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Immunochemical characterization and biological properties of a cell surface antigen extracted from encapsulated Staphylococcus epidermidis strain SE-10.

Protection inducing antigen (PIA) was mechanically extracted from Staphylococcus epidermidis (encapsulated strain SE-10) and purified by DEAE-Sephadex A 25 (C1- form) ion exchange chromatography. Major carbohydrate constituents of PIA were galactose, glucose, and N-acetylglucosamine at the molar ratio 1.00:0.96:0.78. Antigenic activity was considerably reduced after sodium metaperiodate oxidation, however, pronase digestion was not effective. N-acetylglucosamine residues were shown to be closely related to the antigenic determinant. No cross reactivity to PIAs from other encapsulated strains of S. epidermidis was found which indicates type specificity. Protection of mice after immunization and enhancement of human granulocyte function suggests that PIA might be considered to be a biological response modifying substance.

Antigens, Bacterial↗

Agar overlay method to measure adherence of Staphylococcus epidermidis to four plastic surfaces.

The comparative adherence of seven strains of Staphylococcus epidermidis to plastic surfaces was measured by an agar overlay technique in which adherent organisms were counted by their ability to form colonies under an agar overlay. The degree of adherence to plastics decreased in the order polystyrene, polyvinyl chloride, Silastic, and polytetrafluoroethylene.

Bacteriological Techniques↗

Identification of antigenic components of Staphylococcus epidermidis expressed during human infection.

A spectrum of in vivo-expressed Staphylococcus epidermidis antigens was identified by probing a bacteriophage lambda library of S. epidermidis genomic DNA with human serum from infected and uninfected individuals. This analysis resulted in identification of 53 antigen-encoding loci. Six antigenic polypeptides were expressed from these loci and purified. These polypeptides were the propeptide, mature amidase, and repeat sequence domains of the major autolysin AtlE, GehD (lipase), and two members of a conserved family of surface proteins (ScaA [AaE] and ScaB). AtlE, ScaA, and ScaB all exhibit human ligand binding capacity. Screening a bank of human serum samples revealed that there were significant increases in the amounts of reactive immunoglobulin G in infected individuals compared to the amounts in healthy individuals for the repeat sequence and mature amidase domains of AtlE, ScaB, and GehD. Vaccination of mice with recombinant antigens stimulated an immune response which in vitro opsonized S. epidermidis. In this study we identified prospective candidate antigens for prophylaxis or immunotherapy to control disease.

Amino Acid Sequence↗

Effect of minimal amounts of thymidine on activity of trimethoprim-sulfamethoxazole against Staphylococcus epidermidis.

The antibacterial activity of trimethoprim-sulfamethoxazole against 99 strains of Staphylococcus epidermidis was tested on media known to be low in thymidine content, as determined by screening with Streptococcus faecalis. Eighty-one percent of the isolates were susceptible by agar dilution. Trimethoprim-sulfamethoxazole was bactericidal against two strains of S. epidermidis when thymidine phosphorylase was added to the medium, indicating utilization of minimal amounts of thymidine that were undetected by screening. Because bacteria vary in their utilization of thymidine and body tissues vary in thymidine content, in vitro susceptibility tests may not correlate with in vivo bactericidal activity.

Anti-Bacterial Agents↗

Molecular relatedness of Staphylococcus epidermidis isolates obtained during a platelet transfusion-associated episode of sepsis.

Staphylococcus epidermidis was isolated from the blood of a 25-year-old pregnant woman following the administration of eight units of platelets. She had developed chills and a fever of 41.4 degrees C soon after the transfusions were completed. S. epidermidis was also obtained from all eight platelet units, as well as from the packed-erythrocyte unit associated with the first unit of platelets. The isolation of the same organism from these epidemiologically related sources provided us with the opportunity to phenotypically and genetically characterize the isolates. Several typing methods, including four molecular techniques, were used to increase our chances of finding any differences between the isolates under investigation. Phenotypic analyses demonstrated that S. epidermidis isolates from the patient, platelet units, and erythrocyte unit reacted in exactly the same manner in 15 biochemical tests, exhibited slime production, and had the same antibiotic susceptibility pattern. Genetic analyses, which included plasmid profiles, plasmid cross-hybridization, field inversion gel electrophoresis, and ribotyping, substantiated the relationships between the S. epidermidis isolates from the patient, platelet units, and erythrocyte unit. Eight S. epidermidis control strains unrelated to the case were found to differ significantly from the platelet-related strain.

Adult↗

mecA is not involved in the sigmaB-dependent switch of the expression phenotype of methicillin resistance in Staphylococcus epidermidis.

