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

Cellular Substrates for Cell-Based Tissue Engineering of Human Corneal Endothelial Cells

Corneal endothelial tissue engineering aims to find solutions for blindness due to endothelial dysfunction. A suitable combination of endothelial cells, substrates and environmental cues should be deployed for engineering functional endothelial tissues. This manuscript reviews up-to-date topics of corneal endothelial tissue engineering with special emphasis on biomaterial substrates and their properties, efficacy, and mechanisms of supporting functional endothelial cells in vitro.

Factors responsible for subclinical mastitis in cows caused by Staphylococcus chromogenes and its susceptibility to antibiotics based on bap, fnbA, eno, mecA, tetK, and ermA genes

The aim of this study was to recognize selected factors of virulence determining the adhesion of Staphylococcus chromogenes to cows' udder tissues in subclinical mastitis and to evaluate the susceptibility of this pathogen to antibiotics. The subjects of the study were 38 isolates of Staph. chromogenes from 335 samples of milk from cows with subclinical coagulase-negative staphylococci mastitis. Somatic cell count ranged between 216,000 and 568,000/mL of milk (average 356,000/mL of milk). We confirmed the ability to produce slime in 24 isolates (63.2%), and the ability to produce protease in 29 isolates (76.3%). In each slime-producing isolate, the bap gene was not found, and the fnbA and eno genes were not detected. In vitro tests showed that ceftiofur had the highest effectiveness against Staph. chromogenes (89.5% of susceptible isolates). Minimum inhibitory concentrations ranged from 0.06 to 2µg/mL for susceptible isolates. The minimum concentrations required to inhibit growth of 90 and 50% of the isolates for ceftiofur were at or below the cutoffs recommended by the Clinical and Laboratory Standards Institute (2 and 0.06µg/mL, respectively). A significant percentage of the isolates were susceptible to other β-lactam antibiotics: amoxicillin with clavulanic acid (84.2%) and ampicillin (81.6%). The lowest effectiveness among β-lactams was for penicillin (73.7% of susceptible isolates), and the minimum inhibitory concentration for penicillin ranged from <0.06 to 8µg/mL. None of the examined isolates had the mecA gene, but β-lactamase was detected in 4 isolates (10.5%). Erythromycin and oxytetracycline exhibited the lowest activity against Staph. chromogenes (71.1 and 63.2% of susceptible isolates, respectively). The genes tetK (6 isolates) and ermA (1 isolate) were also detected.

The N-terminal repeat and the ligand binding domain A of SdrI protein is involved in hydrophobicity of S. saprophyticus

Staphylococcus saprophyticus is an important cause of urinary tract infection, and its cell surface hydrophobicity may contribute to virulence by facilitating adherence of the organism to uroepithelia. S. saprophyticus expresses the surface protein SdrI, a member of the serine-aspartate repeat (SD) protein family, which has multifunctional properties. The SdrI knock out mutant has a reduced hydrophobicity index (HPI) of 25%, and expressed in the non-hydrophobic Staphylococcus carnosus strain TM300 causes hydrophobicity. Using hydrophobic interaction chromatography (HIC), we confined the hydrophobic site of SdrI to the N-terminal repeat region. S. saprophyticus strains carrying different plasmid constructs lacking either the N-terminal repeats, both B or SD-repeats were less hydrophobic than wild type and fully complemented SdrI mutant (HPI: 51%). The surface hydrophobicity and HPI of both wild type and the complemented strain were also influenced by calcium (Ca(2+)) and were reduced from 81.3% and 82.4% to 10.9% and 12.3%, respectively. This study confirms that the SdrI protein of S. saprophyticus is a crucial factor for surface hydrophobicity and also gives a first significant functional description of the N-terminal repeats, which in conjunction with the B-repeats form an optimal hydrophobic conformation.

UafB is a serine-rich repeat adhesin of Staphylococcus saprophyticus that mediates binding to fibronectin, fibrinogen and human uroepithelial cells

Staphylococcus saprophyticus is an important cause of urinary tract infection (UTI), particularly among young women, and is second only to uropathogenic Escherichia coli as the most frequent cause of UTI. The molecular mechanisms of urinary tract colonization by S. saprophyticus remain poorly understood. We have identified a novel 6.84 kb plasmid-located adhesin-encoding gene in S. saprophyticus strain MS1146 which we have termed uro-adherence factor B (uafB). UafB is a glycosylated serine-rich repeat protein that is expressed on the surface of S. saprophyticus MS1146. UafB also functions as a major cell surface hydrophobicity factor. To characterize the role of UafB we generated an isogenic uafB mutant in S. saprophyticus MS1146 by interruption with a group II intron. The uafB mutant had a significantly reduced ability to bind to fibronectin and fibrinogen. Furthermore, we show that a recombinant protein containing the putative binding domain of UafB binds specifically to fibronectin and fibrinogen. UafB was not involved in adhesion in a mouse model of UTI; however, we observed a striking UafB-mediated adhesion phenotype to human uroepithelial cells. We have also identified genes homologous to uafB in other staphylococci which, like uafB, appear to be located on transposable elements. Thus, our data indicate that UafB is a novel adhesin of S. saprophyticus that contributes to cell surface hydrophobicity, mediates adhesion to fibronectin and fibrinogen, and exhibits tropism for human uroepithelial cells.

