Application of the polymerase chain reaction on formalin-fixed, paraffin-embedded tissue in the recognition of tuberculous osteomyelitis

Multifocal tuberculosis revealed by a sternal swelling in an immunocompetent child

Tuberculosis (TB) is one of the most common pathogens of bacterial lung infections, especially in underdeveloped nations like Morocco, where the incidence of TB was 97 cases per 100 000 persons in 2019. Thanks to its national TB prevention and control plan, Morocco was able to achieve remarkable progress in the management of TB with an 80% reduction in the total number of patients diagnosed with TB between 1980 and 2018. The national plan also allowed us to reach and maintain a therapeutic rate above 86% since 2002. Sternal TB is a rare clinical condition accounting for 1% of all musculoskeletal TB cases. Due to its rarity and the lack of awareness of clinical presentations, the diagnosis of sternal TB can be quite complex. We describe the case of a 14-year-old Moroccan patient consulting in the Military Hospital Mohammed V-Rabat with central chest pain for 4 months which was not associated with breathing, physical exercise or eating. The patient also had a history of asthenia, fever and weight loss. A computed tomography scan of the chest showed a destructive lesion of the sternum. Afterward, a chirurgical biopsy was performed and enabled to confirm the microbiological diagnosis of TB with the realization of the real-time PCR. The antitubercular therapy was given to the patient who had complete resolution of symptoms. This condition should be included in the differential diagnosis of chronic chest pain that mimics costochondritis particularly in patients from endemic areas.

Performances of single tube nested polymerase chain reaction and GeneXpert ultra on Formalin fixed paraffin embedded tissues in the diagnosis of tuberculous spondylodiscitis

INTRODUCTION

Tuberculous Spondylodiscitis is the most common form of musculoskeletal tuberculosis. Molecular techniques on fresh tissues are proved to improve the diagnosis of tuberculous spondylodiscitis and to allow a rapid diagnosis to initiate the treatment and prevent neurological complications.

OBJECTIVES

The objective of the present study was to assess the diagnostic performances of single tube nested PCR and GeneXpert ultra in the diagnosis of tuberculous spondylodiscitis on formalin fixed paraffin embedded tissues.

METHODS

This study included 63 tuberculous spondylodiscitis cases collected from June 2014 to January 2020 and corresponding to 27 definite tuberculous spondylodiscitis with positive microbiology, and 36 probable tuberculous spondylodiscitis, with histopathological, clinical and radiological findings consistent with tuberculous spondylodiscitis but with negative microbiology. The sensitivity, specificity, positive predictive value and negative predictive value of nested PCR and GeneXpert ultra were determined with reference to microbiology.

RESULTS

Nested PCR was positive in 47 (75%) cases: 26/27 definite tuberculous spondylodiscitis and 21/36 probable tuberculous spondylodiscitis. GeneXpert ultra was positive in only 6 (10%) cases corresponding to definite tuberculous spondylodiscitis. The sensitivity, specificity, positive predictive value and negative predictive value of nested PCR on formalin fixed paraffin embedded tissues were 96%, 100%, 100%, 83% respectively. For GeneXpert ultra, these rates were 22%, 100%, 100% and 25% respectively.

CONCLUSION

Nested PCR and GeneXpert ultra on formalin fixed paraffin embedded tissues are useful tools for the diagnosis of tuberculous spondylodiscitis, especially for cases where microbiological investigations were not carried out. Both techniques have excellent specificity but single tube nested PCR is more sensitive. Key Points • Molecular techniques are routinely performed on fresh tissues • GeneXpert and nested PCR on formalin fixed paraffin embedded tissues are reliable for the diagnosis of tuberculous spondylodiscitis • Nested PCR is more sensitive than Genexpert for diagnosing tuberculous spondylodiscitis.

Tuberculous coxitis with trochanteric bursitis manifesting a year after immigration to Germany: a case report

Background

Osteoarticular tuberculosis is rare in Germany. In particular, trochanteric bursitis is an extremely rare manifestation of osteoarticular tuberculosis. We describe a case of tuberculous coxitis with trochanteric bursitis, successfully treated with a fourfold tuberculostatic therapy.

Case presentation

We report the case of a 43-year-old human immunodeficiency virus-negative Sudanese man with osteoarticular tuberculosis, who was originally admitted with the suspected diagnosis of ankylosing spondylitis. Low grade fever together with the positive result of an interferon-gamma release assay test as well as findings from magnetic resonance imaging provided clues to the diagnosis. A definitive diagnosis could be set after a computed tomography-guided biopsy.

Conclusions

Apart from a rare involvement pattern of osteoarticular tuberculosis, including trochanteric bursitis, this case highlights the increasing importance of osteoarticular tuberculosis as a differential diagnosis of rheumatic disorders. With the growing migration flows from tuberculosis-endemic African countries, clinicians in central and northern Europe may be more frequently confronted with atypical involvement patterns of osteoarticular tuberculosis.

