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PubMed2001

Identification of the sigB operon in Staphylococcus epidermidis: construction and characterization of a sigB deletion mutant.

The role of the alternative sigma factor sigma(B) in Staphylococcus epidermidis was investigated by the construction, complementation, and characterization of a sigB deletion mutant. Electrophoretic analyses confirmed a profound influence of sigma(B) on the expression of exoproteins and cytoplasmic proteins. Detailed investigation revealed reduced lipase and enhanced protease activity in the sigma(B) mutant. Furthermore, no significant influence of sigma(B) on heterologous biofilm formation or on the activity of the global regulator agr was detected.

Bacterial Proteins↗

PubMed2000

Screening for Staphylococcus epidermidis markers discriminating between skin-flora strains and those responsible for infections of joint prostheses.

Fifty-four Staphylococcus epidermidis strains responsible for infections of joint prostheses and 23 strains isolated from skin flora were studied for markers of virulence, to discriminate invasive strains from normal flora. They were screened for binding to polystyrene and matrix proteins and for the presence of staphylococcal genes involved in adhesion. The ica operon involved in biofilm formation was the only marker discriminating between these 2 categories of strains.

Bacterial Adhesion↗

PubMed1989

Effects of extracellular slime produced by Staphylococcus epidermidis on oxidative responses of rabbit alveolar macrophages.

Bacterial slime produced in mass cultures of the RP 12 strain of Staphylococcus epidermidis was extracted with 4 M guanidine-HCl plus 0.05 M sodium acetate and 0.5% CHAPS, concentrated, dialyzed, and subjected to separation on DEAE sephacel columns. Three fractions, I-2A, I-2B, and I-4, were eluted with linear gradients of NaCl. Fractions I-2A and I-2B were alcian blue positive, whereas I-4 was alcian blue negative but the most electronegative fraction. The crude polysaccharide fraction and the three purified fractions were incubated individually for 2.5 or 20 h with normal rabbit alveolar macrophages (AM) to determine their effect on a subsequent PMA-induced oxidative burst. The crude fraction (50-200 micrograms/mL) and I-2B (50-200 micrograms/mL) primed the AM to give approximately a threefold increase in the PMA-induced burst after 2.5 h incubation. In contrast, a 20-h incubation resulted in a 30-40% inhibition of the PMA-induced burst with AM incubated with the same concentrations of the crude, I-2A, or I-2B fractions. Fraction I-4 had no detectable effect. The fractions also were tested to determine if they could elicit an oxidative burst in BCG-immune AM. None of the fractions (up to 500 micrograms/mL) elicited a significant oxidative burst even though BCG-immune AM yielded a PMA-induced burst 100 times that observed with normal resident AM. These data suggest that slime from S. epidermidis can impair the PMA-induced oxidative burst of normal AM during a 20-h incubation period and could explain in part why host defenses are compromised by slime-producing S. epidermidis.

Animals↗

PubMed1980

The early serological detection of colonisation by Staphylococcus epidermidis of ventriculo-atrial shunts.

Simple quantitative serological tests demonstrating Staphylococcus epidermidis agglutinins and C-reactive protein were used for the early detection of ventriculo-atrial shunt colonization by this organism. Tests in normal children and adults in various age groups throughout life confirmed Bayston's ovservations that those tested attained a titre up to 1:160 TO S. epidermidis agglutinogen. In contrast, the titre in children with colonised shunts and in adults with S. epidermidis endocarditis, both conditions which are usually accompanied by bacteraemia, rose to much higher levels, sometimes up to 1:5120. The routine combination of both tests has proven to be of considerable diagnostic value, particularly in early or recent colonisation.

Adolescent↗

PubMed1990

Spontaneous sterilization in experimental Staphylococcus epidermidis endophthalmitis.

We created a standardized model of endophthalmitis in the aphakic rabbit eye using a laboratory strain of Staphylococcus epidermidis of known characteristics (ATCC 155). Eyes were injected with the following number of organisms: 170, 3760, 8750, 170,000 and 460,000. Serial quantitative cultures, clinical grading of infection and histopathologic studies were performed on days 1, 2, 3, 7 and 14. Bacteria appeared to multiply rapidly during the first 24 hr with peak recovery at 8 to 24 hr. Fewer bacteria were cultured on the third day after injection, and positive cultures were rare after the third day. Inflammatory scores were initially higher with each increased number of injected bacteria and tended to increase for the first 3 to 5 days.

Animals↗

PubMed1990

Nucleotide sequence of the fosB gene conferring fosfomycin resistance in Staphylococcus epidermidis.