Genotypic and phenotypic variation among Staphylococcus saprophyticus from human and animal isolates

Background

The main aim of this study was to examine the genotypic and phenotypic diversity of Staphylococcus saprophyticus isolates from human and animal origin.

Findings

In total, 236 clinical isolates and 15 animal isolates of S. saprophyticus were characterized in respect of the occurrence of 9 potential virulence genes and four surface properties. All strains were PCR positive for the regulatory genes agr, sar >it>A and rot as well as for the surface proteins UafA and Aas. Nearly 90% of the clinical isolates were found to possess the gene for the surface-associated lipase Ssp and 10% for the collagen binding MSCRAMM SdrI. All animal isolates were negative forsdrI. Lipolytic activity could be detected in 66% of the clinical and 46% of the animal isolates. Adherence to collagen type I was shown of 20% of the clinical strains and 6% of the strains of animal origin. Most S. saprophyticus strains showed hydrophobic properties and only few could agglutinate sheep erythrocytes.

Conclusions

We described a broad analysis of animal and human S. saprophyticus isolates regarding virulence genes and phenotypic properties such as lipase activity, hydrophobicity, and adherence. While S. saprophyticus strains from animal sources have prerequisites for colonization of the urinary tract like the D-serine-deaminase, out findings suggested that they need to acquire new genes e.g. MSCRAMMS for adherence like sdrI and to modulate their existing properties e.g. increasing the lipase activity or reducing hydrophobicity. These apparently important new genes or properties for virulence have to be further analyzed.

SdrI of Staphylococcus saprophyticus is a multifunctional protein: localization of the fibronectin-binding site

Staphylococcus saprophyticus, an important cause of urinary tract infections in young women, expresses the surface protein SdrI, a member of the serine-aspartate repeat (SD) protein family. Here we analyse the fibronectin-binding ability of SdrI, as S. saprophyticus is known to bind fibronectin and there is no known SD protein with this function. This protein does not contain the binding motif typical for fibronectin-binding proteins. Using recombinant fragments of SdrI, we localized the binding domain in the A region and show that SdrI bound to the N-terminal 30-kDa fragment of fibronectin. The fibronectin-binding function was shown in the natural host using an SdrI knockout mutant that showed decreased binding to fibronectin compared with wild-type strain 7108.

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.

SdrI, a serine-aspartate repeat protein identified in Staphylococcus saprophyticus strain 7108, is a collagen-binding protein

A gene encoding a serine-aspartate repeat protein of Staphylococcus saprophyticus, an important cause of urinary tract infections in young women, has been cloned and sequenced. In contrast to other SD repeat proteins, SdrI carries 21 additional N-terminal repeats with a consensus sequence of (P/A)ATKE(K/E)A(A/V)(T/I)(A/T/S)EE and has the longest SD(AD)(1-5) repetitive region (854 amino acids) described so far. This highly repetitive sequence contains only the amino acids serine, asparagine, and a distinctly greater amount of alanine (37%) than all other known SD repeat proteins (2.3 to 4.4%). In addition, it is a collagen-binding protein of S. saprophyticus and the second example in this organism of a surface protein carrying the LPXTG motif. We constructed an isogenic sdrI knockout mutant that showed decreased binding to immobilized collagen compared with wild-type S. saprophyticus strain 7108. Binding could be reconstituted by complementation. Collagen binding is specifically caused by SdrI, and the recently described UafA protein, the only LPXTG-containing protein in the genome sequence of the type strain, is not involved in this trait. Our experiments suggest that, as in other staphylococci, the presence of different LPXTG-anchored cell wall proteins is common in S. saprophyticus and support the notion that the presence of matrix-binding surface proteins is common in staphylococci.

The surface-associated protein of Staphylococcus saprophyticus is a lipase

Staphylococcus saprophyticus surface-associated protein (Ssp) was the first surface protein described for this organism. Ssp-positive strains display a fuzzy layer of surface-associated material in electron micrographs, whereas Ssp-negative strains appear to be smooth. The physiologic function of Ssp, however, has remained elusive. To clone the associated gene, we determined the N-terminal sequence, as well as an internal amino acid sequence, of the purified protein. We derived two degenerate primers from these peptide sequences, which we used to identify the ssp gene from genomic DNA of S. saprophyticus 7108. The gene was cloned by PCR techniques and was found to be homologous to genes encoding staphylococcal lipases. In keeping with this finding, strains 7108 and 9325, which are Ssp positive, showed lipase activity on tributyrylglycerol agar plates, whereas the Ssp-negative strain CCM883 did not. Association of enzyme activity with the cloned DNA was proven by introducing the gene into Staphylococcus carnosus TM300. When wild-type strain 7108 and an isogenic mutant were analyzed by transmission electron microscopy, strain 7108 exhibited the fuzzy surface layer, whereas the mutant appeared to be smooth. Lipase activity and the surface appendages could be restored by reintroduction of the cloned gene into the mutant. Experiments using immobilized collagen type I did not provide evidence for the involvement of Ssp in adherence to this matrix protein. Our experiments thus provided evidence that Ssp is a surface-associated lipase of S. saprophyticus.

