Detection of Mtb and NTM: preclinical validation of a new asymmetric PCR-binary deoxyribozyme sensor assay.

Tuberculosis (TB) and infectious diseases caused by non-tuberculous mycobacteria (NTM) are global concerns. The development of a rapid and accurate diagnostic method, capable of detecting and identifying different mycobacteria species, is crucial. We propose a molecular approach, the BiDz-TB/NTM, based on the use of binary deoxyribozyme (BiDz) sensors for the detection of Mycobacterium tuberculosis (Mtb) and NTM of clinical interest. A panel of DNA samples was used to evaluate Mtb-BiDz, Mycobacterium abscessus/Mycobacterium chelonae-BiDz, Mycobacterium avium-BiDz, Mycobacterium intracellulare/Mycobacterium chimaera-BiDz, and Mycobacterium kansasii-BiDz sensors in terms of specificity, sensitivity, accuracy, and limit of detection. The BiDz sensors were designed to hybridize specifically with the genetic signatures of the target species. To obtain the BiDz sensor targets, amplification of a fragment containing the hypervariable region 2 of the 16S rRNA was performed, under asymmetric PCR conditions using the reverse primer designed based on linear-after-the-exponential principles. The BiDz-TB/NTM was able to correctly identify 99.6% of the samples, with 100% sensitivity and 0.99 accuracy. The individual values of specificity, sensitivity, and accuracy, obtained for each BiDz sensor, satisfied the recommendations for new diagnostic methods, with sensitivity of 100%, specificity and accuracy ranging from 98% to 100% and from 0.98 to 1.0, respectively. The limit of detection of BiDz sensors ranged from 12 genome copies (Mtb-BiDz) to 2,110 genome copies (Mkan-BiDz). The BiDz-TB/NTM platform would be able to generate results rapidly, allowing the implementation of the appropriate therapeutic regimen and, consequently, the reduction of morbidity and mortality of patients.IMPORTANCEThis article describes the development and evaluation of a new molecular platform for accurate, sensitive, and specific detection and identification of Mycobacterium tuberculosis and other mycobacteria of clinical importance. Based on BiDz sensor technology, this assay prototype is amenable to implementation at the point of care. Our data demonstrate the feasibility of combining the species specificity of BiDz sensors with the sensitivity afforded by asymmetric PCR amplification of target sequences. Preclinical validation of this assay on a large panel of clinical samples supports the further development of this diagnostic tool for the molecular detection of pathogenic mycobacteria.

Beyond conventional approaches: Enhancing photodynamic therapy for refractory feline sporotrichosis caused by Sporothrix brasiliensis.

Male cat, 2 years old, with a refractory infection by Sporothrix brasiliensis, presents a single nodular lesion in the left auricular pavilion. To confirm the diagnosis, cytology, fungal culture, antifungal susceptibility test, molecular analysis, and, to aid in the differential diagnosis, bacterial culture, antibiogram, and histopathology of the lesion were performed. In the absence of therapeutic success with conventional antifungals, photodynamic therapy (PDT) was introduced, demonstrating a satisfactory response in the sixth treatment session.

Description of new species of Mycobacterium terrae complex isolated from sewage at the São Paulo zoological park foundation in Brazil.

Five mycobacterial isolates from sewage were classified as members of the genus Mycobacterium but presented inconclusive species assignments. Thus, the isolates (MYC017, MYC098, MYC101, MYC123 and MYC340) were analyzed by phenotypical, biochemical, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and genomic features to clarify their taxonomic position. Phenotypic analysis and biochemical tests did not distinguish these isolates from other non-pigmented mycobacteria. In contrast, MALDI-TOF MS analysis showed that isolates were not related to any previously described Mycobacterium species. Comparative genomic analysis showed values of ANI and dDDH between 81.59-85.56% and 24.4-28.8%, respectively, when compared to the genomes of species of this genus. In addition, two (MYC101 and MYC123) presented indistinguishable protein spectra from each other and values of ANI = 98.57% and dDDH = 97.3%, therefore being considered as belonging to the same species. Phylogenetic analysis grouped the five isolates within the Mycobacterium terrae complex (MTC) but in a specific subclade and separated from the species already described and supported by 100% bootstrap value, confirming that they are part of this complex but different from earlier described species. According to these data, we propose the description of four new species belonging to the Mycobacterium genus: (i) Mycobacterium defluvii sp. nov. strain MYC017T (= ATCC TSD-296T = JCM 35364T), (ii) Mycobacterium crassicus sp. nov. strain MYC098T (= ATCC TSD-297T = JCM 35365T), (iii) Mycobacterium zoologicum sp. nov. strain MYC101T (= ATCC TSD-298T = JCM 35366T) and MYC123 (= ATCC BAA-3216 = JCM 35367); and (iv) Mycobacterium nativiensis sp. nov. strain MYC340T (= ATCC TSD-299T = JCM 35368T).