We have determined the nucleotide sequence of gene fosB of plasmid pIP1842, which confers resistant to fosfomycin in Staphylococcus epidermidis BM2641. The resistance gene was identified as a coding sequence of 417 bases pairs corresponding to a protein with a calculated Mw of 16,345 daltons. This value is in good agreement with that of 15,000, estimated by SDS-polyacrylamide gel electrophoresis of a bacterial cell-free coupled transcription-translation system. The fosB gene product exhibits 48% sequence homology with the fosfomycin resistance protein FOSA of Enterobacteriaceae. The substitutions are scattered throughout indicating that the two corresponding genes have diverged from a common ancestor. Downstream from fosB is located an open reading frame that was partially sequenced. The deduced amino-acid sequence was 50% homologous to REP alpha 1, a protein involved in the replication of the Enterococcus faecalis plasmid pAM alpha 1.

Amino Acid Sequence↗

PubMedDate not supplied

Therapy for experimental endocarditis due to Staphylococcus epidermidis.

Vancomycin was evaluated with and without gentamicin and/or rifampin in therapy for endocarditis due to methicillin-resistant Staphylococcus epidermidis in rabbits. Vancomycin (30 mg/kg iv every 12 hr), gentamicin (3.5 mg/kg im every 8 hr), rifampin (20 mg/kg im every 12 hr), combinations of vancomycin plus gentamicin, vancomycin plus rifampin, and vancomycin plus gentamicin plus rifampin were injected for two days, and the number of bacteria in vegetations was determined. Ratios of minimal inhibitory concentrations to minimal bactericidal concentrations (microgram/ml) for S. epidermidis were 3.1:25 for vancomycin, 0.2:0.8 for gentamicin, and 0.4:0.4 for rifampin. After two days of therapy, mean log colony-forming units +/- SD in vegetations were 7.1 +/- 1.5 (none of eight animals were sterile) for vancomycin; 4.6 +/- 2.2 (two of nine) for gentamicin; 4.5 +/- 2.2 (two of eight) for rifampin; 3.3 +/- 1.3 (three of 10) for vancomycin plus gentamicin; 2.7 +/- 1.2 (three of nine) for vancomycin plus rifampin; 2.1 +/- 0.2 (eight of nine) for vancomycin plus gentamicin plus rifampin; and 8.1 +/- 1.3 (none of 12) for the control group. Gentamicin, rifampin, vancomycin plus gentamicin, and vancomycin plus rifampin were significantly more effective than was vancomycin; vancomycin plus rifampin was more effective than was gentamicin alone; and the combination of vancomycin plus gentamicin plus rifampin was more effective than were the drugs administered alone or in the combinations vancomycin plus gentamicin and vancomycin plus rifampin. Two days of treatment followed by seven days of no treatment resulted in 71%, 29%, and 14% sterile vegetations in rabbits receiving the combination therapy vancomycin plus gentamicin plus rifampin, vancomycin plus rifampin, and vancomycin plus gentamicin, respectively.

Animals↗

PubMed2003

The effects of magnesium, calcium and EDTA on slime production by Staphylococcus epidermidis strains.

Effect of magnesium, calcium and EDTA on slime production by 15 slime-positive and 13 slime-negative Staphylococcus epidermidis strains isolated from various clinical specimens was determined. The slime production on tryptic soy broth was significantly enhanced after addition of 128 mumol/L Mg2+. Similarly, the addition of Ca2+ caused a significant increase in slime production of all tested strains when concentration of Ca2+ exceeded 64 mumol/L. In contrast, in the presence of EDTA the slime production by all strains was significantly reduced. Hence Ca2+ and Mg2+ increase slime production of S. epidermidis. This finding is important in the context of the pathogenesis of biomedical implant infections caused by S. epidermidis.

Bacterial Adhesion↗

PubMedDate not supplied

The efficacy of intravitreal levofloxacin and intravitreal dexamethasone in experimental Staphylococcus epidermidis endophthalmitis.

This study was designed to investigate the efficacy of intravitreal levofloxacin, and intravitreal levofloxacin and dexamethasone combined in Staphylococcus epidermidis endophthalmitis. Albino rabbits (n = 25), infected with an intravitreal inoculum of S. epidermidis (1.0 x 10(5) colony forming units/0.1 ml), were divided into five groups (n = 5). Groups 1 and 2 received treatment 24 h after the inoculation, and groups 3 and 4 48 h after the inoculation. No treatment was given to the control group. Treatment efficacy was assessed by vitreous culture, clinical examination and histopathology. Five days after treatment, groups 1 and 2 had significantly lower clinical scores than the control group (p = 0.004, p = 0.007). The culture results of the treatment groups were sterile. The histopathological scores of the treatment groups were lower than the control group (p = 0.007). Studies on retinal toxicity and dose-response relation are needed to prove the efficacy of levofloxacin in S. epidermidis endophthalmitis.

