Mediation of Staphylococcus saprophyticus adherence to uroepithelial cells by lipoteichoic acid

Can the Risk of Peritonitis be Predicted for New Continuous Ambulatory Peritoneal Dialysis (CAPD) Patients?

Serum and overnight dialysate samples were obtained from 36 adult uraemic patients at the end of their continuous ambulatory peritoneal dialysis (CAPD) training. The samples were analysed for albumin, IgG, C3, and antistaphylococcal peptidoglycan antibody. None of the dialysate measurements correlated with the risk of peritonitis during up to one year's CAPD treatment.

Nineteen of the 36 patients were retested 6 to 20 months after starting CAPD. There were significant rises in serum C3 ( p < 0.02) and albumin ( p < 0.001) and a significant fall in dialysate IgG ( p < 0.02). Eight further patients were sampled at the end of training and three weeks later. They had a significant fall in dialysate IgG ( p < 0.05).

During CAPD training peritoneal permeability appears to be transiently increased. Analysis of overnight dialysate samples during training does not allow prediction of those at risk of subsequent peritonitis.

Significance of the D-serine-deaminase and D-serine metabolism of Staphylococcus saprophyticus for virulence

Staphylococcus saprophyticus is the only species of Staphylococcus that is typically uropathogenic and possesses a gene coding for a D-serine-deaminase (DsdA). As D-serine is prevalent in urine and toxic or bacteriostatic to many bacteria, it is not surprising that the D-serine-deaminase gene is found in the genome of uropathogens. It has been suggested that D-serine-deaminase or the ability to respond to or to metabolize D-serine is important for virulence. For uropathogenic Escherichia coli (UPEC), a high intracellular D-serine concentration affects expression of virulence factors. S. saprophyticus is able to grow in the presence of high D-serine concentrations; however, its D-serine metabolism has not been described. The activity of the D-serine-deaminase was verified by analyzing the formation of pyruvate from D-serine in different strains with and without D-serine-deaminase. Cocultivation experiments were performed to show that D-serine-deaminase confers a growth advantage to S. saprophyticus in the presence of D-serine. Furthermore, in vivo coinfection experiments showed a disadvantage for the ΔdsdA mutant during urinary tract infection. Expression analysis of known virulence factors by reverse transcription-quantitative PCR (RT-qPCR) showed that the surface-associated lipase Ssp is upregulated in the presence of D-serine. In addition, we show that S. saprophyticus is able to use D-serine as the sole carbon source, but interestingly, D-serine had a negative effect on growth when glucose was also present. Taken together, D-serine metabolism is associated with virulence in S. saprophyticus, as at least one known virulence factor is upregulated in the presence of D-serine and a ΔdsdA mutant was attenuated in virulence murine model of urinary tract infection.

Systematic review of membrane components of gram-positive bacteria responsible as pyrogens for inducing human monocyte/macrophage cytokine release

Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch–Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch–Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria.

Lactobacillus johnsonii La1 shares carbohydrate-binding specificities with several enteropathogenic bacteria

The carbohydrate-binding specificities of the probiotic lactic acid bacterium Lactobacillus johnsonii La1 (a health-beneficial bacterial strain able to be incorporated into the human intestinal microflora) were investigated in vitro. First various soluble complex carbohydrates were tested as potential inhibitors of the strain adhesion onto Caco-2 intestinal epithelial cells, and then bacterial binding to glycolipids immobilized on TLC plates was probed. Two major carbohydrate-binding specificities of Lactobacillus johnsonii La1 were identified. A first one for an Endo-H treated yeast cell wall mannoprotein carrying mainly O:-linked oligomannosides, and a second one for the gangliotri- and gangliotetra-osylceramides (asialo-GM1). Similar carbohydrate-binding specificities are known to be expressed on cell surface adhesins of several enteropathogens, enabling them to adhere to the host gut mucosa. These findings corroborate the hypothesis that selected probiotic bacterial strains could be able to compete with enteropathogens for the same carbohydrate receptors in the gut.

