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PubMed1998

In vitro Staphylococcus epidermidis growth in some viscoelastic substances containing sodium hyaluronate.

The aim of our study was to verify the in vitro growth of Staphylococcus epidermidis in various dilutions of some viscoelastic substances containing hyaluronic acid (Healon and Healon GV, IAL, Biolon). Serial twofold dilutions of each sterile viscoelastic substance, prepared so as to obtain a final concentration ranging from 50 to 0.78% of the product in sterile saline solution (0.85% NaCl), were taken out with a pipette that delivered 1.0 ml/tube. One hundred microliters of the S. epidermidis inocula, used for the evaluation of the positive control of the test organism, was dispensed into each tube. After 24 h of aerobic incubation at 37 degrees C, 100 microl of sample was taken out from each tube and plated into the specific medium for the growth of the test organism. After 24 h of incubation at 37 degrees C, these agar plates were examined and the colony-forming unit count of the test organism was compared to the corresponding total colony count, acting as a positive control, in order to determine the quantitative variation of the test organism grown in the presence of the viscoelastic compounds. For the lowest dilutions (from 1:2 to 1:8) statistically significant bacterial growth was detected in all tested viscoelastic substances. For the highest dilutions (1:64 and 1:128) Biolon and Healon GV showed a significant inhibition of S. epidermidis growth. A significant inhibition was also observed in the highest dilution (1:128) of Healon. In every dilution of IAL a statistically significant increase in bacterial growth was observed. It remains to be carefully considered whether S. epidermidis, accidentally penetrating the eye via the intraocular lens, could find a culture medium in a small amount of sodium hyaluronate left in the capsular bag behind the optic.

Bacteriological Techniques↗

PubMed1990

Conjugal transfer of plasmid pWBG637 from Staphylococcus aureus to Staphylococcus epidermidis and Streptococcus faecalis.

Plasmids pWBG636 (GmR) and pWBG642 (EmR) derived from the conjugative plasmid pWBG637 were tested for ability to transfer conjugatively to Staphylococcus epidermidis, Streptococcus faecalis, Bacillus subtilis and Escherichia coli. Both plasmids transferred to S. epidermidis and Strept. faecalis but not to B. subtilis and E. coli. Once in S. epidermis and Strept. faecalis they were transferred back to S. aureus. Restriction endonuclease analysis showed that the plasmids were stably maintained in S epidermidis and Strept. faecalis.

Conjugation, Genetic↗

PubMed1989

Surface phagocytosis of Staphylococcus epidermidis and Escherichia coli by human neutrophils: serum requirements for opsonization and chemiluminescence.

We examined the serum requirements for surface phagocytosis of Staphylococcus epidermidis and Escherichia coli and for the subsequent chemiluminescent response of human neutrophils. Substantial surface phagocytosis of S. epidermidis occurred in the absence of opsonins, although the presence of 10% pooled or heat-inactivated serum significantly increased phagocytosis. There was no significant difference between these opsonins, indicating that surface phagocytosis of S. epidermidis did not require complement. Unopsonized E. coli were not as readily phagocytized as S. epidermidis (33% versus 57%). In contrast to S. epidermidis optimal phagocytosis of E. coli required complement as 10% heat inactivated donor serum (HHS) was significantly less effective as an opsonin than 10% pooled healthy donor serum (PHS). The time kinetics for phagocytosis of each organism were similar, with most of the phagocytosis occurring in the first 10 min. The chemiluminescent response of neutrophils produced discrepant results. Maximal chemiluminescence was observed when neutrophils were stimulated with bacteria opsonized in PHS. The response to HHS-opsonized bacteria was less, and chemiluminescence to unopsonized bacteria was only marginally higher than the control, even though there was relatively good phagocytosis. These results define the opsonic requirements for surface phagocytosis of S. epidermidis and E. coli and indicate that although complement may not be required for phagocytosis, it is necessary for generation of a maximal oxidative burst, and thus may be essential for efficient intracellular killing.

