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.

2,3,5-triphenyl tetrazolium chloride as colorimetric indicator for drug susceptibility testing against nontuberculous mycobacteria.

This study aimed to propose and evaluate a drug susceptibility testing (DST) using the 2,3,5-triphenyl tetrazolium chloride (TTC) as a colorimetric indicator against Mycobacterium abscessus complex (MABC), M. avium complex (MAC), and M. kansasii strains, main nontuberculous mycobacteria (NTM) of clinical relevance. Our results demonstrated that the assay using TTC and the broth microdilution method recommended by the Clinical and Laboratory Standards Institute had essential agreement above 91%, 92%, and 100%, for drugs tested against MABC, MAC, and M. kansasii strains, respectively. Categorical agreement above 91% was obtained for most drugs tested against MABC, except to cefoxitin (76.5%). For drugs tested against MAC and M. kansasii, categorical agreement above 92% and 100% was observed, respectively. TTC showed to be a promising colorimetric indicator of growth to be used in DST for NTM, allowing an easier reading of results.

Genotyping methods and their contributions to the study of tuberculosis dynamic in Latin America.

INTRODUCTION: Mycobacterium tuberculosis genotyping has impacted evolutionary studies worldwide. Nonetheless, its application and the knowledge generated depend on the genetic marker evaluated and the detection technologies that have evolved over the years. Here we describe the timeline of main genotypic methods related to M. tuberculosis in Latin America and the main findings obtained. METHODOLOGY: Systematic searches through the PubMed database were performed from 1993 to May 2021. A total of 345 articles met the inclusion criteria and were selected. RESULTS: Spacer oligonucleotide typing (spoligotyping) was the most widely used method in Latin America, with decreasing use in parallel with increasing use of mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) and whole genome sequencing (WGS). Among the countries, Brazil, Mexico, and Argentina had the most publications, and a considerable part of the articles were in collaboration with Latin American or non-Latin American institutions; a small proportion of studies needed partnerships to perform the genotypic methods. The genotypic methods allowed the identification of M. tuberculosis genotypes with greater capacity for clonal expansion and revealed the predominance of the Euro-American lineage in Latin America. There was a notable presence of the Beijing family in Peru and Colombia. CONCLUSIONS: The data obtained demonstrated the importance of expanding collaborative networks of tuberculosis (TB) research groups to countries with low productivity in this area, the commitment of the few Latin American countries to advance TB research, as well as the inestimable value of building a Latin America database, considering ease of population mobility between countries.

Rapid identification of Mycobacterium tuberculosis in cultures by molecular and immunological methods / Identificação rápida de Mycobacterium tuberculosis em culturas por método molecular e método imunológico

Objective: The study aimed to evaluate molecular and immunological methods and to propose a workflow using them for tuberculosis (TB) diagnosis routine. Methods: A cross-sectional retrospective study was performed, including 121 liquid cultures from a TB laboratory located in the extreme south of Brazil. All cultures were positive for Mycobacterium tuberculosis complex (MTBC) by in-house Polymerase Chain Reaction (PCR) using DNA extracted by the CTAB method (PCR-CTAB) for IS6110 detection. These cultures were subjected to faster tests than this one, the immunological MPT64 assay and the PCR using DNA extracted by thermal lysis method (PCR-TL), and these were evaluated for MTBC identification using PCR-CTAB as a reference method. Results: The sensitivity of MPT64 assay and PCR-TL to identify MTBC in positive cultures by PCR-CTAB were 73.6% (89/121) and 98.3% (119/121), respectively. We proposed a workflow based on the use of MPT64 assay in liquid cultures suggestive of MTBC, and in case of a negative result, we suggest the performance of PCR-TL. The PCR-CTAB is suggested only if faster tests are negative. Conclusions: Methods capable of confirming MTBC in cultures should continue to be standardized, tested, and optimized to meet the ideal requirements of simplicity, quickness, and effectiveness. The molecular and immunological methods evaluated have differences in the execution and detection of MTBC in cultures, but they are rapid tools for laboratory TB diagnosi