Cell surface-associated lipoteichoic acid acts as an adhesion factor for attachment of Lactobacillus johnsonii La1 to human enterocyte-like Caco-2 cells

The influence of pH on the adhesion of two Lactobacillus strains to Caco-2 human intestinal cells was investigated. One strain, Lactobacillus johnsonii La1, was adherent at any pH between 4 and 7. The other one, L. acidophilus La10, did not attach to this cell line under the same experimental conditions. On the basis of these results, we used the monoclonal antibody technique as a tool to determine differences on the surface of these bacteria and to identify a factor for adhesion. Mice were immunized with live La1, and the hybridomas produced by fusion of spleen cells with ONS1 cells were screened for the production of antibodies specific for L. johnsonii La1. A set of these monoclonal antibodies was directed against a nonproteinaceous component of the L. johnsonii La1 surface. It was identified as lipoteichoic acid (LTA). This molecule was isolated, chemically characterized, and tested in adhesion experiments in the same system. The adhesion of L. johnsonii La1 to Caco-2 cells was inhibited in a concentration-dependent way by purified LTA as well as by L. johnsonii La1 culture supernatant that contained LTA. These results showed that the mechanism of adhesion of L. johnsonii La1 to human Caco-2 cells involves LTA.

Agglutination of Staphylococcus saprophyticus: a structural and cytochemical study

Staphylococcus saprophyticus was shown to be agglutinated by wheat germ agglutinin, wheat germ agglutinin-biotin and bovine serum albumin-p-aminophenyl-N-acetyl-beta-D-glucosaminide (GlcNAc-BSA), and sheep red blood cells. In these agglutinations, filamentous or amorphous structures radiating from the surface of S. saprophyticus were demonstrated by electron microscope observation. Cytochemical analyses of the agglutination revealed the binding sites of wheat germ agglutinin in S. saprophyticus and the binding sites of GlcNAc in the sheep red blood cells and S. saprophyticus. Since GlcNAc-BSA contains N-acetylglucosamine to which wheat germ agglutinin can bind, it is most likely that an interaction between a wheat germ agglutinin-bindable substance in S. saprophyticus and an N-acetylglucosamine-bindable substance in sheep red blood cells is involved in the agglutination.

Continuing the search for bacterial urovirulence factors

Bacteria that commonly cause infections of the normal urinary tract (eg Escherichia coli, Proteus mirabilis and Staphylococcus saprophyticus) do so because they possess specific urovirulence factors. Adhesions of various types (often fimbriae) seem to be the most important of these. In E. coli several other factors have been recognized, and sub-sets of defined uropathogenic clones exist. On the other hand, urovirulence determinants are less easy to distinguish in species such as S. epidermidis and Klebsiella pneumoniae, that rarely cause such infections, or are pathogenic only in the presence of some abnormality or deficiency in host defences.

Identification and characterization of surface proteins from Staphylococcus saprophyticus

Staphylococcus saprophyticus, a well known cause of urinary tract infections, possesses several properties, such as hemagglutination of sheep erythrocytes, adherence to various cell types and production of urease, which may be virulence factors. In this contribution, we summarise the present knowledge about recently discovered surface proteins of Staphylococcus saprophyticus, a 95 kDa surface-associated protein (Ssp) and the hemagglutinin, a 160 kDa surface polypeptide. We describe culture conditions conducive to production of these surface proteins and discuss the molecular and clinical implications of our findings.

Thymocyte proliferation and maturation in response to staphylococcal lipoteichoic acid

Lipoteichoic acid (LTA) from Staphylococcus saprophyticus strain S1 could be shown to induce thymocyte proliferation and maturation in BALB/c-mice after systemic administration. The increase in thymocyte numbers per mg organ weight was statistically significant. Determination of thymic lymphatic subsets revealed a considerable up-regulation of mature cells expressing helper/inducer (L3T4) or cytotoxic/suppressor (Lyt-2) phenotypes. Thus administration of staphylococcal LTA obviously accelerated murine thymocyte proliferation and maturation. Counts of BALB/c-mouse peripheral blood lymphocytes (PBL) revealed no evident fluctuation within one week after LTA administration, however, statistically significant increases could be detected two weeks after treatment. The determination of activated PBL expressing IL-2 receptors suggested that injection of staphylococcal LTA apparently induced an immunostimulation since those cells were significantly enhanced within one week after LTA administration.

