Diagnosis of intestinal tuberculosis using a monoclonal antibody to Mycobacterium tuberculosis

Immunohistochemistry and real-time Polymerase Chain Reaction: importance in the diagnosis of intestinal tuberculosis in a Peruvian population

INTRODUCTION

The diagnosis of intestinal tuberculosis is challenging even nowadays. This study aims to report the positivity rates of new diagnostic methods such as immunohistochemistry and Real-Time Polymerase Chain Reaction in patients with intestinal tuberculosis, as well as describe the pathological and endoscopic features of intestinal tuberculosis in our population.

METHODS

This was a retrospective observational study conducted in patients diagnosed with intestinal tuberculosis, between 2010 to 2023 from the Hospital Nacional Daniel Alcides Carrion and a Private Pathology Center, both located in Peru. Clinical data was obtained, histologic features were independently re-evaluated by three pathologists; and immunohistochemistry and real-time Polymerase Chain Reaction evaluation were performed. The 33 patients with intestinal tuberculosis who fulfilled the inclusion criteria were recruited.

RESULTS

Immunohistochemistry was positive in 90.9% of cases, while real-time Polymerase Chain Reaction was positive in 38.7%. The ileocecal region was the most affected area (33.3%), and the most frequent endoscopic appearance was an ulcer (63.6%). Most of the granulomas were composed solely of epithelioid histiocytes (75.8%). Crypt architectural disarray was the second most frequent histologic finding (78.8%) after granulomas, but most of them were mild.

CONCLUSION

Since immunohistochemistry does not require an intact cell wall, it demonstrates higher sensitivity compared to Ziehl-Neelsen staining. Therefore, it could be helpful for the diagnosis of paucibacillary tuberculosis.

Diagnostic value of tuberculosis-specific antigens ESAT-6 and CFP10 in lymph node tuberculosis

Objective

To assess the diagnostic value of immunohistochemical (IHC) staining for detecting the tuberculosis-secreted antigens ESAT-6 and CFP10 in lymph node tuberculosis.

Methods

Archived, paraffin-embedded lymph node specimens from 72 patients diagnosed with lymph node tuberculosis and 68 patients with lymphoma were retrospectively collected from the Department of Pathology at the Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan Province, China between January 2016 and March 2023. These specimens were subjected to acid-fast and immunohistochemical staining to compare the effectiveness of these methods, with their sensitivity and specificity evaluated against a comprehensive reference standard.

Results

Acid-fast staining demonstrated a sensitivity of 12.3% and a specificity of 100%. IHC staining for ESAT-6 showed a sensitivity of 87.5% and a specificity of 85.3%, whereas IHC staining for CFP10 exhibited a sensitivity of 75.0% and a specificity of 89.7%.

Conclusion

The study indicates that IHC detection of ESAT-6 and CFP10 in paraffin-embedded lymph node tuberculosis tissues has a markedly higher sensitivity compared to acid-fast staining. Thus, IHC staining may serve as a supplementary diagnostic tool for the pathological evaluation of lymph node tuberculosis.

Utility of anti-Mycobacterium tuberculosis antibody (ab905) for detection of mycobacterial antigens in formalin-fixed paraffin-embedded tissues from clinically and histologically suggestive extrapulmonary tuberculosis cases

Background

The detection of acid-fast bacilli in extrapulmonary tissue samples is challenging due to its paucibacillary nature. The present study assessed the utility of immunohistochemistry (IHC) using anti-Mycobacterium tuberculosis antibody (ab905) for detecting the presence of mycobacterial antigens in archived formalin-fixed paraffin-embedded (FFPE) tissues.

Methods

FFPE tissues [surgical biopsies (n = 32) and post-mortem tissues (n = 8)] from clinically and histologically suggestive extrapulmonary tuberculosis (EPTB) cases at the Korle Bu Teaching Hospital, Accra, Ghana from 2015 to 2020 were stained with IHC (anti-Mycobacterium tuberculosis antibody) and Ziehl-Neelsen (ZN) stain. The staining outcomes of IHC and ZN were compared, and their sensitivity and specificity determined against histopathology as reference standard.

