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Introducción: La infección por tuberculosis repercute en el mundo a pesar de los años de estudio y avances tecnológicos en su diagnóstico. El ensayo Xpert® MTB/RIF permite, en gran medida, la identificación del bacilo de Koch en cualquier muestra patológica, y lo hace con una alta sensibilidad, especificidad y rapidez con respecto a otros métodos. Objetivo: Realizar el diagnóstico de tuberculosis con ensayo Xpert® MTB/RIF. Método: Se realizó un estudio transversal en 46 muestras analizadas (n=46) de las provincias orientales de Cuba con ensayo Xpert® MTB/RIF, entre abril y septiembre de 2023, por el Centro Provincial de Higiene, Epidemiología y Microbiología de Holguín. Las variables estudiadas fueron: provincia de procedencia, edad, sexo, tipo de muestra, factores de riesgo, resultado al ensayo y resistencia a la rifampicina. Resultados: Santiago de Cuba y Guantánamo fueron las provincias que mayor cantidad de casos reportaron, con 14 casos cada una (30,4 porciento). El sexo masculino fue el de mayor incidencia, 33 casos (71,7 porciento), independientemente de la provincia. El grupo de edad de 25 a 34 años fue el de mayor prevalencia, con el 26,1 porciento. Los grupos de riesgos más afectados fueron: los fumadores (37,0 porciento), los reclusos (32,6 porciento), los adultos mayores de 60 años (26,6 porciento) y los alcohólicos (23,9 porciento). Conclusiones: La introducción del GeneXpert en su diagnóstico es muy efectivo, por su alta sensibilidad y especificidad con relación a los estudios tradicionales, como son la baciloscopia y el cultivo, además de la rapidez en la obtención del resultado.Informa también sobre la resistencia a la rifampicina, atribuible al gen rpoβ lo que resulta muy oportuno en momentos en que la multidrogorresistencia aumenta aceleradamente.(AU)

Introduction: Tuberculosis infection affects the world despite years of study and technological advances in its diagnosis.The Xpert® MTB/RIF test allows, to a largeextent, the identification of Koch bacillus in any pathological sample, and does so with high sensitivity, specificity and speed compared too ther methods. Objective: To diagnose tuberculosis with the Xpert® MTB/RIF test. Method: A cross-sectional study was carried out on 46 analyzed samples (n 46) from the eastern provinces of Cuba with the Xpert® MTB/RIF test, between April and September 2023, by the Centro Provincial de Higiene, Epidemiología y Microbiología de Holguín (Provincial Center of Hygiene, Epidemiology and Microbiology of Holguín).The variables studied were: province of origin, age, sex, type of sample, risk factors, test resultand resistance to rifampicin. Results: Santiago de Cuba and Guantánamo were the provinces that reported the highest number of cases, with 14 cases each(30.4 percent).The maleshad the highest incidence, 33 cases (71.7 percent), regardless of the province.The age group of 25 to 34 years was the one with the highest prevalence, with 26.1 percent.The most affected risk groups were: smokers (37.0 percent), prisoners (32.6 percent), adults over 60 years of age (26.6 percent) and alcoholics (23.9 percent). Conclusions: The introduction of GeneXpert in tuberculosis diagnosis is very effective, due to its high sensitivity and specificity in relation to traditional studies, such as smear microscopy and culture, in addition to the speed in obtaining the result. It also reports on resistance to rifampicin, attributable to the rpoβ gene, which is timely at a moment when multidrug resistance is increasing rapidly.(AU)

Introdução: A infecção tuberculosa afeta o mundo apesar de anos de estudo e avanços tecnológicos no seu diagnóstico.O ensaio Xpert® MTB/RIF permite, em grande medida, a identificação do bacilo de Koch em qualquer amostra patológica, e fá-lo com elevada sensibilidade, especificidade e rapidez em comparação com outros métodos. Objetivo: Diagnosticar tuberculose com o ensaio Xpert® MTB/RIF. Método: Foi realizado um estudo transversal em 46 amostras analisadas (n 46) das províncias orientais de Cuba com o ensaio Xpert® MTB/RIF, entre abril e setembro de 2023, pelo Centro Provincial de Higiene, Epidemiologia e Microbiologia de Holguín.As variáveis estudadas foram: província de origem, idade, sexo, tipo de amostra, fatores de risco, resultado de exame e resistência à rifampicina. Resultados: Santiago de Cuba e Guantánamo foram as províncias que notificaram o maior número de casos, com 14 casos cada (30,4 porcento).O sexo masculino teve a maior incidência, 33 casos (71,7 porcento), independentemente da província.A faixa etária de 25 a 34 anos foi a que apresentou maior prevalência, com 26,1 porcento.Os grupos de risco mais acometidos foram: fumantes (37,0 porcento), presidiários (32,6 porcento), adultos acima de 60 anos (26,6 porcento) e alcoolistas (23,9 porcento). Conclusões: A introdução do GeneXpert no seu diagnóstico é muito eficaz, devido à sua alta sensibilidade e especificidade em relação aos estudos tradicionais, como baciloscopia e cultura, além da rapidez na obtenção do resultado.Também relata a resistência à rifampicina, atribuível ao gene rpoβ, que é muito oportuna numa altura em que a resistência a múltiplos medicamentos está a aumentar rapidamente.(AU)

