Search Results (7)

The culture confirmation of Mycobacterium tuberculosis (MTB) remains the gold standard for the diagnosis of Tuberculosis (TB) with culture conversion representing proof of cure. However, over 40% of TB samples fail to isolate MTB even though many patients remain infectious due to the presence of viable non-culturable forms. Previously, we have shown that two short cationic peptides, T14D and TB08L, induce a hormetic response at low concentrations, leading to a stimulation of growth in MTB and the related animal pathogen Mycobacterium bovis (bTB). Here, we examine these peptides showing they can influence the mycobacterial membrane integrity and function through membrane potential reduction. We also show this disruption is associated with an abnormal reduction in transcriptomic signalling from specific mycobacterial membrane sensors that normally monitor the immediate cellular environment and maintain the non-growing phenotype. We observe that exposing MTB or bTB to these peptides at optimal concentrations rapidly represses signalling mechanisms maintaining dormancy phenotypes, which leads to the promotion of aerobic metabolism and conversion into a replicative phenotype. We further show a practical application of these peptides as reagents able to enhance conventional routine culture methods by stimulating mycobacterial growth. We evaluated the ability of a peptide-supplemented sample preparation and culture protocol to isolate the MTB against a gold standard routine method tested in parallel on 255 samples from 155 patients with suspected TB. The peptide enhancement increased the sample positivity rate by 46% and decreased the average time to sample positivity of respiratory/faecal sampling by seven days. The most significant improvements in isolation rates were from sputum smear-negative low-load samples and faeces. The peptide enhancement increased sampling test sensitivity by 19%, recovery in samples from patients with a previously culture-confirmed TB by 20%, and those empirically treated for TB by 21%. We conclude that sample decontamination and culture enhancement with D-enantiomer peptides offer good potential for the much-needed improvement of the culture confirmation of TB. Full article

Tuberculosis (TB) is among the more frequent causes of death in many countries. For pulmonary TB, early diagnosis greatly increases the efficiency of therapies. Although highly sensitive tests based on nucleic acid amplification tests (NAATs) and loop-mediated isothermal amplification (TB-LAMP) are available, smear microscopy is still the most widespread diagnostics method in most low–middle-income countries, and the true positive rate of smear microscopy is lower than 65%. Thus, there is a need to increase the performance of low-cost diagnosis. For many years, the use of sensors to analyze the exhaled volatile organic compounds (VOCs) has been proposed as a promising alternative for the diagnosis of several diseases, including tuberculosis. In this paper, the diagnostic properties of an electronic nose (EN) based on sensor technology previously used to identify tuberculosis have been tested on-field in a Cameroon hospital. The EN analyzed the breath of a cohort of subjects including pulmonary TB patients (46), healthy controls (38), and TB suspects (16). Machine learning analysis of the sensor array data allows for the identification of the pulmonary TB group with respect to healthy controls with 88% accuracy, 90.8% sensitivity, 85.7% specificity, and 0.88 AUC. The model trained with TB and healthy controls maintains its performance when it is applied to symptomatic TB suspects with a negative TB-LAMP. These results encourage the investigation of electronic noses as an effective diagnostic method for future inclusion in clinical practice. Full article

The diagnosis of malaria in Honduras is based mainly on microscopic observation of the parasite in thick smears or the detection of parasite antigens through rapid diagnostic tests when microscopy is not available. The specific treatment of the disease depends exclusively on the positive result of one of these tests. Given the low sensitivity of conventional methods, new diagnostic approaches are needed. This study evaluates the in-field performance of a device (Gazelle™) based on the detection of hemozoin. This was a double-blind study evaluating symptomatic individuals with suspected malaria in the department of Gracias a Dios, Honduras, using blood samples collected from 2021 to 2022. The diagnostic performance of Gazelle™ was compared with microscopy and nested 18ssr PCR as references. The sensitivity and specificity of Gazelle™ were 59.7% and 98.6%, respectively, while microscopy had a sensitivity of 64.9% and a specificity of 100%. The kappa index between microscopy and Gazelle™ was 0.9216 using microscopy as a reference. Both methods show similar effectiveness and predictive values. No statistical differences were observed between the results of the Gazelle™ compared to light microscopy (p = 0.6831). The turnaround time was shorter for Gazelle™ than for microscopy, but the cost per sample was slightly higher for Gazelle™. Gazelle™ showed more false-negative cases when infections were caused by Plasmodium falciparum compared to P. vivax. Conclusions: The sensitivity and specificity of Gazelle™ are comparable to microscopy. The simplicity and ease of use of the Gazelle™, the ability to run on batteries, and the immediacy of its results make it a valuable tool for malaria detection in the field. However, further development is required to differentiate Plasmodium species, especially in those regions requiring differentiated treatment. Full article

