Search

Background: In a previous study, we detected the presence of a Mycobacterium avium species-specific insertion sequence, IS1245, in Mycobacterium kansasii. Both species were isolated from a mixed M. avium-M. kansasii bone marrow culture from an HIV-positive patient. The transfer mechanism of this insertion sequence to M. kansasii was investigated here. Methodology/Principal Findings: A linear plasmid (pMA100) was identified in all colonies isolated from the M. avium-M. kansasii mixed culture carrying the IS1245 element. The linearity of pMA100 was confirmed. Other analyses suggested that pMA100 contained a covalently bound protein in the terminal regions, a characteristic of invertron linear replicons. Partial sequencing of pMA100 showed that it bears one intact copy of IS1245 inserted in a region rich in transposase-related sequences. These types of sequences have been described in other linear mycobacterial plasmids. Mating experiments were performed to confirm that pMA100 could be transferred in vitro from M. avium to M. kansasii. pMA100 was transferred by in vitro conjugation not only to the M. kansasii strain from the mixed culture, but also to two other unrelated M. kansasii clinical isolates, as well as to Mycobacterium bovis BCG Moreau. Conclusions/Significance: Horizontal gene transfer (HGT) is one of most important mechanisms leading to the evolution and diversity of bacteria. This work provides evidence for the first time on the natural occurrence of HGT between different species of mycobacteria. Gene transfer, mediated by a novel conjugative plasmid, was detected and experimentally reproduced, This study received financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (www.fapesp.br) (FAPESP – 06/01533-9) and from Cooperación Interuniversitaria UAM-Banco Santander con América Latina (CEAL), UAM, Spain (http://www.uam.es/ss/Satellite/es/1234886374208/listado/CEAL_(Centro_de_Estudios_de_America_Latina.htm). MCSR was the recipient of fellowships from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (www.cnpq.br) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes) (www.capes.gov.br)

To report the presence of viable mycobacteria in a patient with keratitis treated for 6 months. Species identification was performed using the PRA method (polymerase chain reaction followed by restriction endonuclease analysis). Clonality was evaluated with RAPD (randomly amplified polymorphic DNA) and ERIC-PCR (enterobacterial repetitive intergenic consensus - polymerase chain reaction) methods. The patient reported trauma due to a metallic foreign body 3 weeks prior to presentation. Initial corneal scraping cultures revealed Mycobacterium abscessus. After 6 months of topical and systemic treatment the patient presented with no active inflammation and was considered clinically cured. An optic penetrating keratoplasty was performed. Culture of the excised cornea revealed Mycobacterium abscessus. Both isolates had the same clonal origin. The most interesting finding of this case report was the positive culture of the excised cornea after 6 months of intensive specific topical therapy. To our knowledge, this is the first report in the literature showing this possibility in the treatment of Mycobacterial keratitis. Thus, Mycobacterium abscessus may present viable bacteria after long-term treatment and should be followed carefully for a long period of time after tapering the medication.

To report the presence of viable mycobacteria in a patient with keratitis treated for 6 months. Species identification was performed using the PRA method (polymerase chain reaction followed by restriction endonuclease analysis). Clonality was evaluated with RAPD (randomly amplified polymorphic DNA) and ERIC-PCR (enterobacterial repetitive intergenic consensus - polymerase chain reaction) methods. The patient reported trauma due to a metallic foreign body 3 weeks prior to presentation. Initial corneal scraping cultures revealed Mycobacterium abscessus. After 6 months of topical and systemic treatment the patient presented with no active inflammation and was considered clinically cured. An optic penetrating keratoplasty was performed. Culture of the excised cornea revealed Mycobacterium abscessus. Both isolates had the same clonal origin. The most interesting finding of this case report was the positive culture of the excised cornea after 6 months of intensive specific topical therapy. To our knowledge, this is the first report in the literature showing this possibility in the treatment of Mycobacterial keratitis. Thus, Mycobacterium abscessus may present viable bacteria after long-term treatment and should be followed carefully for a long period of time after tapering the medication. O objetivo do caso é descrever a presença de micobactérias viáveis em pacientes com ceratite, 6 meses após tratamento intensivo. A identificação de espécies, foi efetuada usando método PRA (polymerase chain reaction seguida pela restriction endonuclease analysis). Clonalidade foi avaliada pelos métodos RAPD (randomly amplified polymorphic DNA) e ERIC-PCR (enterobacterial repetitive intergenic consensus - polymerase chain reaction). Paciente refere trauma com corpo estranho metálico há 3 semanas. A cultura da córnea revelou Mycobacterium abscessus. Após 6 meses de tratamento tópico e sistêmico, paciente apresentava-se sem inflamação, sendo considerado clinicamente curado. Realizou-se então, uma ceratoplastia penetrante com intuitos ópticos. A cultura da córnea transplantada revelou micobactérias de mesma origem clonal. O achado mais interessante neste relato, foi a positividade da cultura da córnea transplantada após 6 meses de intenso tratamento específico. Ao nosso conhecimento, esse é o primeiro caso relatado na literatura mostrando essa possibilidade em tratamento de ceratites por micobactérias. Assim, os pacientes com ceratite por Mycobacterium abscessus podem apresentar bactérias viáveis após longo tempo de tratamento específico e precisam ser seguidos cuidadosamente por um longo período de tempo.