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Abstract Objectives: Evaluate the association between rifampicin resistance and the presence of at least one SNP in the rpoB and ponA1 genes and the spoligotype defined lineages. Material and Methods: This study analyzed two databases of 484 genomes of M. tuberculosis from strains isolated from patients in the cities of Lima and Callao, for which the odds ratio (OR) was calculated considering belonging to a certain spoligotype defined lineages as an exposure factor. Results: No statistically significant association (ρ value> 0.05) was found between the presence of at least one SNP in the rpoB gene and the lineages included in the study (LAM, Haarlem, T and Beijing). However, a statistically significant association was found between the presence of at least one SNP in the ponA1 gene and the LAM and Haarlem lineages (ρ value <0.05). An association was found between the P631S SNP in the ponA1 gene and the LAM and Haarlem lineages; and the A516T SNP, of this same gene, presented an association with the LAM lineage. Likewise, an association was found between rifampicin resistance and the LAM lineage. Conclusions: The presence of SNPs in the ponA1 gene is associated with the LAM and Haarlem lineages.

Resumen Objetivos: Evaluar la asociación entre la resistencia a rifampicina y la presencia de al menos un SNP en los genes rpoB y ponA1 y los linajes definidos por espoli gotipos. Material y Métodos: Este estudio analizó dos bases de datos de 484 genomas de M. tuberculosis de cepas aisladas de pacientes de las ciudades de Lima y Callao, para lo cual se calculó el odds ratio (OR) considerando la pertenencia a determinado linaje definido por espoligotipos como un factor de exposición. Resultados: No se encontró una asociación estadísticamente significativa (valor de ρ >0.05) entre la presencia de al menos un SNP en el gen rpoB y los linajes incluidos en el estudio (LAM, Haarlem, T y Beijing). No obstante, se halló una asociación estadísticamente significativa entre la presencia de al menos un SNP en el gen ponA1 y los linajes LAM y Haarlem (valor de ρ <0.05). Se encontró una asociación entre el SNP P631S del gen ponA1 y los linajes LAM y Haarlem; y el SNP A516T, de este mismo gen, presentó una asociación con el linaje LAM. Asimismo, se halló una asociación entre la resistencia a rifampicina y el linaje LAM. Conclusiones: La presencia de SNPs en el gen ponA1 está asociada con los linajes LAM y Haarlem.

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Background: Rifampicin (RIF) resistance in Mycobacterium tuberculosis is frequently caused by mutations in the rpoB gene. These mutations are associated with a fitness cost, which can be overcome by compensatory mutations in other genes, among which rpoC may be the most important. We analyzed 469 Peruvian M. tuberculosis clinical isolates to identify compensatory mutations in rpoC/rpoA associated with RIF resistance. Methods: The M. tuberculosis isolates were collected and tested for RIF susceptibility and spoligotyping. Samples were sequenced and aligned to the reference genome to identify mutations. By analyzing the sequences and the metadata, we identified a list of rpoC mutations exclusively associated with RIF resistance and mutations in rpoB. We then evaluated the distribution of these mutations along the protein sequence and tridimensional structure. Results: One hundred and twenty-five strains were RIF susceptible and 346 were resistant. We identified 35 potential new compensatory mutations, some of which were distributed on the interface surface between rpoB and rpoC, arising in clusters and suggesting the presence of hotspots for compensatory mutations. Conclusion: This study identifies 35 putative novel compensatory mutations in the ß' subunit of M. tuberculosis RNApol. Six of these (S428T, L507V, A734V, I997V, and V1252LM) are considered most likely to have a compensatory role, as they fall in the interaction zone of the two subunits and the mutation did not lead to any change in the protein's physical-chemical properties.