Staphylococcus saprophyticus hemagglutinin is a 160-kilodalton surface polypeptide

Many strains of Staphylococcus saprophyticus cause direct hemagglutination of sheep erythrocytes. For a high proportion of clinical isolates, a surface protein (Ssp) that is apparently not involved in this property has been described. In this study, S. saprophyticus CCM883, a hemagglutinating but Ssp-negative strain, was used for the identification, purification, and characterization of a 160-kDa surface polypeptide that appears to be the major component of the hemagglutinin. Expression of the protein required the addition to the growth medium of EDTA in micromolar quantities, suggesting an inhibitory role for some unidentified metal ion. The protein was purified by means of Sephacryl S-300 chromatography, and antisera were raised in rabbits. Antibody against this protein inhibited the hemagglutination of two other, unrelated strains and was used to demonstrate, by electron microscopy, the presence of the protein on the surface of the cells. In a confirmatory experiment, the purified antigen was incubated with erythrocytes and binding was detected by the Western immunoblot technique with the antibody to the 160-kDa polypeptide. These experiments indicate that this surface protein is the hemagglutinin of S. saprophyticus.

Diferenças nas propriedades adesivas de Staphylococcus saprophyticus a células HEp-2 e eritrócitos

S. saprophyticus é freqüentemente isolado de infecções do trato urinário de mulheres jovens e sexualmente ativas. Ao contrário de S. aureus, esta espécie não possui fatores de virulência bem definidos. O objetivo deste estudo é analisar a aderência de S. saprophyticus a células HEp-2 e eritrócitos de carneiro. As amostras foram isoladas a partir da urina de pacientes com infecção urinária. Foram realizados testes de hemaglutinação, aderência a células HEp-2 e a capacidade de carboidratos específicos inibirem as interações entre estes tipos celulares e S. saprophyticus. A maioria das cepas se mostrou hemaglutinante e sensível a inibição da hemaglutinação pela manose (100mM). Foram verificados altos níveis de aderência às células HEp-2. As diferenças em especificidade e nível de aderência do microrganismo a células de HEp-2 e eritrócitos sugerem a participação de diferentes adesinas nos processos de interações celulares.

Heterogeneity of lipoteichoic acid detected by anion exchange chromatography

A complex polydispersity became apparent when the poly(glycerophosphate) lipoteichoic acid of Enterococcus faecalis was chromatographed on DEAE-Sephadex. The chain length varied between 13 and 33 glycerophosphate residues per lipid anchor. In parallel, the extent of chain glycosylation increased from 0.2 to 0.4 diglucosyl residues per glycerophosphate unit. Substitution with D-alanine ester showed a reverse distribution dropping with increasing chain length from 0.53 to 0.23 mol D-alanine per mol phosphorus. Variations in the fatty acid composition were also observed. The results extent and modify the current picture of lipoteichoic acid biosynthesis. They further suggest that during infection the mammalian organism may be confronted particularly with long-chain less hydrophobic molecular species.

Identification and characterization of a surface-associated protein (Ssp) of Staphylococcus saprophyticus

A 95-kDa protein was isolated from Staphylococcus saprophyticus 7108 grown on dialysis membranes placed on the surface of brain heart infusion agar. Strain CCM883 did not produce this protein. Ultrathin sections revealed the presence of very thin, tuftlike, 50- to 75-nm-long structures on the surface of strain 7108, whereas strain CCM883 was comparably smooth. The surface material could be removed by digestion with proteinase K, suggesting that the surface structures contain protein. High-resolution scanning electron microscopy showed a thick layer of surface material on strain 7108, whereas strain CCM883 appeared smooth. The 95-kDa protein was purified by Sephacryl S-300 chromatography, and an antiserum was raised in rabbits. This antiserum was used in immunogold labeling experiments, which showed that the protein is associated with the surface structures. Our experiments thus demonstrate the presence of a fibrillar protein on the surface of S. saprophyticus (Ssp for S. saprophyticus surface-associated protein).

