Ivy Bastos Ramis

Molecular Basis of Pathogenicity in Helicobacter pylori Clinical Isolates

ABSTRACT This study identified pathogenicity genes in 40 Helicobacter pylori clinical isolates. The cagA, vacA, and iceA genes were detected in 65%, 97.5%, and 97.5% of the isolates, respectively. The cagA, iceA1, and vacAs1a/m1 genes were related to erosive gastritis, whereas the vacAs2/m2 and iceA2 genes were associated with enanthematous gastritis.

Evaluation of the speed-oligo Mycobacteria assay for the identification of nontuberculous mycobacteria

Nontuberculous mycobacteria (NTM) causing human infectious disease have become increasingly common. Rapid and accurate identification to the species level is, therefore, critical. The Speed-Oligo Mycobacteria assay is an oligochromatographic method that was made available recently for the identification and differentiation of mycobacteria. The present study aimed to evaluate the performance of the Speed-Oligo Mycobacteria assay for the identification of NTM. We examined a total of 62 strains (9 type strains, 19 reference strains and 34 clinical isolates) belonging to 13 different species (Mycobacterium intracellulare, M. fortuitum, M. gordonae, M. kansasii, M. marinum, M. peregrinum, M. scrofulaceum, M. abscessus, M. bovis BCG, M. chelonae, M. avium, M. malmoense and M. xenopi). The Speed-Oligo Mycobacteria assay was performed according to the manufacturers instructions. Discrepant results between Speed-Oligo Mycobacteria and the original identification were reassessed by the Speed-Oligo Mycobacteria assay and resolved by the GenoType Mycobacterium CM assay and by sequencing of 16S rRNA and protein-encoding genes. We found 93.5 % (58/62) concordance for the identification of NTM as compared with the original identification. Three strains were erroneously identified by Speed-Oligo Mycobacteria: one M. kansasii strain was identified as Mycobacterium tuberculosis complex, and one M. chelonae strain and one M. peregrinum strain were both identified as Mycobacterium abscessus. Moreover, one M. chelonae strain was not identified by Speed-Oligo Mycobacteria since it did not react with any species-specific probe. For these strains, sequencing of the genes hsp65, 16S rRNA and rpoB and the GenoType Mycobacterium CM assay were performed. The Speed-Oligo Mycobacteria assay can be a useful tool for the rapid and easy identification of the most common NTM. If applied in clinical practice it could reduce diagnostic delays and contribute to correct clinical and better management of infections caused by NTM.

Activity of Rifabutin and Hemi-synthetic Derivatives Against Mycobacterium abscessus

BACKGROUND Mycobacterium abscessus causes a wide range of clinical diseases that are difficult to treat. This microorganism is resistant not only to the classical antituberculosis agents but also to most of the antimicrobials that are currently available, resulting in limited therapeutic options and treatment failure. This scenario stresses the need to search for new drugs with activity against M. abscessus. OBJECTIVE To evaluate in vitro the antimycobacterial activity and cytotoxicity of rifabutin (RFB 1) and ten derivatives (2-11) against M. abscessus ATCC 19977. METHOD The minimum inhibitory concentration (MIC) of the molecules was determined by the microdilution broth method according to the guideline described in CLSI. The toxicity evaluation was carried in 96-well microplates, using the cell line J774A.1 (ATCC TIB-67). RESULT From the eleven molecules tested, RFB 1 and RFB 4 were the compounds showing higher activities against M. abscessus, with MICs of 0.9 and 1.0 µM, respectively. The R1 and R2 moieties seem to have deciding influence over the final activity. Furthermore, N-oxide derivatives 9, 10, and 11 were also active against M. abscessus, with MICs of 7.2 µM, 1.8 µM and 3.8 µM, respectively. An explanatory hypothesis for the better activities of compounds RFB 1, RFB 4, RFB 10 and RFB 11 considers the likely hydrogen bonding between ligands and receptor, balancing the global flexibility and interaction energies. RFB 1 and its most effective derivatives were found to be not toxic. CONCLUSION Besides RFB 1, its derivatives 4, 10 and 11 show potential for clinical development in the M. abscessus treatment.

Análise genotípica do Helicobacter pylori pelo método Multiple-Locus Variable-Number Tandem-Repeats no sul do Brasil

Justificativa e objetivos: Apesar de ser utilizado como um metodo de genotipagem para diferentes microrganismos, poucos estudos relatam a utilizacao de Multiple-Locus Variable Number of Tandem Repeats Analysis (MLVA) para analise da diversidade clonal do Helicobacter pylori. O objetivo deste estudo foi determinar a variabilidade genetica de cepas de H. pylori pelo MLVA no sul do Brasil. Metodos: 95 amostras de DNA de H. pylori foram obtidas a partir de biopsias gastricas de pacientes H. pylori-positivos provenientes de duas cidades do sul do Brasil e a diversidade genetica das cepas foi avaliada pelo metodo MLVA utilizando eletroforese em gel de agarose. Para a selecao dos loci a serem analisados neste estudo, foi realizada uma analise in silico de 12 loci previamente descritos na literatura. Resultados: A partir da analise in silico, apenas quatro loci foram considerados viaveis para a analise genotipica das cepas, resultando em 90 cepas distribuidas em oito grupos diferentes e cinco cepas orfas. Conclusoes: Apesar de o metodo MLVA permitir fazer inferencias acerca da diversidade genetica de uma populacao, nossos resultados mostraram que os metodos de genotipagem do H. pylori devem ser criticamente avaliados antes de serem utilizados nessa regiao do Brasil.