Induction of inflammatory cytokines and nitric oxide in J774.2 cells and murine macrophages by lipoteichoic acid and related cell wall antigens from Staphylococcus epidermidis

Staphylococcus epidermidis causes infections associated with medical devices including central venous catheters, orthopaedic prosthetic joints and artificial heart valves. This coagulase-negative staphylococcus produces a conventional cellular lipoteichoic acid (LTA) and also releases a short-glycerophosphate-chain-length form of LTA (previously termed lipid S) into the medium during growth. The relative pro-inflammatory activities of cellular and short-chain-length exocellular LTA were investigated in comparison with peptidoglycan and wall teichoic acid from S. epidermidis and LPS from Escherichia coli O111. The ability of these components to stimulate the production of pro-inflammatory cytokines [interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α] and nitric oxide was investigated in a murine macrophage-like cell line (J774.2), and in peritoneal and splenic macrophages. On a weight-for-weight basis the short-chain-length exocellular LTA was the most active of the S. epidermidis products, stimulating significant amounts of each of the inflammatory cytokines and nitric oxide, although it was approximately 100-fold less active than LPS from E. coli. By comparison the full-chain-length cellular LTA and peptidoglycan were less active and the wall teichoic acid had no activity. As an exocellular product potentially released from S. epidermidis biofilms, the short-chain-length exocellular LTA may act as the prime mediator of the host inflammatory response to device-related infection by this organism and act as the Gram-positive equivalent of LPS in Gram-negative sepsis. The understanding of the role of short-chain-length exocellular LTA in Gram-positive sepsis may lead to improved treatment strategies.

Theories of prostatitis etiology

Prostatitis reflects a broad spectrum of prostatic infections, both acute and chronic. Chronic prostatitis, known as National Institutes of Health category III or chronic pelvic pain syndrome, broadly defines a disease that is still poorly understood, and as a consequence, difficult to treat. Typical symptoms include pelvic pain and voiding dysfunction. Infection is often cited as the cause of this condition, despite frequent negative cultures. A close look at the local prostatic microenvironment may yield clues. The role of inflammatory mediators and what stimulates them can point to potential sites of prevention. A genetic link or relationship to other diseases may prove to be part of the cause. Furthermore, a neurologic source, whether anatomic or psychologic, has been strongly debated. Ultimately, it may become clear that chronic prostatitis represents the final common result of a disease that originates from a cascade of multiple stimuli.

Binding of vitronectin and clusterin by coagulase-negative staphylococci interfering with complement function

Coagulase-negative staphylococci (CoNS) are commonly associated with infections of prosthetic devices mediated by adsorbed host factors on biomaterial surfaces. Complement activation is known to occur and induce unspecific inflammation around the biomaterials. Human vitronectin (Vn) and clusterin (Clu), two potent inhibitors of complement, can be bound by CoNS. With a hypothesis whether binding of Vn or Clu influences complement activation, two measurements were determined. For Vn, complement activation was measured with a mouse anti-activated human C9 antibody. In the presence of Vn-binding strain, Staphylococcus hemolyticus SM13I, complement activation on a surface pre-coated with Vn occurred as it did in the absence of Vn pre-coating. For S. epidermidis 3380, which does not express binding of Vn, complement activation on a Vn-presented surface was significantly decreased. For Clu, erythrocytes lysis was measured to reflect the end product of complement activation (membrane attack complex). The complement-induced hemolysis increased when human serum was pre-incubated with Clu-binding strains, S. epidermidis J9P. The enhancement of hemolysis by J9P decreased when serum was supplemented by exogenous Clu. The data imply that interaction between CoNS and Vn or Clu interferes with one of their physiological functions, complement inhibition.

The serine-aspartate repeat (Sdr) protein family in Staphylococcus epidermidis

Staphylococcus epidermidis can express three different cell-surface-associated proteins, designated SdrF, SdrG and SdrH, that contain serine-aspartate dipeptide repeats. Proteins SdrF and SdrG are similar in sequence and structural organization to the Sdr proteins of Staphylococcus aureus and comprise unique 625- and 548-residue A regions at their N termini, respectively, followed by 110-119-residue B-repeat regions and SD-repeat regions. The C termini contain LPXTG motifs and hydrophobic amino acid segments characteristic of surface proteins covalently anchored to peptidoglycan. In contrast, SdrH has a short 60-residue A region at its N terminus followed by a SD-repeat region, a unique 277-residue C region and a C-terminal hydrophobic segment. SdrH lacks a LPXTG motif. Recombinant proteins representing the A regions of SdrF, SdrG and SdrH were expressed and purified from Escherichia coli. Antisera specific to these proteins were raised in rabbits and used to identify Sdr proteins expressed by S. epidermidis. Only SdrF was released from lysostaphin-generated protoplasts of cells grown to late-exponential phase. SdrG and SdrH remained associated with the protoplast fraction and thus appear to be ineffectively sorted along the conventional pathway used for cell-wall-anchored proteins. In Southern hybridization analyses, the sdrG and sdrH genes were present in all 16 strains tested, whilst sdrF was present in 12 strains. Antisera from 16 patients who had recovered from S. epidermidis infections contained antibodies that reacted with recombinant A regions of SdrG and SdrH, suggesting that these proteins can be expressed during infection.