Objetivos: O estudo objetivou avaliar métodos molecular e imunológico e propor um fluxo de trabalho utilizando-os para a rotina de diagnóstico da tuberculose (TB). Métodos: Foi realizado um estudo transversal retrospectivo, incluindo 121 culturas líquidas de um laboratório de TB localizado no extremo sul do Brasil. Todas as culturas foram positivas para o complexo Mycobacterium tuberculosis (CMTB) por Reação em Cadeia da Polimerase (PCR) in-house para detecção do IS6110, usando DNA extraído pelo método CTAB (PCR-CTAB). Essas culturas foram submetidas a testes mais rápidos que este, o ensaio imunológico MPT64 e a PCR com DNA extraído pelo método de lise térmica (PCR-LT), e estas foram avaliadas para identificação de CMTB usando PCR-CTAB como método de referência. Resultados: A sensibilidade do ensaio MPT64 e da PCR-LT para identificar o CMTB em culturas positivas pela PCRCTAB foi de 73,6% (89/121) e 98,3% (119/121), respectivamente. Propusemos um fluxo de trabalho baseado no uso do ensaio MPT64 em culturas líquidas sugestivas de CMTB e, em caso de resultado negativo, sugerimos a realização de PCR-LT. Sugere-se a PCR-CTAB apenas se os testes mais rápidos forem negativos. Conclusões: Os métodos capazes de confirmar o CMTB em culturas devem continuar sendo padronizados, testados e otimizados para atender aos requisitos ideais de simplicidade, rapidez e eficácia. Os métodos molecular e imunológico avaliados apresentam diferenças na execução e detecção do CMTB em culturas, mas são ferramentas rápidas para o diagnóstico laboratorial da TB.

Thesis and dissertations examining tuberculosis in Brazil between 2013 and 2019: an overview.

BACKGROUND: Tuberculosis (TB) remains a serious public health problem, with approximately 10 million new cases reported annually. Knowledge about the quantitative evolution of theses and dissertations (T&Ds) examining human TB in Brazil can contribute to generating strategic planning for training professionals in this field and disease control. Therefore, this study highlights the role of T&Ds on TB in national scientific disclosures. METHODS: An integrative review related to TB was performed, including T&Ds produced in Brazil and completed between 2013 and 2019. RESULTS: A total of 559,457 T&Ds were produced, of which 1,342 were associated with TB, accounting for 0.24% of the total number of T&Ds in Brazil. This was evidenced by a predominance of themes such as attention/health care, epidemiology, and TB treatment, and 80.2% of the T&Ds on TB were related to the large areas of health and biological sciences. Only 19.7% of T&Ds were associated with groups of patients considered at risk for TB, and 50.9% were produced in southeastern Brazil. The 1,342 T&Ds on TB were developed in 416 postgraduate programs linked to 121 higher education institutions (HEIs). We highlight that 72.7% of T&Ds on TB were produced in federal HEIs, 27.4% in state HEIs, and 8.5% in private HEIs. CONCLUSIONS: Strategic themes, such as TB control, require public policies that aim to increase the number of doctors and masters with expertise in TB, with geographic uniformity, and in line with the priorities for disease control.

Thesis and dissertations examining tuberculosis in Brazil between 2013 and 2019: an overview

ABSTRACT Background: Tuberculosis (TB) remains a serious public health problem, with approximately 10 million new cases reported annually. Knowledge about the quantitative evolution of theses and dissertations (T&Ds) examining human TB in Brazil can contribute to generating strategic planning for training professionals in this field and disease control. Therefore, this study highlights the role of T&Ds on TB in national scientific disclosures. Methods: An integrative review related to TB was performed, including T&Ds produced in Brazil and completed between 2013 and 2019. Results: A total of 559,457 T&Ds were produced, of which 1,342 were associated with TB, accounting for 0.24% of the total number of T&Ds in Brazil. This was evidenced by a predominance of themes such as attention/health care, epidemiology, and TB treatment, and 80.2% of the T&Ds on TB were related to the large areas of health and biological sciences. Only 19.7% of T&Ds were associated with groups of patients considered at risk for TB, and 50.9% were produced in southeastern Brazil. The 1,342 T&Ds on TB were developed in 416 postgraduate programs linked to 121 higher education institutions (HEIs). We highlight that 72.7% of T&Ds on TB were produced in federal HEIs, 27.4% in state HEIs, and 8.5% in private HEIs. Conclusions: Strategic themes, such as TB control, require public policies that aim to increase the number of doctors and masters with expertise in TB, with geographic uniformity, and in line with the priorities for disease control.

Whole-genome sequencing as a tool for studying the microevolution of drug-resistant serial Mycobacterium tuberculosis isolates.