A lack of sigma(B) activity reduces methicillin resistance in heterogeneous Staphylococcus epidermidis 1057, whereas inactivation of the anti-sigma factor RsbW switched the phenotype to homogeneous expression of resistance. Oxacillin induction of mecA transcription is reduced in a sigma(B)-negative strain. However, mecA is not involved in the switch of expression phenotype.

Bacterial Proteins↗

Molecular epidemiology of Staphylococcus epidermidis blood isolates from neonatal intensive care unit patients.

Twelve episodes of Staphylococcus epidermidis bacteraemia occurred within three months in a neonatal intensive care unit. Plasmid profiles and Southern blot hybridization with five different probes were used to determine whether an endemic strain of S. epidermidis could be identified among the contemporary isolates. It was concluded that this methodology was satisfactory for differentiation between isolates of coagulase-negative staphylococci: fifteen isolates were divided in eight groups indicating that there was no single endemic strain causing the outbreak.

Bacteremia↗

Effects of temperature on the bactericidal activities of ciprofloxacin and levofloxacin against Staphylococcus aureus and Staphylococcus epidermidis.

The bactericidal activities of the 4-quinolones ciprofloxacin and levofloxacin against Staphylococcus aureus and Staphylococcus epidermidis in nutrient broth were dramatically reduced when the temperature of incubation was decreased from 37 to 20 degrees C. For S. aureus the relative reduction in the activities was 86- and 46-fold with ciprofloxacin or levofloxacin, respectively. For S. epidermidis the corresponding reduction in activities was 82- and 19-fold, respectively. At infectious sites which are at lower-than-body temperature the reduced activity of 4-quinolones may contribute to clinical failure and/or the development of resistance. Levofloxacin was more bactericidal than ciprofloxacin against either of the staphylococci at every temperature tested. These results tend to suggest that levofloxacin may be preferable to ciprofloxacin for staphylococcal infections especially at skin and soft-tissue sites.

Body Temperature↗

Phagocytosis and killing of slime-producing Staphylococcus epidermidis bypolymorphonuclear leukocytes. Effects of sparfloxacin.

The interaction of slime-producing Staphylococcus epidermidis (S+ strain) with human polymorphonuclear leukocytes (PMNs) was analyzed. The phagocytosis index (PI) and the killing index (KI) were evaluated, and the effect of subinhibitory concentrations (sub-MICs) of sparfloxacin in this interaction was determined. The study was carried out in parallel with a non-slime-producing strain (S- strain). The MIC values of sparfloxacin against both strains was 0. 06 mg/ml. In the S- strain the mean values of PI and KI were 82% and 31%, respectively, whereas in the S+ strain these values diminished to 49% and 8%, respectively (p <0.05) when the inocula were prepared in aerobiosis. In a constant flow atmosphere of 5% CO2, the results were similar to the previous ones in the S- strain (PI = 79% and KI = 27%), whereas in the S+ strain a increase in the PI (59%) and a similar value to the KI (9%) were observed. Significant increases (p <0.05) in the PI were noted when PMNs were preincubated with 1/4 and 1/16 MIC of sparfloxacin, and S. epidermidis S+ grown in aerobiosis were used. In the other assays the variations in PI and KI were not statistically significant (p >0.05). Our results confirm that slime protects against phagocytosis and killing by PMNs, although they also suggest that the S+ strains possess additional properties which make them resistant to the action of the PMNs.

Aerobiosis↗

Reactive arthritis by staphylococcus epidermidis: report of an unusual case.

In the literature many cases of Staphylococcus epidermidis (SE) complications are reported, but we have not found any reference about reactive arthritis secondary to SE. We report an unusual case of a patient with SE bacteriaemia, who developed elbow arthritis, asymmetrical sacroiliitis, keratoderma and restrictive cardiomyopathy. The clinical pictures, the instrumental and biochemical findings, in particular the positivity of HLA B27, allow us to set this case in the complex and heterogeneous chapter of reactive arthritis.

Adult↗

Staphylococcus epidermidis biofilms: unexpected outcome of double and triple antibiotic combinations with rifampin.

Staphylococcus epidermidis, in contact with artificial surfaces, may produce a protective glue-like matrix or biofilm. The authors demonstrated that rifampin alone among 35 antibiotics penetrated the biofilm within a 24 hr exposure producing a major but incomplete killing. Antibiotics of the cell-wall active class (including vancomycin) were synergistic with rifampin, completing the bactericidal action. The addition of these antibiotics to a rifampin-vancomycin combination did not alter the synergy. Other antibiotics (including aminoglycosides) antagonized rifampin activity. This antagonism of rifampin was maintained when the antibiotics were added to the rifampin-vancomycin synergistic combination. These results may have implications for the choice of optimal therapeutic regimens in the management of implant-associated infection.

