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PubMed2001

The electrophoretic softness of the surface of Staphylococcus epidermidis cells grown in a liquid medium and on a solid agar.

Many Staphylococcus epidermidis strains possess capsule or slime layers and consequently the staphylococcal cell surface should be regarded as a soft, polyelectrolyte layer allowing electrophoretic fluid flow through a layer of fixed charges. The presence of such a soft layer decreases the energy barrier due to electrostatic repulsion in the interaction of the organisms with negatively charged substrata [Morisaki, H., Nagai, S., Ohshima, H., Ikemoto, E. & Kogure, K. (1999), MICROBIOLOGY: 145, 2797-2802] and hence plays an important role in their adhesion. In this paper, the authors compare the electrophoretic softness and amount of fixed charge in the outer cell surface layers of 20 S. epidermidis strains, grown in a liquid medium or on a solid agar, as determined from the dependencies of their electrophoretic mobilities upon the ionic strength of a suspending fluid. Most of the staphylococcal cell surfaces were relatively soft, with a mean cell surface softness (1/lambda) for strains grown in liquid medium of 1.7+/-0.6 nm (standard deviation over all 20 strains) which is soft by comparison with a completely bald, peptidoglycan-rich streptococcal cell surface (1/lambda=0.7 nm). When the staphylococcal strains were grown on solid agar, the cell surface softness of 17 of the 20 strains increased, sometimes by a factor of two. On average for 20 strains, the cell surface softness increased significantly (P:<0.05, Student's t-test) to 2.8+/-1.8 nm. The amount of fixed charge in the outer cell surface layer was -28+/-9 mM for bacteria grown in liquid medium and -24+/-12 mM for bacteria grown on agar. A soft, highly negatively charged polyelectrolyte layer was inferred by microelectrophoresis for all the staphylococcal cell surfaces, regardless of whether staining had indicated the presence of a capsule or slime layer.

Culture Media↗
PubMed2004

Localization and functional analysis of PepI, the immunity peptide of Pep5-producing Staphylococcus epidermidis strain 5.

Pep5 is a cationic pore-forming lantibiotic produced by Staphylococcus epidermidis strain 5. The producer strain protects itself from the lethal action of its own bacteriocin through the 69-amino-acid immunity peptide PepI. The N-terminal segment of PepI contains a 20-amino-acid stretch of apolar residues, whereas the C terminus is very hydrophilic, with a net positive charge. We used green fluorescent protein (GFP)-PepI fusions to obtain information on its localization in vivo. PepI was found to occur outside the cytoplasm and to accumulate at the membrane-cell wall interface. The extracellular localization appeared essential for conferring immunity. We analyzed the functional role of the specific segments by constructing various mutant peptides, which were also fused to GFP. When the hydrophobic N-terminal segment of PepI was disrupted by introducing charged amino acids, the export of PepI was blocked and clones expressing such mutant peptides were Pep5 sensitive. When PepI was successively shortened at the C terminus, in contrast, its export properties remained unchanged whereas its ability to confer immunity was gradually reduced. The results show that the N-terminal part is required for the transport of PepI and that the C-terminal part is important for conferring the immunity phenotype. A concept based on target shielding is proposed for the PepI immunity mechanism.

Amino Acid Sequence↗
PubMed1995

Sequence analysis by NMR spectroscopy of the peptide lantibiotic epilancin K7 from Staphylococcus epidermidis K7.

