Diagnosis of gastrointestinal tuberculosis: Using cytomorphological, microbiological, immunological and molecular techniques - A study from Central India

Meta-analysis of diagnostic accuracy of nucleic acid amplification tests for abdominal tuberculosis

BACKGROUND

Abdominal tuberculosis (TB) is a severe extrapulmonary TB, which can lead to serious complications. Early diagnosis and treatment are very important for the prognosis and the diagnosis of abdominal TB is still difficult.

METHODS

We searched PubMed, the Cochrane Library, Embase, China National Knowledge Infrastructure, and the Wanfang database for studies evaluating the diagnostic accuracy of NAATs for abdominal TB until August 2020. Any types of study design with full text were sought and included. The risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. Subgroup analysis, meta-regression analysis and sensitivity analysis were used to explore the sources of heterogeneity. Stata version 15.0 with the midas command packages was used to carry out meta-analyses.

RESULTS

We included a total of 78 independent studies from 53 articles; 64 with CRS as the reference standard, and 14 with culture as the reference standard. The pooled sensitivity, specificity, and the areas under summary receiver operating characteristic (SROC) curves (AUC) were 58% (51%-64%; I2 = 87%), 99% (97%-99%; I2 = 81%), and 0.92 (0.89-0.94) compared with CRS, respectively. The pooled sensitivity, specificity, and the AUC values of the SROC were 80% (66%-90%; I2 = 56%), 96% (92%-98%; I2 = 84%), and 0.97 (0.95-0.98) compared with culture, respectively. The heterogeneity of sensitivity and specificity was significant.

CONCLUSIONS

NAATs had excellent efficacy in the diagnosis of abdominal TB regardless of the reference standard and regardless of the subtype of abdominal TB. Multiplex PCR with multiple target genes may improve diagnostic sensitivity, and stool specimens may also be used for the diagnosis of abdominal TB in addition to tissue and ascites.

Role of mitochondrial oxidative stress on lymphocyte homeostasis in patients diagnosed with extra-pulmonary tuberculosis

Extra-pulmonary tuberculosis is often an underrated illness. Recent clinical studies have pointed out that lymphocyte homeostasis is dramatically disturbed as revealed through a series of signs and symptoms. Lymphocytes, the known effector cells of our immune system, play an important role in providing immunologic resistance against Mycobacterium infection. It is important to have quantitative insights into the lifespan of these cells; therefore, we aimed to study the precise effect of gastrointestinal tuberculosis infection on peripheral blood lymphocyte subpopulations and function. Our results indicated that gastrointestinal tuberculosis could increase mitochondrial oxidative stress, lower mitochondrial DNA copy number, promote nuclear DNA damage and repair response, decrease mitochondrial respiratory chain enzyme activities, and upregulate Bcl-2 and caspase-3 gene expression in lymphocytes. We further revealed that Mycobacterium infection induces autophagy for selective sequestration and subsequent degradation of the dysfunctional mitochondrion before activating cellular apoptosis in the peripheral lymphocyte pool. Together, these observations uncover a new role of mitochondrial-nuclear crosstalk that apparently contributes to lymphocyte homeostasis in gastrointestinal tuberculosis infection.

Abdominal tuberculosis of the gastrointestinal tract: Revisited

Abdominal tuberculosis is an increasingly common disease that poses diagnostic challenge, as the nonspecific features of the disease which may lead to diagnostic delays and development of complications. This condition is regarded as a great mimicker of other abdominal pathology. A high index of suspicion is an important factor in early diagnosis. Abdominal involvement may occur in the gastrointestinal tract, peritoneum, lymphnodes or solid viscera. Various investigative methods have been used to aid in the diagnosis of abdominal tuberculosis. Early diagnosis and initiation of antituberculous therapy and surgical treatment are essential to prevent morbidity and mortality. Most of the patients respond very well to standard antitubercular therapy and surgery is required only in a minority of cases. Imaging plays an important role in diagnosis of abdominal tuberculosis because early recognition of this condition is important. We reviewed our experience with the findings on various imaging modalities for diagnosis of this potentially treatable disease.