Results

Lymph nodes were about 40% (16/40) of the samples analyzed. IHC stained positive in 43.8% (7/16) biopsies and 87.5% (4/5) post-mortem samples ranging from 43.8% (7/16) in lymph nodes to 80% (4/5) in gastrointestinal organs. The overall sensitivity for IHC was 52.50% (95% CI: 36.13%-68.49%) and 0% (95% CI: 0.00%-8.81%) for ZN. Specificity was 72.50% (95% CI: 56.11%-85.40%) and 75% (95% CI: 58.80-87.31%) for IHC and ZN respectively.

Conclusions

IHC using anti-Mycobacterium tuberculosis antibody (ab905) can detect mycobacterial antigens in diverse range of paucibacillary extrapulmonary tissue sections. It is potentially a useful tool for the diagnosis of EPTB in FFPE tissues in a routine pathology laboratory.

Characteristics and Endoscopic Classification of Ulcerative Lesions Affecting the Ileocecal Valve

OBJECTIVES

The aim of this study was to propose an endoscopic classification system for ulcerative lesions on the ileocecal valve and investigate its relevance to the underlying etiology.

METHODS

Among the 60,325 patients who underwent colonoscopy at our hospital from January 2006 to December 2018, patients with ulcerative lesions on the ileocecal valve were included. The following data were obtained using the hospital's medical records: sex, age, clinical diagnosis, laboratory data, and endoscopic and histological findings. Patients who have ulcerative colitis and who were not evaluated by histological examination were excluded. Ulcerative lesions on the ileocecal valve were classified into 3 groups according to their endoscopic appearance: small shallow ulcerative lesions without edematous change (group A), lateral spreading shallow ulcerative lesions with edematous change (group B), and deep deformed ulcerative lesions (group C). The association between this endoscopic classification and its clinical diagnosis, clinical course, and the interobserver reliability were evaluated.

RESULTS

Of 72 patients who were eligible for analysis, 18 were assigned to group A, 9 to group B, and 45 to group C. Infectious enteritis was mainly assigned to group A (group A, 12; group B, none; and group C, 6; p < 0.0001), inflammatory bowel disease was mainly assigned to group C (group A, none; group B, 5; and group C, 35; p < 0.0001), and malignant tumor was assigned to group C only. Interobserver reliability was extremely high among the 3 examining doctors (kappa value 0.7-0.8).

CONCLUSION

Endoscopic classification was divided into 3 groups for ulcerative lesions on the ileocecal valve, and this system could be beneficial for presuming their clinical diagnoses.

Application value of tissue tuberculosis antigen combined with Xpert MTB/RIF detection in differential diagnoses of intestinal tuberculosis and Crohn's disease

Background

The purpose of this study was to examine the value of Xpert MTB/RIF assay and detection of additional Mycobacterium tuberculosis complex (MTBC) species antigens from intestinal tissue samples in differentiating intestinal tuberculosis (ITB) from Crohn’s disease (CD).

Methods

Several clinical specimens of intestinal tissue obtained by either endoscopic biopsy or surgical excision were used for mycobacteriologic solid cultures,Xpert MTB/RIF assays, immunohistochemistry, and histological examinations. Four antigens (38KDa, ESAT-6, MPT64, and Ag85 complex) of MTBC in the intestinal tissue were detected by immunohistochemical analysis.

Results

The study included 42 patients with ITB and 46 with CD. Perianal lesions and longitudinal ulcers were more common in patients with CD, while caseating granuloma and annular ulcers were more common in patients with ITB. The positive rate of MTBC detected by Xpert MTB/RIF in intestinal tissues of patients with ITB was 33.33%, which was significantly higher than that in patients with CD and that detected using acid-fast staining smears. It was also higher than that detected by tissue MTBC culture, but the difference was not statistically significant. The positive MPT64 expression rate in patients with ITB was 40.48%, which was significantly higher than that observed in patients with CD. The sensitivity of parallelly combined detection of tuberculosis protein MPT64 and Xpert MTB/RIF in diagnosing ITB was 50.0%.

Conclusions

The detection of Xpert MTB/RIF in intestinal tissue is a rapid and useful method for establishing an early diagnosis of ITB. The detection of MTBC using Xpert MTB/RIF and MPT64 antigen in intestinal tissues has a definitive value in the differential diagnosis ofITB and CD. The combination of these two methods can improve the detection sensitivity.

