Descrição
In this study a biofilm-forming strain of Staphylococcus epidermidis was used
in order to evaluate, in a murine model, the immune response to bacteria
grown either as planktonic cells or biofilm. Groups of male BALB/c mice were
infected intra-peritoneally (i.p.), with 2×10^8 S. epidermidis cells per mice,
obtained either from a mature biofilm (grown for 48h) or from a planktonic cell
culture. Mice were sacrificed 6h, 24h and 8 days after the i.p. infection. Flow
cytometric and qualitative cytospin analysis of cells recovered from peritoneal
exsudates, 24h after infection, indicates that the bacterial cells obtained from
the biofilm were less inflammatory than planktonic. Splenomegaly was
observed in mice 8 days after the bacterial challenge, more pronounced in mice
challenged with planktonic cells. Flow cytometric analysis of spleen cells
showed in both groups of bacteria-challenged mice an increase in the number
of lymphocyte cells, more marked in the animals challenged with planktonic
cells. The isotypic profile of the imunoglobulins present in the sera of each
group of mice was analysed by ELISA. Extracellular polymeric substance
(EPS) isolated from a S. epidermidis biofilm grown for 48h inhibited in vitro
nitrite production by macrophages stimulated with LPS and interferon-gamma.
Our results indicate that S. epidermidis biofilm-grown cells were less
inflammatory than planktonic cells, and suggest that EPS could diminish the
inflammatory response elicited in the host by this bacterium.
; Teixeira, Luzia 