Treatment of drug-resistant tuberculosis requires extended use of more toxic and less effective drugs and may result in retreatment cases due to failure, abandonment or disease recurrence. It is therefore important to understand the evolutionary process of drug resistance in Mycobacterium tuberculosis. We here in describe the microevolution of drug resistance in serial isolates from six previously treated patients. Drug resistance was initially investigated through phenotypic methods, followed by genotypic approaches. The use of whole-genome sequencing allowed the identification of mutations in the katG, rpsL and rpoB genes associated with drug resistance, including the detection of rare mutations in katG and mixed populations of strains. Molecular docking simulation studies of the impact of observed mutations on isoniazid binding were also performed. Whole-genome sequencing detected 266 single nucleotide polymorphisms between two isolates obtained from one patient, suggesting a case of exogenous reinfection. In conclusion, sequencing technologies can detect rare mutations related to drug resistance, identify subpopulations of resistant strains, and identify diverse populations of strains due to exogenous reinfection, thus improving tuberculosis control by guiding early implementation of appropriate clinical and therapeutic interventions.

Genomic-based surveillance reveals high ongoing transmission of multi-drug-resistant Mycobacterium tuberculosis in Southern Brazil.

Genomic-based surveillance on the occurrence of drug resistance and its transmission dynamics has emerged as a powerful tool for the control of tuberculosis (TB). A whole-genome sequencing approach, phenotypic testing and clinical-epidemiological investigation were used to undertake a retrospective population-based study on drug-resistant (DR)-TB in Rio Grande do Sul, the largest state in Southern Brazil. The analysis included 305 resistant Mycobacterium tuberculosis strains sampled statewide from 2011 to 2014, and covered 75.7% of all DR-TB cases identified in this period. Lineage 4 was found to be predominant (99.3%), with high sublineage-level diversity composed mainly of 4.3.4.2 [Latin American and Mediterranean (LAM)/RD174], 4.3.3 (LAM/RD115) and 4.1.2.1 (Haarlem/RD182) sublineages. Genomic diversity was also reflected in resistance of the variants to first-line drugs. A large number of distinct resistance-conferring mutations, including variants that have not been reported previously in any other setting worldwide, and 22 isoniazid-monoresistant strains with mutations described as disputed in the rpoB gene but causing rifampicin resistance generally missed by automated phenotypic tests as BACTEC MGIT. Using a cut-off of five single nucleotide polymorphisms, the estimated recent transmission rate was 55.1%, with 168 strains grouped into 28 genomic clusters. The most worrying fact concerns multi-drug-resistant (MDR) strains, of which 73.4% were clustered. Different resistance profiles and acquisition of novel mutations intraclusters revealed important amplification of resistance in the region. This study described the diversity of M. tuberculosis strains, the basis of drug resistance, and ongoing transmission dynamics across the largest state in Southern Brazil, stressing the urgent need for MDR-TB transmission control state-wide.

Tuberculosis cases in a prison in the extreme south of Brazil.

Introduction. Tuberculosis (TB) control is a challenge, especially in vulnerable populations, such as prisoners.Hypothesis. In prison houses, the transmission of micro-organisms that cause infectious diseases can occur due to the susceptibility and immune compromise of prisoners, and due to the precarious physical conditions of the prison houses. However, strategies such as monitoring by health professionals, can mitigate the transmission of these micro-organisms, as well as, reduce the number of coinfections and antimicrobials resistance.Aim. This study attempted to analyse the dynamics of transmission and the antimicrobial resistance profile of Mycobacterium tuberculosis strains obtained from prisoners and to characterize the epidemiological, clinical and laboratory profiles of prisoners diagnosed with TB.Methodology. A cross-sectional and retrospective study was conducted with sputum samples collected from 228 distinct prisoners who were treated at the Health Unit located in the Regional Penitentiary of Rio Grande, Rio Grande do Sul, Brazil. The antimicrobial resistance profile of the strains was evaluated using the Resazurin Microtiter Assay and the transmission dynamics was investigated using 15-loci MIRU-VNTR.Results. Thirty-five patients (15.4 %) were diagnosed with TB, and when a TB/HIV coinfection was assessed, 8.6 % (3/35) of the patients were positive. In addition, all patients with results available for HBV, HCV, syphilis and diabetes mellitus were negative. Based on the genotypic profile, 55.9 % of the clinical isolates were grouped into five groups. One isolate with mono-resistance to isoniazid and two with mono-resistance to streptomycin were found.Conclusion. The presence of a Health Unit may have influenced the low numbers of TB/HIV, TB/HBV, TB/HCV, TB/syphilis coinfections and TB cases resistant to antimicrobials. Recent M. tuberculosis transmission can be inferred based on the high percentage of formatting of clusters. This situation stresses the need to improve active and passive detection, the screening of individuals for TB upon entrance into prison for early detection, and the implementation of prophylactic measures to reduce M. tuberculosis transmission.

