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PubMed1995

Characterization of the gene for the chromosomal dihydrofolate reductase (DHFR) of Staphylococcus epidermidis ATCC 14990: the origin of the trimethoprim-resistant S1 DHFR from Staphylococcus aureus?

The gene for the chromosomally encoded dihydrofolate reductase (DHFR) of Staphylococcus epidermidis ATCC 14990 has been cloned and characterized. The structural gene encodes a polypeptide of 161 amino acid residues with a calculated molecular weight of 18,417. This trimethoprim-sensitive (Tmps) DHFR, SeDHFR, differs in only three amino acids (Val-31-->Ile, Gly-43-->Ala, and Phe-98-->Tyr) from the trimethoprim-resistant (Tmpr) S1 DHFR encoded by transposon Tn4003. Since in addition the S. epidermidis gene also forms part of an operon with thyE and open reading frame 140 as in Tn4003, the chromosomally located gene encoding the Tmps SeDHFR is likely to be the molecular origin of the plasmid-located gene encoding the Tmpr S1 DHFR. Site-directed mutagenesis and kinetic analysis of the purified enzymes suggest that a single Phe-->Tyr change at position 98 is the major determinant of trimethoprim resistance.

Amino Acid Sequence↗

PubMed2001

The Fbe (SdrG) protein of Staphylococcus epidermidis HB promotes bacterial adherence to fibrinogen.

Staphylococcus epidermidis strains HB and K28 express surface proteins called Fbe or SdrG, respectively, that have sequence similarity to the clumping factors ClfA and ClfB of Staphylococcus aureus. A mutation in the fbe gene of strain HB was isolated by directed plasmid integration using the broad-host-range temperature-sensitive plasmid pG(+)Host9 (pVE6155). An internal fragment of fbe was cloned into pG(+)Host9 and the chimaeric plasmid was mobilized from S. aureus RN4220 to S. epidermidis 9142 by conjugation promoted by plasmid pGO1. The plasmid was then transferred to S. epidermidis strain HB by phage-48-mediated transduction. The plasmid integrated into the chromosomal fbe gene at a frequency of 2.8 x 10(-4). All the survivors tested had a copy of pG(+)Host9'fbe' integrated into the chromosomal fbe gene either as a single copy or as a tandem array. Western immunoblotting showed that the wall-associated Fbe protein was absent in the mutant. Wild-type S. epidermidis HB adhered to immobilized fibrinogen in a dose-dependent and saturable fashion whereas the mutant did not bind. The Fbe proteins of HB and K28 were expressed at a high level in Lactococcus lactis MG1363 using the expression vector pKS80. These strains adhered strongly to immobilized fibrinogen. These results confirm that Fbe is a fibrinogen-binding adhesin.

Adhesins, Bacterial↗

PubMed1986

Sources of Staphylococcus epidermidis at the inguinal incision during peripheral revascularization.

Staphylococcus epidermidis has been implicated as a major etiologic agent of delayed synthetic vascular graft infection and/or pseudoaneurysm formation at the femoral anastomosis. The source of possible operative graft contamination is debated. Forty-five inguinal incisions in consecutive patients undergoing elective peripheral revascularization were studied. No opening cultures were positive: 30 per cent showed positive nodal cultures; 25 per cent showed positive arterial wall cultures; and 20 per cent showed positive closing cultures, 95 per cent of which were S. epidermidis. There was no correlation with preoperative transfemoral angiography. This high incidence in the tissues of the inguinal incision may be related to the delayed development of S. epidermidis graft infections.

Extremities↗

PubMed1991

In vitro selection of resistance to vancomycin in bloodstream isolates of Staphylococcus haemolyticus and Staphylococcus epidermidis.

