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

A Case Report on Scrofuloderma: A Cutaneous Manifestation of Tuberculosis

Scrofuloderma, a manifestation of cutaneous tuberculosis, is a less common but clinically significant form of mycobacterial infection. It typically arises from the contiguous spread of Mycobacterium tuberculosis from an underlying infected lymph node or osseous structure to the adjacent skin. The condition manifests predominantly as chronic, granulomatous inflammation that leads to skin ulcers and abscesses. Despite its rarity, scrofuloderma presents substantial diagnostic challenges, primarily due to its nonspecific clinical presentation, which may mimic other dermatological conditions. This case report delineates the clinical journey of a patient with scrofuloderma who was attended to in a tertiary care setting. It emphasizes the diagnostic complexities encountered, underscored by a comprehensive discussion of the investigative modalities used to establish the diagnosis. This report elaborates on the therapeutic regimen taken, showcasing the effectiveness of a customized antituberculosis treatment plan.

The Need for Persistence in the Diagnosis of Mycobacterium Tuberculosis Mono-arthritis: A Unique Case Presentation

Although tuberculosis (TB) is considered to be a common disease confined to undeveloped or developing countries, it may also appear in countries that accept great migrant influx from endemic areas. In terms of the skeletal system, it can be involved in 1-6% of tuberculosis patients while the knee joint is the third most frequently affected site after spine and hip. Given that systemic symptoms are present in only one-third of patients with skeletal tuberculosis and secondary septic arthritis, TB is often indolent and diagnosis can hence be missed or delayed. As a result, a high index of suspicion is imperative. Here, we aim to report a case of mono-arthritis caused by Mycobacterium tuberculosis in a native 77-year-old man who was suffering from low-grade knee pain for six months and despite multiple presentations to the Accident and Emergency department, diagnosis had not been established.

Diagnostic Utility of Biplex/Multiplex Polymerase Chain Reaction in Infectious Granulomatous Dermatitis in North Indian Population

BACKGROUND

A definite diagnosis of infectious granulomatous dermatitis (IGD) is difficult for both practicing dermatologists and dermatopathologists due to overlapping clinical and histomorphological features. We aimed to explore the role of multiplex polymerase chain reaction (PCR) for identifying a definite etiological agent for diagnosis and appropriate treatment in IGD in formalin-fixed paraffin-embedded tissue.

MATERIALS AND METHODS

Sixty-two cases of IGD were included, excluding leprosy. The histochemical stains including Ziehl-Neelsen, periodic acid-Schiff, and Giemsa were performed in all cases. A multiplex PCR was designed for detection of tuberculosis (TB) (IS6110 and mpt64), fungal infections (ITS1, ITS2; ZM1, and ZM3), and leishmaniasis (kDNA). The results of histomorphology, histochemical stains, and multiplex PCR were compared.

RESULTS

Among 62 cases, the sensitivity rate of PCR detection for organisms was 16.7%, 0%, 100%, 72%, 75%, and 66.7% in patients with TB, suggestive of TB, leishmaniasis, fungal infections, and granulomatous dermatitis not otherwise specified and granulomatous dermatitis suggestive of fungus, respectively. The TB PCR using IS6110 primers was negative in all cases; however, PCR using mpt64 primers was positive in 33.33% cases of scrofuloderma. The histochemical stains including Ziehl-Neelsen for acid-fast bacilli, periodic acid-Schiff for fungus, and Giemsa for Leishman-Donovan bodies showed positivity in 11.3%, 43.5%, and 3.2%, respectively.

CONCLUSION

A multiplex PCR (Mycobacterium tuberculosis, Leishmania, and panfungal) is highly recommended in all cases of IGD where an etiological agent is difficult to establish by skin biopsy and histochemical stains along with a clinicopathological correlation. This will augment in appropriate treatment and will reduce empirical treatment and morbidity in such patients.

Reduction of turnaround time for non-tuberculous mycobacteria detection in heater-cooler units by propidium monoazide-real-time polymerase chain reaction

BACKGROUND

Invasive non-tuberculous mycobacteria (NTM) infections are emerging worldwide in patients undergoing open-chest cardiac bypass surgery exposed to contaminated heater-cooler units (HCUs). Although this outbreak has been investigated by culturing bacteria isolated from HCU aerosol and water samples, these conventional methods have low-analytic sensitivity, high rates of sample contamination, and long turnaround time.

