Particle agglutination assays for rapid detection of fibronectin, fibrinogen, and collagen receptors on Staphylococcus aureus

Inactivation of a fibronectin-binding TonB-dependent protein increases adhesion properties of Bacteroides fragilis

Bacteroides fragilis is the Gram-negative strictly anaerobic bacterium most frequently isolated from clinical infections, including intra-abdominal abscess and bacteraemia. A number of factors can contribute to its virulence, including the expression of adhesins. Some of them are already characterized and can recognize and bind to extracellular matrix components, such as fibronectin. One of the molecules responsible for fibronectin-binding is an outer-membrane protein previously described by our group, which belongs to the TonB-dependent family. The aim of the present work was to characterize this protein. Initially, it was confirmed by fluorescence and electron microscopy that the fibronectin-binding molecules were located in the bacterial surface, but the distribution of these molecules on the surface was not uniform. To further evaluate the role of this protein, the gene bf1991, responsible for encoding this protein, was inactivated by a suicide vector and the mutant strains generated were used in several experiments to verify possible phenotypical alterations. In adherence assays with fibronectin immobilized on latex beads an increased adhesion was observed with the mutant strains compared with the wild-type strain. Western blot analysis in the mutant strain revealed the absence of the 120 kDa TonB-dependent outer-membrane protein and an alteration in the expression of an unknown 30 kDa protein. Killing assays using peritoneal macrophages were performed to evaluate the role of this protein as a virulence attribute and it was observed that the mutant strains were more efficiently internalized than the wild-type strains, with more internalization in the samples covered with fibronectin than in the samples not covered with it.

Candida albicans-epithelial interactions: dissecting the roles of active penetration, induced endocytosis and host factors on the infection process

Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by penetrating through epithelial barriers. C. albicans is a remarkable pathogen because it can invade epithelial cells via two distinct mechanisms: induced endocytosis, analogous to facultative intracellular enteropathogenic bacteria, and active penetration, similar to plant pathogenic fungi. Here we investigated the contributions of the two invasion routes of C. albicans to epithelial invasion. Using selective cellular inhibition approaches and differential fluorescence microscopy, we demonstrate that induced endocytosis contributes considerably to the early time points of invasion, while active penetration represents the dominant epithelial invasion route. Although induced endocytosis depends mainly on Als3-E–cadherin interactions, we observed E–cadherin independent induced endocytosis. Finally, we provide evidence of a protective role for serum factors in oral infection: human serum strongly inhibited C. albicans adhesion to, invasion and damage of oral epithelial cells.

Antibiotic resistance and adhesion potential of Bacteroides fragilis clinical isolates from Cape Town, South Africa

The minimum inhibitory concentrations of 23 Bacteroides fragilis clinical isolates from Cape Town, South Africa, were established using the E-test method. Eight percent of the strains were found to be highly resistant to metronidazole (≥256 mg/L) imipenem and cefoxitin. This is an 8% increase in resistance compared to the previous metronidazole susceptibility screening performed in South Africa in 1998. Clindamycin was the most effective antibiotic with all strains showing sensitivity. Most of the strains (65%) were tetracycline resistant, while one strain, B. fragilis GSH15, showed multidrug resistance to metronidazole, imipenem, cefoxitin and tetracycline. PCR screening revealed that none of the strains contained any of the published nim genes. The particle agglutination assay was employed to determine the ability of the isolates to bind the ECM components fibronectin, laminin, mucin and collagen. This revealed that 78% of the clinical isolates adhered to all four ECM components to varying extents, with the strongest being to laminin and weakest to mucin and collagen Type I.

The redox potential interferes with the expression of laminin binding molecules in Bacteroides fragilis

The Bacteroides fragilis ATCC strain was grown in a synthetic media with contrasting redox potential (Eh) levels [reduced (-60 mV) or oxidised (+100 mV)] and their adhesion capacity to extracellular matrix components was evaluated. The strain was capable of adhering to laminin, fibronectin, fibronectin + heparan sulphate and heparan sulphate. A stronger adherence to laminin after growing the strain under oxidising conditions was verified. Electron microscopy using ruthenium red showed a heterogeneous population under this condition. Dot-blotting analyses confirmed stronger laminin recognition by outer membrane proteins of cells cultured at a higher Eh. Using a laminin affinity column, several putative laminin binding proteins obtained from the cultures kept under oxidising (60 kDa, 36 kDa, 25 kDa and 15 kDa) and reducing (60 kDa) conditions could be detected. Our results show that the expression of B. fragilis surface components that recognise laminin are influenced by Eh variations.

A TonB-dependent outer membrane protein as a Bacteroides fragilis fibronectin-binding molecule

The binding of Bacteroides fragilis to plasmatic fibronectin was investigated using strains isolated from healthy subjects and from patients with bacteremia. They were cultivated in a synthetic media in which variations in cysteine concentrations determined alterations in the oxidation-reduction potential (Eh). All the strains assayed were capable of adhering to plasmatic fibronectin when cultivated under oxidizing and reducing conditions. Bacteroides fragilis 1405 showed the greatest difference when the results under these conditions were compared and it was selected for further investigations. Chemical treatments suggested the involvement of a protein in the interaction between B. fragilis and plasmatic fibronectin. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of outer membrane proteins (OMPs) revealed differences between the extracts obtained from cultures grown under the two conditions. Protein bands of c. 102, 100, 77, 73, 50 and 40 kDa were more highly expressed under oxidizing than reducing conditions. Dot blot analysis showed a stronger recognition of plasmatic fibronectin by OMPs obtained from cultures grown under higher Eh, and Western blot assays confirmed a band of c. 102 kDa as fibronectin-binding protein. This protein was sequenced and revealed to be a putative TonB-dependent OMPs. PCR analysis confirmed the presence of this gene in all the studied strains.

Potential of enterococci isolated from horses

Faecal samples of 122 horses (from farms in Slovakia) were examined to select enterococci to study their probiotic potential for their further use as additives. Each gram of faeces contained 1.0-5.0 cfu (log 10) of enterococci. Of the 43 isolates, 25 (58.1%) were identified as Enterococcus faecium, 3 strains were (6.9%) Enterococcus mundtii and one strain was identified as E. faecalis. Fourteen isolates were not characterized further. A significant proportion of the isolates were resistant to kanamycin, vancomycin and gentamicin. Low urease activity of enterococci dominated. The values of lactic acid ranged from 0.98 to 1.91 mmol/L. Porcine fibronectectin and bovine lactoferrin were bound weakly by tested enterococci, while bovine fibrinogen was bound more strongly. Enterococci from horses did not bind bovine apotransferrin. The isolates adhered with the same ability to human as well as to canine mucus. At least one enterocin gene was detected among 16 analyzed isolates. Ent B gene was detected in all strains tested (16, 100%), followed by the genes ent A, ent P and ent L50B. Three suitable candidates-the strains of E. faecium EF 412, EF 462 and EF 491 were selected for further detail studies and possibilities to be used as additives.