Repurposing Benzimidazoles against Causative Agents of Chromoblastomycosis: Albendazole Has Superior In Vitro Activity Than Mebendazole and Thiabendazole.

Chromoblastomycosis (CBM) is a neglected human implantation mycosis caused by several dematiaceous fungal species. Currently available therapy is usually associated with physical methods, especially surgery, and with high refractoriness. Therefore, drug discovery for CBM is essential. Drug repositioning is a strategy used to facilitate the discovery of new treatments for several diseases. The aim of this study was to discover substances with antifungal activity against CBM agents from a collection of drugs previously approved for use in human diseases. A screening was performed with the NIH Clinical Collection against Fonsecaea pedrosoi. Ten substances, with clinical applicability in CBM, inhibited fungal growth by at least 60%. The minimum inhibitory concentration (MIC) of these substances was determined against other CBM agents, and the benzimidazoles albendazole, mebendazole and thiabendazole presented the lowest MIC values. The selectivity index, based on MIC and cytotoxicity of these substances, revealed albendazole to be more selective. To investigate a possible synergism of this benzimidazole with itraconazole and terbinafine, the chequerboard method was used. All interactions were classified as indifferent. Our current results suggest that benzimidazoles have repositioning potential against CBM agents. Albendazole seems to be the most promising, since it presented the highest selectivity against all dematiaceous fungi tested.

Drug susceptibility profile of Mycobacterium kansasii clinical isolates from Brazil.

OBJECTIVES: Mycobacterium kansasii (M. kansasii) pulmonary infection can cause disease with clinical and radiological features similar to tuberculosis. Failure to treat M. kansasii infection is usually associated with resistance; to increase the chance of successful treatment it is important to identify the species and know the susceptibility profile. This study aimed to evaluate the antimycobacterial susceptibility profiles of M. kansasii isolates from Brazil. METHODS: Sixty-nine M. kansasii isolates from 69 patients were identified by partial sequencing of the hsp65 gene, and their susceptibility profiles were analysed by minimal inhibitory concentration (MIC) assays. RESULTS: From 69 isolates, 68 showed susceptibility to clarithromycin, amikacin, and moxifloxacin. Most strains showed high rates of resistance to trimethoprim-sulfamethoxazole and ciprofloxacin. Resistance to rifampicin and ethambutol was found in 12% and 25% of isolates, respectively. CONCLUSIONS: Worrying results were found regarding susceptibility to some drugs used as first-line agents in the treatment of diseases caused by M. kansasii.

Mortality in patients with HIV-1 and tuberculosis co-infection in Rio de Janeiro, Brazil - associated factors and causes of death.