Texto completo: acesso restrito. p. 5628-5634 Submitted by Suelen Reis (suelen_suzane@hotmail.com) on 2012-12-12T15:19:35Z No. of bitstreams: 1 5628.full.pdf: 1147506 bytes, checksum: 4052954928ce04e0ed9567c72d31dee5 (MD5) Made available in DSpace on 2012-12-12T15:19:35Z (GMT). No. of bitstreams: 1 5628.full.pdf: 1147506 bytes, checksum: 4052954928ce04e0ed9567c72d31dee5 (MD5) Previous issue date: 2002-10 The virulence of different isolates of Mycobacterium has been associated with two morphologically distinguishable colonial variants: opaque (SmOp) and transparent (SmTr). In this report we used an in vitro assay to compare macrophage (Mφ) responses to SmOp and SmTr Mycobacterium fortuitum variants, taking advantage of the fact that these variants were derived from the same isolate. Cells preactivated or not with gamma interferon (IFN-γ) were infected with SmOp or SmTr M. fortuitum. We showed that SmOp and SmTr induced different levels of nitric oxide (NO) production by IFN-γ-stimulated Mφ. Indeed, the amount of IFN-γ-induced NO production by J774 cells was 4.8 to 9.0 times higher by SmOp (23.1 to 37.7 μM) compared to SmTr infection (3.9 to 4.8 μM) (P = 0.0332), indicating that virulent SmTr bacilli restricted NO production. In addition, IFN-γ-induced NO production by Mφ was higher when correlated with reduction of only avirulent SmOp bacillus viability. SNAP (S-nitroso-N-acetyl-dl-penicillamine) -induced NO production did not modify SmTr viability, indicating its resistance to nitrogen radicals. Electron microscopy studies were performed to evaluate the capacity of phagosomes to fuse with lysosomes labeled with bovine serum albumin-colloidal gold particles. By 24 h postinfection, 69% more phagosome-containing SmOp variant had fused with lysosomes compared to the SmTr-induced phagosomes. In conclusion, these data indicate that virulent SmTr bacilli may escape host defense by restricting IFN-γ-induced NO production, resisting nitrogen toxic radicals, and limiting phagosome fusion with lysosomes.

