomes. A p-value < 0.05 reflected statistically significant findings.

Results

A total of 213 children RR/MDR-TB (84 RR and 129 MDR-TB) were included in the study. Majority of them were females (74%), belonged to the age group 10–14 years (82.2%) and suffered from pulmonary TB (85.9%). A notable proportion (37.1%) of patients had no history of previous TB treatment. Patients were resistant to a median of two drugs (interquartile range: 1–4) and 23% were resistant to any second line anti-TB drug. A total of 174 (81.7%) patients achieved successful treatment outcomes with 144 (67.6%) patients being cured and 30 (14.1%) declared treatment completed. Among the 39 (18.3%) patients with unsuccessful outcomes, 35 (16.4%) died and 4 (1.9%) experienced treatment failure. In multivariable analysis, the use of ethambutol had statistically significant negative association with unsuccessful outcomes (odds ratio = 0.36, p-value = 0.02).

Conclusions

In this study, the WHO target of successful treatment outcomes (≥ 75%) among childhood RR/MDR-TB patients was achieved. The notable proportion of patients with no history of previous TB treatment (37.1%) and the disproportionately high number of female patients (74%) respectively stress for infection control measures and provision of early and high quality care for female drug susceptible TB patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06935-6.

Effect of Neutralization of Gastric Aspirate on culture yield of mycobacterium tuberculosis in children with pulmonary tuberculosis

INTRODUCTION

Conventionally gastric aspirates are neutralized with sodium bicarbonate to improve the culture yield of MTB. However, only limited data is there to support this practice. The aim of this study was to compare the contamination rate, culture yield and time to detection of Mycobacterium tuberculosis (MTB) in neutralized and non-neutralized gastric aspirate samples and report the drug resistance.

MATERIALS AND METHODS

A total of 336 neutralized and non-neutralized gastric aspirate samples were simultaneously cultured by both LJ culture and MGIT 960 to compare the difference in isolation rate, time to detection and contamination rate. First line drug susceptibility testing was performed using MGIT 960 SIRE kit.

RESULTS

MTB was isolated from 8.6% (29/336) of GA samples by one or more of the culture methods. The isolation rate of MTB from neutralized and non-neutralized GA samples by combined LJ and MGIT 960 culture was 7.1% (24/336) and 6.8% (23/336), respectively. Both of them detected 18 MTB isolates in common. However, the neutralized and non-neutralized GA samples detected additional 6 and 5 MTB isolates, respectively. The mean time to detection of MTB were similar. In MGIT 960 culture, contamination rate of non-neutralized samples (17%) was significantly lower when compared to neutralized samples (21.1%) (P = 0.044). Drug susceptibility testing of MTB isolates revealed that, out of 26 isolates, 2 were resistant to ethambutol, one each was resistant to isoniazid and rifampicin.

CONCLUSION

The findings of this study suggest that non-neutralized samples should be routinely processed in addition to the neutralized samples for optimum isolation of MTB from gastric aspirate samples.

Diagnostic accuracy of Mycobacterium tuberculosis cell-free DNA for tuberculosis: A systematic review and meta-analysis

BACKGROUND

Diagnosis of tuberculosis (TB) is still difficult. The purpose of our study was to evaluate the diagnostic accuracy of Mycobacterium tuberculosis cell-free DNA (cfDNA) for diagnosing of TB.

METHODS

We searched relevant databases for studies that used cfDNA to diagnose TB. We evaluated the accuracy of cfDNA compared with the composite reference standard (CRS) and culture. True positive, false positive, false negative, and true negative values for cfDNA were obtained first, then the estimated pooled sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic odds ratio (DOR), and the area under the summary receiver operating characteristic (SROC) curve (AUC) of cfDNA for diagnosing TB were calculated with 95% confidence intervals (CIs). Heterogeneity was determined using the I2 statistic. When the heterogeneity was obvious, the source of heterogeneity was further discussed.