Exposure of plasma proteins on Dacron and ePTFE vascular graft material in a perfusion model

OBJECTIVES

to compare the exposure of plasma proteins adsorbed onto three vascular graft materials (polytetrafluoroethylene ePTFE and two modifications of polyethyleneterephthalate Dacron).

METHODS

surface exposure of fibronectin, vitronectin, thrombospondin, antithrombin III, IgG, high molecular-weight kininogen, fibrinogen, albumin and plasminogen was studied by incubation with radiolabelled antibodies in a perfusion model. Perfusion times with human plasma were 1, 4, 24 and 48 hours.

RESULTS

all proteins could be detected at 1, 4, 24 and 48 hours after the start of perfusion. Overall, the least amount of proteins adsorbed onto ePTFE.

CONCLUSIONS

the low adsorption of proteins onto ePTFE may be one of the reasons for the lower incidence of infections reported with this material.

Vitronectin interaction with glycosaminoglycans. Kinetics, structural determinants, and role in binding to endothelial cells

Vitronectin (VN) is a high affinity heparin-binding protein. The physiological role of this binding has hitherto received little attention, and its molecular determinants are subject to controversy. In this study, we characterized vitronectin interaction with heparin, heparin analogues, bacterial extracts, and cell surface glycosaminoglycans. As assessed by (i) fluorescence assays, (ii) precipitation with heparin-Sepharose beads, or (iii) Western blotting with antibodies against VN(347-361) (the heparin-binding site), we demonstrate an exposure of the VN heparin-binding site in multimeric but not monomeric vitronectin. Through its heparin-binding site, vitronectin also bound other glycosaminoglycans and Staphylococcus aureus extracts. The kinetics of heparin binding to vitronectin were complex. After a fast association phase (tau = 0.3 s), a slow conversion of an unstable to a stable heparin-vitronectin complex (tau = 180 s) occurred. Heparin binding kinetics and transition to a stable complex were mimicked by VN(347-361), demonstrating that this area is the fully functional heparin-binding site of vitronectin. Multimeric vitronectin bound to endothelial cells. This binding was blocked by soluble heparin and was not observed when endothelial cells were pretreated with glycosaminoglycan-removing enzymes. Glycosaminoglycan-dependent interaction of endothelial cells with multimeric vitronectin might be a relevant mechanism for removal of multimeric vitronectin from plasma. Conversion of an unstable to a stable glycosaminoglycan-vitronectin complex is likely to be relevant for association with endothelial cells under flow conditions.

A lithium chloride-extracted, broad-spectrum-adhesive 42-kilodalton protein of Staphylococcus epidermidis is ornithine carbamoyltransferase

To identify novel putative staphylococcal adhesins, lithium chloride extraction (an established method for selective surface molecule solubilization) was employed. N-terminal sequencing and functional assays identified a 42-kDa fibronectin-binding protein from Staphylococcus epidermidis as ornithine carbamoyltransferase (OCTase). However, OCTase was not recognizable extracellularly, and this fact together with the fact that LiCl induced DNA release and a decrease in viability suggests that LiCl extraction may not be the method of choice for selective surface molecule extraction from staphylococci.

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.

Prostatitis

The laboratory diagnosis of acute bacterial prostatitis is straightforward and easily accomplished in clinical laboratories. Chronic bacterial prostatitis, and especially chronic idiopathic prostatitis (most often referred to as abacterial prostatitis), presents a real challenge to the clinician and clinical microbiologist. Clinically, the diagnosis of chronic idiopathic prostatitis is differentiated from that of acute prostatitis by a lack of prostatic inflammation and no "significant" (controversial) leukocytes or bacteria in the expressed prostatic secretions. Despite these diagnostic criteria, the etiology of chronic idiopathic prostatitis is unknown. While this review covers the entire spectrum of microbially caused acute prostatitis (including common and uncommon bacteria, viruses, fungi, and parasites) and microbially associated chronic prostatitis, a special focus has been given to chronic idiopathic prostatitis. The idiopathic syndrome is commonly diagnosed in men but is poorly treated. Recent data convincingly suggests a possible bacterial etiology for the condition. Provocative molecular studies have been published reporting the presence of 16S rRNA bacterial sequences in prostate biopsy tissue that is negative for ordinary bacteria by routine culture in men with chronic idiopathic prostatitis. Additionally, special culture methods have indicated that difficult-to-culture coryneforms and coagulase-negative staphylococci are present in expressed prostatic secretions found to be negative by routine culture techniques. Treatment failures are not uncommon in chronic prostatitis. Literature reports suggest that antimicrobial treatment failures in chronic idiopathic prostatitis caused by organisms producing extracellular slime might result from the virulent properties of coagulase-negative staphylococci or other bacteria. While it is difficult to definitively extrapolate from animal models, antibiotic pharmokinetic studies with a murine model have suggested that treatment failures in chronic prostatitis are probably a result of the local microenvironment surrounding the persistent focal and well-protected small bacterial biofilms buried within the prostate gland. These conclusions support the molecular and culture data implicating bacteria as a cause of chronic idiopathic prostatitis.