The amino acid sequence of the novel lantibiotic epilancin K7 from Staphylococcus epidermidis K7 was determined by NMR spectroscopy. NMR spectroscopy was used because sequencing by conventional Edman degradation techniques was prohibited by internal sequence blocks owing to the presence of modified residues. Epilancin K7 consists of 31 residues, including two alpha,beta-didehydroalanine (one-letter code U) and two alpha,beta-didehydrobutyrine (O) residues, one lanthionine (A-S-A), two beta-methyllanthionines (A*-S-A), and six lysines. Epilancin K7 has a molecular mass of 3032 +/- 1.5 Da. The amino acid sequence of epilancin K7 was derived from both through-space dipolar proton-proton interactions and through-bond scalar proton-carbon interactions as detected by two-dimensional 1H-NOESY, 1H-ROESY and three-dimensional 1H-TOCSY-NOESY, and by two-dimensional 1H,13C-heteronuclear multiple-bond correlation spectroscopy, respectively. The sequence is as follows: [sequence: see text] The N-terminal residue X partly resembles an alanine but its exact nature is unclear. The organization of the sulfide-bridge-containing (beta-methyl-)lanthionines was revealed by 1H-NMR and 1H,13C-NMR spectroscopy. Epilancin K7 has a linear structure and a high positive net charge, and therefore is classified as a type-A lantibiotic. NMR analysis of a degraded though still active form of epilancin K7 showed that two N-terminal residues of epilancin K7 were missing, owing to decomposition at the alpha,beta-didehydro alanine at position 3; it was called the epilancin K7-(3-31)-peptide (peptide fragment of epilancin K7 consisting of positions 3-31). The usefulness of three-dimensional 1H-TOCSY-NOESY, and two-dimensional 1H,13C-heteronuclear multiple-bond correlation spectroscopy at natural abundance for the study of (modified) polypeptides is demonstrated.

Amino Acid Sequence↗
PubMed1988

Staphylococcus aureus and Staphylococcus epidermidis strains differ in interleukin 2 inducing activity.

Heat-killed preparations of different Staphylococcus aureus and Staphylococcus epidermidis strains were compared for interleukin 2 (IL-2) inducing activity in cultures of human mononuclear cells (MNC). S. aureus strains exhibited a strong individual variation, but they induced considerably more IL-2 than did S. epidermidis strains. Enterotoxin production, coagulase production, pigment formation and the phage type of the staphylococci showed no strict correlation of any of these properties with the IL-2 inducer activity. The results indicate that the IL-2 inducing activity may be a differential feature of S. aureus and S. epidermidis.

Cells, Cultured↗
PubMedDate not supplied

[Staphylococcus epidermidis causing infections in trauma surgery].

During 27 months at the Tübingen Accident Hospital, Staphylococcus epidermidis could be found in 464 of 1824 bacteriological wound swabs. This normally had to be considered as contamination. However, in at least 69 cases, S. epidermidis alone undoubtedly caused or maintained a fresh or chronic infection of the bone and soft tissue following aseptic orthopedic surgery, whereby the infection was temporarily sustained by S. epidermidis during pathogen change. The findings are demonstrated and compared with the literature.

Fracture Fixation↗
PubMed1996

Effect of Staphylococcus epidermidis on hydrogel contact lens retention on the rabbit eye.

A slime-producing isolate of Staphylococcus epidermidis attached to FDA Group II hydrogel contact lenses persisted on rabbit eyes for up to 14 days, but except for minor redness of the eye no other effect was observed. Eye flora of eight representative New Zealand White rabbits included four different species of Staphylococcus including S. epidermidis and one species of Micrococcus, none of which produced overtly obvious biofilms. The slime-producing strain of S. epidermidis adhered more effectively to lenses than a non-slime-producing strain, and lenses challenged with the slime-producing strain remained on the rabbit eye for longer time periods than those with a non-slime-producing strain. Bacteria associated with the contact lens may affect the retention of the lens on the rabbit cornea during experimental studies.

Animals↗
PubMed1992

A study of phenotypic variation of Staphylococcus epidermidis using Congo red agar.

This study examines a series of phenotypic variants of Staphylococcus epidermidis that were generated from a pair of parent variants, isolated from valvular tissue of a patient with prosthetic valve endocarditis. The variants were initially classified by examining their colonial morphology on Congo red agar. In addition to differences in Congo red binding and colonial morphology, they differed in the expression of several surface components and enzymes. Despite these phenotypic differences, all variants had the same restriction endonuclease profile of plasmid DNA. Examination of a collection of clinical isolates demonstrated that phenotypic variation is a common property of S. epidermidis. The ability to express different combinations of surface components and enzymes could contribute to the virulence of S. epidermidis strains by enabling these organisms to colonize a range of diverse environments.

Agar↗
PubMed1976

Phage typing of Staphylococcus epidermidis.