RESULTS

We included 14 independent studies comparing cfDNA with the CRS, and 4 studies compared with culture. The pooled sensitivity, specificity, PPV, NPV, DOR, and AUC of the SROC were 68%, 98%,99%, 62%, 83, and 0.97 as compared with the CRS, respectively. The pooled sensitivity, specificity, PPV, NPV, DOR, and AUC of the SROC were 48%, 91%, 92%, 60%, 5, and 0.88 as compared with culture, respectively. The heterogeneity between studies was significant.

CONCLUSIONS

The accuracy of cfDNA testing for TB diagnosis was good compared with CRS and culture. cfDNA can be used for rapid early diagnosis of TB.

The clinical diagnostic value of Xpert MTB/RIF for the detection of Mycobacterium tuberculosis in gastric aspirates

BACKGROUND

At present, the infection and prevalence rates of tuberculosis (TB) are still high in worldwide. The Xpert MTB/RIF technology has improved the diagnosis speed of Mycobacterium tuberculosis (MTB) and facilitated the rapid treatment of TB patients.

METHODS

We searched experimental data derived from Xpert MTB/RIF for detecting MTB in gastric aspirates in PubMed, Embase, Web Of Science, and the Cochrane Library databases between January 2012 to April 2019. A summary receiver operating characteristic curve (SROC curve) was used to analyze the pooled sensitivity, pooled specificity, PLR, NLR, and DOR for determining the accuracy of the test.

RESULTS

Our database search resulted in 10 relevant articles. The pooled sensitivity of Xpert MTB/RIF for detecting TB in GA was 86% (95% CI, 83-89%), and I2 = 93.4%. The pooled specificity was 92% (95% CI, 90-93%) and I2 = 97.8%. In addition, the positive LR was 12.12 (95% CI, 5.60-26.21), negative LR was 0.20 (95% CI, 0.11-0.36), and the diagnostic odds ratio (DOR) was 147.04 (95% CI, 37.20-581.19). Using the SROC curve, the AUC was 0.9730 and Q* was 0.9248 (SE = 0.0261). The publication bias was P=0.517 (P>0.05).

CONCLUSIONS

The Xpert MTB/RIF for detecting MTB in gastric aspirates was highly accurate. In addition, we observed that the publication bias in the present study was low. Hence, the Xpert MTB/RIF technology is highly accurate and has the advantage of rapid testing for MTB in clinical samples.

Microbiological Testing of Gastric Aspirate Improves the Diagnosis of Pulmonary Tuberculosis in Unconscious Adults with TB Meningitis

Conventional sputum collection for TB diagnosis is difficult in TB meningitis patients since most of them are admitted with decreased consciousness. It is assumed that unconscious patients swallow their sputum; therefore, gastric aspiration can replace sputum collection in unconscious patients. A prospective study was conducted to see whether examining gastric aspirate could increase the diagnosis certainty of pulmonary TB in such subjects. The inclusion criteria were age 18–60 years, decreased level of consciousness, and use of a nasogastric tube. Subjects who had taken antituberculosis drugs for more than 3 days were excluded. Gastric lavage was performed in the morning after an overnight fast. Specimens were examined for direct smear, culture, and rapid molecular testing. Demographic, clinical, chest X-ray, and laboratory data were also recorded. During the study period, 31 subjects were available. The positivity rates for microbiological tests were 19.3%, 41.9%, and 48.4% for smear, culture, and rapid molecular testing, respectively. All positive smears were confirmed by either culture or rapid molecular testing. Gastric lavage can be considered a tool for improving extraneural TB diagnosis in unconscious patients.