Quantitation of bacterial adhesion to polymer surfaces by bioluminescence

Quantitation of microbes adhering to a surface is commonly used in studies of microbial adhesion to different surfaces. We have quantified different staphylococcal strains adhering to polymer surfaces by measuring bacterial ATP (adenosine triphosphate) by bioluminescence. The method is sensitive, having a detection limit of 10(4) bacterial cells. Viable counting of bacterial cells may yield falsely low results due to the presence of "dormant" and adherent bacteria. By using bioluminescence, this can be avoided. Cells of different bacterial species and cells of strains of the same species were shown to differ significantly in their basal ATP content (8.7 x 10(-13) - 5.2 x 10(-22) MATP). The size of adherent and planktonic bacteria decreased with time (0.7 micron-->0.3 micron, 20 days). During incubation in nutrient-poor buffer ("starvation"), the ATP content of adherent bacteria decreased after 24-96 h whereas that of planktonic bacteria was stable over 20 days. The presence of human serum or plasma did not interfere significantly with the test results. Since the ATP concentration of bacterial strains of different species varies and is also influenced by the growth conditions of bacteria (solid or liquid culture medium), a species-specific standard curve has to be established for bacteria grown under the same culture conditions. We conclude that the method is a sensitive tool to quantify adherent bacteria during experiments lasting for less than 6 h and constitutes a valuable method to be used in conjunction with different microscopical techniques.

Cryptic bacterial infection in chronic prostatitis

Chronic idiopathic prostatitis, sometimes called prostatodynia or abacterial prostatitis, is a commonly diagnosed and poorly treated urological syndrome. Clinically, this condition frustrates the patient and physician due to its chronicity and resistance to therapy. Recent studies suggest that the etiology of chronic idiopathic prostatitis may be of bacterial origin. Three types of provocative data have demonstrated bacterial presence from prostatic specimens (tissue and secretions) that were negative by traditional clinical microbiologic tests: (i) presence of bacterial gene sequences in prostatic tissue encoding 16S rRNA and tetracycline resistance (tetM-tetO-tetS); (ii) controlled cultural findings showing coagulase-negative staphylococci as the most common isolates (68%) in prostatodynia (chronic idiopathic prostatitis); and (iii) culture of difficult-to-grow coryneforms in expressed prostatic secretions (EPS) on enriched culture media and direct microscopic observation of these pleomorphic bacteria in EPS. Additionally, earlier experimental studies in a rat model support the concept that antibiotic therapy in chronic bacterial prostatitis may not be due to altered antibiotic pharmacokinetics in the chronically inflamed prostate gland. Rather, ineffective antimicrobial eradication might result from protected bacterial micro-colonies within an infection-induced altered micro-environment deep within the prostate gland. We postulate that extracellular slime substances produced by bacteria that are buried in prostatic tissues could impair host defenses by their anti-phagocytic and anti-chemotactic properties that affect neutrophils as well as anti-proliferative characteristics that affect lymphocytes. These extracellular slime substances could also have cytoprotective properties which can conceal bacteria from otherwise bactericidal levels of antibiotics and lead to recrudescent infections resistant to therapy. Persistence of bacterial antigens might initiate a cascade of cellular immunologic events resulting in chronic inflammation of the prostate gland.

Protein depositions on one hydrocephalus shunt and on fifteen temporary ventricular catheters

Biomaterials are commonly used in modern medicine. Proteins are adsorbed to the surface of the biomaterial immediately after insertion. This report demonstrates the presence of adsorbed proteins in one infected cerebrospinal shunt from a child with hydrocephalus and on fifteen temporary ventricular catheters from adult patients with spontaneous or traumatic brain injuries. Depositions of vitronectin, fibrinogen and thrombospondin-fibronectin to some extent--on the shunt surface was imaged by field-emission scanning electron microscopy. Vitronectin, fibronectin, fibrinogen, and thrombospondin on the ventricular catheters were shown with radio-actively labelled antibodies. Furthermore, protein adsorption from human cerebrospinal fluid to heparinized and unheparinized polymers was studied under flowing conditions in vitro. On heparinized polymer, significantly reduced levels of vitronectin, fibronectin, and thrombospondin were exposed, as measured after 4 hours in vitro perfusion. After 24 hours perfusion, the differences in protein exposition between heparinized and unheparinized polymers were substantially reduced.

Expression of slime interferes with in vitro detection of host protein receptors of Staphylococcus epidermidis

We hypothesized that slime may mask bacterial molecules important in the attachment of Staphylococcus epidermidis to inanimate surfaces. In support of this hypothesis, we found that slime-negative strains attached significantly better to fibrinogen or fibronectin than the parent strains and exhibited greater surface hydrophobicity. Comparable results were obtained with 53 clinical isolates.