The purpose of the study was to determine whether vancomycin-resistant strains of Staphylococcus haemolyticus could be selected regardless of the initial MIC of vancomycin. Twenty-one bloodstream isolates of Staphylococcus haemolyticus were studied by broth and agar selection methods. The broth method selected strains for which MICs of vancomycin ranged from 4 to 32 micrograms/ml and MBCs from 16 to greater than 128 micrograms/ml. The agar method selected strains for which MICs ranged from 8 to 32 micrograms/ml and MBCs from 8 to greater than 128 micrograms/ml. For comparison, seven strains of Staphylococcus epidermidis were evaluated by the agar selection method. Final MICs of vancomycin ranged from 8 to 16 micrograms/ml; MBCs ranged from 16 to 64 micrograms/ml. Clearly, in vitro exposure to vancomycin can select strains of Staphylococcus haemolyticus and Staphylococcus epidermidis for which MIC values are beyond the susceptible breakpoint.

Bacteremia↗

PubMed1991

[Effect of subinhibitory concentrations of beta-lactams on the production of slime, surface hydrophobicity and adhesion of Staphylococcus epidermidis].

The activity of subinhibitory concentrations of oxacillin, imipenem, cefalotin, cefuroxime, cefotaxime and amoxycillin-clavulanic acid upon slime production, surface hydrophobicity and polystyrene adherence of S. epidermidis was evaluated. Slime production and polystyrene adherence of three Staphylococcus epidermidis strains was assessed using test tube (safranin stained film) or in microtiter plate. The surface hydrophobicity was determined using a biphasic system (water/p-xylene). Using one-half and one-quarter of MIC for all antibiotics tested, a reduction in slime production and polystyrene adherence was observed in all three strains used. Regarding surface hydrophobicity, in one of the strains used we have observed a rise in surface hydrophobicity values as compared to control strains whenever one-half of MCI was used for all six antimicrobial agents and also with one-quarter of amoxicillin-clavulanate MCI. Subinhibitory MCI of all six antibiotics tested inhibits slime production and adherence of Staphylococcus epidermidis. This inhibitory effect is not related to changes in surface hydrophobicity.

Anti-Bacterial Agents↗

PubMed1999

Molecular mechanisms of Staphylococcus epidermidis biofilm formation.

Coagulase-negative staphylococci, mainly Staphylococcus epidermidis, are the predominant cause of implanted medical-device related infections. The formation of adherent multi-layered biofilms embedded into a glycocalyx composed of exopolysaccharides on implanted devices is believed to be essential for the pathogenesis of S. epidermidis infections. Biofilm formation may be separated into primary attachment of bacteria to native or modified polymer surfaces followed by proliferation of attached bacterial cells leading to accumulation of multi-layered cell-clusters and glycocalyx formation. Recent progress in the understanding of the molecular mechanisms cooperating in S. epidermidis biofilm formation is reviewed and current thinking on the relevance of these mechanisms for S. epidermidis device-related infections is discussed.

Bacterial Adhesion↗

PubMed1984

Staphylococcus epidermidis sepsis in surgical patients.

We examined 58 surgical patients with two or more blood cultures positive for Staphylococcus epidermidis to determine factors associated with risk, mortality, and invasive sepsis. Bacterial sepsis was associated with gastrointestinal (GI) operations, total parenteral nutrition, and a regimen of two or more parenteral antibiotics. Mortality was 46% overall and significantly increased with age greater than 50 years, GI operations, other gram-positive sepsis, recurrent sepsis (positive blood culture 24 hours or more after the first blood culture), and the presence of organisms sensitive to three or less antibiotics. Antibiotic therapy appropriate for more than 50% of the S epidermidis organisms cultured from each patient resulted in significant reduction in mortality. Staphylococcus epidermidis should be considered a significant pathogen in critically ill surgical patients. Invasive S epidermidis sepsis can be recognized and requires specific antibiotic therapy.

Adolescent↗

PubMed1980

Plasmid profiles in epidemiologic studies of infections by Staphylococcus epidermidis.