Binding of extracellular matrix proteins to the surface of Bacteroides spp

The binding of fibronectin an vitronectin to 207 Bacteroides strains and the binding of collagen and sialoproteins to 55 Bacteroides strains were investigated by means of latex agglutination tests. The binding of fibronectin, collagen and lactoferrin to the same 55 strains was also tested by using 125I-labelled proteins. The 207 strains, belonging to ten Bacteroides species, were isolated from different infections (51%) and from faeces of healthy subjects (49%). Most of the strains displaying fibronectin binding belonged in the species B. fragilis or B. vulgatus. The binding could be inhibited by preincubation of the cells with an excess amount of fibronectin. No inhibition of the binding was observed with carbohydrates. The vitronectin binding of the strains was less common, but was always observed to accompany fibronectin binding. None of the examined 55 strains exhibited any binding to fetuin or asialofetuin. The radiolabelling method indicated a low binding to 125I-fibronectin. The binding of 125I-collagen-I and 125I-lactoferrin in the Bacteroides strains tested was higher than that of 125I-fibronectin.

Binding of extracellular matrix molecules by probiotic bacteria

AIMS

The aim of this study was to investigate extracellular matrix (ECM) and mucin binding of selected bacterial isolates with probiotic features in comparison with commercially used probiotic bacteria.

METHODS AND RESULTS

ECM molecules were immobilized in microtitre plates (mucin and fetuin) or on the surface of latex beads. Porcine mucin was bound by all 13 probiotic strains tested with important inter-strain differences; however, fetuin binding was similar (weak) for all 14 strains tested. Strongly positive (three) binding of bovine fibrinogen was expressed by strains from fermented food (Lactobacillus rhamnosus GG, L. casei Shirota and L. johnsonii La1) as well as by L. casei L.c., Lactobacillus sp. 2I3 and by L. plantarum LP. The other strains expressed moderate (2) or weakly positive (1) binding of bovine fibrinogen. Strongly positive (3) binding of porcine fibronectin was observed only with two strains; however, all other strains also bound this molecule. Bovine lactoferrin was bound to a higher extent than transferrins.

SIGNIFICANCE AND IMPACT OF THE STUDY

Some animal strains (at least L. casei L.c. and Lactobacillus sp. 2I3) are comparable with the commercially used strains with respect to their ECM binding ability. As this feature is important for probiotic bacteria to be able to colonize intestine, these strains should be considered for their wider use in fermented feed (or probiotic preparations) for animals.

Lectin-like binding and antibiotic sensitivity of enterococci from wild herbivores

Fifty eight enterococcal isolates from wild herbivores were tested for their antibiotic sensitivity pattern and lectin-like binding of extracellular matrix (ECM) and serum proteins. Kanamycin resistance was very frequent; many multiresistant strains were also isolated. All isolates were sensitive to rifampicin. Resistance to gentamicin, novobiocin, and tetracycline was widely distributed in the microflora of wild herbivores breeded in zoological garden in Kosice. No autoaggregating strains were detected among these 58 enterococcal isolates. Various degrees of binding of mucins, fetuin, heparin, fibrinogen, and fibronectin were observed in individual strains. However, bovine lactoferrin binding by enterococci from deers and chamoises was either negative (0) or strongly positive (3). With regard to influence of growth media, TH agar was found to be better for the expression of lectin-like binding than blood agar, TH broth and Nutrient broth. A significant effect (P < 0.001 or P < 0.05) of proteolytic treatment was observed in six selected strains. However, there is a difference between the effect of trypsin and pronase P. Pronase treatment more effectively decreased binding of some strains (1H, 6A, EF 1111, EC 1292), while trypsin treatment decreased more binding of other enterococcal strains (EF 953 and 1E). Significant (P < 0.001) influence of metaperiodate, which cleaves the C-C bond between vicinal groups of sugars, on collagen I binding by three selected strains (1E, 1H, 6A) and bovine lactoferrin binding (by EF 1111, EC 1292, EF 953) was also observed. However, its influence was very different. In two strains (1H and EC 1292), ECM binding was decreased, while in four other strains (1E, 6A, EF 1111, EF 953) it was increased.

rgf encodes a novel two-component signal transduction system of Streptococcus agalactiae

The adhesion of gram-positive bacteria to extracellular matrix (ECM) proteins is regarded as an important determinant of pathogenicity. A comparison of the adhesion of Streptococcus agalactiae strain O90R to different ECM proteins showed that the most pronounced binding could be observed for immobilized fibrinogen. To investigate the genetic determinants of S. agalactiae fibrinogen binding, a pGhost9:ISS1 mutant library was screened for mutants displaying reduced agglutination of fibrinogen-coated latex beads. A putative two-component signal transduction system was identified and designated rgfBDAC. It comprises genes encoding a putative response regulator of 218 amino acids and a putative histidine kinase of 426 amino acids. Comparison of the deduced proteins with the GenBank database revealed a significant similarity to quorum-sensing systems of gram-positive pathogens. Transcription analysis of the rgf locus showed that the encoding genes are located on one transcript. To further characterize the influence of the putative histidine kinase encoded in the rgf locus on the adhesion of S. agalactiae to immobilized fibrinogen, a targeted mutant of rgfC was generated. In comparison to the wild-type strain this mutant demonstrated altered fibrinogen binding capacities depending on bacterial cell density. Transcription analysis of secreted and surface-localized S. agalactiae proteins in the wild type and the rgfC mutant strain revealed that mRNA levels of the C5a peptidase gene scpB were increased in the mutant strain while the transcription of the secreted CAMP factor gene cfb was unaffected by this mutation. Based on these results, we hypothesize that rgf regulates the expression of bacterial cell surface components.

