Rapid real-time PCR for detection of Mycobacterium tuberculosis complex DNA in formalin-fixed paraffin embedded tissues: 16% of histological 'sarcoid' may contain such DNA

A comparative study of ultrasound-guided puncture biopsy combined with histopathology and Xpert MTB/RIF in the diagnosis of lymph node tuberculosis

Background

Cervical tuberculous lymphadenitis (CTBL) is a disease often ignored in clinical work, and pathology and Xpert MTB/RIF (Xpert) are the commonly used methods for tuberculosis diagnosis. This study aimed to compare ultrasound-guided puncture biopsy combined with histopathology and Xpert in the diagnosis of lymph node tuberculosis.

Methods

A total of 217 patients highly suspected for CTBL were retrospectively enrolled. All patients underwent ultrasound-guided puncture sampling. All samples were subjected to pathological examination and Xpert test. The sensitivity and specificity of the two methods were compared for all samples. The kappa value was calculated to assess the consistency of the pathological examination and Xpert test using comprehensive diagnosis as the gold standard. Receiver operating characteristic curves of the pathological examination, Xpert test, and their combination were generated, and the areas under the curve (AUCs) were calculated to compare the diagnostic value of the three methods.

Results

The sensitivity and specificity of the pathological diagnosis of CTBL were 70.1 and 100%, respectively. The sensitivity and specificity of Xpert for CTBL diagnosis were 82.5 and 97.5%, respectively. The results of the pathological examination and Xpert test showed poor consistency in the diagnosis of CTBL, with a kappa value of 0.388. The AUC of the pathological diagnosis of CTBL was 0.850 (95% CI: 0.796-0.895), whereas that of Xpert was 0.900 (95% CI: 0.852-0.936), and the difference was statistically significant (P = 0.0483). The AUC of pathological examination combined with Xpert for the diagnosis of CTBL was 0.956 (95% CI: 0.920-0.979), and the difference between pathological examination combined with Xpert for the diagnosis of CTBL was statistically significant compared with pathological examination and Xpert alone, respectively (both P < 0.001).

Conclusion

The diagnostic efficiency of Xpert test is higher than that of pathological examination, but its sensitivity is still not ideal for clinical diagnosis. According to this study, the consistency of Xpert test and pathological diagnosis is poor, and the combination of Xpert test and pathological diagnosis can significantly increase the diagnostic efficiency.

Improved Conventional and New Approaches in the Diagnosis of Tuberculosis

Tuberculosis (TB) is a life-threatening infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). Timely diagnosis and effective treatment are essential in the control of TB. Conventional smear microscopy still has low sensitivity and is unable to reveal the drug resistance of this bacterium. The traditional culture-based diagnosis is time-consuming, since usually the results are available after 3–4 weeks. Molecular biology methods fail to differentiate live from dead M. tuberculosis, while diagnostic immunology methods fail to distinguish active from latent TB. In view of these limitations of the existing detection techniques, in addition to the continuous emergence of multidrug-resistant and extensively drug-resistant TB, in recent years there has been an increase in the demand for simple, rapid, accurate and economical point-of-care approaches. This review describes the development, evaluation, and implementation of conventional diagnostic methods for TB and the rapid new approaches for the detection of M. tuberculosis.

A rare case of primary sinonasal tuberculosis presented with phlyctenular keratoconjunctivitis in a pediatric patient: A case report and literature review

RATIONALE

Tuberculosis is a common cause of phlyctenular keratoconjunctivitis, especially for patients who live in a high endemic area of tuberculosis. We report a rare case of pediatric phlyctenular keratoconjunctivitis associated with primary sinonasal tuberculosis.

PATIENT CONCERNS

A 7-year-old boy presented with a 5-month history of redness of the left eye accompanied by mild visual impairment. Physical examination revealed elevated pinkish-white nodules with a circumcorneal hypervascularized lesion on the left conjunctiva.

DIAGNOSIS

Computed tomography revealed an enhancing soft tissue mass in the left maxillary sinus with bone destruction. Histopathology of maxillary tissue showed chronic inflammation without granuloma. Special stain, culture and polymerase chain reaction for mycobacterium were initially negative. Left maxillary sinus tuberculosis was diagnosed by positive Mycobacterium tuberculosis polymerase chain reaction from formalin-fixed paraffin-embedded maxillary tissue.

INTERVENTIONS

Two month of oral isoniazid, rifampicin, pyrazinamide, and ethambutol, followed by 10 months of oral isoniazid and rifampicin without topical eye drops agent were prescribed.

OUTCOMES

Two months after initiation of treatment, the phlyctenular lesion had significantly improved. A follow-up computed tomography showed a significant reduction in the size of the maxillary sinus lesion and the extent of adjacent bone destruction.

LESSONS

Primary sinonasal tuberculosis is an uncommon cause of phlyctenular keratoconjunctivitis in children. When microbiological and histopathological evidences are absent, polymerase chain reaction analysis has a crucial role in the diagnosis of tuberculosis, especially in patient with uncommon presentation.

Using droplet digital PCR in the detection of Mycobacterium tuberculosis DNA in FFPE samples

BACKGROUND

Droplet digital PCR (ddPCR) is a technology that has higher sensitivity than real-time PCR for the identification of trace DNA. However, the use of ddPCR for the detection of Mycobacterium tuberculosis DNA in pathological samples has not been fully studied.