Animals↗

PubMed1999

Gelatin-sealed polyester resists Staphylococcus epidermidis biofilm infection.

BACKGROUND: The purpose of this study was to show that gelatin-impregnated polyester grafts inhibit Staphylococcus epidermidis biofilm infection in a canine model of aortic graft interposition. A clinically native species and two engineered strains, which differed in slime and adhesin antigen components, were compared to determine differential gelatin and slime interactions. METHODS: In vitro bacterial graft colonization was validated by immersion of graft segments in inoculating solutions (10(6) colony forming units/ml) of a clinically native species RP62A and two genetically engineered S. epidermidis species, M187sn3 (SN3: slime and adhesin negative) or M187sp11 (SP11: slime and adhesin positive), for 18 h at 23 degrees C. The grafts were washed, sonicated, and cultured to assess in vitro bacterial graft adherence. Grafts similarly inoculated were placed as aortic interposition grafts in dogs. Three sterile grafts were implanted as controls. Grafts were excised after 6 weeks and cultured for bacterial growth as in the in vitro study. Infection was defined by a positive culture in the excised grafts. Data were analyzed with nonparametric statistical methods. RESULTS: In vitro bacterial graft adherence in colony forming units per milliliter was similar at 18 h postsonication for RP62A (8 x 10(4) +/- 1 x 10(4)), SN3 (7 x 10(4) +/- 2 x 10(4)), and SP11 (6 x 10(4) +/- 2 x 10(4)) (P = NS). Only one of five grafts inoculated with RP62A was culture positive after 6 weeks. No grafts inoculated with the engineered strains SN3 or SP11 were culture positive after explanation. CONCLUSION: In vitro bacterial inoculation of gelatin-impregnated polyester was similar among the species and not dependent upon the presence of slime and adhesin components. Gelatin-impregnated polyester grafts demonstrated in vivo resistance to coagulase-negative staphylococcal biofilm infection.

Animals↗

PubMed1993

Enhanced ability to colonize the skin: a possible explanation for the epidemic spread of certain strains of Staphylococcus epidermidis.

Experimental skin colonization was attempted on healthy volunteers using one epidemic and two non-epidemic strains of Staphylococcus epidermidis isolated from a bone marrow transplant unit. Although the three strains had similar biochemical reactions, they had different antibiograms and plasmid patterns, and the epidemic strain grew rather more slowly when in a mixture in broth. Two experiments involving sets of 5 volunteers were performed. The epidemic strain was mixed with one non-epidemic strain for experiment 1, and with the other for experiment 2. Each volunteer had an inoculum of a mixture of 10(7) cfu of each strain inoculated onto the antecubital fossae of both arms; one of the arms had had a prior treatment with chlorhexidine to see if this would prevent colonization. Quantitative skin cultures were continued until the test strains could no longer be isolated. Colonization occurred in all but one volunteer, and lasted from a few weeks to 17 months. Maximal counts of the epidemic strain were significantly higher than the maximal counts of the non-epidemic strains. Chlorhexidine had no effect in experiment 1, and caused a reduction in intensity and duration of colonization in experiment 2, although this did not achieve statistical significance. Plasmid patterns were unchanged throughout, but in two instances a variant of the epidemic strain that had lost resistance to methicillin and tobramycin was isolated together with the parent strain. The enhanced ability of the epidemic strain to colonize skin may be an important factor in allowing cross-infection.

Chlorhexidine↗

PubMed1969

Some properties of the beta-lactamase genes in Staphylococcus epidermidis.

Eighty-three per cent of 200 different freshly isolated cultures of Staphylococcus epidermidis produced beta lactamase. Growth in the presence of acridine orange or ethidium bromide or growth at 44 C resulted in a high frequency of loss of the beta lactamase genes in some strains of S. epidermidis. The relationship between beta-lactamase production and resistance to mercuric, cadmium and arsenate ions differed from that observed in Staphylococcus aureus. It is postulated that the genes for beta lactamase in certain strains of S. epidermidis are on a plasmid.

Acridines↗

PubMed1982

Toxigenic strains of Staphylococcus epidermidis and their experimental corneal pathogenicity in rabbits.