Teichoic acid enhances adhesion of Staphylococcus epidermidis to immobilized fibronectin

Adhesion is a prerequisite for coagulase-negative staphylococci to cause invasive disease and may be mediated by adhesive host molecules adsorbed on implanted polymers. In this study, we can confirm previous observations demonstrating binding of Staphylococcus epidermidis to fibronectin (FN) adsorbed polymer surfaces. So far, the nature of FN-recognizing adhesin(s) in S. epidermidis remains elusive. Since teichoic acids (TA) have been shown to exert binding functions for extracellular matrix molecules in several Gram-positive species, we have purified wall TA of S. epidermidis laboratory strains KH11 and RP62A, as well as clinical isolate AB9. Using a polymethylmethacrylate (PMMA) coverslip adhesion assay, a microtitre plate assay and a particle agglutination assay, we found that purified TA significantly enhanced adhesion of S. epidermidis KH11 and RP62A to FN coated surfaces. Enhanced adhesion was dose-dependent and saturable. Preincubation, either of microorganisms or of FN coated surfaces, with TA promoted adhesion, while adhesion to TA-adsorbed PMMA was comparably low. This observation may suggest a potential role of cell wall carbohydrates as bridging molecules between microorganisms and immobilized FN in early steps of S. epidermidis pathogenesis.

Binding of oral streptococci to human fibrinogen

The interaction of oral streptococci with human fibrinogen was investigated. Streptococcus gordonii was chosen as a representative species to study the binding to fibrinogen. S. gordonii DL1 adhered to immobilized fibrinogen and bovine serum albumin. Binding to immobilized fibrinogen was saturable, concentration and temperature dependent. The binding of S. gordonii DL1 to fibrinogen was inhibited by anti-fibrinogen antibody. Heating of the bacteria for 1 h at 95 degrees C resulted in 90% inhibition of the binding. Trypsin treatment of the bacteria resulted in decreased binding. Neither lipoteichoic acid nor culturing of the bacteria in a sucrose-supplemented medium had any effect on the binding. S. gordonii, Streptococcus sanguinis, Streptococcus mitis, and Streptococcus oralis bound to the immobilized fibrinogen, but mutans streptococci did not. None of the oral streptococci tested bound to the fibrinogen in fluid phase. These results suggest that the binding of S. gordonii DL1 to immobilized fibrinogen is mediated through a specific protein adhesin-receptor interaction, and fibrinogen acts as a cryptitope.

Starvation-induced changes in the cell surface of Azospirillum lipoferum

Three starvation regimes (a deficient culture medium, a saline buffer solution and distilled water) were evaluated for their possible effect on cell surface characteristics of Azospirillum lipoferum 1842 related to the initial adsorption of the bacterium to surfaces. The bacteria survived for 7 days in all media although they did not multiply. Upon transfer from a rich growth medium (nutrient agar) to starvation conditions, cell surface hydrophobicity dropped sharply but recovered its initial value within 24 to 48 h, except in phosphate-buffered saline, the length of the recovery period depending on the starvation medium. Starvation affected the sugar affinity of the A. lipoferum cell surface mainly towards p-aminophenyl-alpha-D-mannopyranoside, to a lesser extent to glucose, but not to other monosaccharides tested. Starvation changed the concentration of several cell surface proteins but did not induce the synthesis of new ones. The cell surface hydrophobic protein (43 kDa) of A. lipoferum 1842 was unaffected by any starvation treatment for a period of up to 48 h, but later disappeared. These data showed that starvation is not a major factor in inducing changes in the cell surface which lead to the primary phase of attachment of Azospirillum to surfaces.

Binding of extracellular matrix proteins by animal strains of staphylococcal species

All 81 strains of Staphylococcus species isolated mainly from animals express high surface hydrophobicity as a stable property upon cultivation on blood agar. Bovine lactoferrin, human vitronectin, human fibronectin, heparin, human and bovine serum albumin were immobilized on latex beads to detect protein-binding cell surface components of 67 non-autoaggregating staphylococcal strains by a particle agglutination assay. Bovine lactoferrin was bound well by 22 strains (3 or 2) while 15 strains reacted weakly (1) and 30 did not react (0) with the lactoferrin-coated latex beads. The particle agglutination assay showed similar differences among staphylococcal strains in binding other proteins with the exception of human and bovine serum albumins for which 66 of 67 strains were negative (0). The specificity of the agglutination reaction was confirmed by a particle agglutination inhibition assay by preincubating bacterial cells with the protein (lactoferrin, vitronectin, etc.) used subsequently in particle agglutination assay. Autoaggregating strains together with some non-autoaggregating strains were selected for microtitre plate assay. According to absorbance at 570 nm, 14 strains were classified as non-adherent, 16 strains as weakly adherent and 18 strains as strongly adherent to bovine lactoferrin in microtitre plate assays. A direct correlation was found between the absorbance values at 570 nm of microtitre plate binding assay and test values obtained in particle agglutination assay. Binding of bovine lactoferrin to 81 staphylococcal strains as well as of human vitronectin and human fibronectin to a selected number of these strains was studied with radiolabeled (125I-labeled) proteins. Radiolabeled bovine lactoferrin was bound common by all except four strains (7 to 39%). Staphylococcal strains isolated from diseased pigs commonly bound 125I-labeled vitronectin (21 to 42% of the vitronectin added). Binding of vitronectin and lactoferrin was efficiently inhibited by preincubating of staphylococcal cells with sulphated carbohydrate compounds as heparin, dextran sulphate and fucoidan, but not by other non-sulphated highly charged glycoconjugates such as hyaluronic acid.

Fibronectin and laminin binding of urogenital and oral prevotella species

88 strains of five Prevotella species--P. bivia, P. buccae, P. disiens, P. oralis, and P. oris--were examined for their fibronectin and laminin binding properties with the aid of latex particle agglutination assays. Beside single protein binding activities, all species showed strains that adhered to both fibronectin and laminin. The oral species, P. buccae, P. oralis, and P. oris were found to interact with laminin to a pronouncedly higher extent than with fibronectin. The urogenital species, P. bivia and P. disiens showed comparable activities of binding to fibronectin and laminin, with P. bivia exhibiting higher matrix protein binding rates than P. disiens. Within the oral species group, P. oralis showed a higher percentage of fibronectin and laminin reactive strains than did P. buccae and P. oris. The finding of species-related different binding properties may throw some light on the known differences in clinical relevance and pathogenicity of the urogenital species, P. bivia and P. disiens, but does so only in part concerning the oral species, P. buccae, P. oralis, and P. oris. Moreover, the observed differences in matrix protein binding of Prevotella species may have implications in chemotaxis and opsonization on the one hand and maintenance of colonization activities under antibiotic therapy on the other.