Aptamer Detection of Mycobaterium tuberculosis Mannose-Capped Lipoarabinomannan in Lesion Tissues for Tuberculosis Diagnosis

Tuberculosis (TB) is the leading infectious cause of mortality worldwide. However, the diagnosis of TB, especially extrapulmonary TB (EPTB) diagnosis from lesion tissues, remains a challenge. Nucleic acid aptamers are analogous to antibodies and have advantages of easier modification, high specificity, and affinity. Mannose-capped lipoarabinomannan (ManLAM) is a unique surface lipoglycan component or constantly released from mycobacterium tuberculosis (M.tb) cell wall, which makes it a perfect candidate biomarker for TB diagnosis. Our present study aims to establish M.tb ManLAM aptamer-based immunohistochemistry (IHC) method for TB diagnosis. We performed TB diagnosis using 263 formalin-fixed paraffin-embedded tissue samples including 213 TB samples (pulmonary TB (PTB) and EPTB), and 8 samples from latent TB infection (LTBI) high risk subjects, and 42 samples from other non-TB patients with ManLAM aptamer-based IHC and routine laboratory TB diagnostic methods parallelly. The sensitivity and specificity of the ManLAM aptamer-based IHC were 86.38% and 92.86%, with much higher sensitivity than those of mycobacterial culture (9.66%) and acid-fast staining (AFS) (43.01%) and comparability to Interferon-gamma Release Assay (IGRA) (84.38%) and GeneXpert (79.31%). High agreement between ManLAM based-IHC and IGRA or GeneXpert for TB diagnosis were observed. Furthermore, ManLAM aptamer-based IHC combination with other routine TB laboratory diagnostic methods significantly increased the sensitivity up to 88.64%–97.92%. As our knowledge, this is the first report about aptamer-based IHC for disease diagnosis. Thus, ManLAM aptamer-based IHC has potentials for TB diagnosis, including PTB, and EPTB, and assists the diagnosis of LTBI with high effectiveness, feasibility, and easy production.

Application of Laser Scanning Confocal Microscopy for the Visualization of M. tuberculosis in Lung Tissue Samples with Weak Ziehl-Neelsen Staining

One of the key requirements for the diagnosis of pulmonary tuberculosis is the identification of M. tuberculosis in tissue. In this paper, we present the advantages of specific fluorescent antibody labelling, combined with laser scanning confocal microscopy (LSCM), for the detection of M. tuberculosis in histological specimens of lung tissues. We demonstrate that the application of LSCM allows: (i) The automatic acquisition of images of the whole slice and, hence, the determination of regions for subsequent analysis; (ii) the acquisition of images of thick (20–40 μm) slices at high resolution; (iii) single bacteria identification; and (iv) 3D reconstruction, in order to obtain additional information about the distribution, size, and morphology of solitary M. tuberculosis; as well as their aggregates and colonies, in various regions of tuberculosis inflammation. LSCM allows for the discrimination of the non-specific fluorescence of bacteria-like particles and their aggregates presented in histological lung samples, from the specific fluorescence of labelled M. tuberculosis, using spectrum emission analysis. The applied method was effective in the identification of M. tuberculosis in lung histological samples with weak Ziehl–Neelsen staining. Altogether, combining immunofluorescent labelling with the application of LSCM visualization significantly increases the effectiveness of M. tuberculosis detection.

Gastrointestinal Tuberculosis

Gastrointestinal tuberculosis (TB) is a fascinating disease which can be observed both in the clinical context of active pulmonary disease and as a primary infection with no pulmonary involvement. It represents a significant clinical challenge because of the resurgence of TB as well as the diagnostic challenges it poses. A high clinical suspicion remains the most powerful tool in an era of medicine when reliance on diagnostic technology increases. Antimicrobial therapy is the mainstay of therapy, but surgical and endoscopic interventions are frequently required for intestinal TB. Gastrointestinal TB is truly the "great mimic" and continues to require the astute clinical acumen of skillful clinicians to diagnose and treat.

