Staphylococcus epidermidis biofilms with higher proportions of dormant bacteria induce a lower activation of murine macrophages

• Tipo: Artigo em Revista Científica Internacional
• Data: 2011

Autores

Filipe Cerca (Autor) Outra; Filipa Andrade (Autor) Outra; Angela Franca (Autor) Outra; Elva Bonifacio Andrade (Autor) Outra; Adilia Ribeiro (Autor) ICBAS; Agostinho A Almeida (Autor) FFUP; Nuno Cerca (Autor) Outra; Gerald Pier (Autor) Outra; Joana Azeredo (Autor) Outra; Manuel Vilanova (Autor) ICBAS

Revista

Título: Journal of Medical Microbiology

Vol. 60

Páginas: 1717-1724

ISSN: 0022-2615

Editora: Microbiology Society

Indexação

ISI Web of Knowledge - 46 Citações

Scopus - 47 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Ciências biológicas

CORDIS: Ciências da Saúde > Ciências Médicas > Medicina > Imunologia

Outras Informações

ID Authenticus: P-002-J1J

DOI: 10.1099/jmm.0.031922-0

Abstract (EN): Staphylococcus epidermidis is an opportunistic pathogen and, due to its ability to establish biofilms, is a leading causative agent of indwelling medical device-associated infection. The presence of high amounts of dormant bacteria is a hallmark of biofilms, making them more tolerant to antimicrobials and to the host immune response. We observed that S. epidermidis biofilms grown in excess glucose accumulated high amounts of viable but non-culturable (VBNC) bacteria, as assessed by their low ratio of culturable bacteria over the number of viable bacteria. This effect, which was a consequence of the accumulation of acidic compounds due to glucose metabolism, was counteracted by high extracellular levels of calcium and magnesium added to the culture medium allowing modulation of the proportions of VBNC bacteria within S. epidermidis biofilms. Using bacterial inocula obtained from biofilms with high and low proportions of VBNC bacteria, their stimulatory effect on murine macrophages was evaluated in vitro and in vivo. The inoculum enriched in VBNC bacteria induced in vitro a lower production of tumour necrosis factor alpha, interleukin-1 and interleukin-6 by bone-marrow-derived murine macrophages and, in vivo, a lower stimulatory effect on peritoneal macrophages, assessed by increased surface expression of Gr1 and major histocompatibility complex class II molecules. Overall, these results show that environmental conditions, such as pH and extracellular levels of calcium and magnesium, can induce dormancy in S. epidermidis biofilms. Moreover, they show that bacterial suspensions enriched in dormant cells are less inflammatory, suggesting that dormancy can contribute to the immune evasion of biofilms.

Idioma: Inglês

Tipo (Avaliação Docente): Científica