Staphylococcal lipoteichoic acid exerts growth factor-like activity towards human and murine cells

Lipoteichoic acid (LTA) was extracted from Staphylococcus saprophyticus strain S1 and tested for the capacity to induce hematopoietic and lymphatic cell proliferation. As compared to nontreated cells, the number of human bone marrow cells significantly increased in the presence of low LTA concentrations. Optimal growth was observed on the fifth day of in vitro incubation. After exposure to LTA, the lymphocyte proliferation rate also increased in a dose and time dependent manner. On the other hand, human epithelial cells and fibroblasts did not show enhanced growth activities in the presence of LTA.

Stimulation of monokine production by lipoteichoic acids

Lipoteichoic acids (LTAs) isolated from bacterial species, including Staphylococcus aureus, Streptococcus pyogenes A, Enterococcus faecalis, Streptococcus pneumoniae, and Listeria monocytogenes, were tested for their ability to stimulate the production of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha in cultured human monocytes. LTAs from S. aureus and S. pneumoniae failed to induce monokine production when applied in the concentration range of 0.05 to 5.0 micrograms/ml. However, LTAs from several enterococcal species (0.5 to 5 micrograms/ml) induced the release of all three monokines at levels similar to those observed after lipopolysaccharide stimulation. The kinetics of IL-1 beta and tumor necrosis factor alpha release elicited by LTAs closely resembled those observed following lipopolysaccharide application. Cytokine production occurred in the presence of both fetal calf serum and autologous human serum. Hence, it was not dependent on complement activation and could not be suppressed by naturally occurring human antibodies. Deacylation caused the total loss of monocyte stimulatory capacity. Deacylated LTAs were unable to prevent monocyte activation by intact LTAs, so primary binding of these molecules probably does not involve a simple interaction of a membrane receptor with the hydrophilic portion of the molecule. The results identify some species of LTAs as inducers of monokine production in human monocytes.

Adhesion of Staphylococcus saprophyticus to renal tubular epithelial cells is mediated by an N-acetyl-galactosamine-specific structure

S. saprophyticus CCM883 and 9325 were found to adhere to the tubular cell line LLC-PK1. An ELISA technique was used to determine adherence of bacteria and inhibition of adherence by various carbohydrates. Only N-acetyl-galactosamine was found to significantly inhibit adhesion (p less than 0.001), which suggests that the surface component mediating adhesion recognizes structures on the target cell that contain this carbohydrate.

Activation of mononuclear immune cells in response to staphylococcal lipoteichoic acid

The goal of the present study was to evaluate the influence of staphylococcal lipoteichoic acid (LTA) on the activation of mononuclear immune cells. A murine tumor necrosis-like factor (TNF-like) was induced in the sera of CD-1 mice which had been primed with heat/formalin-inactivated Propionibacterium avidum KP-40 and subsequently exposed to LTA extracted from Staphylococcus saprophyticus strain S 1. Monoclonal antibody against murine TNF (anti-TNF) significantly inhibited the cytostatic activity of mice sera against transformed L-929 cells. Freshly isolated lymphocytes did not display interleukin 2 (Il-2) receptors, but receptors were expressed on Con A incubated cells and in significantly higher numbers after coexposure to staphylococcal LTA in vitro. Since the induction of TNF (macrophages) and Il-2 receptors (lymphocytes) represent stimulation of the mononuclear immune system, staphylococcal LTA may be considered to be an immunomodifier.

Biological properties of staphylococcal lipoteichoic acid and related macromolecules

Lipoteichoic acids (LTAs) and related macromolecules (e.g. cell surface substance, CSS; cell surface antigen, CSA; cell surface complex, CSC) are a group of phosphate-containing polymers associated with the cell walls of Gram-positive bacteria (32). They may be considered as surface-reactive antigens (immunogens, biological response modyfiers) as well as membrane components which mediate the attachment of certain bacteria (S. saprophyticus, S. aureus, group A streptococci) to host cell tissues.

