Molecular profiling of drug resistant isolates ofMycobacterium tuberculosis in the state of Santa Catarina, southern Brazil

Drug resistance is a global threat and one of the main contributing factors to tuberculosis (TB) outbreaks. The goal of this study was to analyse the molecular profile of multidrug-resistant TB (MDR-TB) in the state of Santa Catarina in southern Brazil. Fifty-three MDR Mycobacterium tuberculosisclinical isolates were analysed by spoligotyping and a partial region of therpoB gene, which is associated with rifampicin resistance (RMP-R), was sequenced. Some isolates were also distinguished by their mycobacterial interspersed repetitive units (MIRU). S531L was the most prevalent mutation found within rpoBin RMP-R isolates (58.5%), followed by S531W (20.8%). Only two MDR isolates showed no mutations withinrpoB. Isolates of the Latin American Mediterranean (LAM) family were the most prevalent (45.3%) found by spoligotyping, followed by Haarlem (9.4%) and T (7.5%) families. SIT106 was found in 26.4% of isolates and all SIT106 isolates typed by MIRU-12 (5 out of 14) belong to MIT251. There was a high correlation between the S531W mutation and the LAM family mainly because all SIT2263 (LAM9) isolates carry this mutation. Among isolates with the S531W mutation in rpoB MIRU demonstrates a cluster formed by four isolates (SIT2263 and MIT163) and very similar profiles were observed between eight of the nine isolates. Better characterisation of TB isolates may lead to new ways in which to control and treat TB in this region of Brazil.

Mycobacteria mobility shift assay: a method for the rapid identification of Mycobacterium tuberculosis and nontuberculous mycobacteria

The identification of mycobacteria is essential because tuberculosis (TB) and mycobacteriosis are clinically indistinguishable and require different therapeutic regimens. The traditional phenotypic method is time consuming and may last up to 60 days. Indeed, rapid, affordable, specific and easy-to-perform identification methods are needed. We have previously described a polymerase chain reaction-based method called a mycobacteria mobility shift assay (MMSA) that was designed for Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) species identification. The aim of this study was to assess the MMSA for the identification of MTC and NTM clinical isolates and to compare its performance with that of the PRA-hsp65 method. A total of 204 clinical isolates (102 NTM and 102 MTC) were identified by the MMSA and PRA-hsp65. For isolates for which these methods gave discordant results, definitive species identification was obtained by sequencing fragments of the 16S rRNA and hsp65 genes. Both methods correctly identified all MTC isolates. Among the NTM isolates, the MMSA alone assigned 94 (92.2%) to a complex or species, whereas the PRA-hsp65 method assigned 100% to a species. A 91.5% agreement was observed for the 94 NTM isolates identified by both methods. The MMSA provided correct identification for 96.8% of the NTM isolates compared with 94.7% for PRA-hsp65. The MMSA is a suitable auxiliary method for routine use for the rapid identification of mycobacteria.

Micobactérias: epidemiologia e diagnóstico / Mycobacteria: epidemiology and diagnosis

Estima-se que um terço da população mundial esteja infectada com Mycobacterium tuberculosis, oque resulta em 2 milhões de mortes anualmente. No mundo, são registrados mais de 8 milhões de novos casos de tuberculose (TB) por ano e o Brasil ocupa o décimo nono lugar dentre os 23 países detentores da maior carga de TB. Os fatores determinantes para o controle desta doença incluem a detecção rápida, a terapia adequada e os meios para que sejam evitadas futuras transmissões. O diagnósticoconvencional (baciloscopia e cultura do microrganismo) apresenta limitações quanto ao tempo de execução e à operacionalidade, visto que o resultado pode levar até 60 dias para ser liberado.Portanto, a importância da detecção precoce do bacilo se torna fundamental para o bloqueio da cadeia de transmissão da TB. Já as micobacterioses, doenças causadas pelas micobactérias não tuberculosas, também estão provocando um importante impacto em razão do aumento dos surtos de infecções cirúrgicas. A identificação rápida e específica destes microrganismos é importante para o diagnóstico e a consequente escolha do tipo de tratamento do paciente, que está diretamente relacionada com a espécie. Portanto, o conhecimento dos agentes etiológicos das doenças causadaspelas micobactérias e o diagnóstico sensível e específico permitem o tratamento adequado e,consequentemente, o bloqueio da cadeia de transmissão da TB e o controle dos surtos relacionados às micobactérias não tuberculosas.

It is estimated that one third of the world population is infected with Mycobacterium tuberculosis, resulting in 2 million deaths annually. More than 8 million new cases of tuberculosis (TB) are registered per year worldwide, and Brazil ranks 19th among the top 23 countries with the highest rates of TB. The determining factors for the control of this disease include early detection, appropriate therapy and measuresfor avoiding transmission. The conventional diagnoses (smear and microorganism culture) have time limitations for implementation and operation, since the result may take up to 60 days to be released. Therefore, early detection is critical for blockingthe chain of TB transmission. Mycobacterial diseases caused by nontuberculous mycobacteria are also having a major impact due to increased outbreaks of surgical infections. Thereby, the rapid and specific identification of microorganisms is important for the diagnosis, which will determine the type of treatment (treatment according to species). Knowledge of etiologic agents of mycobacterial diseases, as well as sensitive and specific diagnosis allows proper treatment by blocking the chain of TB transmission and controlling nontuberculous mycobacteria outbreaks.