[Isolated sternal tuberculosis in immunocompétent adult]

Isolated sternal tuberculosis is a rarely described entity even in countries where tuberculosis is endemic. We report the case of 25 old years patient who presented with a chest wall mass. Imaging concluded to a (ring-enhancing hypodense soft tissue mass surrounding the sternum with sternal fracture). Malignancy was eliminated by a core needle biopsy. We noted clinical and radiological recovery with medical tuberculosis treatment. Neoplastic origin was removed by biopsy and anatomopathological study of the lesion.

Does Polymerase Chain Reaction of Tissue Specimens Aid in the Diagnosis of Tuberculosis?

Background

Mycobacterial culture is the gold standard test for diagnosing tuberculosis (TB), but it is time-consuming. Polymerase chain reaction (PCR) is a highly sensitive and specific method that can reduce the time required for diagnosis. The diagnostic efficacy of PCR differs, so this study determined the actual sensitivity of TB-PCR in tissue specimens.

Methods

We retrospectively reviewed 574 cases. The results of the nested PCR of the IS6110 gene, mycobacterial culture, TB-specific antigen-induced interferon-γ release assay (IGRA), acid-fast bacilli (AFB) staining, and histological findings were evaluated.

Results

The positivity rates were 17.6% for PCR, 3.3% for the AFB stain, 22.2% for mycobacterial culture, and 55.4% for IGRA. PCR had a low sensitivity (51.1%) and a high specificity (86.3%) based on the culture results of other studies. The sensitivity was higher (65.5%) in cases with necrotizing granuloma but showed the highest sensitivity (66.7%) in those with necrosis only. The concordance rate between the methods indicated that PCR was the best method compared to mycobacterial culture, and the concordance rate increased for the methods using positive result for PCR or histologic features.

Conclusions

PCR of tissue specimens is a good alternative to detect tuberculosis, but it may not be as sensitive as previously suggested. Its reliability may also be influenced by some histological features. Our data showed a higher sensitivity when specimens contained necrosis, which indicated that only specimens with necrosis should be used for PCR to detect tuberculosis.

Diagnosis of extrapulmonary tuberculosis by PCR

During the last two decades, the resurgence of tuberculosis (TB) has been documented in both developed and developing nations, and much of this increase in TB burden coincided with human immunodeficiency virus (HIV) epidemics. Since then, the disease pattern has changed with a higher incidence of extrapulmonary tuberculosis (EPTB) as well as disseminated TB. EPTB cases include TB lymphadenitis, pleural TB, TB meningitis, osteoarticular TB, genitourinary TB, abdominal TB, cutaneous TB, ocular TB, TB pericarditis and breast TB, although any organ can be involved. Diagnosis of EPTB can be baffling, compelling a high index of suspicion owing to paucibacillary load in the biological specimens. A negative smear for acid-fast bacilli, lack of granulomas on histopathology and failure to culture Mycobacterium tuberculosis do not exclude the diagnosis of EPTB. Novel diagnostic modalities such as nucleic acid amplification (NAA) can be useful in varied forms of EPTB. This review is primarily focused on the diagnosis of several clinical forms of EPTB by polymerase chain reaction (PCR) using different gene targets.

Rapid, sensitive, and specific detection of Mycobacterium tuberculosis complex by real-time PCR on paraffin-embedded human tissues

The detection of Mycobacterium tuberculosis complex (MTB) in clinical specimens is important for diagnosing and caring for patients in whom tuberculosis is clinically suspected. We collected 129 FFPE specimens, including 56 nontuberculosis cases, 63 MTB cases, and 10 nontuberculous mycobacteria (NTM) cases determined by acid-fast bacilli (AFB) culture. We performed AFB staining; nested MTB PCR, targeting the IS6110 gene; and real-time MTB PCR, targeting the senX3-regX3 intergenic region in the 129 FFPE specimens. The sensitivity and specificity of AFB staining were 37.0% and 98.2%, respectively, using AFB culture results as the reference standard. The sensitivity and specificity of detecting MTB were 68.3% and 98.5%, respectively, by nested PCR; and 74.6% and 98.5% by real-time PCR, respectively. Among the 129 specimens, four were positive by AFB staining but negative by nested or real-time PCR. NTM grew in all four of these cases by AFB culture. AFB density in FFPE tissue sections significantly correlated with MTB DNA load. Thus, real-time PCR is a useful diagnostic tool for rapid and sensitive MTB detection in FFPE specimens, whereas NTM should be included in differential diagnoses of cases positive by AFB staining but negative by PCR.

Mycobacterium tuberculosis sternal wound infection after open heart surgery: a case report and review of the literature

Tuberculous osteomyelitis of sternum after open heart surgery is a rare disease entity. We report a case of wound infection with osteomyelitis caused by Mycobacterium tuberculosis in a patient with diabetic nephropathy, requiring peritoneal dialysis after coronary artery bypass grafting, who was successfully treated with antituberculous agents and surgical debridement. In addition, we provide a literature review on reported cases of tuberculous sternal osteomyelitis and mediastinitis after open heart surgery, and discuss about the risk factors, clinical features, and treatment of this infection.