Fibronectin binding and cell surface hydrophobicity contribute to adherence properties of group B streptococci

The matrix protein, fibronectin, which is detectable in various tissues, when present in the vaginal fluid of women in labour, indicates the rupture of membranes. It is known that many bacteria adhere to fibronectin, thus establishing a first step of infection. In women in labour, group B streptococci are common agents of chorioamnionitis. For group B streptococci, unspecific adherence mechanisms like negative net charge and hydrophobic interactions have already been discussed in literature. In the present study, group B streptococci isolates from 57 patients with premature rupture of membranes were studied for fibronectin binding activities, using a particle agglutination assay and for cell surface hydrophobicity, by testing adhesion to hydrocarbons. Particle agglutination assays and adhesion assays were done with strains grown on blood-containing media and media without blood. Fibronectin binding was shown to be present in 14 and 11 out of 57 isolates grown on Mueller-Hinton and Tryptic Soy agar, respectively. When the strains were grown on blood-containing media, fibronectin-binding was found to be concomitant with decreased hydrophobicity. According to the results obtained in a total of 57 strains, cell surface hydrophobicity is an unspecific adhesion factor in group B streptococci. Fibronectin binding seems to be an additional adherence factor in some of the strains and may be assumed to play a major role in establishing infectious processes.

Lactoferrin inhibits herpes simplex virus type 1 adsorption to Vero cells

This paper describes the ability of human and bovine lactoferrins (HLf; BLf), iron-binding proteins belonging to the non-immune defense system, to interfere with herpes simplex virus type 1 (HSV-1) infection. Since lactoferrins are known to bind to heparan sulphate proteoglycans and to low density lipoprotein receptor, which in turn act as binding sites for the initial interaction of HSV-1 with host cells, we tested the effect of these proteins on HSV-1 multiplication in Vero cells. Both HLf and BLf are found to be potent inhibitors of HSV-1 infection, the concentrations required to inhibit the vital cytopathic effect in Vero cells by 50% being 1.41 microM and 0.12 microM, respectively. HLf and BLf exerted their activity through the inhibition of adsorption of virions to the cells independently of their iron withholding property showing similar activity in the apo- and iron-saturated form. The binding of [35S]methionine-labelled HSV-1 particles to Vero cells was strongly inhibited when BLf was added during the attachment step. BLf interacts with both Vero cell surfaces and HSV-1 particles, suggesting that the hindrance of cellular receptors and/or of viral attachment proteins may be involved in its antiviral mechanism.

Fibronectin and laminin binding of eighteen Clostridium species

The ability of Clostridium difficile, Clostridium perfringens, Clostridium sporogenes and fifteen other Clostridium species to bind to human serum fibronectin or laminin was tested by using protein-coated latex particles. Three groups of Clostridium species were formed, namely the pseudomembranous colitis-causing species Clostridium difficile, the gas gangrene-causing Clostridium species and other Clostridium species, which are infrequently found in human infections. Significantly more strains of gas gangrene-causing Clostridium species, and strains of Clostridium species other than Clostridium difficile recognized fibronectin or laminin than did Clostridium difficile. Experiments with monoclonal antibodies revealed the specificity of the bacterial binding to fibronectin or laminin.

Bacteroides fragilis adheres to laminin significantly stronger than Bacteroides thetaiotaomicron and other species of the genus

The laminin binding properties of eight species of the genus Bacteroides were examined using latex particle agglutination assay. B. fragilis was found to bind strongly to laminin, whereas all other species tested showed no or only weak laminin adherence. The pronounced differences in laminin binding activity between B. fragilis on the one side and B. thetaiotaomicron and B. ovatus on the other were determined to be statistically significant (p < 0.001 and p < 0.01, respectively). With regard to the relevance of laminin adherence for bacterial pathogenicity and invasiveness, our results give a possible explanation for the well-known finding that B. fragilis is the most frequently isolated pathogen in anaerobic bacteremia.

In vitro indices of tissue adherence in Staphylococcus intermedius

In vitro indices of adherence showed that strains of Staphylococcus intermedius from lesions of canine pyoderma differed from strains isolated from normal carrier sites in that a significantly greater proportion of pyoderma strains adhered to extracellular matrix proteins whilst fewer adhered to polystyrene. Slime production and a hydrophobicity index did not differ between the groups. This suggests that exposure of extracellular matrix proteins due to underlying disease may result in the selection of a narrower spectrum of strains from amongst those at carrier sites.

Fibronectin and vitronectin binding of Bacteroides fragilis and eight other species of the genus

The fibronectin and vitronectin bindings of 152 strains belonging in 9 Bacteroides species of different origins were tested by means of latex agglutination. 23% of the strains isolated from faeces exhibited fibronectin binding, as did 46% of the strains obtained from severe infections. Most of the strains displaying fibronectin binding belonged to the species Bacteroides fragilis or Bacteroides vulgatus. The binding could be inhibited by preincubation of the cells with an excess amount of fibronectin. Vitronectin binding was less common, but was always observed in parallel with fibronectin binding.

Effect of lactoferricin B, a pepsin-generated peptide of bovine lactoferrin, on Escherichia coli HB101 (pRI203) entry into HeLa cells

Bovine lactoferrin and a pepsin-generated peptide of bovine lactoferrin, known as lactoferricin B, were tested for an ability to influence the cell-invasive properties of an Escherichia coli HB101 strain carrying the plasmid pRI203, which encodes the Yersinia pseudotuberculosis inv gene. At non-cytotoxic and non-bactericidal concentration (0.5 mg/ml) lactoferricin B lowered by about tenfold the cell invasion capability of E. coli HB101 (pRI203), whereas no effect was observed when bovine lactoferrin was added during the infection of HeLa cell monolayers. The step of the invasion process affected by lactoferrin B was the internalization since the adhesion of bacteria to HeLa cells was unaltered in the presence of the peptide. Latex beads coated with lactoferrin B bound to HeLa cell monolayers and induced the agglutination of bacterial cells, indicating that this highly cationic peptide interacts directly with both eukaryotic and bacterial surfaces. Moreover, we demonstrated that the anti-invasive effect induced by lactoferrin B was reversed when the medium was supplemented with Ca2+, Mg2+ and Fe2+ ions which diminished its affinity binding. Our findings suggest that lactoferrin B effectiveness towards E. coli HB101 (pRI203) invasion is correlated to its binding capability on the eukaryotic and bacterial cell surfaces.

Cell surface hydrophobicity and adherence to extra-cellular matrix proteins in two collections of methicillin-resistant Staphylococcus aureus

Non-specific and specific mechanisms of adherence have been examined in two collections of methicillin-resistant Staphylococcus aureus (MRSA). Determination of hydrophobicity by salt aggregation, hydrophobicity indices and of adherence to the extra-cellular matrix proteins fibronectin, vitronectin, laminin and collagen type 1 have failed to reveal any correlation with phage-type, plasmid profile or antibiogram. Further, the strain collections, made over a period of years in two countries, differ markedly in their adherence characteristics; MRSA are heterogeneous in this respect. Such heterogeneity may explain the polarization of views on the epidemicity or 'virulence' of MRSA. With the exception of adherence to collagen a small group of methicillin sensitive S. aureus had characteristics intermediate between the two groups of MRSA.

