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PubMedDate not supplied

Experimental Staphylococcus epidermidis implant infection in the mouse. Kinetics of rifampin and vancomycin action.

Staphylococcus epidermidis implant infections remain a therapeutic challenge; they frequently result in failure of conservative management and require removal of the implant. This resistance to antibiotic therapy has been ascribed to the presence of a protective bacterial biofilm at the surface of the implant. An animal model of implant associated infection has been developed in which preformed bacterial biofilm catheter segments are implanted intraperitoneally, resulting in a chronic standardized localized infection. The authors have determined the superior rapid action of rifampin (Cieba-Geigy) compared to vancomycin hydrochloride (Eli Lilly) and determined that the combination is superior to either used alone. No rifampin resistant surviving infection was noted, which indicates the significant contribution of mammalian host defenses. This animal model is an excellent vehicle for the study of Staphylococcus epidermidis implant associated infection and the evaluation of the relative efficacy of antibiotic regimens, singly and in combination.

Animals↗
PubMed2007

Polyclonality of Staphylococcus epidermidis residing on the healthy ocular surface.

Staphylococcus epidermidis is part of the normal bacterial flora on the ocular surface. The chromosomal DNA of bacterial isolates obtained from the conjunctival sac, upper and lower lid margins, and upper and lower Meibomian glands of healthy volunteers was subjected to SmaI digestion and PFGE to study the genetic diversity of the organisms. Multiple colonies were also examined of S. epidermidis derived from the conjunctival sac of the same subjects. Lastly, commensal bacteria were harvested from the ocular surfaces of four healthy subjects once a month for 6 months, and the genetic background of the S. epidermidis isolates was analysed. It was found that bacterial strains not only from different subjects but also from multiple ocular surface sites of the same subject exhibited different PFGE patterns. In five of 42 subjects multiple colonies of S. epidermidis were isolated from the conjunctival sac; three harboured multiple colonies with different PFGE patterns, and two manifested multiple colonies with identical PFGE patterns. S. epidermidis isolated from the conjunctival sac of the same subjects over a 6-month period exhibited varying PFGE patterns. The data demonstrate the polyclonality of S. epidermidis on the healthy ocular surface.

Conjunctiva↗
PubMed1999

A novel mechanism of phase variation of virulence in Staphylococcus epidermidis: evidence for control of the polysaccharide intercellular adhesin synthesis by alternating insertion and excision of the insertion sequence element IS256.

Biofilm formation of Staphylococcus epidermidis on smooth polymer surfaces has been shown to be mediated by the ica operon. Upon activation of this operon, a polysaccharide intercellular adhesin (PIA) is synthesized that supports bacterial cell-to-cell contacts and triggers the production of thick, multilayered biofilms. Thus, the ica gene cluster represents a genetic determinant that significantly contributes to the virulence of specific Staphylococcus epidermidis strains. PIA synthesis has been reported recently to undergo a phase variation process. In this study, biofilm-forming Staphylococcus epidermidis strains and their PIA-negative phase variants were analysed genetically to investigate the molecular mechanisms of phase variation. We have characterized biofilm-negative variants by Southern hybridization with ica-specific probes, polymerase chain reaction and nucleotide sequencing. The data obtained in these analyses suggested that in approximately 30% of the variants the missing biofilm formation was due to the inactivation of either the icaA or the icaC gene by the insertion of the insertion sequence element IS256. Furthermore, it was shown that the transposition of IS256 into the ica operon is a reversible process. After repeated passages of the PIA-negative insertional mutants, the biofilm-forming phenotype could be restored. Nucleotide sequence analyses of the revertants confirmed the complete excision of IS256, including the initially duplicated 8 bp target sites. These results elucidate, for the first time, a molecular mechanism mediating phase variation in staphylcocci, and they demonstrate that a naturally occurring insertion sequence element is actively involved in the modulation of expression of a Staphylococcus virulence factor.

Bacterial Adhesion↗
PubMed1998

Alteration in the GyrA subunit of DNA gyrase and the ParC subunit of DNA topoisomerase IV in quinolone-resistant clinical isolates of Staphylococcus epidermidis.