Occurrence and structure of lipoteichoic acids in the genus Staphylococcus

Lipoteichoic acids were isolated from eleven species of the genus Staphylococcus using phenol-water partition and hydrophobic chromatography on octyl-Sepharose CL-4B. The lipoteichoic acids purified could be visualized by SDS-PAGE. They were shown to be composed of a hydrophilic poly(glycerophosphate) chain covalently linked to gentiobiosyldiacylglycerol, the common lipid anchor of these molecules. Glycerophosphate units of the hydrophilic chain were found to be partly substituted with ester-linked D-alanine, except in the case of S. cohnii. The lipoteichoic acids isolated from S. cohnii, S. hominis, S. saprophyticus and S. simulans contain alpha(1-2)-linked N-acetylglucosamine as an additional substituent of the poly(glycerophosphate) backbone.

Lipoteichoic acid as a new target for activity of antibiotics: mode of action of daptomycin (LY146032)

Daptomycin at the MIC allowed the cell mass increase of enterococcal strains and Bacillus subtilis to continue for 2 to 3 h at rates comparable to those of the controls. During this time the cell shape of the former changed to a rod configuration and that of the latter changed to long rods. In these bacteria, in which cell mass continued to increase, the MIC of daptomycin inhibited peptidoglycan synthesis by no more than 20% after 20 min of incubation and by roughly 50% after 2 h of incubation. Other macromolecules, such as DNA, RNA, and proteins, were only slightly affected. In contrast, incorporation of [14C]acetate into lipids was reduced by about 50% in the various strains after 20 min of treatment with daptomycin at the MIC. When the effect of the major lipid-containing polymers on synthesis was evaluated in detail, it was found that under conditions in which peptidoglycan and the other macromolecules mentioned above were inhibited only slightly (20%) and total lipid synthesis was inhibited by 50%, synthesis of teichoic and lipoteichoic acid was inhibited by 50 and 93%, respectively. Daptomycin was not found to enter the cytoplasm of either bacterial or mammalian cells. It bound, in the presence of calcium ions only, to whole bacterial cells, cell walls (both those that contained and those that did not contain membranes), and isolated membranes of bacterial and mammalian cells. Washing with EDTA removed daptomycin from all cells mentioned above and cell fractions except the bacterial membrane. It is concluded that lipoteichoic acid is most likely the primary target of daptomycin.

Adherence of Staphylococcus epidermidis to fibrin-platelet clots in vitro mediated by lipoteichoic acid

The adherence of two strains of Staphylococcus epidermidis to human fibrin-platelet clots in vitro was investigated. Both strains were noncapsulated, nonhemagglutinating, and nonslime producers. Binding was not related to surface charge, carbohydrate profile, or hydrophobicity of the bacteria. Adherence was reduced four- to sixfold (P less than 0.001) on pretreatment of bacteria with lipase, while neuraminidase, trypsin, phospholipase C, and sodium periodate did not alter their binding. Pretreatment of bacteria with substances known to bind lipoteichoic acid (LTA), such as human albumin and anti-LTA antibodies, also resulted in a fourfold (P less than 0.001) reduction in adherence. Prior incubation of clots with free LTA, but not with deacylated LTA, produced a fourfold (P less than 0.001) decrease in the adherence of homologous and heterologous strains of S. epidermidis. A similar reduction was also observed when LTAs derived from Staphylococcus aureus and Streptococcus pyogenes were used. These data provide evidence that the lipid moiety of LTA has a central role in the adherence of S. epidermidis to fibrin-platelet clots in vitro.