Use of commercial particle agglutination systems for the rapid identification of methicillin-susceptible and methicillin-resistant Staphylococcus aureus

The performance of a recently introduced Staphylococcus aureus identification system (Slidex Staph-Kit) was compared with that of currently available systems (Immuno Scan Staphlatex, Staphyloslide, Staphaurex and SeroSTAT II) for the identification of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus. The new system, which detects a capsular antigen common in MRSA, performed with equal or greater sensitivity than the other systems. None of the commercial systems was adversely affected by the methicillin susceptibility of the staphylococci when isolates were recovered from non-selective media. The greatest advantage of the anti-capsular monoclonal reagent was its improved performance on isolates recovered from selective media.

Rapid detection and characterization of sialic acid-specific lectins of Helicobacter pylori

A particle agglutination assay (PAA) using fetuin (Ft) covalently coupled to carboxylate-modified latex (CML) particles was evaluated for rapid detection of sialic acid-specific haemagglutinins/lectins (SALs) of Helicobacter pylori isolates which bind sialoglycoconjugates. Sixty-three percent (20/32) of the isolates examined gave a positive PAA test. Cell-bound SALs were extracted by washing the bacteria with deionized water or isotonic saline, and their expression was influenced by pH and culture conditions. The Ft-CML reactivity of the PAA-positive isolates was inhibited by bovine submaxillary mucin, transferrin, fetuin, orosomucoid, vitronectin and lactoferrin in a manner which suggested that the isolates contain a lectin recognizing the alpha(2-6) linkage of terminal sialic acid. Western blots of strain NCTC 11637 SALs probed with horseradish peroxidase (HRP)-labelled Ft identified three bands (MW 64 kD, 62 kD, 56 kD) which also reacted with HRP-labelled mucin, transferrin, lactoferrin, orosomucoid, vitronectin and laminin. Sera from patients with a H. pylori infection and one polyclonal rabbit antiserum (strain NCTC 11637) also reacted with the SALs. Immunogold labelling of a polyclonal rabbit antiserum raised against the 64 kD protein of strain NCTC 11637 that reacted strongly with Ft-CML showed that abundant SALs were loosely cell-associated with the cell surface of both spiral and coccoidal forms of H. pylori. SALs were also present in low amounts on the surface of strain NCTC 11638 and 66, a clinical isolate that did not react with Ft-CML.

Relapsing severe Trichophyton rubrum infections in an immunocompromised host: evidence of onychomycosis as a source of reinfection based on lectin typing

A 64-year-old patient developed recurrent (about 3-6 times a year) generalized skin lesions due to Trichophyton rubrum during long-term steroid treatment of lung fibrosis. Additionally, he suffered for years from onychomycosis of all toes. In the past, short-term internal treatment with griseofulvin and ketoconazole resulted in fast clearing of skin symptoms. Since 1991 relapses have been treated with itraconazole orally. In 1992 material was collected from diseased nails and toe and other skin lesions during three severe attacks of fungal infections and in addition once from toenails during a period without skin manifestations. Trichophyton rubrum was isolated from each sample. Lectin typing of the isolates using five lectins of plant origin resulted in identical lectin patterns for all isolates, thus localizing the toenails as the source of reinfection. The results indicate that lectin typing may play an important role in clinical and epidemiological analysis of dermatophytes.

Binding of collagen, fibronectin, lactoferrin, laminin, vitronectin and heparan sulphate to Staphylococcus aureus strain V8 at various growth phases and under nutrient stress conditions

We have examined how Staphylococcus aureus strain V8 cells interact with 125I-labelled extracellular matrix (ECM) and serum proteins (collagen type I and IV), fibronectin, lactoferrin, laminin, vitronectin, and heparan sulphate at various phases of the growth cycle. Maximal binding of these glycoproteins and heparan sulphate to the bacteria occurred after 17 to 20 h in the late stationary phase except for fibronectin-binding, which was maximal after 12 to 14 h. Binding of the glycoproteins and heparan sulphate to S. aureus V8 under nutrient stress conditions exhibited complex patterns based on different starving conditions and various binding ligands. In general, bacteria starved in distilled water and 0.02 M potassium phosphate buffer (pH 7.2) at room temperature showed high susceptibility to all binding ligands within the first 18 h, followed by entering a lower binding period (except for collagen-binding which still remained high). The binding was not correlated to cell surface charge or hydrophobicity of the bacteria. Furthermore, extracellular and cell-associated proteolytic activity of starved cells against ECM and serum proteins was found to be greater than for non-starved cells. Thus, S. aureus could sustain its ability to bind various connective tissue and cell surface components during a long period of time even in the absence of energy-yielding substrates.

Binding of Lactobacillus reuteri to fibronectin immobilized on glass beads

Human fibronectin was immobilized on glass beads. The beads were used to evaluate binding of Lactobacillus reuteri to fibronectin. Organisms bound to the glass beads were detected using fluorescence microscopy after treatment with acridine orange. This binding was confirmed and quantified with the use of [3H]-labelled organisms. Three strains of Lactobacillus reuteri, three strains of Lactobacillus acidophilus and one strain of Lactobacillus fermentum were tested for binding capacity. L. reuteri strain 1063 exhibited a strong binding to the immobilized fibronectin, and L. acidophilus 1754 showed a slight binding. The binding of L. reuteri to the fibronectin was mediated by a protein as judged by the absence of binding after treatment of the bacteria with proteolytic enzymes. Treatment of the bacteria with urea, SDS and heat (80 degrees C) also reduced binding. Treatment of the bacterial cells prior to the assay with fibronectin interfered with binding. Albumin did not show this interaction.