Introduction: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of mediastinal lymph nodes is currently considered to be the most effective minimally invasive diagnostic method in patients with suspected stage I and II sarcoidosis. However, diagnostic effectiveness depends on the experience and skills of the doctor which is dependent on the number of correctly performed procedures. The aim of the study is to compare the diagnostic effectiveness of the EBUS-TBNA test obtained by an expert in this field vs that of his student. Material and methods: in patients with a clinical and radiological suspicion of sarcoidosis, EBUS-TBNA procedures were performed by an expert (over 1000 previously performed tests) and by his student who completed basic training (15 procedures performed). In the expert’s opinion, the student was experienced enough to perform the EBUS-TBNA on his own. Previously, more than 100 conventional fibreoptic bronchoscopies had been performed by the student. During that time, he had been working in the department of pulmonary diseases and tuberculosis for two years. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), negative likelihood ratio (LR-), and accuracy of the EBUS-TBNA test in diagnosing sarcoidosis were calculated. Statistical evaluation was made using ROC curves for the expert and for the student. Results: The study included 215 patients between 22–68 years of age with suspected sarcoidosis who were diagnosed between 2013–2016. 124 EBUS-TBNA tests were performed by the expert, and 91 procedures were performed by the student. The presence of sarcoid granulomas was confirmed by a biopsy in 165 (76.7%) patients. In terms of the diagnosis of sarcoidosis, a higher sensitivity and accuracy of the EBUS test was found in the procedures done by the expert (76.7% and 95.3%, respectively) as compared to the results obtained by the student (66.1% and 93.1%, respectively). However, these differences were not statistically significant (p = 0.11). All tests were assessed in a hospital pathology unit, but not necessarily by one person, which may be a limitation of our research. In this study, only cytological smears were taken into consideration. Conclusions: In the diagnosis of sarcoidosis, the student, after appropriate training by an expert, achieved a comparable level of diagnostic effectiveness with EBUS-TBNA after performing 90 tests independently. Full article

Leishmaniases are neglected tropical diseases of public health concern in Algeria. To update the geographical distribution of Leishmania spp. causing cutaneous affection, we examined a set of Giemsa-stained smears prepared from skin lesions of the patients suspected to have cutaneous leishmaniasis (CL) in various geographical areas in Algeria. The identification of Leishmania parasites was performed using microscopy, conventional PCR, and PCR–RFLP (PCR-Restriction Fragment Length Polymorphism) targeting ITS1-rDNA. Among 32 smears provided from 27 suspected patients with cutaneous lesions, no trace of parasites was observed in the smear of three patients using microscopy and molecular approaches. Furthermore, four patients presented at least two lesions. PCR–RFLP confirmed the presence of Leishmania in 29 smears prepared from 24 patients. Two biopsies, negative after microscopic examination, were found positive by PCR. Of these 29 PCR positive smears (24 patients), 20 were identified using RFLP–PCR as L. major, two as L. tropica, and two as L. infantum. We found L. major infected patients from Ain skhouna, Biskra, El M’hir, Ghardaïa, M’Sila, and Saida, in agreement with previously reported cases. Furthermore, we highlighted for the first time, the identification of L. major in the patients from Bourkika, Bou Kremissa, Bou Saada Clef, Hajout, Maghnia, Médéa, Menaceur, Messad, Mostaghanem, Nador, Oran, and Sidi Okba. A phylogenetic reconstruction performed with sequences collected from the PCR products confirmed these identifications. Our data provide additional information on the geographical extension of CL caused by L. tropica and L. infantum in Algeria. Full article

As a strategy to improve the sensitivity of nucleic acid-based testing in acid-fast bacilli (AFB) negative samples, larger volumes of sputum (5–10 mL) were tested with Xpert^® MTB/RIF from 176 individuals with smear-negative sputum undergoing tuberculosis evaluation. Despite larger volumes, this strategy had a suboptimal sensitivity of 50% (4/8). Full article

Background: Tuberculosis is a major public health problem. Almost 30% of cases of tuberculosis are known to be sputum smear negative. There is a diagnostic dilemma in such cases leading to inadvertent delays in management of these cases. The present study was planned to assess the role of bronchoscopy in immediate diagnosis of smear negative pulmonary tuberculosis. Material and Methods: The present study is a retrospective analysis of 132 sputum smear negative tuberculosis suspects who underwent bronchoscopic evaluation during the period 2002–2013. The diagnosis of tuberculosis was based on the finding of bacilli in aspirate or in tissue biopsy or the demonstration of caseous necrosis on tissue biopsy. Results: The present study showed that bronchoscopy could lead to immediate, accurate diagnosis in 68.2% of suspected smear negative cases. Bronchial aspirate and bronchoalveolar lavage alone were diagnostic in 51.5% of such cases while tissue biopsy added to the yield in another 16.5% cases. Conclusions: The results of the present study suggests an important place of bronchoscopy in immediate diagnosis of suspected smear negative tuberculosis, thus avoiding inadvertent delays in diagnosing and instituting appropriate treatment. Full article