Plasmid profiles of cultures of Staphylococcus epidermidis obtained by agarose gel electrophoresis were used, in conjunction with phage typing, biotyping, and antibiograms, in epidemiologic studies of infections in neonates and patients with cancer. In some cases, patients had cultures that were lysed by a single phage, belonged to the same biotype, and had identical antibiograms, but had distinctly different plasmid profiles. In other instances, almost identical plasmid profiles were observed in cultures lysed by a single phage, belonging to the same biotype, and with markedly different antibiograms. The plasmid profile technique was valuable in detecting distinct strains of S. epidermidis, and its use could be helpful in epidemiologic studies of infections by other organisms.

Bacteriological Techniques↗

PubMed1975

Purification and properties of a fructose-1,6-diphosphate activated L-lactate dehydrogenase from Staphylococcus epidermidis.

L-(+)-lactate dehydrogenase (LDH) from Staphylococcus epidermidis ATCC 14990 was purified by affinity chromatography. The purified enzyme was specifically activated by fructose-1,6-diphosphate (FDP). The concentration of FDP required for 50% maximal activity was about 0.15 mM. The enzyme activity was inhibited by adenosine diphosphate (ADP) and oxamate. The inhibition by ADP appeared to be competitive with respect to reduced nicotinamide adenine dinucleotide (NADH). The catalytic activity of the LDH for pyruvate reduction exhibited an optimum at pH 5.6. The enzyme is composed of four, probably identical, subunits. Sephadex gel filtration and sedimentation velocity at pH 5.6 Yielded molecular weights of about 130 000 and 126 000, respectively. The molecular weight at pH 6.5 and 7.0 was found to be only about 68 000. Polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate and sedimentation velocity at pH 2.0 or 8.5 revealed monomeric subunits with an approximate molecular weight of 36000. The thermostability of the heat labile enzyme was increased in the presence of FDP, NADH and pyruvate. The purified LDH exhibited an anomalous type of kinetic behavior. Plots of initial velocity vs. different concentrations of pyruvate, NADH or FDP led to saturation curves with intermediary plateau regions. As a consequence of these plateau regions the Hill coefficient alternated between lower and higher n-values. Some distinguishing properties of the S. epidermidis LDH and other LDHs activated by FDP are discussed.

Adenine Nucleotides↗

PubMed1994

Interaction between clarithromycin and biofilms formed by Staphylococcus epidermidis.

Interactions between clarithromycin and biofilms formed by Staphylococcus epidermidis were investigated by using a clarithromycin-resistant strain. Treatment of the colonization with a relatively low concentration of clarithromycin resulted in the eradication of slime-like structure and a decrease in the quantity of hexose. Another result was increased penetration of antibiotics through the biofilm of S. epidermidis.

Clarithromycin↗

PubMed2006

Use of a putative transcriptional regulator gene as target for specific identification of Staphylococcus epidermidis.

AIMS: To investigate the use of a Staphylococcus epidermidis transcriptional regulator gene as target for species-specific determination. METHODS AND RESULTS: Staph. epidermidis genes encoding putative transcriptional regulators were retrieved from GenBank and those showing no homology with other bacterial sequences were selected. Of the four PCR primer sets analysed, the primers Serp0107F/R from serp0107 amplified a specific product of 581 bp from Staph. epidermidis DNA only, and they did not cross-react in PCR with nonepidermidis staphylococci and other common bacteria. CONCLUSION: Being uniquely present in Staph. epidermidis, putative transcriptional regulator gene serp0107 offers a valuable target for specific identification of Staph. epidermidis. SIGNIFICANCE AND IMPACT OF THE STUDY: As a member of a specialized gene group, putative transcriptional regulator gene serp0107 may be important to Staph. epidermidis adaptation to its niche environment. Further analysis of serp0107 and its related protein may help reveal new insights on the molecular regulation of Staph. epidermidis survival and virulence.

