The role of cytokines in gram-positive infections is still relatively poorly defined. The purpose of this study was to establish whether or not intact staphylococci and purified peptidoglycans and peptidoglycan components derived from staphylococci are capable of stimulating the release of tumor necrosis factor (TNF) by human monocytes. We show here that intact staphylococci and purified peptidoglycans, isolated from three Staphylococcus epidermidis and three S. aureus strains, were indeed able to induce secretion of TNF by human monocytes in a concentration-dependent fashion. TNF release was detected by both enzyme immunoassay and the L929 fibroblast bioassay. In the enzyme immunoassay, a minimal concentration of peptidoglycan of 1 ,ug/ml was required to detect TNF release by monocytes, whereas in the bioassay a peptidoglycan concentration of 10 ,ug/ml was needed to detect a similar amount of TNF release. Peptidoglycan components such as the stem peptide, tetra-and pentaglycine, and muramyl dipeptide were unable to induce TNF release from human monocytes.

Coagulase-negative staphylococci (CoNS) have evolved into important agents of foreign body-related infections. Adhesion of causative bacteria to biomaterials is considered to be an essential step in these infections. We and others have shown that adhesion of CoNS to biomaterials may be mediated by protease-sensitive surface constituents. In the present study we expanded on these investigations by characterizing a biomaterial adhesin of Staphylococcus epidermidis 354 by using a strain-specific monoclonal antibody (MAb 36.4). MAb 36.4 was strongly and exclusively reactive with strain 354 in an enzyme-linked immunosorbent assay in which whole bacteria were used as antigens. Immunoblotting of cell wall polypeptides of strain 354 revealed strong reactivity with a 200- to 220-kDa band and a weaker reaction in the 100- to 110-kDa range. Preincubation of strain 354 with MAb 36.4 resulted in a 54 to 91% (mean +/- standard deviation, 74% +/- 14%; n = 10) inhibition of adhesion to polystyrene spheres. Fab fragments prepared from MAb 36.4 also inhibited adhesion effectively, indicating specific blocking of an adhesion antigen rather than aspecific inhibition. Immunogold electron microscopy with MAb 36.4 revealed deposition of gold particles on the cell surface and possibly also on fimbrialike surface projections. It is concluded that a surface-located protein antigen of S. epidermidis 354 recognized by MAb 36.4 acts as an adhesin mediating attachment to uncoated foreign material. It is speculated that this type of adhesion to biomaterials may play an important role in the pathogenesis of foreign body-related infections caused by CoNS.

Detection of intestinal protozoa by PCR methods has been described as being sensitive and specific, and as improving the diagnostic yield. Here we present the outcome of the transition from microscopy to molecular screening for detection of a select group of intestinal protozoa in faeces in our laboratory. Introduction of molecular screening for intestinal protozoa resulted in higher sensitivity, reduced hands-on-time, reduced time-to-results, leading to improved diagnostic efficiency.

Summary. The purpose of this study was to define cell-wall components of Staphylococcus epidermidis responsible for activation of human polymorphonuclear leucocytes (PMNL). Metabolic activation of PMNL was determined by chemiluminescence (CL). Purified peptidoglycan (PG) induced a concentration-dependent metabolic burst in PMNL. The minimal concentration needed for CL induction was 1 pglml. Comparison between different S. epidermidis strains showed variation in the capacity to induce CL in PMNL. Purified PG induced a higher CL response in PMNL than its intact parent strain; this effect was found in all S. epidermidis strains. Lipoteichoic acid (LTA), PG stem peptide and muramyldipeptide (MDP) did not induce CL; teichoic acid induced a CL response only at very high concentrations. No differences in CL inducing capacity were found between PG, crude cell walls, and purified cell walls of S. epidermidis. Sonication of PG strongly diminished CLinducing capacity. PG treatment with mutanolysin immediately resulted in decreased CLinducing capacity. Treatment of PG with S. aureus lytic enzyme (SALE) 10 pg/ml for up to 15 min enhanced the CL response to PMNL; a similar increase in CL was induced by PG treated with SALE at 1 pg/ml for up to 120 min. Beyond these times, a continuous decrease in PG-induced CL was observed. In conclusion, PG was found to be the major cell-wall component of S. epidermidis involved in CL induction. Moreover, a minimal fragment size or a specific tertiary structure of PG, or both, is required for metabolic activation of PMNL.

No abstract