Vitronectin-binding staphylococci enhance surface-associated complement activation

Coagulase-negative staphylococci are well recognized in medical device-associated infections. Complement activation is known to occur at the biomaterial surface, resulting in unspecific inflammation around the biomaterial. The human serum protein vitronectin (Vn), a potent inhibitor of complement activation by formation of an inactive terminal complement complex, adsorbs to biomaterial surfaces in contact with blood. In this report, we discuss the possibility that surface-immobilized Vn inhibits complement activation and the effect of Vn-binding staphylococci on complement activation on surfaces precoated with Vn. The extent of complement activation was measured with a rabbit anti-human C3c antibody and a mouse anti-human C9 antibody, raised against the neoepitope of C9. Our data show that Vn immobilized on a biomaterial surface retains its ability to inhibit complement activation. The additive complement activation-inhibitory effect of Vn on a heparinized surface is very small. In the presence of Vn-binding strain, Staphylococcus hemolyticus SM131, complement activation on a surface precoated with Vn occurred as it did in the absence of Vn precoating. For S. epidermidis 3380, which does not express binding of Vn, complement activation on a Vn-precoated surface was significantly decreased. The results could be repeated on heparinized surfaces. These data suggest that Vn adsorbed to a biomaterial surface may serve to protect against surface-associated complement activation. Furthermore, Vn-binding staphylococcal cells may enhance surface-associated complement activation by blocking the inhibitory effect of preadsorbed Vn.

Fibronectin exposes different domains after adsorption to a heparinized and an unheparinized poly(vinyl chloride) surface

The adsorption of fibronectin to poly(vinyl chloride) catheters with end-point attached (EPA) heparin and tridodecylmethylammonium chloride-heparinized poly(vinyl chloride) was compared to that of unheparinized poly(vinyl chloride) using antibodies directed against four different domains of the protein. After perfusion of human plasma on the EPA-heparinized surface, the exposure of the N-terminal 29-kD fragment increased during the first 5 h of perfusion. Also, the exposure of the 30-kD gelatin-binding and 65-kD cell-binding fragments increased with time, but at a lower level. On the unheparinized catheter, low levels of antibodies bound to the different domains, and the binding showed little variation during the 5 h of plasma perfusion, indicating that the fibronectin molecule does not change configuration to a significant extent on this surface after the initial adsorption. When the EPA-heparinized surface was preabsorbed with human fibrinogen before incubation with fibronectin, significantly less of the 29-kD (fibrin-binding) domain was exposed, and the 30-kD domain was not exposed. Exposure of the 31- and 65-kD domains increased after preadsorption of fibrinogen to the surface. Since fibronectin has heparin-binding domains, it adsorbs differently to a heparinized versus an unheparinized surface. This will influence subsequent binding of other proteins to the surface, as well as potential binding of microbes. The use of antibodies to defined domains of the fibronectin molecule provides a powerful tool in studies of configurational changes of fibronectin after adsorption to different surfaces.

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.

Murine laminin binds to Histoplasma capsulatum. A possible mechanism of dissemination

Histoplasmosis, an increasingly important opportunistic infection in immunosuppressed subjects, is characterized by hematogenous dissemination of the yeast from the lung. The mechanism of this dissemination is not fully understood. Laminin, the major glycoprotein of the extracellular matrix, is known to mediate the attachment of various invasive pathogens to host tissues. In the current study, laminin is demonstrated to bind to Histoplasma capsulatum in a rapid, specific, and saturable manner. Scatchard analysis with 125I-labeled laminin revealed an estimated 3.0 x 10(4) binding sites per yeast with an apparent Kd for laminin binding of 1.6 x 10(-9) M. Laminin binding to H. capsulatum was decreased from 62 +/- 1 to 17 +/- 1 ng (P < 0.001) in the presence of 3,000 nM of Ile-Lys-Val-Ala-Val, a pentapeptide within one major cell attachment site of laminin. A 50-kD H. capsulatum laminin-binding protein was demonstrated using an 125I-Ln blot of H. capsulatum cell wall proteins. The 50-kD protein is also recognized by antibodies directed at the 67-kD laminin receptor, suggesting they are related. This study proposes a possible mechanism for H. capsulatum attachment to laminin, an important first step required for the yeast to recognize and traverse the basement membrane.

Biomaterial-associated staphylococcal peritoneal infections in a neutropaenic mouse model

