Polymerase chain reaction based detection of Mycobacterium tuberculosis in tissues showing granulomatous inflammation without demonstrable acid-fast bacilli

Should antituberculosis treatment be prescribed in erythema induratum? A case-control and incidence correlation study in Taiwan, 2001-2020

BACKGROUND

Erythema induratum (EI) is a tuberculid associated with Mycobacterium tuberculosis infection. Using polymerase chain reaction (PCR), M. tuberculosis has been identified in Taiwan with a high percentage of EI. However, this pathogen is now rarely detected in Taiwan.

OBJECTIVES

To explore the association between EI, the annual incidence of tuberculosis (TB) in Taiwan and treatment outcomes over the last two decades.

METHODS

Patients diagnosed with EI between 2001 and 2020 were enrolled based on histopathology, tissue culture and positive M. tuberculosis PCR tests. Other cases of panniculitis with positive M. tuberculosis PCR results were used as controls. The clinical information of participants was obtained. The results were correlated with the annual incidence of TB and compared between groups.

RESULTS

Fifty-five biopsy specimens from patients with EI met the inclusion criteria; three (5%) had positive M. tuberculosis PCR results. One patient diagnosed with erythema nodosum in the control group had a positive M. tuberculosis PCR (n = 1/27; 4%). There was no significant relationship between M. tuberculosis and EI (odds ratio 1.5, 95% confidence interval -0.964 to 3.964). The correlation between the incidence of M. tuberculosis and the number of EI cases was not statistically significant (r = -0.185, P = 0.45). Only four patients received anti-TB treatment; they all showed clinical improvement without recurrence. One patient with M. tuberculosis PCR-positive EI was not treated with anti-TB therapy; however, the skin lesion improved after 3 months. No other patients in the EI group were diagnosed with M. tuberculosis infection over a follow-up period of 508 person-years.

CONCLUSIONS

Most cases of EI in Taiwan are nodular vasculitis and not tuberculid, owing to well-controlled TB. This condition can be alleviated without anti-TB treatment.

Cutaneous tuberculosis. Part II: Complications, diagnostic workup, histopathologic features, and treatment

Despite the availability of effective treatment regimens for cutaneous tuberculosis, challenges to disease control result from delayed diagnosis, infection with multidrug-resistant mycobacterial strains, and coinfection with HIV. Delayed diagnosis can be mitigated when dermatologists are sensitized to the clinical signs and symptoms of infection and by the incorporation of appropriate diagnostic tests. All cases of cutaneous tuberculosis should be confirmed with histopathology and culture with or without molecular testing. In each case, a thorough evaluation for systemic involvement is necessary. Mycobacteria may not be isolated from cutaneous tuberculosis lesions and therefore, a trial of antituberculosis treatment may be required to confirm the diagnosis. The second article in this 2-part continuing medical education series describes the sequelae, histopathology, and treatment of tuberculosis.

Multifocal Tuberculosis Verrucosa Cutis: Case Report and Review of the Literature

Cutaneous tuberculosis (TB) is still a major public health problem worldwide. Tuberculosis verrucosa cutis (TBVC) is a cutaneous form of exogenous TB caused by exogenous reinfection in previously sensitized individuals. TBVC typically presents as a unifocal condition. Multifocal cutaneous lesions without any other tubercular foci are extremely rare in exogenous TB and few cases are reported in the literature. We describe the first case of multifocal TBVC in an 81-year-old Greek man. In total, 14 cases of multifocal TBVC have been reported in the literature (8 males and 6 females), with mean age 47.64 years (SD = 20.75) and mean time to diagnosis of 9.69 years (SD = 15.31). Most cases (11/12) responded rapidly to treatment, implying the accuracy of diagnosis, while no one was reported to be immunocompromised. Finally, in 10 cases (71.4%), history of skin microtrauma was reported (related either to daily life habits or to professional praxis), confirming it as the main risk factor. The tuberculin skin test was positive in 10 cases and tissue culture for mycobacteria was negative in all cases. TBVC can present with multiple lesions, even in countries where TB prevalence is not high, especially in patients with history of skin abrasions. Prompt specialist assessment can expedite the establishment of diagnosis.