We examined 22 clinical isolates of Staphylococcus epidermidis to analyze the association of alterations in GyrA and ParC with fluoroquinolone resistance. The simultaneous presence of GyrA and ParC alterations was associated with a high level of fluoroquinolone resistance in the clinical isolates of S. epidermidis.

4-Quinolones↗
PubMed2006

Adherence of Staphylococcus epidermidis to biomaterials is augmented by PIA.

Staphylococcus epidermidis is the most common cause of orthopaedic prosthetic device infections. Polysaccharide intercellular adhesin (PIA) is important in the pathogenesis of intravascular catheter-associated infection, and has an essential role in cellular aggregation and biofilm formation. However, the role of PIA in orthopaedic infections is less well understood. We used genetically defined strains of S. epidermidis in an in vitro adherence assay to assess the importance of PIA in the adherence to various orthopaedic biomaterials. On all biomaterials tested (zirconia, ultra-high molecular weight polyethylene, polymethylmethacrylate, cobalt chromium, titanium, stainless steel, and silastic), PIA-positive S. epidermidis 1457 exhibited greater levels of adherence thanS. epidermidis 1457 M10, an isogenic icaA Tn917 mutant. PIA appears to play a critical role in the adherence of S. epidermidis to orthopaedic biomaterials, and may serve as an important virulence determinant in orthopaedic prosthetic device infections.

Bacterial Adhesion↗
PubMed1991

Protection against endocarditis due to Staphylococcus epidermidis by immunization with capsular polysaccharide/adhesin.

BACKGROUND: Staphylococcus epidermidis is the principal pathogen in prosthetic valve endocarditis. The capsular polysaccharide adhesin (PS/A) has been shown to mediate attachment of bacteria to medical devices. In this study, we investigated the efficacy of active and passive immunization against PS/A in preventing S. epidermidis endocarditis in a rabbit model. METHODS AND RESULTS: Aortic valve vegetations were produced by inserting a Teflon catheter into the left ventricle through the right carotid artery. Bacteremia and endocarditis were then established by implanting in the left jugular vein a catheter that was attached to an osmotic pump and contaminated with S. epidermidis strain RP62A. During a 3-week study period, of 64 blood cultures taken every second or third day from six nonimmune rabbits, 54 (84%) yielded strain RP62A. In rabbits actively immunized with PS/A, eight of 60 blood cultures (13%) were positive (odds ratio 5.0, 95% CI, 2.0-12.3, p = 0.005). At death, all six nonimmune rabbits had infected vegetations that yielded 10(6)-10(11) colony-forming units (cfu)/g of vegetation, whereas only one PS/A-immunized rabbit had an infected vegetation. Immunization protocols designed to elicit antibody to teichoic acid but not to PS/A afforded no protection against bacteremia or endocarditis. Infusion of monoclonal antibody to PS/A through a catheter in the right jugular vein provided a level of protection against both bacteremia and endocarditis comparable to that produced by active immunization. In vitro, antibody against PS/A was opsonic for S. epidermidis. CONCLUSIONS: Immunoprophylaxis targeted at staphylococcal PS/A is a promising new approach to the prevention of prosthetic valve endocarditis.

Animals↗
PubMed2002

Penetration of rifampin through Staphylococcus epidermidis biofilms.

Rifampin penetrated biofilms formed by Staphylococcus epidermidis but failed to effectively kill the bacteria. Penetration was demonstrated by a simple diffusion cell bioassay and by transmission electron microscopic observation of antibiotic-affected cells at the distal edge of the biofilm.

Antibiotics, Antitubercular↗
PubMed2004

Presence of the ica operon in clinical isolates of Staphylococcus epidermidis and its role in biofilm production.