Bacterial Typing Techniques↗

PubMed1980

Antibiotic-resistant Staphylococcus epidermidis in patients undergoing cardiac surgery.

Staphylococcus epidermidis isolates containing subpopulations resistant to 100 microgram of methicillin per ml were found on the chests of only 3 of 80 (4%) patients before cardiac surgery, whereas these highly resistant staphylococci were isolated from the chest wounds of 43 of 80 (54%) patients 5 days postoperatively. The percentage of patients colonized with methicillin-resistant S. epidermidis increased with time postoperatively. Methicillin-resistant postoperative isolates also contained organisms resistant to other antibiotics frequently used during these patients' hospitalizations. The percentages of patients with organisms resistant to various antibiotics were: nafcillin (100%), penicillin (100%), cephalothin (93%), cefamandole (80%), streptomycin (67%), and gentamicin (20%). Preoperative methicillin-susceptible isolates were generally susceptible to other antibiotics. Two patients with S. epidermidis prosthetic valve endocariditis caused by multiple antibiotic-resistant isolates were among the study patients. Antibiotic susceptibility patterns of each isolate from these two patients were identical to those of postoperative chest isolates from the same patient.

Anti-Bacterial Agents↗

PubMed2001

In vitro adherence of Staphylococcus epidermidis to silicone punctual plugs and collagen implants.

PURPOSE: To evaluate in vitro adherence of Staphylococcus epidermidis to silicone punctal plugs and collagen implants. SETTING: Loyola University Medical Center, Maywood, Illinois, USA. METHODS: Silicone punctal plugs and collagen implants were exposed to S epidermidis (3 x 10(8) colony forming units/mL) for 0, 5, 30, and 60 minutes, rinsed in sterile saline, and processed for light, scanning (SEM), and transmission (TEM) electron microscopy. Scanning electron microscopy (x2000) was used to quantify bacteria/mm2 adhering to the devices. RESULTS: The mean S epidermidis/mm2 +/- (SD) adhering to each device were as follows: baseline, silicone punctal plug, 1593 +/- 899, and collagen implant, 7168 +/- 2895 (P =.000, paired Student t test); 5 minutes, silicone punctal plug, 3833 +/- 537, and collagen implant, 6571 +/- 2240 (P =.008); 30 minutes, silicone punctal plug, 13 988 +/- 9076, and collagen implant, 10 404 +/- 1731 (P =.2616); and 60 minutes, silicone punctal plug, 12 644 +/- 10 402, and collagen implant, 11 748 +/- 2685 (P =.8056). CONCLUSIONS: Staphylococcus epidermidis adhered significantly more to collagen implants than to silicone punctal plugs at 0 and 5 minutes. No significant difference in bacterial adherence was seen at 30 and 60 minutes. For both devices, bacterial adherence increased with increasing exposure.

Bacterial Adhesion↗

PubMed1994

Genotyping of Staphylococcus epidermidis by small-fragment restriction endonuclease analysis and pulsed-field gel electrophoresis of genomic restriction fragments.

Small-fragment restriction endonuclease analysis (SF-REA) was established as a typing tool for Staphylococcus epidermidis. A total of 60 isolates comprising 48 epidemiologically nonrelated strains and 12 putatively linked isolates from 7 patients in 2 wards were analyzed. Nonrelated isolates were characterized by unique fingerprints when DNA was cleaved with EcoRI or ClaI, electrophoretically separated in a polyacrylamide gel, and silver stained. Three blood culture isolates from one patient in an intensive care unit, 4 isolates obtained from a child over a span of 2 weeks, and 5 isolates from 5 newborns in the same ward were grouped into 3 DNA pattern types, indicating identity of sequential isolates from 2 patients and nosocomial transmission of one Staphylococcus epidermidis strain between 5 babies. Results from pulsed-field gel electrophoresis of SmaI and SacII DNA digests and conventional marker systems such as antibiogram and plasmid profile were in accordance with these interpretations, whereas slight variation was observed in the biotypes of several strains. From the results of this study, we conclude that SF-REA is a precise and efficient method for the genotypic characterization of Staphylococcus epidermidis strains that can be used as a rapid and reliable typing tool.