A Clinico-Histopathological Study of Lupus Vulgaris at a Tertiary Care Centre

Background and objectives Lupus vulgaris is a chronic, progressive, paucibacillary form of cutaneous tuberculosis that occurs in persons with moderate to high immunity. Due to its varied clinical presentation, it can masquerade as different dermatological conditions. This study describes the demographic patterns and varieties of clinical manifestations that can be possible in this curable illness. Methods This study was conducted over two years and included 19 patients with histopathologically confirmed lupus vulgaris in Odisha, India. Demographic data, clinical features, and response to treatment are presented. Results Thirteen cases (68.4%) were seen in adults and six (31.6%) in pediatric patients. The lower limbs were the more affected (n=10), followed by the upper limb (6), the face (2), and the chest (1). All but one patient had plaque-type lesions. On histopathology, all showed a tuberculoid granuloma with no demonstration of acid-fast bacilli with Ziehl-Neelsen staining. Conclusion In the present study, the incidence was mostly observed in the young and higher activity age groups (5-40 years). Plaque-type lesions were most commonly encountered. In histopathology, all the cases had tubercular granuloma-type lesions without any incidence of malignant transformations. All the patients responded well to conventional multi-drug anti-tubercular chemotherapeutic regimens.

Diagnostic Dilemma of Cutaneous Tuberculosis: Opening of the Pandora's Box

ABSTRACT

Tuberculosis in all forms, that is, pulmonary (PTB) or extrapulmonary (EPTB), is a universal health problem. Cutaneous tuberculosis (CTb) remains one of the least studied and often under-reported variants of EPTB because of its wide and protean clinical presentation. The diagnosis of CTb remains challenging because of lack of sensitive and specific investigations for its diagnosis. The sensitivity of some of the traditional tests is low because of low concentration of mycobacteria in paucibacillary lesions. Besides it is difficult to distinguish between M. tuberculosis (MTb) and other mycobacterial species in skin biopsies morphologically. Molecular methods may target either MTb DNA or RNA, and serve as promising tools in the diagnosis of various forms of CTb, with high sensitivity and rapidity. This review is focused on diagnostic challenges of CTb and to discuss various methods and newer technologies for diagnosing CTb. This will help the dermatologists and dermatopathologists to elucidate and accurately diagnose CTb from other infectious granulomatous dermatitis for appropriate timely treatment of the patient.

Erythema induratum of Bazin in a 10-year-old boy

Erythema induratum of Bazin (EIB) is a form of tuberculid resulting from hypersensitivity to tuberculosis antigen. EIB occurs most commonly in middle-aged women and is not typically seen in children. Here, we present a rare case of EIB, presenting as a chronic nodular panniculitis, in a 10-year-old Korean boy.

Nested Polymerase Chain Reaction and Cutaneous Tuberculosis

The role of Mycobacterium tuberculosis in the etiology and pathogenesis of cutaneous tuberculosis is controversial because of the difficulties associated with demonstrating the presence of these mycobacteria in tuberculid cutaneous lesions by routinely available microbiological and histological techniques. In this study, we aimed to demonstrate the presence of M. tuberculosis in cutaneous tuberculosis. Multiple polymerase chain reaction (PCR) followed by nested PCR was used to amplify genomic fragments from 3 different mycobacteria species. DNA was isolated from 30 paraffin-embedded skin biopsies. Samples were selected randomly from patients with a clinical and histopathological diagnosis of the most frequent groups of cutaneous tuberculosis in Mexico as follows: 5 cases of scrofuloderma tuberculosis; 2 cases of lupus vulgaris tuberculosis; and 5 cases of tuberculosis verrucosa cutis. The other cases denominated tuberculids in some countries such as Mexico and included the following: 7 cases of rosacea-like tuberculosis; one case of papulonecrotic tuberculosis; and 10 cases of erythema induratum of Bazin. Four normal skin biopsies were included as controls. M. tuberculosis DNA was amplified successfully by nested PCR in 80% of the samples (24 of the 30 samples) assayed. Mycobacterial DNA was not detected in the normal skin biopsies used as controls. Detection of M. tuberculosis DNA in 80% of cutaneous tuberculosis analyzed implicates this mycobacterium in the pathogenesis of multiple clinical forms of cutaneous tuberculosis.

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.

Vulvar Tuberculosis Cutis Orificialis Concomitant to Pulmonary Tuberculosis: A Case Report

Tuberculosis (TB) is a common condition with increasing incidence worldwide. Cutaneous TB represents a small portion of extrapulmonary TB. Health care professionals must be aware of cutaneous forms of TB to avoid delay in diagnosis and treatment. We present a case of a 59-year-old woman with vulvar TB cutis orificialis in association with pulmonary TB without any other involvement of genitourinary system. We discuss epidemiological aspects, classification, treatment, range of histopathological patterns, and use of ancillary techniques for diagnosis.