A highly rifampicin resistant Mycobacterium tuberculosis strain emerging in Southern Brazil.

Here we described phenotypical, molecular and epidemiological features of a highly rifampicin-resistant Mycobacterium tuberculosis strain emerging in Southern Brazil, that carries an uncommon insertion of 12 nucleotides at the codon 435 in the rpoB gene. Employing a whole-genome sequencing-based study on drug-resistant Mycobacterium tuberculosis strains, we identified this emergent strain in 16 (9.19%) from 174 rifampicin-resistant clinical strains, all of them belonging to LAM RD115 sublineage. Nine of these 16 strains were available to minimum inhibitory concentration determination and for all of them was found a high rifampicin-resistance level (≥to 32 mg/L). This high resistance level could be explained by structural changes into the RIF binding site of RNA polymerase caused by the insertions, and consequent low-affinity interaction with rifampicin complex confirmed through protein modeling and molecular docking simulations. Epidemiological investigation showed that most of the individuals (56.25%) infected by the studied strains were prison inmate individuals or that spent some time in prison. The phylogenomic approach revealed that strains carrying on insertion belonged to same genomic cluster, evidencing a communal transmission chain involving inmate individuals and community. We stress the importance of tuberculosis genomic surveillance and introduction of measures to interrupt Mycobacterium tuberculosis transmission chain in this region.

Laboratory diagnosis for Covid-19: A mini-review.

Coronavirus disease (COVID-19) is a pandemic caused by a new coronavirus, called SARS-CoV-2. This disease was first identified in December 2019 and rapidly developed into a challenge to the public health systems around the world. In the absence of a vaccine and specific therapies, disease control and promotion of patient health are strongly dependent on a rapid and accurate diagnosis. This review describes the main laboratory approaches to making a diagnosis of COVID-19 and identifying those previously infected with SARS-CoV-2.

Prevalence and associated factors with depression and anxiety in prisoners in South of Brazil

Abstract Background Brazil has the third largest prison population in the world. Research in the world has confirmed a high prevalence of mental disorders in this population. Objective To identify prevalence and associated factors with depression and anxiety in prisoners of the closed prison system. Methods This is a cross-sectional study with 643 prisoners were interviewed in six prisons in Rio Grande do Sul, Brazil. To evaluate depression and anxiety, the Mini International Neuropsychiatric Interview 5.0 (MINI) was used and sociodemographic, inprisonment and lifestyle habits variables were also collected. Results The prevalence of depression found in the study was 20.6% (95% CI: 17.5-23.8) and of anxiety was 19.9% (95% CI: 16.8-23.0). The following were identified as risk factors for depression: being female, having a history of mental illness, non-white skin color, having a religion, not receiving visits, smoking, using drugs and not performing physical activities. Risk factors for anxiety were: being female, having a history of mental illness, a family history of mental illness, smoking and using drugs. Discussion The study confirmed the high rates of depression and anxiety in the population deprived of liberty. In addition, women were twice as likely to have both disorders compared to men.

First insights into circulating XDR and pre-XDR Mycobacterium tuberculosis in Southern Brazil.

Drug-resistant tuberculosis (DR-TB) is major problem in the fight against TB. Multidrug resistant (MDR) TB patients have a reduced treatment success rates and for, extensively drug-resistant (XDR) TB the cure rate does not exceed 25% in many countries. To evaluate the pre-XDR-TB and XDR-TB prevalence and transmission in Rio Grande do Sul State, in southern Brazil, we performed a retrospective WGS-based analysis of 87 MDR-TB cases, aiming to identify resistance-conferring mutations and its phylogenetic distinctiveness. Using a five SNP threshold for genomic clustering, 60 strains were genomically linked within 10 clusters, including 14 likely transmission events identified by retrospective conventional epidemiological investigation. Moreover, five likely transmission events involved 17 patients deprived of liberty in the same prison establishment. Mutations associated with isoniazid and rifampicin resistance were identified respectively in 97.70% and 98.85% of MDR M.tb strains, more frequently in katG and rpoB genes. In total, we identified eight (9.19%) pre-XDR and four (4.59%) XDR M.tb strains. Resistance to ofloxacin was observed in seven (8.04%) strains, all of them presenting resistance-conferring mutations. Phenotypic resistance from capreomycin and kanamycin was found in seven (8.04%) and four (4.59%) strains respectively, but no classic mutations associated with resistance to these drugs was identified. The results put in evidence a scenario involving multiple phylogenetically distinctive clades associated with pre-XDR and XDR-TB in the largest state of southern Brazil, while stressing the potential of using WGS to predict anti-TB drug resistance and need to halt MDR-TB transmission in the region.