Staphylococcus epidermidis is an important cause of catheter-associated infections, which are attributed to its ability to form a multilayered biofilm on polymeric surfaces. This ability depends, in part, on the activity of the icaADBC locus and the icaR gene, which are involved in the production of the polysaccharide intercellular adhesin (PIA) that is functionally necessary for cell-to-cell adhesion and biofilm accumulation. The present study determined: (1) the prevalence of the icaADBC operon in S. epidermidis isolates from catheter-related and other nosocomial infections; (2) the correlation between the presence of this operon, biofilm production and resistance to antibiotics; (3) the expression of ica genes and biofilm production; and (4) the genetic relatedness of the isolates. The results showed that icaRADBC was present in 45% of the isolates included in the study, and that such isolates were significantly more resistant to the main antibiotics tested than were ica-negative isolates. The presence of the entire cluster did not always correlate with biofilm production, determined under different culture conditions, but there was evidence to suggest a correlation when at least two genes (icaAD) were co-transcribed. Eight of 18 ica-positive isolates had the entire operon in the same restriction fragment after pulsed-field gel electrophoresis, but the isolates were not clonal. Estimation of genetic relatedness indicated that ica-positive S. epidermidis isolates belonged to different lineages, distributed in only one of two major clusters, with a genetic distance of c. 0.12.

Bacterial Adhesion↗
PubMed2004

Enzymatic detachment of Staphylococcus epidermidis biofilms.

The gram-positive bacterium Staphylococcus epidermidis is the most common cause of infections associated with catheters and other indwelling medical devices. S. epidermidis produces an extracellular slime that enables it to form adherent biofilms on plastic surfaces. We found that a biofilm-releasing enzyme produced by the gram-negative periodontal pathogen Actinobacillus actinomycetemcomitans rapidly and efficiently removed S. epidermidis biofilms from plastic surfaces. The enzyme worked by releasing extracellular slime from S. epidermidis cells. Precoating surfaces with the enzyme prevented S. epidermidis biofilm formation. Our findings demonstrate that biofilm-releasing enzymes can exhibit broad-spectrum activity and that these enzymes may be useful as antibiofilm agents.

Aggregatibacter actinomycetemcomitans↗
PubMed1992

Ribotyping of coagulase-negative staphylococci with special emphasis on intraspecific typing of Staphylococcus epidermidis.

Coagulase-negative staphylococci (CoNS), particularly Staphylococcus epidermidis, are increasingly being recognized as opportunistic pathogens. They are often multiply antibiotic resistant and can cause nosocomial outbreaks. For clinical and epidemiological reasons, accurate species identification and typing are imperative. Ribotyping, i.e., the generation of characteristic fragment patterns by hybridization of restriction endonuclease fragments of total DNA with labeled standard rRNA from Escherichia coli, has been applied to CoNS for species identification by various investigators. The present study, involving 115 randomly collected clinical isolates of CoNS, provides ambiguous evidence with respect to those findings. Eighty six S. epidermidis strains were ribotyped intraspecifically. Eleven different ribotypes were found after digestion with EcoRI, and 10 were found with HindIII. A combination of the two restriction endonucleases resulted in an increase in the discriminatory power (DP) from 14.3 to 31.6%. A combination of ribotyping with biotyping raised the DP to a maximum of 48.6%. The reproducibility of ribotyping was 100% after greater than 400 generations of growth. No correlation between methicillin resistance and certain ribotypes among the S. epidermidis strains was observed. Ribotyping is considered a useful tool for the intraspecific typing of CoNS for epidemiological purposes. The DP can be increased by the use of additional restriction endonucleases.

Bacterial Typing Techniques↗
PubMed1984

Investigation on extracellular slime substance produced by Staphylococcus epidermidis.