Tuberculosis terminal ileitis: A forgotten entity mimicking Crohn’s disease

Intestinal tuberculosis (TB) is an uncommon lesion for which differential diagnosis can be difficult. We present a case of a 53-year-old male and a systematic review of the literature, from clinical symptoms to differential diagnosis, unusual complications and therapy. The patient was admitted to the hospital with signs of acute abdomen as a result of a perforated terminal ileitis. Based on the skip lesions of the terminal ileum and cecum, Crohn’s disease (CD) was clinically suspected. An emergency laparotomy and right colectomy with terminal ileum resection was performed and systematic antibiotherapy was prescribed. The patient’s status deteriorated and he died 4 d after the surgical intervention. At the autopsy, TB ileotyphlitis was discovered. The clinical criteria of the differential diagnosis between intestinal TB and CD are not very well established. Despite the large amount of published articles on this subject, only 50 papers present new data regarding intestinal TB. Based on these studies and our experience, we present an update focused on the differential diagnosis and therapy of intestinal TB. We highlight the importance of considering intestinal TB as a differential diagnosis for inflammatory bowel disease. Despite the modern techniques of diagnosis and therapy, the fulminant evolution of TB can still lead to a patient’s death.

Granulomas as the Most Useful Histopathological Feature in Distinguishing between Crohn's Disease and Intestinal Tuberculosis in Endoscopic Biopsy Specimens

The incidence of Crohn's disease (CD) is increasing in Chinese populations in whom intestinal tuberculosis (ITB) is prevalent.This study aimed to identify differential diagnostic microscopic and endoscopic characteristics of CD from those of ITB.Patients with CD (N = 52) and patients with ITB (N = 16) diagnosed between 2010 and 2013 were identified. Specimens obtained via endoscopy were analyzed microscopically by a pathologist. The relationship between endoscopic appearance and histopathological features was analyzed. The χ test, Fisher's exact probability test, and the Mann-Whitney U test were used.Granulomas were present in 81.3% of ITB cases and in 67.3% of CD cases (P = 0.36). Granulomas in ITB cases were denser than those in CD cases (mean 5.29 ± 4.30 vs. 2.46 ± 3.50 granulomas per 10 low power fields; each low power field = 3.80 mm; P = 0.005). Granulomas in ITB cases were larger (mean widest diameter, 508 ± 314 μm; range, 100-1100 μm) than those in CD cases (mean widest diameter, 253 ± 197 μm; range, 50-800 μm). Basal plasmacytosis was more common in CD cases than in ITB cases (77.0% vs. 37.5%, P = 0.000). Endoscopy findings such as longitudinal ulcer, aphthous ulcer, and cobblestone appearance were only seen in CD cases (34.6%, 21.2%, and 23.1%, respectively). Granulomas were detected in the majority of cases with longitudinal ulcers (88.9%). Basal plasmacytosis was exclusively detected in cases with longitudinal ulcer and a cobblestone appearance.Characteristics of granulomas maybe the most important distinguishing features between CD and ITB. However, the histopathological characteristics of both diseases may overlap on endoscopic biopsy specimens. An accurate diagnosis should be made that considers clinical, endoscopic features, and pathologic findings.

Double staining of bacilli and antigen Ag85B improves the accuracy of the pathological diagnosis of pulmonary tuberculosis

BACKGROUND

A pathological examination plays an important role in the confirmation of a diagnosis of tuberculosis, especially for smear- and culture-negative cases. However, conventional Ziehl-Neelsen staining and histological tests lack sensitivity and specificity.

OBJECTIVE

To evaluate the diagnostic value of immunohistochemical staining to detect Mycobacterium tuberculosis protein Ag85B and a newly developed double staining (ZC staining) method that can simultaneously detect acid-fast bacilli and M. tuberculosis antigen in the same histological section.

METHODS

A total of 282 formalin-fixed paraffin-embedded lung tissues were identified following histological examination, including 212 cases of pulmonary tuberculosis and 70 other pulmonary diseases. Ziehl-Neelsen staining, Ag85B-immunohistochemistry and the newly developed ZC staining were performed on serial sections of all the specimens.