Blood Bactericidal Activity↗

PubMed1995

Lectin-biotin assay for slime present in in situ biofilm produced by Staphylococcus epidermidis using transmission electron microscopy (TEM).

A lectin-biotin assay was developed for use in the specific detection of slime produced by Staphylococcus epidermidis RP62A and M187sp11 grown in a chemically defined medium. Mature biofilm was formed on polyvinylchloride (PVC) disks using a combined chemostat-modified Robbins device (MRD) model system. Specimens fixed in situ were: 1) stained with ruthenium red; 2) reacted overnight with biotin-labeled lectins (WGA, succinyl-WGA, Con A, or APA) followed by treatment with gold-labeled extravidin; or 3) reacted with antibodies against S. epidermidis RP62A capsular polysaccharide/adhesin (PS/A) using an immunogold procedure. WGA and succinyl-WGA (S-WGA), which specifically bind N-acetylglucosamine, were shown by TEM to react only with slime, both cell-associated and exocellular. In contrast, Con A, APA and anti-PS/A reacted with the bacterial cell surface but did not react with slime. These results indicate the usefulness of WGA lectin as a specific marker for detection of the presence and distribution of slime matrix material in S. epidermidis biofilm.

Biocompatible Materials↗

PubMed1978

Anaerobic transport of serine and 2-aminoisobutyric acid by Staphylococcus epidermidis.

A membrane-bound ATPase detected in extracts of anaerobically grown Staphylococcus epidermidis was inhibited by a variety of compounds which inhibit ATPases in other organisms. Serine and 2-aminoisobutyric acid (AIB) were shown to enter the organism via the same transport system. The transport of AIB, the membrane potential and the transmembrane pH gradient were partially or completely abolished by the same inhibitors and also by uncoupling agents and lipid-soluble ions. It is proposed therefore that this ATPase generates and maintains an electrochemical gradient of protons across the cytoplasmic membrane of S. epidermidis capable of driving AIB uptake. Studies of AIB-induced proton movements suggested that AIB enters via a proton symport mechanism.

Adenosine Triphosphatases↗

PubMed1998

Analysis of diversity of mutations in the mecI gene and mecA promoter/operator region of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

Genomic diversity of mutation in the mecI gene or mecA promoter/operator region was analyzed for clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE). In most MRSA strains, a single base substitution was detected in either the mecI (three different positions) or the mecA promoter (two different positions), while a 28-base deletion in mecI was found in one strain. In contrast, no mutation was detected in these gene sequences of MRSE strains.

Bacterial Proteins↗

PubMed1988

Inhibitory effect of disodium EDTA upon the growth of Staphylococcus epidermidis in vitro: relation to infection prophylaxis of Hickman catheters.

Granulocytopenic patients with an intravascular catheter are at increased risk for infection with Staphylococcus epidermidis. During the intervals when the catheters are not being used for infusions, it is customary to maintain patency of the catheter lumen with a solution containing heparin. We show that heparin does not inhibit the growth of S. epidermidis isolated from the catheter of an infected patient. A 20-mg/ml solution of disodium EDTA, a chelating agent which effectively anticoagulates blood at this concentration, was shown to be bactericidal for an initial inoculum of 10(3) CFU of staphylococci per ml in 24 h. Vancomycin, an antibiotic which is often employed to treat Staphylococcus infections, was also bactericidal for initial inocula of 10(3) CFU/ml at doses of 6.7 micrograms/ml, a drug concentration in the therapeutic range. When 10(3) staphylococci per ml were cultured in the presence of catheter segments and disodium EDTA or vancomycin, subcultures of the catheters showed minimal or no growth, respectively. In contrast, when cultured with heparin alone, subcultures showed abundant growth. In view of its low cost, effectiveness as an anticoagulant, and bactericidal activity, EDTA should be studied as a replacement for heparin solutions for the maintenance of intravenous catheters in granulocytopenic patients.

Catheters, Indwelling↗

PubMed1997

Influence of N-acetylcysteine on the formation of biofilm by Staphylococcus epidermidis.