Chemiluminescence response of human polymorphonuclear and mononuclear phagocytic cells induced by Staphylococcus saprophyticus, lectinophagocytosis versus opsonophagocytosis

Two strains of Staphylococcus saprophyticus with well characterized cell surface structures were studied to determine the contribution of lectinophagocytosis versus opsonophagocytosis exerted by human phagocytic cells from five healthy donors. The luminol specific chemiluminescence assay was used to evaluate the response of phagocytes. Human polymorphonuclear leukocytes (PMNL) were demonstrated to have surface lectin receptors, since the chemiluminescence response towards both S. saprophyticus strains was inhibited by lectin-specific glycoconjugates for those organisms. Phagocytosis of S. saprophyticus by mononuclear cells was not inhibited by microbial lectin-specific glycoconjugates but was inhibited by D-mannose, suggesting that human monocytes express D-mannose specific lectins on their surface.

Binding of staphylococci to mucus in vivo and in vitro

The association of Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus with tissues of the upper respiratory tract were compared by using an in vivo ferret model. Ferrets were challenged intranasally with a 1-ml volume of radiolabeled staphylococci (3 mg [dry weight]), were allowed to clear the bacteria in vivo for 90 min, and were sacrificed. Tissues from the right nasal fossa were harvested and processed for radioassay or histology. Of the recoverable staphylococci, greater than or equal to 96% was associated with mucus gel overlaying mucosa of the turbinates. A quantitative radioassay was developed to study the binding of labeled staphylococci to immobilized crude ferret nasal mucin (FM) and bovine submaxillary gland mucin (BM). Binding showed saturation kinetics and was blocked specifically by BM but not by human Tamm-Horsfall glycoprotein nor orosomucoid. Binding to both FM and BM was significantly inhibited (P less than or equal to 0.01) when cocci were pretreated with trypsin but not when treated with beta-galactosidase or sodium metaperiodate (except for binding of S. saprophyticus to FM). These results suggest that mucin-binding receptors of the cocci may have protein components. The staphylococcus-binding receptors of both FM and BM appear to contain protein components, based on sensitivity to pretreatment with trypsin.

Adhesiveness and invasiveness of staphylococcal species in a cell culture model

A model was established for the study of adhesiveness and invasiveness of staphylococcal species. Five collection strains from each of the species Staphylococcus aureus, S. epidermidis, and S. saprophyticus and 26 fresh isolates from patients with urinary tract infections were tested for adhesiveness and invasiveness in HEp-2 cell cultures. All the strains of S. saprophyticus were able to invade the cells and localize intracellularly in the cultures, whereas the invasive potential among the strains of S. aureus and S. epidermidis was lower. The number of adhesive bacteria was also highest among the S. saprophyticus strains, whereas S. epidermidis was the least adhesive. The model may be suitable for further study of urinary tract infection strains.

Granulocyte activation by a cell surface complex of Staphylococcus saprophyticus: a receptor-mediated phenomenon

High molecular weight cell surface complex (CSC) from Staphylococcus saprophyticus strain S 1 could be shown to be a potent stimulator of human polymorphonuclear leukocyte (PMN) chemiluminescence whereas human monocytes were not activated. Heating of the CSC (100 degrees C for 5 min) as well as protease treatment significantly (p less than 0.001) inhibited the PMN activating process suggesting that the protein part of the molecule mediates its biological activity. Data on the biochemical character of the CSC are given. Preincubation of PMNs with CSC inhibited another chemiluminescence response to this substance and to homologous opsonized S. saprophyticus, respectively. However, restimulation with formylmethionyl peptides (fMLP) or non-opsonized staphylococci suggested that the PMN function is a receptor-mediated phenomenon. These data were substantiated since fMLP activated PMNs could be evidently re-stimulated with CSC but not with analogue peptides. Evaluation of the bactericidal capacity of human PMNs yielded comparable results.