Laboratory diagnosis for Covid-19: A mini-review

Abstract Coronavirus disease (COVID-19) is a pandemic caused by a new coronavirus, called SARS-CoV-2. This disease was first identified in December 2019 and rapidly developed into a challenge to the public health systems around the world. In the absence of a vaccine and specific therapies, disease control and promotion of patient health are strongly dependent on a rapid and accurate diagnosis. This review describes the main laboratory approaches to making a diagnosis of COVID-19 and identifying those previously infected with SARS-CoV-2.

Tuberculosis caused by Mycobacterium pinnipedii in a wild South American sea lion Otaria flavescens stranded in southern Brazil.

Tuberculosis (TB) in pinnipeds is typically caused by Mycobacterium pinnipedii, which has also been associated with infections in other species, such as cattle and humans. As a result, this pathogen has zoonotic potential and is a public health concern. In 2016, a female South American sea lion Otaria flavescens in southern Brazil presented with emaciation and severe dyspnea and died within 3 h of capture. Gross pathology identified pulmonary granulomas, and Ziehl-Neelsen stain identified acid-fast bacilli. M. tuberculosis complex bacteria were confirmed by a BD BACTEC™ MGIT™ 320 detection system using fibrinous exudate, lung granulomas and thoracic fluid. Molecular characterization by spoligotyping showed a hybridization pattern characteristic of M. pinnipedii (SIT593/PINI1). Currently, there is a paucity of data concerning the transmission and epidemiology of M. pinnipedii in pinniped populations in South America. The case report shows that the disease appeared in a free-ranging beached sea lion on the coast, and further surveillance is needed to determine the origin of this TB because of its potential impact on public health.

Molecular drug susceptibility testing and strain typing of tuberculosis by DNA hybridization.

In Mycobacterium tuberculosis (Mtb) the detection of single nucleotide polymorphisms (SNPs) is of high importance both for diagnostics, since drug resistance is primarily caused by the acquisition of SNPs in multiple drug targets, and for epidemiological studies in which strain typing is performed by SNP identification. To provide the necessary coverage of clinically relevant resistance profiles and strain types, nucleic acid-based measurement techniques must be able to detect a large number of potential SNPs. Since the Mtb problem is pressing in many resource-poor countries, requiring low-cost point-of-care biosensors, this is a non-trivial technological challenge. This paper presents a proof-of-concept in which we chose simple DNA-DNA hybridization as a sensing principle since this can be transferred to existing low-cost hardware platforms, and we pushed the multiplex boundaries of it. With a custom designed probe set and a physicochemical-driven data analysis it was possible to simultaneously detect the presence of SNPs associated with first- and second-line drug resistance and Mtb strain typing. We have demonstrated its use for the identification of drug resistance and strain type from a panel of phylogenetically diverse clinical strains. Furthermore, reliable detection of the presence of a minority population (<5%) of drug-resistant Mtb was possible.

Antimicrobial and Efflux Inhibitor Activity of Usnic Acid Against Mycobacterium abscessus.

New drugs are needed to treat infections with antimicrobial-resistant Mycobacterium abscessus; therefore, we evaluated usnic acid as an antimicrobial agent and efflux inhibitor (EI) against M. abscessus. Usnic acid showed antimicrobial activity, and synergistically, the EI verapamil increased this activity. In addition, when we evaluated the interaction of antimicrobials with usnic acid, the increase of their activity was observed. Finally, usnic acid showed an efflux inhibitory effect between the classical EIs verapamil and carbonyl cyanide m-chlorophenylhydrazine. In conclusion, usnic acid showed both antimicrobial and EI activity, indicating that this natural compound may be a promising scaffold for new drugs against this difficult-to-treat microorganism.

Multiplex detection of extensively drug resistant tuberculosis using binary deoxyribozyme sensors.