The influence of various concentrations (0.003-8 mg/mL) of N-acetylcysteine on the formation of biofilms by 15 strains of Staphylococcus epidermidis has been studied. A dose-related decrease in biofilm formation was observed, except with the lowest concentrations. The 'slime' index relative to the control was 63%, 55%, 46%, 34%, 26% and 26% in the presence of 0.25, 0.5, 1, 2, 4, and 8 mg/mL of N-acetylcysteine, respectively. These data are statistically significant. The inhibitory effect of 2 mg/mL of N-acetylcysteine on slime formation was also verified by electron microscopy.

Acetylcysteine↗

PubMed2006

Mycotic aneurysm of the brachial artery secondary to hospital-acquired methicillin-resistant Staphylococcus epidermidis in a complicated case of infective endocarditis.

We present a case of brachial artery mycotic aneurysm caused by methicillin-resistant Staphylococcus epidermidis in a patient with infective endocarditis. A 66-year-old woman suffered two transient ischemic attacks over an 8-week period secondary to septic emboli from mitral valve endocarditis. Following valve replacement surgery, the patient was troubled by persisting paresthesia in the right hand. A mycotic aneurysm of the brachial artery was diagnosed, and surgical repair was successfully undertaken. The purpose of this case report is to highlight an unusual causative organism for mycotic aneurysm and to underline the increasing threat of multi-drug-resistant bacteria as a cause of vascular disease.

Aged↗

PubMed1987

Teicoplanin and rifampicin singly and in combination in the treatment of experimental Staphylococcus epidermidis endocarditis in the rabbit model.

Teicoplanin and rifampicin were evaluated as single and combined agents in the treatment of endocarditis due to Staphylococcus epidermidis in the rabbit model. Rabbits were treated for ten days and the number of bacteria in vegetations determined. At the end of ten days the geometric mean number of bacteria in the vegetations were 5.53 X 10(8), 6.68 X 10(6). 1.10 X 10(4), 2.57 X 10(1) cfu/g of vegetation for control, teicoplanin, rifampicin, and teicoplanin plus rifampicin groups respectively. The MIC and MBC values of the S. epidermidis isolates were 0.78 mg/l for teicoplanin and less than or equal to 0.10 mg/l for rifampicin. In the rifampicin treated group three post-treatment isolates of S. epidermidis tested exhibited marked resistance to rifampicin with MIC and MBC values greater than or equal to 200 mg/l. Teicoplanin and rifampicin were both effective as single agents in the clearance of S. epidermidis from the bloodstream. Rifampicin was more effective than teicoplanin in the clearance of S. epidermidis from vegetations but teicoplanin in combination with rifampicin was more effective than either drug alone.

Animals↗

PubMed1995

Tolerance of Staphylococcus epidermidis grown from indwelling vascular catheters to antimicrobial agents.

During a prospective study of indwelling vascular catheter-related infections, 134 isolates of Staphylococcus epidermidis were grown from 700 catheter tips. In vitro antimicrobial susceptibility testing of these isolates to oxacillin, vancomycin and ofloxacin was performed using the standard broth microdilution technique. These results were compared to those for the same organisms grown in biofilm before the addition of antimicrobial agents. In 96-well flat bottom microtiter plates, 10(4)-10(5) colony forming units of S. epidermidis in 0.1 ml broth were grown for 18 h at 37 degrees C, at which time a biofilm was observed for all isolates. Different concentrations of antimicrobial agents (0.1 ml) were then added to the plates. The plates were incubated for 18 h at 37 degrees C. Since MICs could not be estimated in these plates, all the wells were subcultured after mixing the biofilm with the broth. Minimum bactericidal concentrations (MBCs) were defined as 99.9% reduction in colony forming units. For organisms grown in suspension, 100% of the isolates were susceptible to vancomycin, 81% to ofloxacin and 40% to oxacillin. MBCs of susceptible isolates were within four-fold differences for vancomycin (53%), oxacillin (50%), and ofloxacin (51%). When grown as a biofilm, 78%, 93% and 71% of isolates had MBCs of > or = 2048 micrograms ml-1 of oxacillin, vancomycin and ofloxacin respectively. These data demonstrate the reduced bactericidal activity of antimicrobial agents against S. epidermidis in a biofilm and a simple method for its detection in the microbiology laboratory.