Absence of factors associated with significant urinary tract infections caused by coagulase-negative staphylococci

Coagulase-negative staphylococci, excluding Staphylococcus saprophyticus, have recently been implicated as pathogens in urinary tract infections, especially in catheterized patients. In order to evaluate any laboratory markers for significant isolates of coagulase-negative staphylococci, we prospectively studied 72 patients with significant, indeterminant, or contaminant urine isolates of coagulase-negative staphylococci. Patients in the three categories did not differ by age, sex, presence of a urinary catheter, or other instrumentation or likelihood of nosocomial acquisition. The isolates from these three groups of patients were similar in antibiotic susceptibility and ability to produce slime. Overall, slime-producing coagulase-negative staphylococci were more likely to be S. epidermidis than any other species, but slime production was not associated with presence of pyuria, symptomatic urinary tract infection, instrumentation, nosocomial acquisition, or multiple antibiotic resistance. In this prospective study, no demographic characteristics or laboratory markers of coagulase-negative staphylococci were associated with clinical significance, as defined by symptoms or the presence of pyuria.

Staphylococcus saprophyticus urease: characterization and contribution to uropathogenicity in unobstructed urinary tract infection of rats

We studied the biochemical properties of the urease of Staphylococcus saprophyticus and the possible role of the urease in experimental urinary tract infections. For this purpose, the nonhemagglutinating and nonadherent strain 9325, which was isolated from a case of symptomatic urinary tract infection, was used. The urease was shown to have a Km of 6.64 mM urea and a Vmax of 4.59 mumol NH3.min-1.mg-1. The enzyme was inhibited by acetohydroxamic acid in a noncompetitive manner. By means of Sephacryl S-300 column chromatography, we determined a mean molecular weight (+/- standard error of the mean) of 420,000 +/- 16,000. To assess the contribution of S. saprophyticus urease to uropathogenicity, a urease-negative mutant was constructed by nitrosoguanidine mutagenesis. In the rat model of ascending unobstructed urinary tract infection, higher numbers of CFU.gram of tissue-1 and more-severe lesions were detected with the parent strain. Moreover, bladder stones were found in animals infected with the urease-positive strain only. Interestingly, the difference in mean bacterial counts of the bladders was found to be significant by the Wilcoxon two-sample test (P less than 0.05), whereas that between the kidney bacterial counts was not. Immunoblot studies revealed a faint antibody response in rats infected with the mutant strain, although bacteria could still be detected in the kidneys after 7 days. Sera of animals challenged with the parent strain reacted strongly with many antigens of S. saprophyticus. Our data indicate that urease is a major factor for invasiveness of S. saprophyticus, especially in the tissue of the bladder, whereas persistence in the urinary tract and nephropathogenicity of this organism are governed by factors other than urease.

Hemagglutinating and adherence properties of Staphylococcus saprophyticus: epidemiology and virulence in experimental urinary tract infection of rats

We studied hemagglutinating and adherence properties in Staphylococcus saprophyticus isolates originating from symptomatic urinary tract infections. 12/13 (92%) of strains adhered to Hep cells and 11/13 (85%) were able to agglutinate sheep erythrocytes. Adherence properties differed markedly between strains (P less than 0.0001). Two strains, one hemagglutinating and adherent and one negative for both properties were chosen for experimental urinary tract infections. Results indicate that presence of the hemagglutinin favours colonization of kidney tissue.

Immunostimulating staphylococcal lipoteichoic acid prevents pulmonary tumor colonization in BALB/c-mice

Immunostimulating and antineoplastic activities of staphylococcal lipoteichoic acid (LTA) were studied in Balb/c-mice. Systemic administration of LTA (1 mg or 2 mg i. p., 7 and 4 days prior to challenge) significantly enhanced chemiluminescence response of peritoneal macrophages (p less than 0.0125) and induced enlargement of the spleen (p less than 0.025) as compared to non-treated controls. In vivo the number of lung colonies was significantly lower (p less than 0.0125) in LTA-treated mice 14 days after challenge with L-1 sarcoma cells.

Immunomodulatory effects of staphylococcal lipoteichoic acid in early Listeria monocytogenes infection in Balb/c-mice

Balb/c-mice were intravenously infected with 5 X 10(4) viable cells of Listeria monocytogenes SLCC 4013. Liver, lung and spleen of the animals showed heavy organ colonization 48 h after infection. Pretreatment of experimental animals with staphylococcal lipoteichoic acid (LTA; 2 mg i.p. 7 and 3 days before challenge) significantly reduced the bacterial count in these organs. In vitro, peritoneal macrophages from LTA-treated mice significantly reduced listerial viability as compared to control cells (p less than 0.0025). In vitro, exposure of macrophages from non-treated animals to LTA did not influence their bacterial killing ability.