Adhesion of staphylococcal cells to polyethylene with end point-attached heparin was quantified by bioluminescence. Staphylococcus epidermidis 3380 and the slime-producing S. epidermidis RP12 adhered to the highest extent, and S. lugdunensis 2342 to the least extent. Preincubation of the polymer with dialysis fluid reduced adhesion of S. epidermidis 3380 and RP12 but enhanced that of S. aureus, and preadsorption of the surface with fibronectin decreased subsequent adhesion of S. epidermidis and S. haemolyticus strains. When staphylococci were grown in the presence of a biomaterial their ability to activate peritoneal cells was decreased. The bactericidal activity was impaired, whereas ingestion of opsonized coagulase-negative staphylococci (CNS) strains was unaffected. With S. epidermidis RP12 the presence of biomaterial did not influence either phagocytosis or bactericidal effect of peritoneal cells. After intra-peritoneal challenge with staphylococcal strains, the organ uptake of S. aureus Cowan 1 was increased in normal mice whereas immunosuppressed mice died. CNS strains increased mainly in the peritoneal cavity of immunosuppressed mice. The uptake of bacteria in liver and kidneys was increased with S. epidermidis 3380, S. lugdunensis 2343 and S. schleiferi 667-88. Generally, CNS strains persisted in the peritoneal cavity of both normal and immunosuppressed mice. These data indicate that host defense mechanisms, mainly polymorphonuclear neutrophils, fail to eliminate CNS infections in the peritoneum, and that initial adhesion to an implanted biomaterial may be of lesser importance in the peritoneal cavity than in e.g. catheter-associated infections. There are strain-specific virulence factors of bacteria, and slime producing strains evade the host defense mechanisms more efficiently than non-slime producing strains.

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.

Use of leukodepletion filters for the removal of bacteria

Recipient exposure to allogeneic donor leukocytes can mediate a number of immunologic complications of transfusion or can transmit leukotropic viruses carried by the donor. Leukocyte depletion of cellular blood components has been shown to reduce the incidence of such complications. In recent years, prestorage leukocyte depletion by filtration has also been suggested as a means of decreasing the incidence of bacterial overgrowth in cellular blood components. This review analyzes published studies on the use of leukodepletion filters for removal of Staphylococcus epidermidis and Yersinia enterocolitica from blood. Although ineffective for removal of S. epidermidis from Platelet Concentrates, inoculation studies demonstrate removal of low levels of Y. enterocolitica from Red Cell Concentrates. Based on these studies, four possible mechanism(s) for removal of bacteria by leukodepletion filters are analyzed: phagocytosis by leukocytes during a prefiltration holding period; complement-mediated bacterial killing enhanced by filtration; adherence of bacteria to leukocyte surfaces retained within the filter; and direct removal of bacteria by the filter media. Just as multiple mechanisms appear to account for the efficiency with which these filters deplete blood of leukocytes, it is likely that more than one mechanism accounts for the experimental observation that leukocyte depletion filters can reduce overgrowth of Y. enterocolitica in stored Red Cell Concentrates.

Staphylococcus saprophyticus hemagglutinin binds fibronectin

Attachment of microorganisms to host tissue is regarded as an important step in the pathogenesis of infections. Staphylococcus saprophyticus adheres to various epithelial cells and hemagglutinates sheep erythrocytes. The hemagglutinin has been identified, but a human target for this surface protein is still not known. In our report, we show that hemagglutinating strains of S. saprophyticus bind to immobilized fibronectin, whereas nonhemagglutinating strains do not. Bacterial binding was inhibited by antibody to the hemagglutinin but not by antibody to Ssp, another surface protein of S. saprophyticus. The purified hemagglutinin but not other surface proteins bound biotin-labeled fibronectin. Binding was saturable and could be inhibited by unbound hemagglutinin, unlabeled fibronectin, and by antibody to the hemagglutinin. We thus conclude that the hemagglutinin of S. saprophyticus may act as a fibronectin receptor in the human host. Heparin, the D3 peptide, or Arg-Gly-Asp-Ser (RGDS) containing peptides did not inhibit binding of fibronectin to the hemagglutinin, indicating that the binding site is different from that of Staphylococcus aureus or Treponema pallidum.

Adhesion of coagulase-negative staphylococci and adsorption of plasma proteins to heparinized polymer surfaces

Protease treatment of cells of coagulase-negative staphylococci reduced the adhesion of bacteria to heparinized polyethylene preadsorbed with serum. Fibronectin (Fn), fibrinogen (Fg), vitronectin, complement factor C3c, plasminogen, laminin and to a low extent albumin were detected on tridodecylmethylammonium chloride (TDMAC)-heparinized polyvinyl chloride (PVC) catheters extirpated from the circulation of patients. Using a perfusion model we show that during the first hours of perfusion with human plasma, Fn and Vn dominate, whereas after 22 h of perfusion Fg is the dominant protein. Field emission scanning electron microscopy and atomic force microscopy studies on TDMAC-heparinized catheters as well as on end-point attached heparinized PVC catheters indicate that quantitatively more Fg than Fn is exposed on these surfaces after prolonged exposure (> 22 h) to human plasma.

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.

Crystal violet reactions of coagulase negative staphylococci

Twenty four reference strains and 112 clinical isolates of coagulase negative staphylococci (CNS) were examined for their reactions in the crystal violet test. Some species gave a white reaction and others a purple reaction. Results were consistent and reproducible and each species gave only one pattern of crystal violet reaction. Within the limited variety of species represented in the clinical isolates, Staphylococcus saprophyticus and S haemolyticus gave crystal violet purple reactions, in contrast to S epidermidis, which always gave a white reaction. Investigations suggested that the mechanism of the crystal violet test in S haemolyticus may be similar to that previously described in S aureus. Further work is needed to characterise the ability of crystal violet to modify S epidermidis and other central nervous system species. The crystal violet reaction, which has strong associations with invasiveness, phage group susceptibilities, colonisation persistence abilities, and nosocomial origin in S aureus may also be useful in studies of CNS disease.