METHODS

A total of 65 formalin-fixed and paraffin-embedded (FFPE) specimens were included in this study. Twenty samples with definite results for tuberculosis (TB) were used to establish the ddPCR system for TB detection. ddPCR was then conducted to detect TB DNA in the 45 patients who were classified as 'possible TB' (real-time PCR results in the gray area, Ziehl-Neelsen staining-negative, and hematoxylin and eosin staining showing morphology suspicious for TB). The clinical treatment and disease outcomes were followed to assess the accuracy of ddPCR in the detection of TB DNA.

RESULTS

Among the 45 possible TB samples, 26 were ddPCR-positive, 12 were ddPCR-negative, and seven were in the gray area. ddPCR improved the positive rate of 57.8% (26/45) for the samples that were in the gray area by real-time PCR. Moreover, several patients received anti-TB therapy, and the effective ratio of therapy for the ddPCR-positive, ddPCR-negative, and ddPCR-gray area cases was 61.9% (13/21), 50.0% (2/4), and 33.3% (1/3), respectively.

CONCLUSIONS

ddPCR is more sensitive for detecting mild TB via FFPE samples than real-time PCR. The ddPCR method is of additional value in the diagnosis of TB from pathological samples.

[Practices in infectious pathology in France in 2015. Results of the national survey]

Pathologists have been, are and will be always implicated in the diagnosis of infectious and tropical diseases. The resurgence of opportunistic infections due to the development of immunosuppressive drugs, the increase of migratory involvements draining tropical infections and the last epidemics spotlight the importance of pathologists in the field of infectious diseases. However, cancer is nowadays the first preoccupation of pathologists, which is constantly subject to evaluate diagnostic and prognostic markers and factors predictive to targeted therapy response or immunotherapy. As tumor pathology, infectious diseases require more sophisticated and rapidly changing complementary techniques, appraisals and perhaps a national network of diagnosis. The infectious pathology club committee carries out here a census of methods used in the diagnosis of infectious diseases in France in 2015 and particularly the different techniques used by laboratories to perform infectious diseases diagnosis. This will lay down the foundation of a future national organization of the infectious pathology in providing efficient services (diagnostic support, complementary tools) for the community of French pathologists in this specific domain of competence.

Acid-fast bacterium detection and identification from paraffin-embedded tissues using a PCR-pyrosequencing method

Aims

Acid-fast bacterium (AFB) identification from formalin-fixed paraffin-embedded (FFPE) tissues is challenging and may not be readily available to the clinical laboratory. A method to detect and identify AFB from FFPE tissues using PCR and pyrosequencing (PCR-Seq) was developed and evaluated.

Methods

The method was validated using spiked cell-clotted paraffin blocks before use with patients’ specimens. DNA was extracted from tissue sections, and a 16S rRNA gene fragment was amplified and a signature sequence was produced on a PyroMark ID system. Sequences were aligned to established databases for AFB identification. Additional tissue sections were stained and examined for AFB.

Results

Both sensitivity and specificity were 100% on spiked cell-clotted blocks without cross-reactivity with non-AFB. Of 302 FFPE tissues from patients, 116 (38%) were AFB-stain positive; 83 (72%) of these had AFB identified. The 21 AFB identified included Mycobacterium tuberculosis complex (14 cases), Mycobacterium leprae (3), Mycobacterium genavense (2), Mycobacterium marinum-ulcerans group (3) and 17 other AFB (61). Thirteen cases were AFB-stain indeterminate and 4 were positive by the PCR-Seq method. Of the AFB stain-negative cases, 167 were negative and 6 were positive by PCR-Seq.

Conclusions

The PCR-Seq method provided specific identification of various AFB species or complexes from FFPE tissues.

Detection of Mycobacterium tuberculosis from paraffin-embedded tissues by GeneXpert MTB/RIF

GeneXpert MTB/RIF (Xpert) assay, a rapid and automated system based on real-time PCR and molecular beacon technology, proved to be a sensitive and specific tool capable of detecting Mycobacterium tuberculosis and rifampin resistance in clinical specimens. In this study we provide a Xpert-dedicated successful protocol for processing paraffin-embedded tissue and assess the feasibility of the Xpert assay-based tuberculosis (TB) diagnosis on these specimens, thus proving the Xpert assay as a valuable TB diagnostic tool in supporting conventional histopathological methods.

Update on sarcoidosis

PURPOSE OF REVIEW

Sarcoidosis is a multisystem inflammatory disease, characterized by the presence of noncaseating granulomas. Ocular inflammation is often the first manifestation of the disease, and uveitis can be the driving force for treatment. The goal of this review was to provide an update on the relationship between ocular and systemic disease, with a particular focus on cardiac sarcoidosis.

RECENT FINDINGS

Chest radiograph remains the best imaging tool for sarcoidosis, although newer modalities, such as whole-body PET scan, cardiac MRI, and chest computed tomography (CT), may provide additional valuable information in select populations. Ocular sarcoidosis is a marker for vascular endothelial dysfunction and increased arterial rigidity. Choroidal involvement is associated with an increased risk of cardiac disease requiring intervention. Cardiac disease continues to be underdiagnosed in patients with sarcoidosis, although it remains a leading cause of death.

SUMMARY

Sarcoidosis is a systemic disease, and ophthalmologists should continually assess patients for extraocular manifestations. Although no screening guidelines exist, baseline ECGs on asymptomatic patients might identify those at risk for adverse cardiac events. Patients with symptoms of cardiac disease, including palpitations, chest pain, and dyspnea, should have an evaluation by a cardiologist.

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.