Anti-Bacterial Agents↗

PubMed2006

Effect of cast molded rifampicin/silicone on Staphylococcus epidermidis biofilm formation.

Infection is one of the most common catheter-related complications, especially in shunt systems used to treat hydrocephalus. Staphylococcus epidermidis is directly related to biomaterial infections owing to its ability to form a biofilm on implanted materials. In this study, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the effect of the antibiotic rifampicin on the colonization and growth of S. epidermidis 35984 on the surface of silicone. A cast molding method was used to load rifampicin into the silicone precursor before it was cured. Bacteria with a diameter of 800-1000 nm and height of 200-500 nm were found to be embedded in the biofilm. Compact multilayer biofilm structures were found on silicone surfaces upon incubation for 4 and 24 h. On the other hand, sparser biofilm structures were observed on rifampicin-loaded surfaces after incubation for the same duration. Deformation of bacteria was observed by AFM. Moreover, different bacterial colony structures on the surfaces of silicone and rifampicin-loaded silicone were observed by AFM and SEM.

Antibiotics, Antitubercular↗

PubMed1988

Characterization of Staphylococcus epidermidis mutants sensitive to ultraviolet radiation.

Five UV-sensitive mutants obtained by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment of the Staphylococcus epidermidis W5 strain were characterized phenotypically by assaying their UV- and MNNG-sensitivities, lysogenic inducibility, host-cell reactivation and Weigle reactivation capacities. The results were compared with those of well-characterized Escherichia coli strains, permitting the identification of: 2 mutants that behave as Uvr- Umu-; 1 mutant that appears analogous to Uvr-; 1 mutant that resembles LexA- and 1 mutant that exhibits a RecA- phenotype. The study of these mutants can contribute to the understanding of the repair mechanisms in S. epidermidis.

DNA Damage↗

PubMed1995

Molecular epidemiology of Staphylococcus epidermidis isolates in a hematological unit during a 4-month survey.

In order to study the strain variety, clonal stability and epidemiology of Staphylococcus epidermidis, isolates from all bacterial cultures taken when clinically indicated in 2 wards of the hematological unit of Helsinki University Hospital, during a 4-month period, were characterized by 3 typing methods: antibiogram, plasmid profile and ribotype. A total of 141 distinct S. epidermidis colonies, from 28 blood cultures and 37 cultures from other sources in 32 patients were studied. Plasmid profiles and ribopatterns revealed 47 different strains of which 16 were bacteremic. One of these strains caused bacteremia in 4 different patients over a 3-month period and it was isolated from blood on 7 different sampling occasions. The occurrence of this clone was constant; it was usually found in both of 2 blood culture bottles inoculated (6/7 pairs) and dominated among the 17 distinct S. epidermidis colonies studied from the positive bottles (94% of the total). The clones causing bacteremias in the 2 wards were distinct. These findings indicate that certain clones of S. epidermidis can predominate in hematological wards and that nosocomial transmission of S. epidermidis strains may occur among patients, particularly within the same ward.

Anti-Bacterial Agents↗

PubMed2005

Conversion of Staphylococcus epidermidis strains from commensal to invasive by expression of the ica locus encoding production of biofilm exopolysaccharide.

To test if biofilm formation in Staphylococcus epidermidis is dependent on the polysaccharide intercellular adhesin, whose biosynthesis is driven by the ica locus, a plasmid containing the ica locus was transferred to three ica-negative strains. Using in vitro biofilm assays and a rat central venous catheter infection model, we confirmed the importance of the ica locus for biofilm production and pathogenesis of S. epidermidis.

Animals↗

PubMed1991

Monoclonal IgM antibody protection in mice against infection with an encapsulated strain of Staphylococcus epidermidis.