The role of lectins and lipoteichoic acid in adherence of Staphylococcus saprophyticus

Staphylococcus saprophyticus strains S 1 and S 35 demonstrated lectin like surface receptors specific for N-acetylgalactosamine (S 1) or N-acetylneuraminic acid (S 35). Adhesion assays with human uroepithelial cells together with blocking experiments with competitive carbohydrates suggested that specific attachment of S. saprophyticus to host cells is apparently mediated by lectins. Staphylococcal lipoteichoic acid (LTA) was also shown to interfere with S. saprophyticus adherence to human uroepithelial cells.

Hemagglutination by Staphylococcus saprophyticus and other coagulase-negative staphylococci

Hemagglutination tests were performed to specify surface lectins (hemagglutinins) of four coagulase-negative staphylococcal species: S. saprophyticus (31 strains), S. epidermidis (5 strains), S. haemolyticus (3 strains), and S. warneri (3 strains). All strains of S. saprophyticus agglutinated sheep red blood cells (RBC) and the hemagglutination was inhibited by N-acetylglucosamine (GlcNAc) plus either N-acetylgalactosamine (GalNAc, 15 strains) or N-acetylneuraminic acid (NANA, 16 strains). Those strains showing inhibition by GalNAc also agglutinated horse RBC while those inhibited by NANA agglutinated rabbit RBC. The former type was more common among urinary tract isolates (10/15) and the second one among respiratory isolates (9/14). The eleven strains of other staphylococci agglutinated rabbit (and not sheep or horse) RBC; this hemagglutination was never inhibited by GlcNAc but instead by NANA alone or together with another sugar (7 strains) or by other sugars (4 strains, 3 different patterns of inhibition).

Stimulation of human monocyte chemiluminescence by staphylococcal lipoteichoic acid

Lipoteichoic acid (LTA) from Staphylococcus saprophyticus strains S1 and S35 was shown to be a potent stimulator of human monocyte chemiluminescence, whereas human granulocytes were not activated. Data on the chemical analysis of these LTA-preparations were given.

Detection of different fimbriae-like structures on the surface of Staphylococcus saprophyticus

In relation to the ability of adhesiveness to HEp-2-cells the sizes of capsules on three strains of Staphylococcus saprophyticus were examined using an electron microscopic India ink technique. There was a good correlation between small amounts of capsular material and good adherence to the tissue culture cells. In contrast to this a very large capsule could be demonstrated on a strain which adhered only in a poor manner. Some indications of fimbriae-like structures could be confirmed by negative staining. Three different appendages: thick, short sticks, long, branched fimbriae and fine, thin filaments on the surface of S. saprophyticus were detected. The possible functions of these surface structures in the adherence process represented in a hypothetical cell model is discussed.

Adherence of group B streptococci to adult and neonatal epithelial cells mediated by lipoteichoic acid

We have investigated the role of lipoteichoic acid in mediating the adherence of different serotypes of group B streptococci to human adult and neonatal epithelial cells. Pretreatment of neonatal buccal and vaginal epithelial cells with lipoteichoic acid, but not with deacylated lipoteichoic acid, induced a marked inhibition in the adherence of all strains tested. Pretreatment of bacteria with substances known to bind lipoteichoic acid, such as monoclonal and polyclonal antipolyglycerophosphate antibodies and albumin, also resulted in adherence inhibition. Group B streptococci adhered in 6- to 10-fold-higher numbers to buccal epithelial cells from neonates older than 3 days than to those from neonates less than 1 day old. This increase in receptiveness for group B streptococci was paralleled by an increased ability of epithelial cells from older neonates to bind group B streptococcal lipoteichoic acid. These data suggest a role for the lipid portion of lipoteichoic acid in the adherence of different serotypes of group B streptococci to vaginal and neonatal epithelial cells.