Adherence of coagulase-negative staphylococci to heparin and other glycosaminoglycans immobilized on polymer surfaces

The adherence of clinical isolates of staphylococci to surfaces immobilized with various glycosaminoglycans (GAGs) was studied. In general, cells of strains of coagulase-negative (CNS) staphylococci showed a greater adherence to polyethylene surfaces than did cells of Staphylococcus aureus, as studied by bioluminescence. When the surface was heparinized, the adherence of staphylococcal cells decreased, but CNS cells still adhered in greater numbers than did cells of S. aureus. The adherence of CNS to serum-coated heparinized surfaces was of the same magnitude, or increased compared with nonheparinized surfaces. When the surfaces were preadsorbed with different proteins with known heparin-binding domains, i.e., vitronectin, fibronectin, laminin, or collagen, the S. epidermidis cells showed higher binding to heparinized surfaces than to nonheparinized ones, and also in greater numbers than did other staphylococcal cells. Different CNS strains showed a greater ability to agglutinate polystyrene beads immobilized with heparin than did S. aureus. The adherence of S. epidermidis strain 3380 to polyethylene coated with various GAGs such as heparin and chondroitin, dextran, dermatan, and heparan sulfate was shown to be pH-dependent, with the highest adherence at pH 7.2. This may indicate that CNS have the ability to bind to other domains of host proteins when they are adsorbed to heparinized surfaces, versus to nonheparinized ones.

Update on clinical significance of coagulase-negative staphylococci

The clinical significance of coagulase-negative Staphylococcus species (CNS) continues to increase as strategies in medical practice lead to more invasive procedures. Hospitalized patients that are immunocompromised and/or suffering from chronic diseases are the most vulnerable to infection. Since CNS are widespread on the human body and are capable of producing very large populations, distinguishing the etiologic agent(s) from contaminating flora is a serious challenge. For this reason, culture identification should proceed to the species and strain levels. A much stronger case can be made for the identification of a CNS etiologic agent if the same strain is repeatedly isolated from a series of specimens as opposed to the isolation of different strains of one or more species. Strain identity initially can be based on colony morphology, and then one or more molecular approaches can be used to gain information on the genotype. Many of the CNS species are commonly resistant to antibiotics that are being indicated for staphylococcal infections, with the exception of vancomycin. The widespread use of antibiotics in hospitals has provided a reservoir of antibiotic-resistant genes. The main focus on mechanisms of pathogenesis has been with foreign body infections and the role of specific adhesins and slime produced by Staphylococcus epidermidis. Slime can reduce the immune response and opsonophagocytosis, thereby interfering with host defense mechanisms. As we become more aware of the various strategies used by CNS, we will be in a better position to compromise their defense mechanisms and improve treatment.

Enteropathogenic and enteroadherent-aggregative Escherichia coli in children with persistent diarrhoea and malnutrition

Our investigation of 61 children with persistent diarrhoea and malnutrition (PDM) aimed to characterize in them the range of enteropathogenic E. coli. Age- and sex-matched control groups consisted of 42 healthy children and 16 children with marasmus but without diarrhoea. E. coli isolates from stool cultures were serotyped, examined for Vero cells cytotoxicity, tested for enterotoxin production (LT, ST, VTI, and VTII). Synthetic oligonucleotide probes were used to test for enteroinvasivity, EPEC adherence factor, and for EAggEC. Classical E. coli serotypes commonly associated with diarrhoea (O18, O26, O119, O126) were isolated from six of 60 (10%) children with PDM. Serotype O126 was isolated from two of 42 (4.8%) healthy children and serotype O119 from one of 16 (6%) marasmic controls. Testing for Vero toxin production was negative in all isolates. Classical ETEC were confirmed in four of 60 (ST 2; LT 2) cases of PDM; no ETEC were recovered from 58 control patients. EAggEC were identified in five children with PDM and in five healthy controls without diarrhoea or malnutrition. This controlled study has shown that, in The Gambia, E. coli carrying known virulence factors are prevalent but, with the exception of enterotoxigenic E. coli, the various forms of pathogenic E. coli do not seem to be important pathogens in children with persistent diarrhoea.

Adhesion of staphylococci to chemically modified and native polymers, and the influence of preadsorbed fibronectin, vitronectin and fibrinogen

A commercially available poly(ether urethane), polyethylene, and modifications of these polymers have been compared with respect to adsorption of fibronectin, fibrinogen and vitronectin. The adhesion of staphylococcal strains (characterized for ability to bind immobilized proteins, cell surface hydrophobicity and charge) was studied by bioluminescence with and without preadsorption of proteins to the surfaces. The least amount of proteins and the fewest bacteria adhered to the amphiphilic surfaces. When polymers were preincubated with plasma or albumin, lower numbers of bacteria adhered, except to Pellethane grafted with PEG 20,000, to which coagulase-negative staphylococci adhered to a higher extent.

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.