Xpert MTB/RIF performance to diagnose tuberculosis and rifampicin resistance in a reference centre in southern Brazil

Effective treatment of tuberculosis (TB) remains a serious public health problem in many countries, including Brazil, especially when considering drug-resistant disease. Xpert MTB/RIF has been implemented in many countries to reduce the time to TB diagnosis and to rapidly detect rifampicin resistance. The study aimed to describe and evaluate Xpert MTB/RIF performance in diagnosing pulmonary TB and rifampicin resistance in a tertiary healthcare facility in Brazil. A cross-sectional study was performed, which included all isolates of confirmed pulmonary TB patients from 2015 to 2018. Both Xpert MTB/RIF and GenoType MTBDRplus assays were performed to detect rifampicin and isoniazid resistance. In addition, isolates with detected resistance to rifampicin and/or isoniazid were analysed by phenotypic testing using MGIT-960 SIRE kit and whole-genome sequencing (WGS) using Illumina MiSeq Sequencing System. 2148 respiratory specimens tested with Xpert MTB/RIF were included: n=1556 sputum, n=348 bronchoalveolar lavage and n=244 gastric washing. The overall Xpert MTB/RIF sensitivity in sputum was 94% and the overall specificity was 98%. The negative predictive value in sputum of all the patients was 99% with a positive predictive value of 89%. The concordance between Xpert MTB/RIF and phenotypic susceptibility test was 94.1%, while its concordance with WGS was 78.9%. Xpert MTB/RIF is a rapid and accurate diagnostic strategy for pulmonary TB, which can contribute to improvement in TB control. However, detection of rifampicin resistance might be associated with false-positive results.

Review of literature on disseminated tuberculosis with emphasis on the focused diagnostic workup

Disseminated tuberculosis (TB) is a life-threatening disease resulting from the hematogenous spread of Mycobacterium tuberculosis. The diagnosis is challenging owing to its subtle nonspecific clinical presentation, which usually reflects the underlying organ involved. Besides, tools for confirmatory laboratory diagnosis are limited. Therefore, a high index of suspicion is required for early diagnosis. Miliary pattern on chest radiography is a common finding that has an important role in the early detection of the disease. Nevertheless, approximately 10%-15% of patients have normal chest radiography. Although abnormalities are present, basic hematologic and biochemical tests as well as tuberculin skin test are nonspecific for the diagnosis. Imaging studies are helpful adjunct tools for disseminated TB as they can help determine the involved sites and guide technicians to obtain appropriate specimens for diagnosis. Clinical confirmation of the diagnosis of disseminated TB is usually based on bacteriological or histological evidence. Response to first-line anti-TB drugs is good as evidenced by many reports. This review aims to present a current update on disseminated TB with emphasis on the diagnostic workup of this devastating condition.

GeneXpert of stool versus gastric lavage fluid for the diagnosis of pulmonary tuberculosis in severely ill adults

PURPOSE

Stool is an alternative specimen matrix for tuberculosis (TB) tests, because Mycobacterium tuberculosis (MTB) can be swallowed and detected in the samples from digestive tract. We aimed to assess the performance of GeneXpert on stool and gastric lavage fluid (GALF) in diagnosing TB among patients with severe pulmonary TB.

METHODS

We enrolled adults with suspected pulmonary TB who were unable to produce sputum at visit between January 2016 and June 2018. Bacteriological samples consisted of one transtracheal aspirate sputum specimen, one stool specimen and/or one gastric lavage fluid specimen. Bacterial culture of transtracheal aspirate sputum provided the gold standard.

RESULTS

Of 65 individuals recruited for analysis, MGIT culture identified the presence of MTB in 32 samples. Overall, 29 of 32 stool samples from culture-positive cases were detected by the GeneXpert test, demonstrating a sensitivity of 90.6%. For GALF, 13 patients were detected as infected with MTB by GeneXpert, yielding a sensitivity of 56.5%. The statistical analysis revealed that GeneXpert showed significantly better sensitivity in detecting MTB from stool samples than GALF samples (P = 0.003). Among individuals with GeneXpert-positive stool, the percentage of individuals with comorbid diabetes was significantly higher than among individuals with GeneXpert-negative stool (19.4% vs. 2.9%, P = 0.034).

CONCLUSIONS

In conclusion, our data reveal that GeneXpert provides a higher detection rate on stool compared to GALF, indicating stool should be considered as an alternative for adult TB patients unable to produce sputum. Individuals with diabetes are more likely to have positive GeneXpert stool than nondiabetic individuals.