Tendo sido comprovada a existência de quatro famílias molecularmente distintas de M. avium (PIG-A, B, C e D) circulando em suínos da região sul do Brasil, e havendo dúvidas a respeito da importância da transmissão horizontal como mecanismo de manutenção da doença, o presente teve por objetivo estudar a virulência dessas estirpes, informação importante para o aperfeiçoamento dos métodos de controle. Uma estirpe representante de cada família foi inoculada pela via intra-peritoneal em 48 hamsters com uma dose de 30.000 U.F.C. por animal. Após 2, 13, 26 e 40 dias da inoculação (T1 a T4), 12 hamsters inoculados de cada família foram anestesiados, sacrificados e os agentes foram quantificados no fígado, baço e pulmão. Os resultados foram expressos em número de U.F.C./g de órgão. A presença das estirpes foi pesquisada no sangue e também foram realizados exames histológicos. As estirpes PIG-A, B, C e D induziram a formação de lesões granulomatosas no fígado e baço a partir do segundo dia pós-inoculação e disseminaram-se pela via hemática, alcançando os pulmões. O baço sempre apresentou maiores contagens de U.F.C., seguido pelo figado e pulmões. Diferenças entre as estirpes foram constatadas através de análises das contagens de U.F.C de baço (T1: p PIG-A> PIG-D> PIG-C. The finding of four clusters of M. avium (PIG-A, B, C and D), typed by the IS1245-RFLP method, infecting the swine population of the south region of Brazil, the possible existence of virulence differences among them, the role of the virulence in the transmission mechanisms of infections and the existence of reasonable doubts regarding the importance of horizontal transmission for swine micobacteriosis, the virulence of these four strains of M. avium were compared. Bacteria from each cluster were inoculated in 48 hamsters by intra-peritoneal route. On the 2nd, 13th, 26th, and 40th days after inoculation, (T1 to T4), 12 animals of each cluster were sacrificed with vapors of ethyl ether and the bacteria were quantified in the liver, spleen and lung. Results were expressed as cfu/g of organ. The presence of the strains was verified in the blood and histological exams were also accomplished. The four strains induced granulomatous lesions in the liver and spleen since 2 days after inoculation and were disseminated to the lungs through the blood stream. The cfu counts from spleen were always bigger them that obtained from liver and lungs. Differences among strains were observed through the analysis of cfu counts from spleen (T1: p PIG-A> PIG-D> PIG-C.

Mais de 70 espécies de micobactérias já foram definidas e algumas delas podem causar enfermidade em humanos, especialmente em pacientes imunocomprometidos. A identificação de espécie, na maioria dos laboratórios clínicos, se baseia em características fenotípicas e testes bioquímicos e resultados definitivos só são obtidos após duas a quatro semanas. Métodos rápidos de identificação reduzem o tempo necessário para o diagnóstico e podem antecipar a instituição do tratamento específico, aumentando as chances de sucesso. A análise de padrões de restrição do gene hsp65 amplificado por PCR (PRA) foi utilizada como método rápido de identificação em 103 isolamentos clínicos. Os padrões de bandas foram interpretados por comparação com tabelas publicadas e padrões disponíveis em um site de Internet (;http://www.hospvd.ch:8005;). Resultados concordantes de PRA e identificação bioquímica foram obtidos em 76 de 83 isolamentos (91,5%). Os resultados de 20 isolamentos não puderam ser comparados porque a identificação fenotípica ou por PRA foi inconclusiva. Os resultados deste trabalho mostram que PRA pode ser útil para identificação de rotina de micobactérias por ser um método acurado, rápido e mais econômico do que a identificação convencional. More than 70 species of mycobacteria have been defined, and some can cause disease in humans, especially in immunocompromised patients. Species identification in most clinical laboratories is based on phenotypic characteristics and biochemical tests and final results are obtained only after two to four weeks. Quick identification methods, by reducing time for diagnosis, could expedite institution of specific treatment, increasing chances of success. PCR restriction-enzyme analysis (PRA) of the hsp65 gene was used as a rapid method for identification of 103 clinical isolates. Band patterns were interpreted by comparison with published tables and patterns available at an Internet site (http://www.hospvd.ch:8005). Concordant results of PRA and biochemical identification were obtained in 76 out of 83 isolates (91.5%). Results from 20 isolates could not be compared due to inconclusive PRA or biochemical identification. The results of this work showed that PRA could improve identification of mycobacteria in a routine setting because it is accurate, fast, and cheaper than conventional phenotypic identification.

Mycobacterium avium complex (MAC) species cannot be discriminated by the usual methods of biochemical identification of mycobacteria. This study showed that amplification by PCR of DT1 and DT6, two single copy sequences identified in the genome of M. avium serotype 2, the insertion sequence IS1245, found to be consistently present in M. avium strains and the heat-shock protein gene hsp65, followed by restriction polymorphism analysis, are rapid and accurate tests for the differentiation of the species M. avium, M. intracellulare, and M. scrofulaceum. A identificação bioquímica de micobactérias não permite a discriminação das espécies do complexo Mycobacterium avium (MAC). Este estudo mostrou que a amplificação por PCR de DT1 e DT6, duas sequências de cópia única identificadas no genoma de M. avium sorotipo 2, da sequência de inserção IS1245, encontrada consistentemente em cepas de M. avium e de um fragmento do gene da proteína de choque térmico hsp65, seguida da análise do polimorfismo de restrição, são testes rápidos e acurados para a diferenciação das espécies M. avium, M. intracellulare e M. scrofulaceum.