Drug Therapy, Combination↗

Challenging the current treatment paradigm for methicillin-resistant Staphylococcus epidermidis peritonitis in peritoneal dialysis patients.

OBJECTIVES: To analyze clinical outcomes of Staphylococcus epidermidis peritoneal dialysis peritonitis before and after an interventional switch from a vancomycin/ tobramycin to a cefazolin/tobramycin regimen for empiric treatment. To examine risk factors associated with clinical failure. DESIGN: A retrospective study. SETTING: A peritoneal dialysis program within a university-affiliated tertiary-care hospital. PATIENTS: 93 episodes of S. epidermidis peritonitis over a 6-year period. INTERVENTIONS: Clinical responses were compared between treatments using chi-square or Fisher's exact test. Univariate and multivariate analyses were used to identify significant risk factors for clinical failure. MEASUREMENTS AND MAIN RESULTS: There was no difference in the overall response rates observed with vancomycin (40/49; 81.6%) and cefazolin (23/29; 79.3%) regimens for episodes of S. epidermidis peritonitis. Furthermore, the presence of methicillin resistance in 63 of 93 cases (67.7%) had no influence on clinical outcome, with response rates of 83.9% (26/31) and 82.4% (14/17) for empiric vancomycin and cefazolin regimens, respectively. Tobramycin therapy of less than 2 days was an independent risk factor for clinical failure in multivariate logistic regression analysis (odds ratio 4.44, 95% confidence interval 1.28 - 15.48; p = 0.02). CONCLUSIONS: Empiric treatment with intraperitoneal cefazolin was as effective as vancomycin for S. epiderimidis peritonitis despite a high prevalence of methicillin resistance. Tobramycin therapy of less than 2 days was strongly associated with treatment failure.

Aged↗

Expression, purification, and characterization of EpiC, an enzyme involved in the biosynthesis of the lantibiotic epidermin, and sequence analysis of Staphylococcus epidermidis epiC mutants.

The plasmid-encoded epidermin biosynthetic gene epiC of Staphylococcus epidermidis Tü3298 was expressed in Escherichia coli by using the T7 RNA polymerase-promoter system, and the gene product EpiC was identified by Western blotting (immunoblotting) with an anti-EpiC-peptide antiserum. EpiC was a hydrophobic but soluble protein. EpiC was purified by hydrophobic-interaction chromatography. The determined amino-terminal amino acid sequence was M I N I N N I .... The electrophoretic migration behavior of EpiC depended on the oxidation state of the enzyme, indicating the formation of an intramolecular disulfide bridge between C-274 and C-321. The cysteine residues in the motifs WC-274YG and C-321HG of EpiC are conserved in all lantibiotic enzymes of the C type (so-called LanC proteins) and in the CylM protein. Mutated epiC genes from S. epidermidis epiC mutants were cloned and expressed in E. coli. Sequence analysis revealed that the mutations occurred in the two motifs -S-X-X-X-G-X-X-G- and -N-X-G-X-A-H-G-X-X-G-, which are conserved in all LanC proteins. For the investigation of EpiC-EpiA interactions, precursor peptide EpiA was coupled to N-hydroxysuccinimide-activated Sepharose High Performance Material (HiTrap). Under reducing conditions, EpiC was retarded on the EpiA-HiTrap column. In the incubation experiments, EpiC did not react with EpiA, with proepidermin, or with oxidative decarboxylated peptides.

Amino Acid Sequence↗

Antibiotic tolerance of Staphylococcus epidermidis.

The phenomenon of antibiotic tolerance was studied in 50 strains of Staphylococcus epidermidis isolated from blood cultures. The antibiotics used for study were methicillin, nafcillin, oxacillin, cephalothin, cefazolin and vancomycin. The MICs and MBCs were determined in Mueller Hinton Broth (MHB) and Brain Heart Infusion broth (BHI) after incubation at 24 and 48 h at 37 degrees C. Tolerance was defined as the MBC/MIC ratio of greater than or equal to 16. About one third of the strains were tolerant to vancomycin and another one third were tolerant to multiple betalactam antibiotics. However, cross tolerance between vancomycin and betalactam antibiotics occurred very infrequently (4 strains). Tolerance was demonstrated for some strains in both MHB and BHI. Other strains were tolerant only in MHB or BHI. Similarly, some strains were tolerant at both 24 and 48 h. However, many strains were tolerant only at 24 and not at 48 h.