Rapid identification of fibronectin, vitronectin, laminin, and collagen cell surface binding proteins on coagulase-negative staphylococci by particle agglutination assays

Seventeen strains of ten different species of coagulase-negative staphylococci were shown to interact with collagen, laminin, fibronectin, and vitronectin immobilized on latex beads. Different species of coagulase-negative staphylococci have different capacities to agglutinate proteins. Cells of 18 strains of Staphylococcus haemolyticus reacted more strongly than did cells of 18 Staphylococcus epidermidis strains with proteincoated latex beads, although no significant difference in cell surface hydrophobicity or charge could be shown. The cell surface receptors of S. haemolyticus were more heat and protease resistant than were Staphylococcus aureus receptors. Strains of Staphylococcus saprophyticus isolated from urinary tract infections showed a high capacity to adhere to laminin. The ability to agglutinate fibronectin and collagen was common among coagulase-negative staphylococci isolated from other infections; 55% (31 of 56) and 63% (35 of 56) agglutinated fibronectin and/or collagen. S. haemolyticus and S. epidermidis bound to both N-terminal (29-kDa) and C-terminal (120-kDa) fragments of fibronectin.

Laminin binding to Prevotella intermedia

The interaction of laminin (Lm), a basement membrane protein abundant in the periodontium, with 66 strains of Prevotella intermedia isolated from diseased pockets, was tested in a 125I-labeled protein binding assay. The mean binding value was 28% of the total protein added. The binding significantly increased to 35% when the environmental pH decreased from 7 to 6. The Lm interaction was characterized in a highly binding (about 65%) strain, OMGS105. The binding was rapid and required about 1 min and 1-2 h for 50% and 100% equilibrium respectively. The 125I-Lm binding was maximum in the pH interval 3.0 to 6.5 and could not be displaced by unlabeled Lm or inhibited by other proteins and carbohydrates. The interaction was stable in the presence of NaCl or urea (concentrations up to 4 M) but was dissociated by > or = 1 M KSCN. The Lm-binding component was thermolabile and sensitive to proteolytic enzymes. Sodium dodecylsulfate-polyacrylamide gel electrophoresis and Western blot analysis revealed a approximately 62 kDa Lm-binding protein, both in the whole cell extract and the outer membrane preparation. Weaker binding was also observed to other proteins. These data establish the ability of P. intermedia to interact with Lm via certain cell surface proteins, a property that might contribute to the colonization of this bacterium in the periodontal pocket.

Binding of Haemophilus ducreyi to extracellular matrix proteins

A collection of Haemophilus ducreyi isolates were screened for the ability to bind to fibrinogen, fibronectin, collagen, gelatin and laminin by a particle agglutination test using latex beads coated with the individual proteins. Thirteen of 21 isolates reacted with all five extracellular matrix proteins. Binding of organisms to protein-coated latex beads was inhibited by pretreatment of the bacteria with detergent, trypsin or boiling. Two isolates did not bind to collagen and gelatin with one of these not reacting with laminin either. Seven strains which failed to react with laminin did not express pili when examined by electron microscopy. This observation suggests a specific interaction with the pili of H. ducreyi.

Fibronectin binding by Salmonella strains: evaluation of a particle agglutination assay

Thirty-five Salmonella strains isolated from human cases of salmonellosis were tested and compared for their fibronectin (fn) binding capacities by using two fn-particle agglutination assays (fn-PAAs) prepared by coating with human fn either (i) latex beads (Difco; 0.81-micron diameter) (L-fn-PAA) or (ii) heat-killed formalin-treated Staphylococcus aureus Cowan 1 cells (C-fn-PAA). Six S. aureus strains were also included in this study as controls. The strains were cultured on colonization factor antigen agar and blood agar and in tryptic soy broth and brain heart infusion broth. The Salmonella and S. aureus strains were cultured at 33 and 37 degrees C, respectively, for optimal expression of fn-binding proteins. Bacterial cells (approximately 10(10) cells per ml) harvested from growth in various culture media and suspended in 0.02 M potassium phosphate buffer (pH 6.8) agglutinated the fn-PAA reagents. These reactions were scored semiquantitatively from + to + depending on the speed or intensity of the reactions within 2 min. Maximum agglutination in fn-PAA systems was observed when the cells were grown in brain heart infusion broth, while tryptic soy broth proved to be least suitable media for culturing cells for fn-PAAS. Although a statistically highly significant correlation was obtained between results of assays of radiolabeled fn and 29-kDa fragment binding, no significant correlation was observed (i) between the results of strains cultured in different media or (ii) when semiquantitative score results of the two fn-PAA systems were compared with those of the conventional radiolabeled fn assay. To enhance the efficiency of the test system, the C-fn-PAA reagent was stained with methylene blue (2% in 0.17 M glycine-NaOH buffer [pH 6.8]). This facilitated easy interpretation of results, which could be performed on hydrophobic paper instead of glass slides. The results obtained with both unstained C-fn-PAA and stained C-fn-PAA were comparable to each other and reproducible. Although the fn-PAAs are simple and easy to perform, the results did not differentiate between negative, low, moderate, and high binding abilities when Salmonella strains were evaluated for fn binding, and the results were not comparable to those obtained by the conventional radiolabeling method.

Effect of biliary infection on common bile duct healing in the rat

It has been postulated that biliary infection plays a role in bile duct stricture formation. The aim of this study was to verify this hypothesis and to evaluate the effect of biliary infection on common bile duct healing. A 3-mm longitudinal choledochotomy was performed in 120 rats and closed with a continuous 11/0 Ethilon suture. Common bile duct division with end-to-end anastomosis using interrupted 11/0 Ethilon sutures was performed in another 30 rats. Biliary infection was achieved in half of the animals with retrograde injection of living 046:K1:H31 strain Escherichia coli recovered from the rat colonic content. All rats with choledochotomy, including those with biliary infection, showed no bile leakage at the suture line, and the bursting pressure at the site of choledochotomy exceeded 40 mmHg as early as 24 h. Rats with common bile duct anastomosis alone showed no stricture formation for up to 6 months after operation. All rats with biliary sepsis developed complete occlusion at the anastomosis. On scanning electron microscopy, the biliary epithelium was well preserved in all rats. The study suggests that in rats with biliary sepsis the risk of bile leakage after primary closure of the common bile duct is negligible, but biliary infection may play a critical role in common bile duct stricture formation.

Comparison between lactoferrin and subepithelial matrix protein binding in Staphylococcus aureus associated with bovine mastitis

Staphylococcus aureus strains (n = 100) isolated from bovine mastitis were classified according to the presence of capsular polysaccharide serotype 5 (n = 46), type 8 (n = 26), and non-5/8 (n = 28). Strains from each type were tested for protein interaction in a 125I-labeled ligand binding assay. A majority of type 5 and type 8 strains showed a higher degree of binding to lactoferrin, fibronectin, and IgG than the non-5/8 strains. Fibrinogen binding was low in all serotypes. Most of the type 5 and non-5/8 strains bound less than 10% laminin, whereas type 8 strains bound laminin in the 11 to 20% range. Non-5/8 strains significantly differed from type 5 in lactoferrin, fibronectin, fibrinogen, and IgG and also from type 8 in fibrinogen and IgG binding. The differences in protein binding between type 5 and type 8 were nonsignificant. The degree of lactoferrin binding in all types positively correlated with laminin binding. Lactoferrin and fibrinogen bindings were correlated in type 5 and type 8 strains. Lactoferrin and fibronectin bindings were correlated only in type 5 strains. These data suggest that bovine lactoferrin binding is common and associated with subepithelial matrix protein interactions in certain serotypes of S. aureus.

