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Latex beads (0.8-,um diameter; Difco Laboratories) were coated with fibronectin, fibrinogen, collagen type 1, or denatured collagen (gelatin) and evaluated in a particle agglutination assay (PAA) for the rapid detection of fibronectin, fibrinogen, or collagen binding to Staphylococcus aureus. These assays were compared with a commercial test for detecting the binding of fibrinogen and immunoglobulin G (Staphaurex). Bacterial cells (approximately 1010 cells per ml) suspended in 0.02 M potassium phosphate buffer (pH 6.8) caused the clumping of standard fibronectin, collagen, gelatin, and fibrinogen latex suspensions within 2 min on glass slides. The test results were scored semiquantitatively from strongly positive (+ + +) to weakly positive (+) and negative (-) reactions. The negative PAA reactions corresponded to a median value of 11.5% relative to the binding of 1251-labeled protein to strain Cowan 1, indicating the high sensitivity of the test. The reactions with fibronectin and fibrinogen latex suspensions and with Staphaurex were optimal for cells grown on tryptic soy and brain heart infusion broth media. Blood agar was optimal for reactions with collagen and gelatin latex suspensions. Media containing high salts (mannitol salt agar and staphylococcus medium 110) enhanced the tendency of cells to autoaggregate. These assays were also clinically evaluated on 187 S. aureus isolates. The PAA reagents were stable, and the assays were highly specific, sensitive, and reproducible, thus making PAA suitable for the rapid screening of the binding of various bacterial pathogens to serum and connective-tissue proteins.

Expression of binding to vitronectin (Vn or S‐protein) and fibronectin (Fn) was common among clinical isolates of Candida albicans. Growth at 37°C enhanced expression of both Vn and Fn binding. Some strains expressed higher binding after growth in liquid media and others after growth on solid media. Most strains expressed higher cell surface hydrophobicity after growth on agar media. Vn binding was less influenced by expression of cell surface hydrophobicity than Fn binding. Vn binding to yeast cells was optimal around pH 4 and Fn binding around pH 6. Binding to soluble Vn was inhibited by unlabelled Vn and to a lesser extent by Fn. Fn binding to the same C. albicans strain was inhibited by unlabelled Fn, Vn, fibrinogen and to some extent collagens. C. albicans strain 3248 expressed specific high binding of Vn, and high binding of Fn. Binding of both proteins was sensitive to heat and protease treatment, but in different ways. Vn binding differed significantly from the earlier reported Fn binding and may represent a novel type of tissue adherence.

Summary. Eleven strains of Staphylococcus lugdunensis from different clinical sources were investigated for their ability to bind 12'I-labelled collagen (Cn) type I and IV, fibronectin (Fn), vitronectin (Vn), laminin (Lm), fibrinogen (Fg), thrombospondin, plasminogen (glu-and lysform) and human IgG. All the strains bound these proteins, although a higher degree of binding was obtained for Cn types I and IV and IgG with mean values of 36 YO, 32 YO and 26 YO binding. respectively. In tests with proteins immobilised on latex beads in a particle agglutination assay, eight of the 11 strains bound Cn type I and seven bound Fg, whereas no strain bound immobilised IgG. Binding to immobilised Cn-I, Fg, Lm and Vn was abolished when the bacterial cells were treated with proteases or heat, indicating cell-surface receptors with protein characteristics. Cell-surface extracts of S . lugdunensis 2342 were able to totally inhibit binding of the homologous strain and S . aureus Cowan 1 to latex-immobilised proteins Cn-I, Lm, Vn, Fn and Fg. The binding of '"I-labelled Cn IV by S. lugdunensis 2342, was heat sensitive, whereas the binding to S. auieus Cowan 1 was heat resistant. The strains gave negative results in tests for the presence of protein A with a S. aureus protein A gene probe and with sensitised red blood cells. No production of heat-stable nuclease (TNase) could be detected by monoclonal antibodies against TNase or by the polymerase chain reaction with an oligonucleotide sequence from S . aureus TNase as primer. When the cell surface characters of the S. lugdunensis strains were studied, five were found to be hydrophobic and negatively charged. four hydrophilic and positively charged and two hydrophobic with positive net charge. lntroduc tionCoagulase-negative staphylococci (CNS) are well recognised as opportunist pathogens causing infections in neonates and neutropenic patients.' They are the most important pathogens in infections associated with intravascular catheters and grafts, peritoneal catheters and prostheses in various organs.' With the recent description of two new species of CNS, Staph?.-lo~~occ~us luqduimsis and S. sclde !'fc.ri,3 there are at present 24 species of CNS. S . epidemviiclis, S. huernolyficws and S. .s~~?rc~~~12.ticIrs are the species isolated most frequently from human infections.' C'ougufase-positive staphylococci, i.e., S. mreus, are more virulent than CNS.' Numerous studies have focused on presumptive virulence factors of S . aureus, and latterly on those of CNS.' Of these factors, only protein A and coagulase are consistently absent in CNS. The presence of heat-stable nuclease is characteristic: of coagulase-positive staphylococci but has not been ascribed any role in pathogenicity.' All other toxin>. enzymes and outer-membrane proteins of S. U14Wli.S have been detected in CNS strains with varying