The extracellular slime substance produced by Staphylococcus epidermidis was investigated. Slime production was assessed by bacterial agglutination in the presence of concanavalin A (Con A) or poly-L-lysine and by bacterial adherence to polyethylene. Media for slime production was optimized using these criteria. A phenol-saline extract of crude slime was separated into four fractions on a DEAE-sepharose column. Total protein and sugar content and the monosaccharide constituents were determined. Crude slime and the phenol-saline extract showed a strong precipitation reaction with Con A and poly-L-lysine (double diffusion). Fractions I and II containing mannose as the most abundant sugar reacted with Con A and two other mannose-specific lectins (Lens culinaris, Pisum sativum). This reaction could be inhibited by mannose. Fractions III and IV were precipitated by poly-L-lysine, probably due to a reaction with glucuronic acid which was only present in these fractions. Precoating of polyethylene with crude slime, phenol-saline extract and fractions III and IV resulted in a marked inhibition of attachment of staphylococcal cells. Production of the extracellular slime substance was completely inhibited by subinhibitory concentrations of the glycosylation inhibitor tunicamycin, whereas penicillin had no influence. Extracellular slime substance produced by S. epidermidis seems to be a complex of glycoconjugate character and plays an important role in the attachment to synthetic polymers. The production of slime by staphylococci can be easily determined using mannose specific lectins and poly-L-lysine.

Adhesiveness↗
PubMed1989

Neonatal Staphylococcus epidermidis meningitis with unremarkable CSF examination results.

We identified 10 infants (mean +/- SD birth weight, 1000 +/- 500 g; gestation, 29 +/- 3 weeks; postnatal age, 24 +/- 19 days) who had Staphylococcus epidermidis meningitis despite unremarkable cerebrospinal fluid (CSF) blood cell counts and glucose and protein levels. Staphylococcus epidermidis meningitis was diagnosed if all the following criteria were satisfied: (1) a CSF culture positive for S epidermidis within 48 hours, (2) a blood culture positive for S epidermidis with antibiotic sensitivities identical to those of the CSF isolate, and (3) clinical symptomatology. Lumbar puncture yielded white blood cell counts lower than 10 x 10(6)/L in 8 infants. Two subjects had CSF white blood cell counts of 11 x 10(6)/L and 14 x 10(6)/L. Cerebrospinal fluid glucose (2.8 +/- 0.9 mmol/L) and protein (1.15 +/- 0.32 g/L) concentrations were also unremarkable. Infants were treated with parenteral antibiotics for 19 +/- 5 days. There was no mortality or short-term morbidity. Staphylococcus epidermidis is a recognized cause of nosocomial meningitis in low-birth-weight infants and frequently occurs without CSF abnormalities.

Cerebrospinal Fluid Proteins↗
PubMed1995

Development of a Staphylococcus epidermidis vascular graft infection model in sheep.

Staphylococcus epidermidis is an increasingly recognized causative organism of vascular graft infections. To increase our understanding of this problem we have tried to establish Staph. epidermidis vascular graft infection in sheep by direct inoculation. A 2 cm long, 5 mm diameter polytetrafluoroethylene (PTFE) or a gelatin sealed Dacron vascular graft was inserted into the left carotid artery. At the completion of the operation 1 mL of normal saline containing either 10(4), 10(6), or 10(8) colony forming units (cfu) of a slime producing Staph. epidermidis was inoculated directly onto the graft. After 3 weeks the grafts were harvested in a sterile fashion. Swabs were taken of the perigraft tissues and the external and internal aspects of the grafts; a 3-5 mm segment of the graft was incubated in broth medium and a second segment was ground for 5 min and then incubated in broth medium. Note was made of the presence of abscess formation, anastomotic failure or thrombosis. Thirteen sheep received a PTFE graft and 14 received a gelatin sealed Dacron graft. Three sheep died immediately postoperatively. The rate of infection was 40% at 10(4), 67% at 10(6) and 80% at 10(8) cfu Staph. epidermidis. In only four cases were all five cultures positive. In nine cases two or less cultures were positive, the majority of these being the broth cultures. Nine other organisms were isolated from nine mixed infections. Nine out of 13 PTFE and seven out of 11 Dacron grafts were infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Azelaic acid: its uptake and mode of action in Staphylococcus epidermidis NCTC 11047.