Anti-Bacterial Agents↗

Use of an in vitro model for studying the eradication of catheter colonisation by Staphylococcus epidermidis.

Silicone rubber catheters were experimentally colonised with three different strains of Staphylococcus epidermidis sensu stricto. The catheters were then perfused with brain-heart infusion broth by means of an in vitro apparatus which simulates the pharmacokinetics of intraventricular administration of antimicrobial agents. When colonisation was established, vancomycin was administered to the dosing chamber three times daily so as to give peak concentrations of 16, 32, 64 and 128 mg/l. Each experiment was performed in triplicate. Samples of fluid taken from each catheter were cultured before treatment and at intervals thereafter during perfusion for 4 weeks or until recolonisation became apparent. Those catheters not showing evidence of recolonisation were examined by scanning electron microscopy for the presence of organisms. Colonisation was eradicated (as judged by cultural examination) in 37% catheters but eradication did not bear any clear relationship to drug concentrations. Electron microscopical examination of all catheters showing eradication by cultural means revealed the presence of organisms.

Catheterization, Central Venous↗

Susceptibility of Propionibacterium acnes, Staphylococcus aureus and Staphylococcus epidermidis to 10 Kampo formulations.

We examined the in vitro sensitivities of three bacteria: Propionibacterium acnes, and Staphylococcus epidermidis, commonly detected in acne lesions, and Staphylococcus aureus, a common cause of skin infections, to 10 Kampo formulations (Chinese herbal medicines; combinations of powdered extracts of crude drugs). Both Staphylococcus species showed similar sensitivities to all 10 formulations, with minimum inhibitory concentrations (MICs) ranging from 25 to 400 mg/ml. P. acnes, however, was particularly sensitive to one formulation, keigai-rengyo-to (MIC, 0.78-25 mg/ml), prompting speculation that it might contain components with strong antibacterial activity to P. acnes. P. acnes showed similar sensitivities to all the other formulations (MIC 6.25-200 mg/ml). The ranges of MICs and the MIC50S (concentrations that inhibit 50% of isolates) were very similar to those previously recorded in 1990 for the two Staphylococcus species.

Acne Vulgaris↗

Immunological responses of the lactating ovine udder following experimental challenge with Staphylococcus epidermidis.

The responses of five lactating ewes to experimental mammary infection with Staphylococcus epidermidis were examined. Infection caused an intense but transient influx of neutrophils into milk, which peaked at 8 h and was accompanied by mild fever and mild leukopaenia in blood. No other signs of systemic infection were observed. Number of staphylococci in milk decreased logarithmically until 24 h, were absent from three ewes at 48 h and then increased in number or re-emerged in four of the five ewes at 72 or 144 h. At all times milk appeared grossly normal. Expression of the adhesion molecules CD11b and CD18 increased on neutrophils in milk at 24 h then tended to decline over subsequent days. The proportion of lymphocytes positive for CD4, CD8, WC1 and MHCII tended to decrease from 24 to 72 h then increased at 144 h. Cytokines in milk were measured by ELISA. IL-8 was elevated in infected glands at 2 h, peaked at 24 h and remained elevated until the final sampling at 144 h. IL-6 was transiently elevated at 4 and 8 h while IL-1beta remained elevated from 8 until 144 h. The results suggest that the intense early neutrophil infiltrate eliminated most but not all bacteria and a state of subclinical infection ensued. After 24 h , leukocyte numbers in milk declined while cytokines, especially IL-8 remained elevated, suggesting that sensitivity or responsiveness of gland to inflammatory signals decreased as infection progressed. This attenuation of the host defence response may have contributed to the failure of the gland to eliminate bacteria and may be an important feature of the development of chronic and subclinical mastitis.

Animals↗

Successful treatment of Staphylococcus epidermidis hip prosthesis infection with oral linezolid.

OBJECTIVE: To report a case of Staphylococcus epidermidis infection of a hip prosthesis successfully treated with oral linezolid. CASE SUMMARY: A 46-year-old woman developed methicillin-resistant S. epidermidis (MRSE) infection of her prosthetic hip. She received oral linezolid 600 mg twice daily for one month; after that time, the biological inflammatory markers returned to normal. DISCUSSION: One of the most serious complications of arthroplasty is joint prosthesis infection. It is mainly caused by gram-positive bacteria, in particular those of the genus staphylococcus. The increasing prevalence of gram-positive cocci that are resistant to antimicrobial agents has complicated the treatment of serious infections. CONCLUSIONS: Oral linezolid appears to be an effective and well-tolerated treatment option for hip prosthesis infections due to MRSE.

Acetamides↗