BACKGROUND: Tuberculosis is the most frequent opportunistic infection and the leading cause of death among persons living with HIV in several low and middle-income countries. Mortality rates during tuberculosis treatment and death causes among HIV-1/TB co-infected patients may differ based on the immunosuppression severity, timing of diagnosis and prompt initiation of tuberculosis and antiretroviral therapy. METHODS: This was a retrospective observational study conducted in the clinical cohort of patients with HIV-1/Aids of the National Institute of Infectious Diseases Evandro Chagas, Rio de Janeiro, Brazil. All HIV-1 infected patients who started combination antiretroviral therapy up to 30 days before or within 180 days after the start of tuberculosis treatment from 2000 to 2010 were eligible. Causes of death were categorized according to the "Coding Causes of Death in HIV" (CoDe) protocol. The Cox model was used to estimate the hazard ratio (HR) of selected mortality variables. RESULTS: A total of 310 patients were included. Sixty-four patients died during the study period. Mortality rate following tuberculosis treatment initiation was 44 per 100 person-years within the first 30 days, 28.1 per 100 person-years within 31 and 90 days, 6 per 100 person-years within 91 and 365 days and 1.6 per 100 person-years after 365 days. Death probability within one year from tuberculosis treatment initiation was approximately 13%. In the adjusted analysis the associated factors with mortality were: CD4 ≤ 50 cells/mm3 (HR: 3.10; 95% CI: 1.720 to 5.580; p = 0.00); mechanical ventilation (HR: 2.81; 95% CI: 1.170 to 6.760; p = 0.02); and disseminated tuberculosis (HR: 3.70; 95% CI: 1.290 to 10.590, p = 0.01). Invasive bacterial disease was the main immediate cause of death (46.9%). CONCLUSION: Our results evidence the high morbidity and mortality among patients co-infected with HIV-1 and tuberculosis in Rio de Janeiro, Brazil. During the first year following tuberculosis diagnosis, mortality was the highest within the first 3 months, being invasive bacterial infection the major cause of death. In order to successfully intervene in this scenario, it is utterly necessary to address the social determinants of health contributing to the inequitable health care access faced by this population.

Accuracy of polimerase chain reaction for the diagnosis of pleural tuberculosis.

INTRODUCTION: Polymerase chain reaction (PCR)-based techniques to detect Mycobacterium tuberculosis DNA in respiratory specimens have been increasingly used to diagnose pulmonary tuberculosis. Their use in non-respiratory specimens to diagnose extrapulmonary tuberculosis is, however, controversial. In this study, we estimated the accuracy of three in-country commercialized PCR-based diagnostic techniques in pleural fluid samples for the diagnosis of pleural tuberculosis. METHODS: Patients underwent thoracenthesis for diagnosis purposes; pleural fluid aliquots were frozen and subsequently submitted to two real time PCR tests (COBAS(®)TAQMAN(®)MTB and Xpert(®)MTB/Rif) and one conventional PCR test (Detect-TB(®)). Two different reference standards were considered: probable tuberculosis (based on clinical grounds) and confirmed tuberculosis (bacteriologically or histologically). RESULTS: Ninety-three patients were included, of whom 65 with pleural tuberculosis, 35 of them confirmed. Sensitivities were 29% for COBAS(®)TAQMAN(®)MTB, 3% for Xpert(®)MTB/Rif and 3% for Detect-TB(®); specificities were 86%, 100% and 97% respectively, considering confirmed tuberculosis. Considering all cases, sensitivities were 16%, 3% and 2%, and specificities, 86%, 100%, and 97%. DISCUSSION: Compared to the 95% sensitivity of adenosine deaminase, the most sensitive test for pleural tuberculosis, the sensitivities of the three PCR-based tests were very low. We conclude that at present, there is no major place for such tests in routine clinical use.

Synthesis and antimycobacterial activity of novel amino alcohols containing central core of the anti-HIV drugs lopinavir and ritonavir.

Eleven new amino alcohol derivatives have been synthesized from reactions of lopinavir intermediate and heteroaromatic aldehyde in good yields. These compounds, the antiretrovirals (lopinavir and ritonavir) and lopinavir key intermediate were evaluated as antibacterial agents against Mycobacterium tuberculosis H37Rv using the Alamar Blue susceptibility test and their activity expressed as the minimum inhibitory concentration (MIC) in µM. Ten amino alcohols evaluated displayed significant activity (MIC between 6.15 and 108.4 µM) when compared to first-line drug ethambutol (MIC = 15.9 µM). Three of them showed more activity than ethambutol (MIC = 6.15; 6.21 and 13.4 µM). The appreciable activity of these compounds can be considered an important finding for the rational design of new leads for anti-TB compounds.