Thirteen phages were isolated from lysogenic cultures of Staphylococcus epidermidis from a clinical laboratory and used to type 223 clinical isolates of this organism. The 18 phages isolated in The Netherlands were used to type these same cultures. No correlation was observed between phage type, biotype, or clinical source of isolation. At phage concentrations of 100 times the routine test dilution, 35.0% of the cultures were typable with out phages and 21.5% were typable with the phages from The Netherlands. When only cultures in biotype 1 were considered, 43.3 and 24.1% of 141 cultures were typable with our phages and those from The Netherlands, respectively. The lytic reactions obtained with our phages were generally stronger and easier to read and the lytic patterns were, almost invariably, shorter. The typability of untypable cultures was increased 12.0% by incubation at 45 C prior to phage typing and 20% by heat shock (55 C for 5 min) prior to typing. Phage typing 5 subcultures of 20 typable cultures on 5 successive days showed that the lytic patterns were reproducible. The present status of phage typing S. epidermidis and the work needed to obtain a set of typing phages for epidemiological studies of infections by this organism are discussed.

Bacteriophage Typing↗
PubMed1981

Antibiotic susceptibility patterns of Staphylococcus aureus and Staphylococcus epidermidis.

The susceptibilities of 100 clinically significant isolates of Staphylococcus aureus and 45 clinically significant isolates of Staphylococcus epidermidis against various antibiotics were determined by the agar dilution method. Rifampin was the most active of all agents tested against both S. aureus and S. epidermidis. Among the beta-lactam antibiotics, penicillin G was least active, but had the lowest MIC in range. All strains of S. aureus were susceptible to cloxacillin and cephalothin at concentrations of 2 and 4 mcg/ml, respectively. Cloxacillin was less active against S. epidermidis, while cephalothin was more active. Minocycline was more active than doxycycline and tetracycline. Chloramphenicol was not only almost as poor in activity against S. aureus as tetracycline, but also the least active of all agents tested against S. epidermidis. Gentamicin was the most active aminoglycoside. Erythromycin, lincomycin and clindamycin showed the bimodal pattern of susceptibility. These results suggest the marked variability in antibiotic susceptibility of staphylococci.

Anti-Bacterial Agents↗
PubMed1990

Sequential release of antigens from chloroform-treated Staphylococcus epidermidis: application towards a possible vaccine.

This study describes the properties of two potential Staphylococcus epidermidis vaccines prepared by chloroform treatment of bacteria and release of antigen from these chloroform-treated organisms. Both vaccines were antigenic on testing with homologous hyperimmune serum and induced immune reactivity in immunized rabbits. There was protective efficacy in mice against intraperitoneal challenge by Staph. epidermidis.

Animals↗
PubMed1973

Plasmid for tetracycline resistance in Staphylococcus epidermidis.

A plasmid determining tetracycline resistance was demonstrated for Staphylococcus epidermidis. Tetracycline resistance was spontaneously lost from a S. epidermidis strain at a frequency of <0.1 to 1.3%. Frequency of loss was not appreciably enhanced by growth at 42 C or in ethyl violet. The rate of transduction of tetracycline resistance in three S. epidermidis crosses was decreased as a function of ultraviolet irradiation of the transducing phage. Plasmid deoxyribonucleic acid (DNA) associated with tetracycline resistance was isolated by CsCl-ethidium bromide dye-buoyant density gradients. The tetracycline plasmids from S. aureus RN 1304 (molecular weight 2.66 Mdals) and S. epidermidis 367(phi367) (T(367)) cosedimented in 5 to 20% neutral and alkaline sucrose gradients and are therefore of similar molecular weights. An extrachromosomal element in the recipient strain, isolated as covalently closed circular DNA, did not retain its integrity in an alkaline sucrose gradient.

Centrifugation, Density Gradient↗
PubMed1978

[Urinary Staphylococcus epidermidis: a pathogen or contamination?].

The alleged pathogenity of Staphylococcus epidermidis for the human urinary tract has been investigated statistically. The finding of this microbe in the urinary bladder punctate (678 suprapubic bladder aspirations) or in conventional urine sampling in the concentration greater than or equal to 10(4) microbes/ml (416 urine samples) shows no statistically significant correlation with the clinical signs of urinary tract disease.

Humans↗
PubMed1992

Growth-rate-independent killing by ciprofloxacin of biofilm-derived Staphylococcus epidermidis; evidence for cell-cycle dependency.