AIM

To develop a simple and effective method to detect NTM in HCUs by real-time polymerase chain reaction (PCR), with a short laboratory turnaround time and reliable culture results.

METHODS

A total of 281 water samples collected from various HCUs at seven Italian hospitals were simultaneously screened for NTM by a propidium monoazide (PMA)-PCR assay and by conventional culture testing. The results were analysed with culture testing as the reference method.

FINDINGS

(i) The agreement between culture testing and PMA-PCR was 85.0% with a cycle threshold (C_T) cut-off value of <38 vs 80.0% with a C_T of <43, with a moderate Cohen's κ-coefficient; (ii) the C_T cut-off value of <42 was deemed more suitable for predicting positive specimens; (iii) given the low concentration of target DNA in water samples, the minimum volume to be tested was 1 L.

CONCLUSION

The use of PMA-PCR for fast detection of NTM from environmental samples is highly recommended in order to ascertain whether HCUs may represent a potential source of human exposure to NTM. This reliable and simple method reduces laboratory turnaround time compared to conventional methods (one to two days vs eight weeks, respectively), thereby improving control strategies and effective management of HCUs.

Complete Resolution of Mycobacterium marinum Infection with Clarithromycin and Ethambutol: A Case Report and a Review of the Literature

A 70-year-old, immunocompetent male presented with mildly painful and pruritic erythematous patches and vesicles on the right dorsal aspect of the distal middle finger present for four weeks. Other skin lesions or systemic symptoms were notably absent. The patient failed to respond to valacyclovir, topical triamcinolone acetonide ointment, trimethoprim-sulfamethoxazole, and cephalexin for presumptive diagnoses of recurrent herpetic whitlow, dyshidrotic eczema, and blistering distal dactylitis, respectively. Furthermore, biopsy findings were inconsistent with eczema, psoriasis, or viral or fungal infection as potential etiologies. Mycobacterium marinum infection was then considered due to the patient's observation that the lesion appeared three weeks after purchasing a home fish tank. Mycobacterium marinum, referred to as "fish tank granuloma" as a result of its typical association with aquarium exposure, is usually diagnosed clinically and treated empirically due to the organism's slow-growing nature. In light of the infection's low prevalence, large studies regarding treatment options are limited. Our patient's lesion resolved within two weeks of treatment with clarithromycin (500mg twice a day) and ethambutol (15mg/kg once a day), which was then continued for two more months. Prior to this treatment, the patient's lesion had cleared completely with minocycline; we attribute recurrence to not continuing therapy past lesion resolution.

Cutaneous Tuberculosis: Clinicopathologic Arrays and Diagnostic Challenges

The clinicopathological manifestations of cutaneous tuberculosis are diverse. The precise diagnosis is often overlooked, due to clinical presentations as those of cutaneous diseases with different etiology and the relative paucity of the pathogens in the lesions. Meanwhile, almost all of the diagnostic methods confer lower sensitivity and specificities which augments further diagnostic challenges. This article revises the current scenario of the disease's physiopathology and underscores clinicopathological challenges, due to multifaceted presentations of cutaneous tuberculosis, in the diagnosis.

Utility of Real-Time Quantitative Polymerase Chain Reaction in Detecting Mycobacterium tuberculosis

This study aimed to assess the value of real-time quantitative polymerase chain reaction (RT-qPCR) for the detection of Mycobacterium tuberculosis (MTB). Samples from 192 patients with suspected MTB were examined by RT-qPCR and an improved Löwenstein-Jensen (L-J) culture method. To evaluate the diagnostic usefulness of RT-qPCR in detecting MTB, a receiver operating characteristic (ROC) curve for RT-qPCR was generated, and the area under the curve (AUC) as well as a cutoff value was calculated. Using the L-J culture method as the gold standard, accuracy of the RT-qPCR method for detecting MTB was 92.7%, with sensitivity and specificity of 62.5% and 97.02%, respectively. In comparison with the improved L-J culture method, the AUC of RT-qPCR ROC curve was 0.957, which was statistically significant (p < 0.001). The Youden Index reached the maximum value (0.88) for gene copy number of 794.5 IU/mL, which was used as the cutoff value. RT-qPCR detection of MTB yielded results consistent with those of the improved L-J culture method, with high accuracy. RT-qPCR may be used as an auxiliary method for etiological diagnosis of tuberculosis.