Passive protective activities of three different classes of monoclonal antibodies in mice against challenge with strain ATCC 31432 (capsular type I) of Staphylococcus epidermidis were examined. Monoclonal IgM antibody passively protected mice against challenge with the homologous strain, whereas monoclonal IgG1 and IgG2b antibodies did not. The protective activity of IgM was absorbed by the cell surface antigen extracted from the homologous strain but not by the antigen from heterologous strains. Rapid reduction of viable cells took place in the peritoneal cavity of mice immunized with monoclonal IgM as early as 6 h after the challenge with the homologous strain. An enzyme-linked immunosorbent inhibition assay showed there was remarkable inhibition with the homologous cell surface antigen but not with heterologous preparations from other strains. Results suggest that in the mouse the major passive protection against the S. epidermidis strain is provided by the IgM antibody to the cell surface antigen.

Animals↗

PubMed1991

Effects of intravitreal dexamethasone on concentration of intravitreal vancomycin in experimental methicillin-resistant Staphylococcus epidermidis endophthalmitis.

Intravitreal corticosteroids in the treatment of bacterial endophthalmitis remain controversial. We utilized an experimental rabbit model of methicillin-resistant Staphylococcus epidermidis endophthalmitis (i) to calculate the intravitreal vancomycin concentration in rabbit eyes receiving intravitreal vancomycin alone or in combination with intravitreal dexamethasone and (ii) to determine whether an intravitreal steroid has any effect on intravitreal vancomycin levels. All right eyes were infected and all left eyes were uninfected. The rabbits were divided into two treatment groups: (i) 32 eyes (group I) were injected with intravitreal vancomycin, 1.0 mg (0.1 ml); (ii) 32 additional eyes (group II) were injected with intravitreal dexamethasone, 400 micrograms (0.1 ml), in addition to vancomycin. Measurement of intravitreal vancomycin concentration was performed following sacrifice, utilizing a microbiologic agar diffusion assay. Analyses of intravitreal vancomycin concentrations were performed by using model-independent parameters, with area under the concentration-time curves derived by trapezoidal approximation. The intravitreal vancomycin concentration was significantly lower in both uninfected and infected group II eyes (P less than 0.002). Analysis of intravitreal vancomycin concentration-time relationships was performed by using a nonlinear least-squares regression program; data best fit a one-compartment model. In addition, no vancomycin-dexamethasone interaction could be demonstrated. The reduced level of intravitreal vancomycin in the presence of intravitreal dexamethasone may have important clinical implications.

Animals↗

PubMed2001

Elucidation of antibiotic effectiveness against Staphylococcus epidermidis during intraocular lens implantation.

The effect of various antimicrobial agents commonly used in irrigating solutions on the hydrophobicity and adherence of Staphylococcus epidermidis ATCC 14990 was investigated. The longest post-antibiotic effect (PAE=3.2 h) was obtained with gentamicin followed by ciprofloxacin (2.7 h), clindamycin (2.2 h), ceftazidime (1.8 h) and vancomycin (1.6 h). The post-antibiotic effect on surface hydrophobicity of cells previously treated with gentamicin, ciprofloxacin, or clindamycin for 120 min resulted in a substantial decrease in affinities to hexadecane (31.4, 28.5 and 27%, respectively) compared with control untreated cells. Less effect was noted with cells previously treated with ceftazidime or vancomycin (20.5 and 15.8%, respectively). Similar but less marked results were obtained when the cells were exposed to antibiotics for 30 or 60 min. The post-antibiotic effect on adherence of cells to both intraocular lenses and to epithelial cells showed that adherence to lenses decreased as the time of exposure to antimicrobial agents increased. Adherence was greatly diminished with cells treated with gentamicin or ciprofloxacin compared with control untreated cells. Adherence was less affected by clindamycin, ceftazidime and vancomycin. The data supported the use of antimicrobial agents in irrigating solution during intraocular surgery, since, reduced adherence (colonization) and might result in a lower incidence of endophthalmitis.

Anti-Bacterial Agents↗