Bovine lactoferrin receptors in Staphylococcus aureus isolated from bovine mastitis

A total of 103 Staphylococcus aureus strains isolated from bovine mastitis were tested for bovine lactoferrin binding in a 125I-labeled protein binding assay. More than 85% of the strains demonstrated high to moderate and a few showed little or no binding. Bovine lactoferrin binding to S. aureus cells was high when grown on blood, nutrient, or proteose-peptone agar, but the binding capacity was low with cells grown on salt rich media, in skim milk, or in broth. The kinetics of 125I-labeled bovine lactoferrin binding required approximately 90 min for complete saturation with optimal interaction in the pH range 4.0 to 7.0. The lactoferrin-staphylococci interaction was specific with a high affinity (association constant, Ka 14 x 10(6) L/mol). Scatchard plot analysis estimated the number of binding sites per cell at 7200 on strain SA-340. Unlabeled bovine lactoferrin effectively displaced the binding of the labeled ligand to strain SA-340 in a dose-dependent manner. Bovine lactoferrin binding was inhibited or displaced by human lactoferrin. Various plasma, connective tissue, or mucosal secretory proteins tested did not inhibit lactoferrin-staphylococci interaction. Bovine lactoferrin binding components on SA-340 were resistant to glycolytic enzymes and moderately susceptible to proteolytic digestion. Two proteins with an estimated molecular weight of approximately 92 and 67 kDa were identified as bovine lactoferrin binding components of S. aureus strain SA-340.

Selection of colony, plasmid, and virulence variants of Staphylococcus epidermidis NRC853 during growth in continuous cultures exposed to erythromycin

A continuous-culture system was developed to study changes in the structure of Staphylococcus epidermidis populations exposed to subminimum inhibitory concentrations of erythromycin. Continuous-culture experiments were carried out in a dextrose-free, tryptic soy broth medium supplemented with lactic acid and sodium lactate (MTSB-D). The multiresistant (penicillin-, tetracycline-, and erythromycin-resistant) S. epidermidis strain NRC853 was subjected to a series of experiments: (i) growth individually in continuous culture in the absence and presence of erythromycin and (ii) growth in mixed culture with the erythromycin-susceptible S. epidermidis strain NRC852 in the absence and presence of erythromycin. Strain NRC853 produced colony morphology variants during continuous culture in the presence of 0.05 and 0.1 microgram of erythromycin per ml. Variants (A, B, and C) were different from their wild-type parent on the basis of colony size, sector pattern, and/or the ability to transmit light. A variants rapidly lost a 2.7-MDa tetracycline resistance plasmid. B and C variants formed an ermC plasmid multimer series from unit size to a 16-mer and exhibited an approximately twofold increase in erythromycin MIC over that of the wild-type parent. They slowly lost the tetracycline resistance plasmid. The small-colony B variant demonstrated an increased virulence in the neonatal mouse weight gain test and an increase in fibronectin binding compared with the wild-type parent. The presence of a competing strain drastically increased the frequency of all variants.

Fibronectin-staphylococcal interactions in endovascular infections

Fibronectin is a large molecular weight protein that is found coating the surfaces of sites where endovascular damage has occurred. These are also the sites most commonly infected by bacteremic strains of staphylococci. Epidemiologic studies show a correlation between expression of fibronectin receptors and development of invasive infections. In vitro studies using cultured cells, artificial matrices containing fibronectin, blood clots, natural inflammatory matrices, and anti-fibronectin antibodies implicate fibronectin as an important ligand for staphylococcal attachment to host tissues and prosthetic devices. In the rat endocarditis model, S. aureus strains that lack the fibronectin receptor due to site-directed mutagenesis were unable to colonize the traumatized heart valves. These data suggest that the fibronectin receptor on staphylococci is important in the pathogenesis of endovascular infections. Because the fibronectin receptor is widely expressed on pathogenic of staphylococci, a broadly protective vaccine against S. aureus might be possible.

Bovine lactoferrin binding to six species of coagulase-negative staphylococci isolated from bovine intramammary infections

Bovine lactoferrin (BLf), an acute-phase iron-binding secretory protein present in secretions of the bovine udder, was demonstrated to bind to the following staphylococcal species associated with bovine intramammary infections: S. epidermidis, S. warneri, S. hominis, S. xylosus, S. hyicus, and S. chromogenes. The degree of 125I-labeled BLf uptake significantly varied among the blood agar-grown cells of all six species of coagulase-negative staphylococci tested. Isolates identified as S. xylosus demonstrated the highest (mean, 35.1 x 10(6) +/- 13.3 x 10(6) nmol) and S. hyicus the lowest (mean, 10.7 x 10(6) +/- 5.9 x 10(6) nmol) binding to 125I-BLf. BLf binding was optimum at an acidic pH, with time-dependent binding saturation ranging from 70 min for S. warneri to 240 min for S. hominis. The BLf-binding mechanism was specific, with affinity constants (Ka values) ranging between 0.96 x 10(6) and 11.90 x 10(6) liters/mol. The numbers of BLf-binding sites per cell, as determined by using Scatchard analysis, were as follows: S. epidermidis, 3,600; S. warneri, 1,900; S. hominis, 4,100; S. xylosus, 4,400; S. hyicus, 6,100; and S. chromogenes, 4,700. 125I-BLf binding to all species was inhibited by unlabled BLf and unlabeled human lactoferrin, whereas none of the various plasma, connective tissue, or mucosal secretory proteins or carbohydrates tested caused significant interference. BLf-binding receptors of the six coagulase-negative staphylococcal species demonstrated marked differences in patterns of susceptibility to proteolytic or glycolytic enzyme digestion and to heat or periodate treatment. These data suggest that the BLf-binding components in S. epidermidis and S. warneri are proteins containing glycosidyl residues. In the remaining four species, the proteinaceous nature of the BLf-binding component was evident, but the involvement of glycosidyl residues was not clear. Results of this study establish the presence of specific binding components for BLf on coagulase-negative staphylococci isolated from bovine intramammary infections.