Cutaneous Tuberculosis

Cutaneous tuberculosis (TB) may present in various clinical manifestations. Skin involvement may occur as a result of exogenous inoculation, contiguous spread from a nearby focus of infection, or by hematogenous spread from a distant focus. Because the clinical presentation of cutaneous TB can vary widely, it is important to have a high index of suspicion in appropriate clinical settings. In this chapter, the various clinical manifestations of clinical TB are classified by source of infection (exogenous, endogenous, and hematogenous spread). These are linked to the clinical appearance and histology of the skin lesions. Hopefully, this will resolve the confusion created by the myriad of terms previously used in the medical literature. Once a diagnosis of cutaneous TB is entertained, a biopsy for both culture and histopathology should be submitted. In some cases histopathology may show nonspecific inflammation without classic granuloma formation. In these cases, monoclonal antibodies and polymerase chain reaction (PCR) testing may be useful. In fact, in recent years, PCR amplification has proven to be invaluable in assisting identification of M. tuberculosis from skin biopsies in patients with negative TB cultures. In most instances, treatment of cutaneous TB requires combination chemotherapy. This is especially important in patients with extra cutaneous disease, multiple skin lesions, and those with profound immunosuppression. Surgery also may play both a diagnostic and therapeutic role.

CUTANEOUS TUBERCULOSIS: A 26-YEAR RETROSPECTIVE STUDY IN AN ENDEMIC AREA OF TUBERCULOSIS, VITÓRIA, ESPÍRITO SANTO, BRAZIL

BACKGROUND

Tuberculosis is a serious health problem in Brazil so that the knowledge on the aspects of cutaneous tuberculosis is medically important.

OBJECTIVE

To assess the characteristics of patients with cutaneous tuberculosis treated at the Cassiano Antonio Moraes University Hospital, located in the city of Vitória, State of Espírito Santo, Brazil.

METHODS

This is a retrospective, descriptive, observational and cross-sectional study using the medical records of 29 patients with cutaneous tuberculosis treated at the Dermatology and Pulmonology services of the hospital from 1986 to 2011. The inclusion criterion was the confirmation of cutaneous tuberculosis taking into account clinical, epidemiological, immunological, and bacteriological findings, as well as the response to specific treatment.

RESULTS

Of the 29 studied patients; 18 (62%) were women with average age of 37 years; the predominant clinical condition was erythema induratum of Bazin in 12 (41.4%) cases; and the cutaneous lesions were in the lower limbs in 19 (65.8%) patients. Extra-cutaneous involvement occurred in eight (27.6%) cases. The tuberculin tests were positive in 15 (79%) individuals and the assessment of the infectious agent was negative in most of the investigated cases.

CONCLUSION

The study found a low frequency (0.44%) of cutaneous tuberculosis in an endemic area of tuberculosis. There was a predominance of infection in women aged thirty to forty years. Erythema induratum was the most common clinical condition, affecting mainly the lower limbs, in contrast to other Brazilian studies that found scrofuloderma as the most common manifestation, predominating in the cervical region of male children and adolescents.

Two rare cases of head and neck tuberculosis

Tuberculosis is an infectious disease, which is the leading cause of mortality and morbidity and is still a serious health concern. The fact that extra pulmonary tuberculosis does not have specific examination and radiographic findings and that clinical findings vary depending on the organ in which it is detected cause diagnostic difficulties. The head and neck region is an uncommon site for tuberculosis and tuberculosis can localise in many different places of the head and neck region. In this article, the authors present a case of nasopharyngeal tuberculosis, which clinically mimics nasopharyngeal carcinoma and rare cutaneous tuberculosis of the pinna. A wide knowledge of head and neck tuberculosis, including the disease in the differential diagnosis and carrying out microbiological examinations are necessary for accurate diagnosis.

A Case of Tuberculous Granulomatous Panniculitis without Vasculitis

We report a case of tuberculous granulomatous panniculitis without vasculitis in an 87-year-old female patient with B-cell chronic lymphocytic leukaemia. One month after starting chemotherapy with chlorambucil and prednisone she presented superficial erythematous plaques on the anterior side of the left leg. Three weeks later erythematous painless deep nodules appeared on the left popliteal fossa and on the left thigh. Cutaneous biopsy revealed granulomatous panniculitis without caseation necrosis or vasculitis. Polymerase chain reaction for Mycobacterium tuberculosis revealed positivity in the skin. The final diagnosis was reactivation of latent tuberculosis (TB) induced by deep immunosuppression associated with chemotherapy and haematological disease. Tuberculous granulomatous panniculitis without vasculitis is a rare presentation of cutaneous TB and may be part of the heterogeneous histopathologic spectrum of erythema induratum of Bazin (nodular vasculitis). Our case shows that the diagnosis of cutaneous TB requires the correlation of clinical findings with histopathology and microbiological tests.