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Small colony variants (SCV) of Staphylococcus aureus have been reported as implicated in chronic infections. Here, we investigated the genomic and transcriptomic changes involved in the evolution from a wild-type to a SCV from in a patient with prosthetic joint infection relapse. The SCV presented a stable phenotype with no classical auxotrophy and the emergence of rifampicin resistance. Whole Genome Sequencing (WGS) analysis showed only the loss of a 42.5 kb phage and 3 deletions, among which one targeting the rpoB gene, known to be the target of rifampicin and to be associated to SCV formation in the context of a constitutively active stringent response. Transcriptomic analysis highlighted a specific signature in the SCV strain including a complex, multi-level strategy of survival and adaptation to chronicity within the host including a protection from the inflammatory response, an evasion of the immune response, a constitutively activated stringent response and a scavenging of iron sources.

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BACKGROUND Mycobacterium tuberculosis (MTB) is one of the most significant causes of mortality and morbidity. Early diagnose is important especially in multiple drug resistant tuberculosis to avoid transmission. Traditional techniques requires at least one to three weeks for diagnosis of tuberculosis. Diagnostic delays with multiple drug resistant tuberculosis are associated with worse clinical outcomes and increased transmission The Xpert MTB/RIF assay is one of the new diagnostic device for the diagnosis of tuberculosis and rapid detection of rifampicin resistance. OBJECTIVE We assessed the performance of Xpert MTB/RIF assay for detecting rifampicin resistance using phenotypic drug susceptibility tests as automated BD MGIT 960. METHODS Total of 2136 specimens were included in the study. Xpert MTB/RIF testing was performed on samples, using version 4 cartridges, according to the manufacturer's recommendations. The MTBC culture and first-line phenotypic DST were performed in automated BD MGIT 960 (Becton & Dickinson, USA) according to the recommendations of the manufacturer. Agar proportion was used in the case of inconsistency for rifampicin resistance. FINDINGS Thirty-four samples (19 respiratory and 15 nonrespiratory samples) were determined as positive for M. tuberculosis complex by Xpert MTB/RIF (Cepheid GeneXpert® System, USA). Xpert MTB/RIF assay detected 4/34 (11.7%) specimens as rifampicin resistant. One of the rifampicin resistant isolates was determined susceptible in MGIT 960 automated system. This isolate was also tested with agar proportion method and found susceptible to rifampicin. MAIN CONCLUSION The Xpert MTB/RIF assay can be used as first-line assay for the detection of M. tuberculosis. However, microbiologists must be aware of the limitations of the assay.

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BACKGROUND To cope with the emergence of multidrug-resistant tuberculosis (MDR-TB), new molecular methods that can routinely be used to screen for a wide range of drug resistance related genetic markers in the Mycobacterium tuberculosis genome are urgently needed. OBJECTIVE To evaluate the performance of multiplex ligaton-dependent probe amplification (MLPA) against Genotype® MTBDRplus to detect resistance to isoniazid (INHr) and rifampicin (RIFr). METHOD 96 culture isolates characterised for identification, drug susceptibility testing (DST) and sequencing of rpoB, katG, and inhA genes were evaluated by the MLPA and Genotype®MTBDRplus assays. RESULTS With sequencing as a reference standard, sensitivity (SE) to detect INHr was 92.8% and 85.7%, and specificity (SP) was 100% and 97.5%, for MLPA and Genotype®MTBDRplus, respectively. In relation to RIFr, SE was 87.5% and 100%, and SP was 100% and 98.8%, respectively. Kappa value was identical between Genotype®MTBDRplus and MLPA compared with the standard DST and sequencing for detection of INHr [0.83 (0.75-0.91)] and RIFr [0.93 (0.88-0.98)]. CONCLUSION Compared to Genotype®MTBDRplus, MLPA showed similar sensitivity to detect INH and RIF resistance. The results obtained by the MLPA and Genotype®MTBDRplus assays indicate that both molecular tests can be used for the rapid detection of drug-resistant TB with high accuracy. MLPA has the added value of providing information on the circulating M. tuberculosis lineages.

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Genotyping and molecular characterization of drug resistance mechanisms in Mycobacterium leprae enables disease transmission and drug resistance trends to be monitored. In the present study, we performed genome-wide analysis of Airaku-3, a multidrug-resistant strain with an unknown mechanism of resistance to rifampicin. We identified 12 unique non-synonymous single-nucleotide polymorphisms (SNPs) including two in the transporter-encoding ctpC and ctpI genes. In addition, two SNPs were found that improve the resolution of SNP-based genotyping, particularly for Venezuelan and South East Asian strains of M. leprae.

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