RESULTS

Expression patterns of Ag85B were consistent with the distribution patterns of acid-fast bacilli. The signal produced by Ag85B-immunohistochemistry was much stronger than that produced by Ziehl-Neelsen staining. The sensitivity of Ag85B-immunohistochemistry was significantly higher than that of Ziehl-Neelsen staining, 53.8% (95% CI 47.0% to 60.5%) vs 34.4% (95% CI 28.0% to 40.9%). The newly developed ZC staining, integrating advantages of both Ziehl-Neelsen staining and immunohistochemistry, further improved the rate of sensitivity up to 65.6% (95% CI 59.1% to 72.0%).

CONCLUSIONS

This new method, detecting both acid-fast bacilli and M. tuberculosis antigen, is a simple and sensitive method for the pathological diagnosis of tuberculosis and can be easily incorporated into routine tests of pathological laboratories.

Immunohistochemistry in the diagnosis of cutaneous bacterial infections

The identification of pathogens is of vital importance for the adequate treatment of infections. During the past 2 decades, the approach to histopathologic diagnosis has been dramatically transformed by immunohistochemistry (IHC) specifically in the diagnosis and classification of tumors and more recently in the diagnosis of infectious diseases in tissue samples. The main goals of this article were to: (1) identify by IHC the cutaneous structures where bacterial pathogens are expressed in the course of infection, (2) identify the specific cells in which bacterial pathogens are expressed in positive cases, and (3) describe the pattern of distribution of the bacterial antigens within these cells (nuclear, cytoplasmatic, or membranous). This article is an up-to-date overview of the potential uses and limitations of IHC in the histopathologic diagnosis of cutaneous bacterial infections. In conclusion, IHC is especially useful in the identification of microorganisms that are present in low numbers, stain poorly, are fastidious to grow, culture is not possible, or exhibit an atypical morphology.

[Morphological diagnosis of tuberculosis under present-day conditions]

The paper presents general statistical data on morbidity and mortality rates of tuberculosis, which show positive trends in recent years, with exception of those of its concurrence with HIV infection. The tasks of the morphological diagnosis of tuberculosis are divided into 4 groups: 1) to refine approaches to detecting mycobacteria in tissues; 2) to optimize the postmortem diagnosis of tuberculosis; 3) to optimize the lifetime differential diagnosis of tuberculosis and to develop methods for predicting its course; 4) to study the pathogenesis of tuberculosis from the standpoint of modern views on an infectious process. The data suggesting that the tissue forms of mycobacteria, the types of inflammatory responses, and the specific features of the pathogenesis of tuberculosis call for further investigations are given. To establish the real role of nontuberculous mycobacteria, to study the likelihood that the patient will be superinfected with other M. tuberculosis genotypes, and to elaborate a uniform (clinical, pathogenetic, and morphological) classification of tuberculosis should be also regarded as the most important tasks in its morphological examination.

Spectrum of pathologies in cases of intestinal obstruction & perforation based on histopathological examination of resected intestine - Report from a third world country

Background and Objective: Cases presenting with intestinal perforation and obstruction constitute a substantial work load on our surgical service. Etiologies vary in underdeveloped and developed countries. Histopathological examination of resected intestine is expected to provide the definite evidence of the underlying etiology- guiding a better health care planning for preventive measures. Our objective was to study the spectrum of histopathological findings in resected intestines from cases of intestinal obstruction and perforation in our local population to document the underlying etiology.

Methods: A total of 120 cases of intestinal resection were included. Detailed gross and microscopic examination with routine stains was performed. Definite evidence of any specific etiology on the basis of morphology was documented.

Results: A total of 95 cases with clinical/radiological diagnosis of obstruction (79.2%) and 25 of intestinal, perforation (20.8%) were included. Tuberculous enteritis was the commonest etiology (n=41; 43.1%) in cases of intestinal obstruction followed by malignant tumours (n=30; 31.5%). ischemic infarct/gangrene, post op illeal adhesions, polyps and ulcerative colitis followed. In cases of perforation, Typhoid enteritis (n=15; 60%), was the commonest pathology followed by idiopathic perforation (n=5; 20%), tuberculous enteritis (n=3;12%), carcinoma (4%) and ulcerative coliti (4%).

Conclusion: In developing countries infective etiology remains a dominant cause of intestinal obstruction and perforation. Its presentation in younger age leading to intestinal resection demands effective preventive measures in this part of the world to prevent morbidity and mortality.