Murine β-defensin-2 may regulate the effect of bacillus Calmette-Guérin (BCG) in normal mouse bladder

PURPOSE

We investigated whether bacillus Calmette-Guérin (BCG)-induced secretion of murine β-defensin-2 (mBD2) and determined whether mBD2 regulated BCG effects in the normal mouse bladder.

MATERIALS AND METHODS

A total of 140 C57BL/6 female mice were divided into 28 groups, and the experiment was performed over 3 steps. In the first step (20 groups), mice bladders were stimulated with different doses of BCG (multiplicity of infection [MOI] 0, 1, 10, 30, and 100) and histological analysis was conducted in bladder specimens isolated at different times (0, 4, 8, and 24h after instillation) to determine optimal dose and time point of BCG internalization and urine mBD2 and cytokine concentration. In the second step (4 groups), BCG internalization and urine cytokine levels were measured after pretreatment of different recombinant mBD2 (rmBD2) (0, 1, 2.5, and 5 ng/ml) at optimal dose and time point. In the third step (4 groups), BCG internalization and urine cytokine levels were compared between pretreatment conditions (control, rmBD2, anti-mBD2 Ab, and rmBD2+anti-mBD2 Ab). Urine was collected for estimating mBD2 levels and a multiplex analysis for 9 cytokines. Real-time polymerase chain reaction assay was used for estimating the relative BCG cell number in mice bladder tissue.

RESULTS

Bladder edema was induced by BCG (MOI 30 and 100), which progressed to an inflammatory infiltrate composed primarily of neutrophils and increased mBD2 secretion at 4 hours after instillation. Relative BCG cell number and urinary cytokine levels (interferon-γ and interleukins [IL]-2, -4, -6, and -10) response pattern was characterized by a peak at 4 hours after instillation followed by rapid decline. The levels of interferon-γ, and IL-1β, -2, -4, -6, and -10 and relative BCG cell numbers decreased in a dose-dependent manner according to pretreatment with rmBD2 protein, and the responses were potentiated in the anti-mBD2 pretreatment group at 4 hours after BCG (MOI 30) instillation.

CONCLUSION

The present results suggest that the mouse urothelium produces mBD2 in response to intravesicular BCG as a defense mechanism against BCG, and blocking mBD2 by an anti-mBD2 antibody increased the effectiveness of BCG.

Cutaneous tuberculosis: diagnosis, histopathology and treatment - part II

The evolution in the knowledge of tuberculosis' physiopathology allowed not only a better understanding of the immunological factors involved in the disease process, but also the development of new laboratory tests, as well as the establishment of a histological classification that reflects the host's ability to contain the infectious agent. At the same time, the increasing bacilli resistance led to alterations in the basic tuberculosis treatment scheme in 2009. This article critically examines laboratory and histological investigations, treatment regimens for tuberculosis and possible adverse reactions to the most frequently used drugs.

Disseminated lupus vulgaris: a case report

Lupus vulgaris is a secondary form of cutaneous tuberculosis which persists for years if not treated. The head and neck are the most commonly affected sites. While less frequently arms and legs, and rarely the trunk and the scalp are involved. Herein, we describe a 73-year-old man with a 5-year history of slowly growing, atrophic, some eroded and ulcerated, red-brown plaques on his forehead, nose, cheeks, ear lobes, trunk and extremites. All of his disseminated lesions healed after antituberculosis therapy.

Erythema induratum: case series illustrating the utility of the interferon-γ release assay in determining the association with tuberculosis

BACKGROUND

The interferon-γ release assay (IGRA) is a novel method for detecting previous sensitization to tuberculosis (TB). Despite having several advantages over the tuberculin skin test (TST), including higher specificity and no influence from past bacille Calmette-Guérin (BCG) exposure, there are a limited number of reports describing its application in patients with erythema induratum (EI)/nodular vasculitis (NV), which is usually but not always related to TB.

OBJECTIVES

The aim of our case series was to evaluate the usefulness of the IGRA for determining a TB association in patients with EI/NV.

METHODS

Retrospective chart reviews were conducted on four patients diagnosed with EI/NV at our institution in whom an IGRA had been performed.