Cell culture methods that allow culture of Staphylococcus epidermidis biofilms at controlled growth rates were used to examine susceptibility to ciprofloxacin. Changes in biofilm susceptibility, dependent upon growth rate, were compared with those for suspended populations grown in chemostat, and also for newly-formed daughter cells shed from the biofilm during its growth and development. Susceptibility increased for intact and resuspended biofilms, and also for planktonic cultures, with increases in growth rate. The dependence of susceptibility upon growth rate was greatest for slow growing cells (mu, 0.01-0.15/h). At any particular growth rate, biofilms appeared more susceptible than their planktonic counterparts. Newly-formed daughter cells were relatively tolerant to ciprofloxacin at all rates of growth. Lack of growth rate dependency for the newly-formed cells suggested a role for the cell-division cycle in determining resistance. This was confirmed by examining the susceptibility of S. epidermidis throughout batch cultures with cell division synchronized. Perfusion of various steady-state biofilms with ciprofloxacin demonstrated killing of the adherent population even at much reduced rates of growth.

Bacterial Adhesion↗
PubMed2006

Bacteriocins Pep5 and epidermin inhibit Staphylococcus epidermidis adhesion to catheters.

Pep5 and epidermin bacteriocins were tested on clinical strains of Staphylococcus epidermidis and S. aureus isolated from catheter-related infections. These bacteriocins were inhibitory to several isolates at a concentration of 640 activity units mL(-1). The ability of bacteriocins in inhibiting adhesion of S. epidermidis to silicone catheters was evaluated. When Pep5 and epidermin were added to in vitro catheter colonization experiments, there was a significant decrease in the cell number of S. epidermidis adhered to silicone catheters. Bacteriocins used to decrease bacterial attachment to medical devices may represent a novel strategy to control catheter-related infections.

Anti-Bacterial Agents↗
PubMed1988

Survival of Staphylococcus epidermidis on the skin of patients of lepromatous leprosy.

The effect of hydration on Staphylococcus epidermidis, the predominant resident bacterial flora, was studied on skin affected by leprosy and known to have impaired sweating. Normal areas served as control. Significantly higher bacterial counts were observed in affected areas compared with normal-looking skin in 16/19 of the patients. Artificial application of Staph. epidermidis on leprosy-affected and unaffected areas, however, showed equivocal results, as in only 50% of the patients were higher counts obtained in affected compared with unaffected sites. The possible responsible factors for the present observation are discussed.

Bacterial Adhesion↗
PubMed1993

Chemiluminescence of human polymorphonuclear leucocytes after stimulation with whole cells and cell-wall components of Staphylococcus epidermidis.

The purpose of this study was to define cell-wall components of Staphylococcus epidermidis responsible for activation of human polymorphonuclear leucocytes (PMNL). Metabolic activation of PMNL was determined by chemiluminescence (CL). Purified peptidoglycan (PG) induced a concentration-dependent metabolic burst in PMNL. The minimal concentration needed for CL induction was 1 microgram/ml. Comparison between different S. epidermidis strains showed variation in the capacity to induce CL in PMNL. Purified PG induced a higher CL response in PMNL than its intact parent strain; this effect was found in all S. epidermidis strains. Lipoteichoic acid (LTA), PG stem peptide and muramyldipeptide (MDP) did not induce CL; teichoic acid induced a CL response only at very high concentrations. No differences in CL inducing capacity were found between PG, crude cell walls, and purified cell walls of S. epidermidis. Sonication of PG strongly diminished CL-inducing capacity. PG treatment with mutanolysin immediately resulted in decreased CL-inducing capacity. Treatment of PG with S. aureus lytic enzyme (SALE) 10 micrograms/ml for up to 15 min enhanced the CL response to PMNL; a similar increase in CL was induced by PG treated with SALE at 1 microgram/ml for up to 120 min. Beyond these times, a continuous decrease in PG-induced CL was observed. In conclusion, PG was found to be the major cell-wall component of S. epidermidis involved in CL induction. Moreover, a minimal fragment size or a specific tertiary structure of PG, or both, is required for metabolic activation of PMNL.

Adult↗
PubMed1997

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.

Antigens, Bacterial↗