Diagnostic yield of EUS-guided FNA and cytology in suspected tubercular intra-abdominal lymphadenopathy

BACKGROUND

Intra-abdominal lymphadenopathy is a common diagnostic challenge faced by clinicians. In the absence of palpable peripheral nodes, tissue is usually obtained from the abdominal nodes by image-guided biopsy or surgery. We speculate that EUS-guided FNA (EUS-FNA) avoids the morbidity of a laparotomy and might be equally effective.

OBJECTIVE

To evaluate the role of EUS-FNA in abdominal lymphadenopathy.

DESIGN

Prospective study conducted over 42 months.

SETTING

Tertiary care center in New Delhi, India.

PATIENTS

Patients with abdominal lymphadenopathy in whom image-guided node biopsy failed were considered for EUS-FNA.

INTERVENTION

A total of 3 passes were performed at each site. Slides were prepared per protocol and sent for cytopathologic evaluation.

RESULTS

A total of 142 patients were enrolled, but only 130 (91.5%) underwent FNA. The mean lymph node size was 22 ± 3.2 mm; 71.8% of the nodes were hypoechoic (n = 102), and 28.1% were heterogeneous with an anechoic center (n = 40). In 120 patients (84.5%), the lymph nodes were intra-abdominal only, and in 22 patients (15.5%), they were both intra-abdominal and mediastinal in location.

MAIN OUTCOME MEASUREMENT

EUS-FNA was successful in establishing a diagnosis in 90.8% of these patients; 76.1% were found to have tuberculosis, 7.04% sarcoidosis, 6.33% Hodgkin's lymphoma, and 0.74% non-Hodgkin's lymphoma.

LIMITATIONS

In 8.4% patients, nodes were inaccessible because of their retropancreatic location.

CONCLUSIONS

EUS-FNA is a safe, accurate, and minimally invasive modality for diagnosing the cause of abdominal lymphadenopathy. In highly endemic areas, tuberculosis is the most common cause.

Molecular surveillance of hepatitis and tuberculosis infections in a cohort exposed to methyl isocyanate

OBJECTIVE

The potential toxic effects on the immune system exerted by occupational and accidental environmental exposures and underlying molecular regulatory mechanisms involved in the etiology and progression of infectious diseases are now being characterized. The Bhopal gas tragedy is undoubtedly one of the worst industrial disasters in the history of mankind. After 25 years of accidental exposure to methyl isocyanate (MIC), severe systemic ailments still continue to pre-occupy the lives of the affected population that survived this tragedy. We have performed a molecular surveillance study to characterize hepatitis and tuberculosis infections amongst the first and the second generation of survivors exposed to MIC.

MATERIALS AND METHODS

Both outdoor and indoor patients referred for molecular diagnosis of hepatitis B virus (HBV), hepatitis C virus (HCV) and Mycobacterium tuberculosis (MTB) were examined. Qualitative analysis for HBsAg, anti-HBc, anti-HCV through ELISA was performed, while BacT/ALERT and Ziehl-Neelson technique were utilized for the assessment of tuberculosis. Detection and quantification of viral and bacterial nucleic acid and characterization of hepatitis genotypes were analyzed using real-time and end-point PCR techniques.

RESULTS

The results suggest that HBV infections are most common among the MIC-exposed cohort, followed by extra-pulmonary and pulmonary MTB and HCV infections. Genotype 3 is the most prevalent HCV genotype among the survivors. Failure to detect HBsAg, anti-HBc and anti-HCV through ELISA, and tuberculosis by culture and Ziehl-Neelson stain, indicates higher prevalence of occult hepatitis and latent tuberculosis in the affected population.

CONCLUSIONS

Our study underscores the importance of hospital-based records used as a data source for monitoring possible environmental health hazards. As the risk of progress of infection is often influenced by conditions and periods of environmental chemical exposure, therefore, insights of interconnected molecular pathways will further illuminate the gene-environment association and might offer valuable information for rational drug design.