RESULTS

All four subjects had positive TST results. The IGRA was also positive and therefore supported a link with TB in two cases. One patient responded completely to anti-TB therapy, whereas the second was lost to follow-up. Both cases unrelated to TB, by virtue of negative IGRAs, demonstrated complete response to immunosuppressive therapy (methotrexate), with one individual having failed anti-TB therapy first.

CONCLUSION

Our case series highlights the utility of the IGRA for establishing a TB association in patients with EI/NV. Although limited by a small sample size, we propose adjunctive use of this test at the time of EI/NV diagnosis, especially in the setting of previous BCG exposure, so that management can be tailored according to whether an underlying relationship with TB exists.

Delayed diagnosis of scrofuloderma misdiagnosed as a bacterial abscess

An 82-year-old woman presented with a four-month history of an ulcerative plaque overlying her left neck. This lesion had developed as a subcutaneous nodule, gradually increased in size, and evolved into ulcers. Before visiting our Dermatology clinic, the patient had been diagnosed as having a bacterial abscess, but treatments with antibiotics were unsuccessful. The presence of a purulent discharge and prominent ulceration caused further confusion as bacterial abscess, and radiologic evaluation on computed tomography also led to the possibilities of secondary lesions from an abscess or malignancy. However, the characteristic appearance of her lesion allowed us to discern cutaneous tuberculosis, especially scrofuloderma. Based on clinical examinations, staining for acid-fast bacilli, and positive findings of polymerase chain reaction, a quick diagnosis of scrofuloderma was made. After that, she was treated successfully with anti-tuberculosis therapy and the ulcer healed. Our case highlights the problem of delayed diagnosis of scrofuloderma presenting as a bacterial abscess. In conclusion, having a high index of suspicion is needed to diagnose cutaneous tuberculosis correctly.

An unusual presentation of cutaneous tuberculosis for surgeons-review of literature

Tuberculosis is one of the oldest diseases on earth. With rising trends of immunosuppressive states, the extrapulmonary manifestations of tuberculosis have emerged and are flourishing. Most often it is the systemic dissemination of the bacilli from the primary infective foci during the periods of low immunity. Cutaneous manifestation of tuberculosis in the form of injection abscess or traumatic inoculation is well known; however, sporadic occurrence of it in the form of abscess with no underlying lesions is quite rare. This would caution the treating units in the endemic areas about the possibility of tuberculosis as the disease in any inflammatory disorder of skin with acute presentations with no systemic symptoms. Only a high index of suspicion would render an early detection and recovery. Our case is one such incident.

Erythema induratum of Bazin in a child: evidence for a cell-mediated hyper-response to Mycobacterium tuberculosis

Tuberculids are chronic nodular skin eruptions believed to be a systemic reaction to Mycobacterium tuberculosis. We report on a 6-year-old boy with tender subcutaneous lesions on his legs. A tuberculin skin test resulted in 2.5 cm of induration and an interferon-gamma releasing assay was also markedly positive. A diagnosis of erythema induratum of Bazin was confirmed on skin biopsy. The patient was successfully treated with multi-drug antituberculosis therapy.

Cutaneous sterile granulomas/pyogranulomas, leishmaniasis and mycobacterial infections

Cutaneous "sterile" granulomas represent a group of uncommon skin disorders of unknown aetiopathogenesis. Many diseases are included in this group (for example, sterile granuloma/pyogranuloma syndrome and reactive histiocytosis). The definition of sterile is based on the exclusion of other possible aetiological agents (for example, microorganisms or foreign body). Many techniques are used to rule out a microbial aetiology including cytology, histology, immunohistochemistry and culture. However, some organisms are "fastidious" and difficult to culture or to identify with routine methods, and molecular studies are necessary. This is particularly true for mycobacteria (for example, canine leproid granuloma syndrome) and Leishmania. Recently, studies in human and veterinary medicine have proved the presence of microorganisms (mycobacteria and Leishmania) using a polymerase chain reaction technique in specimens previously diagnosed as sterile. Therefore, it is very important, with the development of new technologies, to use a multidisciplinary diagnostic approach to definitively rule out any microorganism before declaring a disease sterile.