Adult↗

PubMed1981

Production, purification and chemical properties of an antistaphylococcal agent produced by Staphylococcus epidermidis.

An antibacterial agent produced by Staphylococcus epidermidis strain 5 was isolated from culture supernatants; its spectrum of activity is restricted to staphylococci and micrococci. The bacteriocin-like substance was purified to homogeneity by column chromatography on Servachrome XAD-2, CM-Sephadex C-25 and Sephadex G-50. Chemical analysis showed it to be a peptide with a molecular weight of about 6000 and an isoelectric point of about 10.5. Purified material was rapidly inactivated by trypsin, chymotrypsin and pronase and it was relatively heat-stable. After acidic hydrolysis 10 amino acid residues and two unidentified ninhydrin-positive substances were detected. Production of the bacteriocin-like substance was not inducible with mitomycin C.

Amino Acids↗

PubMed1992

Capsular polysaccharide serotyping scheme for Staphylococcus epidermidis.

A scheme for the capsular typing of Staphylococcus epidermidis that is based on direct slide agglutination between proteinase-treated bacterial cells and specific antisera is described. Antisera were prepared from serum from rabbits immunized with two selected strains of encapsulated S. epidermidis isolated from bacteremic patients. Antisera were shown to be type specific and designated type 1 and type 2. Blood isolates of S. epidermidis from hospitals in different locations within the United States and Europe were serotyped, and it was found that over 90% of all strains were of type 1 or type 2. Type-specific antibodies mediated type-specific opsonophagocytosis and killing of S. epidermidis. The specificity was shown to be due to two distinct capsular polysaccharides. The data presented in this report may open a new window on the pathogenesis of S. epidermidis which could lead to the development of new vaccines and therapies.

Antibodies, Bacterial↗

PubMed1972

Nature and properties of a Staphylococcus epidermidis bacteriocin.

Staphylococcin 1580, produced by Staphylococcus epidermidis 1580, consisted of 41.8% protein, 34% carbohydrate, and 21.9% lipid. In the protein fraction, the acidic amino acids, glutamic and aspartic acid, and the neutral amino acids, glycine and alanine, predominated. Neutral sugars consisted of glucose, galactose, and fucose in a molar ratio of 6:3:1. The purified bacteriocin was not inactivated by heating for 15 min at 120 C in the presence of 0.5% serum albumin and was stable in the pH range from 3.5 to 8.5. The compound was sensitive to the action of the proteolytic enzymes trypsin, Pronase, and chymotrypsin. All gram-negative bacteria tested were resistant; a large number of gram-positive bacteria were sensitive to staphylococcin 1580 action. Growth of stable staphylococcal L-forms was inhibited by the bacteriocin to the same extent as their parent strains. The staphylococcin was adsorbed to cell walls, cell membranes, and resistant cells. The effect of staphylococcin 1580 appeared to be bactericidal but not bacteriolytic.

Adsorption↗

PubMed1980

Fatal Staphylococcus epidermidis sepsis following bone marrow transplantation.

Staphylococcus epidermidis septicemia and pneumonia developed in an 18-year-old male undergoing bone marrow transplantation. The organism was isolated from multiple blood cultures, sputum cultures, an indwelling catheter tip and post-mortem lung biopsy specimens. The bacterium was resistant to penicillin, erythromycin, clindamycin, chloramphenicol, vancomycin, gentamicin, cephalothin and trimethoprim-sulfamethoxazole, but was sensitive to rifampin. The rapid demise of this patient, as well as the difficulty in achieving effective antibiotic therapy, illustrates the potential pathogenicity of this organism in immunosuppressed patients.

Adolescent↗