RESUMO
Staphylococcus aureus is an important pathogen that forms biofilms on the surfaces of medical implants. Biofilm formation by S. aureus is associated with the production of poly N-acetylglucosamine (PNAG), also referred to as polysaccharide intercellular adhesin (PIA), which mediates bacterial adhesion, leading to the accumulation of bacteria on solid surfaces. This study shows that the ability of S. aureus SA113 to adhere to nasal epithelial cells is reduced after the deletion of the ica operon, which contains genes encoding PIA/PNAG synthesis. However, this ability is restored after a plasmid carrying the entire ica operon is transformed into the mutant strain, S. aureus SA113Δica, showing that the synthesis of PIA/PNAG is important for adhesion to epithelial cells. Additionally, S. carnosus TM300, which does not produce PIA/PNAG, forms a biofilm and adheres to epithelial cells after the bacteria are transformed with a PIA/PNAG-expressing plasmid, pTXicaADBC. The adhesion of S. carnosus TM300 to epithelial cells is also demonstrated by adding purified exopolysaccharide (EPS), which contains PIA/PNAG, to the bacteria. In addition, using a mouse model, we find that the abscess lesions and bacterial burden in lung tissues is higher in mice infected with S. aureus SA113 than in those infected with the mutant strain, S. aureus SA113Δica. The results indicate that PIA/PNAG promotes the adhesion of S. aureus to human nasal epithelial cells and lung infections in a mouse model. This study elucidates a mechanism that is important to the pathogenesis of S. aureus infections.
Assuntos
Aderência Bacteriana/genética , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica , Polissacarídeos Bacterianos/metabolismo , Infecções Estafilocócicas/patologia , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Animais , Carga Bacteriana/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Linhagem Celular Tumoral , Modelos Animais de Doenças , Células Epiteliais/microbiologia , Células Epiteliais/patologia , Teste de Complementação Genética , Humanos , Pulmão/microbiologia , Pulmão/patologia , Camundongos , Dados de Sequência Molecular , Óperon , Plasmídeos/química , Plasmídeos/metabolismo , Deleção de Sequência , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/metabolismo , Transformação Bacteriana , beta-Glucanas/metabolismoRESUMO
Multilocus sequence typing was carried out on 95 invasive pneumococcal isolates belonging to the most common 7 serotypes currently circulating in Taiwan. The study confirmed continued prevalence in Taiwan of a few global clones and sequence types (STs) since the mid-1990s and identified the recent emergence of ST320 (19A) and ST902 (6A). Antimicrobial nonsusceptibility was common in the predominant STs of serotypes 14, 19A, 19F, and 23F.