In vitro tests using Staphylococcus epidermidis as a model have shown that at pH 5.6 the micro-organisms are sensitive to azelaic acid, whilst at pH 6.0 and 7.0 the cells become progressively resistant, especially with nutrients present. In a simple defined medium the growth rate was reduced at 1 mmol/l and growth inhibited at 25 mmol/l. The uptake of azelaic acid was pH dependent, higher transport at lower pH values, and required viable cells. Azelaic acid, 457 mumol/l gave 50% inhibition of protein synthesis and this mechanism could account for the bactericidal and bacteristatic effects. DNA and RNA were affected slightly by 100 mmol/l azelaic acid, and respiration by 500 mmol/l.

Carbon Radioisotopes↗
PubMedDate not supplied

Bacteremia due to Staphylococcus epidermidis: microbiologic, epidemiologic, clinical, and prognostic features.

Staphylococcus epidermidis was established as the causal agent of true bacteremia on the basis of microbiologic, epidemiologic, clinical, and prognostic data on 65 episodes of S. epidermidis bacteremia (SEB) recorded in the Hospital Covadonga of Oviedo, Spain, during 1982-1986. All isolates were susceptible in vitro to vancomycin, mercury, silver, cadmium, and malachite green, and 95.2% of isolates were susceptible to cephalothin; a dominant biotype, four resistotypes (ion-dye resistance patterns), and four antibiotypes (antibiotic resistance patterns) were found. A high percentage of isolates (76.7%) produced slime, and several potentially toxic exoproteins were detected in various and generally lower proportions. The main clinical features of SEB were high frequency in male patients greater than 40 years of age, fever, leukocytosis, anemia, and phlebitis. Indwelling devices were the most common portal of entry. The overall death rate was 36.9%. Underlying disease, hemodynamic status, predisposing factors, and treatment were statistically significant parameters in relation to mortality.

Adolescent↗
PubMed1988

Isolation and characterization of a capsular polysaccharide adhesin from Staphylococcus epidermidis.

We isolated a polysaccharide adhesin from Staphylococcus epidermidis strain RP-62A. The adhesin was composed of a complex mix of monosaccharides (with galactose and glucosamine predominating), bound well to silastic catheter tubing, inhibited adherence of strain RP-62A to catheters, and elicited antibodies that both blocked adherence and stabilized an extracellular structure (visualized by transmission electron microscopy) that appeared to be a capsule. Two of three heterologous, highly adherent strains of coagulase-negative staphylococci also produced this adhesin, and their adherence to catheters was inhibited by both purified adhesin and antibody to adhesin. In contrast, the adherence of one highly adherent and two poorly adherent heterologous strains was unaffected by the RP-62A purified adhesin or antibody, a result suggesting the expression of alternate adhesins by these strains. We conclude that the capsular polysaccharide of some strains of coagulase-negative staphylococci is an important factor in adherence to catheter tubing.

Adhesins, Bacterial↗
PubMed1988

Possible common biological and immunological properties for detecting encapsulated strains of Staphylococcus epidermidis.

Twenty strains of capsular type II Staphylococcus epidermidis, determined by the method of Ichiman, were obtained from clinical specimens. Among them, 5, 5, and 10 strains were 4+, 3+, and 2+ in the intensities of their reactions against fluorescent antibody, respectively. Strains exhibiting 4+ and 3+ intensities were mouse virulent and phage nontypable, while 2+ strains were mouse avirulent and phage typable. When three strains randomly selected from each of the mouse-virulent and mouse-avirulent strains were compared in terms of their cell volume indices, all mouse-virulent strains had significantly higher indices (average, 1.86 times) than the mouse-avirulent strains. With intraperitoneal injection of the strains into mice, strains with higher cell volume indices resisted ingestion by peritoneal cells, while strains with low cell volume indices were sensitive to phagocytosis. When the capacity to absorb a definite amount of passive protective activity in rabbit antiserum prepared with capsular type II strains was compared among these strains, 10 to 20 mg of mouse-virulent strains was capable of completely absorbing the passive protective activity, whereas more than 80 mg of the cells was required for similar absorption by mouse-avirulent strains. In ultra-thin sections of three mouse-virulent strains stained with ferritin-conjugated rabbit antiserum, well-defined capsules were detected around cell walls; however, no capsule was seen around the walls of three mouse-avirulent strains.

Animals↗