Use of the real-time PCR assay in conjunction with MagNA Pure for the detection of mycobacterial DNA from fixed specimens

Tuberculosis in immunocompromised patients is often caused by Mycobacterial species other than Mycobacterium tuberculosis. Thus, detection of and differentiation between M. tuberculosis and nontuberculosis species is necessary for diagnosis of disease in these patients. Furthermore, when tissue changes show granulomatous inflammation, quick confirmation testing for mycobacterial infection is needed for conclusive diagnosis. The aim of this study was to validate the utility of a real-time polymerase chain reaction (PCR) assay in conjunction with the MagNA Pure LC automated extraction system for the detection of mycobacterial DNA from formalin-fixed, paraffin-embedded specimens. A total of 46 archived, paraffin-embedded, fixed specimens showing granulomatous inflammation were studied for mycobacterial infection by real-time PCR. Bacterial DNA was extracted and isolated using the MagNA Pure extraction system. Real-time PCR was performed on the LightCycler using the Artus Real Art Mycob Diff ASR kit from Qiagen. Thirteen of the 46 patient specimens were positive for mycobacterial infection by acid-fast bacilli (AFB) stain. Of the13 reported positive by AFB stain, 12 where positive by real-time PCR. All 13 specimens reported positive by AFB were sent for culture confirmation. Eleven of 13 were returned positive by culture. Specimens reported as negative by culture and positive by real-time PCR were confirmed positive by a second PCR method from another reference laboratory. We believe that these studies are beneficial in the differential diagnosis of mycobacterial infection from fixed tissue specimens where tuberculosis might not have been clinically initially suspected and when specimens are not suitable for microbiologic examination.

Application of real-time PCR to recognize atypical mycobacteria in archival skin biopsies: high prevalence of Mycobacterium haemophilum

Atypical mycobacterial skin infections are difficult to diagnose owing to their aspecific histopathologic presentations and to the presence of few bacteria. Therefore, these infections are often not recognized. Molecular detection of mycobacterial DNA has proven to be useful in clinical samples. The aim of this study was to investigate the incidence of mycobacterial involvement in skin biopsies showing granulomatous inflammation, using real-time polymerase chain reaction (PCR). Real-time PCR specific for the genus Mycobacterium and the species Mycobacterium avium and Mycobacterium haemophilum was performed on formalin-fixed/paraffin-embedded biopsies from patients with granulomatous inflammation of the skin, from the period 1984 to 2004. A control group was assembled from patients with proven basal cell carcinoma. Amplicons of all positive reactions were sequenced to confirm or identify the mycobacterial species. Of 30 patients, 13 (43%) were found to be positive for mycobacterial infection, of whom only 5 patients had been previously diagnosed with a mycobacterial disease. M. haemophilum was identified as the most common species (n=7). The other identified species were Mycobacterium malmoense, Mycobacterium gordonae, and Mycobacterium marinum. The results show that real-time PCR is useful in detecting mycobacterial infections in undiagnosed formalin-fixed/paraffin-embedded skin samples and that the application of molecular approaches would improve the diagnoses of mycobacterial skin infections.

Cutaneous tuberculosis

Cutaneous tuberculosis continues to be one of the most elusive and more difficult diagnoses to make for dermatologists practicing in developing countries. Not only because they have to consider a wider differential diagnosis (leishmaniasis, leprosy, actinomycosis, deep fungal infections, etc) but also because of the difficulty in obtaining a microbiological confirmation. Despite all the advances in microbiology, including sophisticated techniques such as polymerase chain reaction, the sensitivity of new methods are no better than the gold standard, that is, the isolation of Mycobacterium tuberculosum in culture. Even now, in the 21st century, we rely on methods as old as the intradermal reaction purified protein derivative (PPD) standard test and therapeutic trials, as diagnostic tools. In this situation, it is important to recognize the many clinical faces of cutaneous tuberculosis to prevent missed or delayed diagnoses.

Biofilm-related infections of cerebrospinal fluid shunts

Cerebrospinal fluid (CSF) shunts carry a high risk of complications. Infections represent a major cause of shunt failure. Diagnosis and therapy of such infections are complicated by the formation of bacterial biofilms attached to shunt surfaces. This study correlated the pathophysiology and clinical course of biofilm infections with microscopical findings on the respective shunts. Surface irregularities, an important risk-factor for shunt colonisation with bacteria, were found to increase over time because of silicone degradation. Scanning electron-microscopy (SEM) documented residual biological material (dead biofilm), which can further promote extant bacterial adhesion, on newly manufactured shunts. Clinical course and SEM both documented bacterial dissemination against CSF flow and the monodirectional valve. In all cases, biofilms grew on both the inner and outer surfaces of the shunts. Microscopy and conventional culture detected all bacterial shunt infections. Analyses of 16S rDNA sequences using conserved primers identified bacteria in only one of three cases, probably because of previous formalin fixation of the samples.