Particle agglutination assays to identify fibronectin and collagen cell surface receptors and lectins in Aeromonas and Vibrio species

A rapid particle agglutination assay (PAA) utilizing latex beads coated with connective tissue and serum proteins was evaluated for its ability to identify fibronectin, collagen (types I and IV), fibrinogen, and transferrin cell surface receptors on Vibrio and Aeromonas strains isolated from diseased fish, human infections, and the environment. Similar tests were performed to screen for cell surface lectins. Vibrio as well as Aeromonas strains were found to bind connective tissue proteins (collagen types I, II, and IV and fibronectin), serum proteins (i.e., fibrinogen), and glycoproteins (bovine submaxillary mucin, hog gastric mucin, orosomucoid, and fetuin) immobilized on the latex particles. The specificity of the agglutination reaction was studied by particle agglutination inhibition assays performed by preincubating bacterial suspensions in solutions containing either gelatin (for the various connective tissue protein PAA reagents) or sialic acid-rich glycoproteins (for the various glycoprotein PAA reagents). Expression of cell surface receptors for connective tissue proteins was found to depend on culture methods.

Type I and IV collagen and fibrinogen binding to Aeromonas species isolated from various infections

Collagen binding is a common property of strains of Aeromonas species. However, agglutination of latex beads coated with types I and IV collagen and fibrinogen with Aeromonas cells varied among strains of Aeromonas species and their source of isolation. Culture media and growth conditions greatly influenced expression of Aeromonas cell surface receptors to bind collagen (types I and IV) and fibrinogen immobilized on the latex particles as suggested by the particle agglutination assay (PAA). Aeromonas cells aggregated with the differentially coated latex beads in a specified manner. Furthermore, the PAA method was found to be rapid, easy to perform and sensitive for routine screening of a large number of strains for serum and connective-tissue protein cell surface receptors.

Evidence for lectin-mediated adherence of S. saprophyticus and P. aeruginosa to polymers

By hemagglutination tests surface lectins on S. saprophyticus strain S 1 with N-acetylgalactosamine (GalNac) and N-acetylglucosamine (GlcNac) specificity and on P. aeruginosa ATCC strain 27853 with N-acetylneuraminic acid (NANA) specificity could be demonstrated. To elucidate the role of bacterial surface lectins for the specific adhesion, polyether urethane discs were preincubated for 15 h at 4 degrees C in human serum or urine. Adhesion studies with S. saprophyticus S1 and P. aeruginosa ATCC 27853 onto precoated polymers revealed that microbial lectins may play a role in the colonization of prosthetic devices since lectin-blocking with competitive glycoconjugates significantly decreased bacterial adherence to the coated surfaces. Non-specific carbohydrates did not inhibit the adherence demonstrating specificity of this process.

Binding of type-I and type-II collagens to Staphylococcus aureus strains isolated from patients with toxic shock syndrome compared to other staphylococcal infections

Toxic shock syndrome toxin-1 (TSST-1) producing strains of Staphylococcus aureus isolated from 18 patients with toxic shock syndrome (TSS) and from 56 patients with other diagnoses were compared for capacity to interact with various serum and connective tissue proteins. TSS associated isolates showed significantly stronger binding of Type-I collagen (Cn-I) and Cn-II than non-TSS strains, in a particle agglutination assay (PAA) as well as in 125I labelled Cn uptake experiments. 125I Cn-IV binding, was similar between the two groups, whereas in PAA, a stronger interaction was observed for non-TSS than TSS associated strains. The median binding of 125I Cn to TSS-associated strains were 52.2 (Cn-I), 30.6 (Cn-II) and 20.0 (Cn-IV) compared to 20.0 (Cn-I), 14.4 (Cn-II) and 24.4 (Cn-IV) values of non-TSS strains. A saturation with 125I Cn-I and Cn-II binding was established for TSS (30 min) and non-TSS (15 min) strains. 125I Cn-IV binding reached a saturation in 10 min and 90 min with TSS and non-TSS strains respectively. Finally, the binding profiles of TSS associated and non-TSS strains to fibronectin, fibrinogen, laminin and IgG did not differ in both PAA and radioisotope assays. In scanning electron microscopy, cells of TSS associated strains bound to the reprecipitated native Cn-I fibrils. In contrast, most cells of non-TSS strains were localized to the distal end or were trapped between the Cn fibrils.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of milk on fibronectin and collagen type I binding to Staphylococcus aureus and coagulase-negative staphylococci isolated from bovine mastitis

Tryptic soy broth (TSB)-grown cells of Staphylococcus aureus isolated from acute and chronic bovine mastitis bound mainly 125I-fibronectin (Fn) [corrected], whereas strains of nine species of coagulase-negative staphylococci showed a predominant interaction with 125I-collagen (Cn) [corrected] type I. A particle agglutination assay (PAA) was used to examine the interaction of coagulase-negative staphylococci with 125I-Fn and 125I-Cn immobilized on latex. All 368 coagulase-negative staphylococci demonstrated high 125I-Cn and moderate to low 125I-Fn interactions in the PAA. Cn-PAA reactivity was high among strains of Staphylococcus xylosus (84.2%), Staphylococcus simulans (77.8%), Staphylococcus epidermidis (76.7%), and Staphylococcus hyicus (74.3%), whereas all six Staphylococcus capitis strains clumped Cn-PAA reagent. Incubating TSB-grown cells in 10% skim milk for 1 h decreased the 125I-Fn- and 125I-Cn-binding affinity in most of the S. aureus and coagulase-negative staphylococci, while growth in 10% skim milk for 18 h resulted in more than 90% decrease or complete loss of interaction with these proteins. Decreased 125I-Fn binding in the presence of milk was correlated with protease production but not with 125I-Cn binding.

Urinary Escherichia coli infection presenting with jaundice

A 53-year-old man with lupus erythematosus (LE) developed an acute hemolytic crisis. Alpha-hemolytic Escherichia coli were isolated from the patient's urine and feces, and high titer anti-alpha-hemolytic antibodies appeared in his serum. The hemolytic crisis could be controlled by specific antibiotic treatment of the urinary tract infection. It is assumed that the patient's basic disease -- and the steroid therapy applied -- facilitated the progression of the urinary tract infection, and before starting with adequate antibiotic treatment his erythrocytes must have been subjected to the effect of massive amounts of alpha-hemolysin. The idea that alpha-hemolysin might contribute to the development of severe hemolysis in man is discussed. It is also assumed that harbouring alpha-hemolytic E. coli in the gut may represent a special risk for the immunocompromised host.