Current diagnostic tools for Mycobacterium tuberculosis (Mtb) have many disadvantages including low sensitivity, slow turnaround times, or high cost. Accurate, easy to use, and inexpensive point of care molecular diagnostic tests are urgently needed for the analysis of multidrug resistant (MDR) and extensively drug resistant (XDR) Mtb strains that emerge globally as a public health threat. In this study, we established proof-of-concept for a novel diagnostic platform (TB-DzT) for Mtb detection and the identification of drug resistant mutants using binary deoxyribozyme sensors (BiDz). TB-DzT combines a multiplex PCR with single nucleotide polymorphism (SNP) detection using highly selective BiDz sensors targeting loci associated with species typing and resistance to rifampin, isoniazid and fluoroquinolone antibiotics. Using the TB-DzT assay, we demonstrated accurate detection of Mtb and 5 mutations associated with resistance to three anti-TB drugs in clinical isolates. The assay also enables detection of a minority population of drug resistant Mtb, a clinically relevant scenario referred to as heteroresistance. Additionally, we show that TB-DzT can detect the presence of unknown mutations at target loci using combinatorial BiDz sensors. This diagnostic platform provides the foundation for the development of cost-effective, accurate and sensitive alternatives for molecular diagnostics of MDR- and XDR-TB.

Latent tuberculosis among professionals from a referral hospital in oncology

Introduction: Tuberculosis (TB) is an ancient contagious disease, and continues to be the leading cause of morbidity and mortality among infectious contagious diseases. It can be considered an occupational infectious disease when it happens in health professionals. These professionals are directly exposed to TB and are considered to be a high risk population for latent tuberculosis infection (LTBI) and active TB. The primary aim of this study was to estimate the prevalence of LTBI among the clinical and administrative staff of an oncology referral hospital in Rio Grande do Sul. The secondary aim of this study was evaluate tuberculin skin test (TST) conversion rate and the risk factors for TST positivity in this population. Methods: A cross-sectional study was carried out in a retrospective cohort with data collected in March 2013 and March 2014. Data of professionals from different hospital units were included. Those with induration ≥ 10 mm were considered as reactors, and conversion rate was assessed by an increase ≥ 10 mm in induration in the second TST compared with the first one. Results: Among the 225 professionals evaluated in 2013, 135 (60%) were reactors and 90 (40%) were non-reactors. The mean age was 32.9 (± 9.55), 176 (78.22%) were female, and most of the reactors worked in the hospital for 4 years or less. Non-reactors in 2013 were recommended to repeat the test in 2014, and the conversion rate was 9.37%. There was no significant difference in prevalence among the different professional categories, and the assessed risk factors were not associated with ILTB. Conclusions: The prevalence of LTBI in the study population was high, reinforcing the need to implement effective control measures to prevent LTBI in the hospital where the study was conducted (AU)

Recent transmission of drug-resistant Mycobacterium tuberculosis in a prison population in southern Brazil.

We conducted a cross-sectional, retrospective study, characterized by classical and molecular epidemiology, involving M. tuberculosis isolates from a regional prison in southern Brazil. Between January of 2011 and August of 2014, 379 prisoners underwent sputum smear microscopy and culture; 53 (13.9%) were diagnosed with active tuberculosis. Of those, 8 (22.9%) presented with isoniazid-resistant tuberculosis. Strain genotyping was carried out by 15-locus mycobacterial interspersed repetitive unit-variable-number tandem-repeat analysis; 68.6% of the patients were distributed into five clusters, and 87.5% of the resistant cases were in the same cluster. The frequency of drug-resistant tuberculosis cases and the rate of recent transmission were high. Our data suggest the need to implement an effective tuberculosis control program within the prison system. RESUMO Estudo transversal, retrospectivo, com isolados de M. tuberculosis de pacientes de um presídio regional no sul do Brasil, caracterizado através de epidemiologia clássica e molecular. Entre janeiro de 2011 e agosto de 2014, 379 detentos foram submetidos a baciloscopia e cultura, sendo 53 (13,9%) diagnosticados com tuberculose ativa. Desses, 8 (22,9%) apresentavam tuberculose resistente a isoniazida. A genotipagem das cepas foi realizada por 15-locus mycobacterial interspersed repetitive units-variable number of tandem repeat analysis; 68,6% dos pacientes estavam distribuídos em cinco clusters, e 87,5% dos casos resistentes estavam em um mesmo cluster. Verificou-se uma frequência elevada de casos de resistência e alta taxa de transmissão recente. Estes dados sugerem a necessidade da implantação de um programa efetivo de controle da tuberculose no sistema prisional.