Thirty strains of Staphylococcus epidermidis, ten each from normal conjunctival sacs, corneal ulcer cases and from those who developed postoperative endophthalmitis, were examined for their dermonecrotic and haemolytic activities. Dermonecrosis was studied on rabbit skin whereas haemolysis was determined against sheep, guinea pig, rabbit and human erythrocytes. None of the cell free filtrates from strains derived from normal sacs showed any evidence of toxin production. Four strains from corneal ulcer cases and five from postoperative infections produced + to + + + dermonecrosis whereas haemolytic activity was exhibited by one strain in the former and by two in the latter. Only those strains that were highly dermonecrotoxic were haemolytic. Experimental corneal lesions in the rabbit were mild by strains from normal sacs. Those showing highest dermonecrotoxic reaction, irrespective of their source, produced identical and most severe corneal pathology when compared to those producing minimal necrosis.

Animals↗

PubMed2000

In vitro adherence of Staphylococcus epidermidis to polymethyl methacrylate and acrysof intraocular lenses.

PURPOSE: To investigate the adherence of one clinically relevant ocular isolate of Staphylococcus epidermidis to polymethyl methacrylate (PMMA) and Acrysof (Alcon Surgical, Fort Worth, TX) intraocular lenses (IOLs). DESIGN: Experimental study. PARTICIPANTS: The authors examined the in vitro adherence of one clinically relevant ocular isolate of S. epidermidis. Adherence was tested on 12 PMMA IOLs and 12 Acrysof IOLs. METHODS: Six IOLs (three of each type) were placed in different test tubes containing bacterial suspension (10(8) cfu/ml) and incubated at 37 degrees C. At different times (3 minutes, 30 minutes, and 90 minutes), each IOL type was removed from the test tube, rinsed in sterile phosphate-buffered saline, and transferred into sterile brain-heart infusion broth. The broth with the IOL was sonicated on low power for 3 minutes to remove adhered bacteria. Two serial 10-fold dilutions of the broth containing the dislodged bacteria were plated on mannitol agar plates. The plates were incubated overnight at 37 degrees C and then bacterial colonies were counted. All assays were performed in triplicate. Additional lenses (three of each type) were incubated with S. epidermidis for different times (3 minutes, 30 minutes, and 90 minutes) and then examined with scanning electron microscopy. MAIN OUTCOME MEASURES: The number of adhered bacteria per area (mm ) of IOL optic was calculated. Statistical analysis included calculation of arithmetic means and 95% confidence intervals (t test). RESULTS: Direct counting of viable adherent bacteria released by sonication showed that the amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes' incubation in S. epidermidis suspension was 0.1 x 10(2)/mm2, 3.6 x 10(2)/mm2, and 11 x 10(2)/mm2 (PMMA IOLs), and 4.4 x 10(2)/mm2, 3.1 x 10(2)/mm2, and 2.3 x 10(2)/mm2 (Acrysof IOLs). Direct counting of adherent bacteria in scanning electron microscopy photographs revealed that the total amount of adhered bacteria per area of IOL optic after 3, 30, and 90 minutes' incubation in S. epidermidis suspension was 1.1 x 10(2)/mm2, 4.4 x 10(2)/mm2, and 5.5 x 10(2)/mm2 (PMMA IOLs) and 13 x 10(2)/mm2, 33.9 x 10(2)/mm2, and 72 x 10(2)/mm2 (Acrysof IOLs). CONCLUSIONS: Results suggest that in vitro adherence of S. epidermidis to IOLs is influenced by IOL materials. After 3 minutes' incubation, Acrysof IOLs appeared to be more permissive to S. epidermidis adherence than PMMA IOLs. The difference was statistically significant (P < 0.05). However, at 90 minutes, Acrysof IOLs had a lower viable bacterial count than did the PMMA IOLs. Bacterial adherence appeared to be greater in areas with surface irregularities. Adherence of S. epidermidis to IOLs may play a role in the pathogenesis of some forms of endophthalmitis after cataract surgery.

Acrylic Resins↗

PubMed2000

In vitro adhesion of Staphylococcus epidermidis to intraocular lenses.

PURPOSE: To compare the in vitro adherence of slime-producing and non-slime-producing Staphylococcus epidermidis to different intraocular lenses (IOLs) to study the organism's contribution to postoperative endophthalmitis. METHODS: Strains of slime-positive (ATCC 35984) and slime-negative (ATCC 12228) S epidermidis were used. The IOLs were made of poly(methyl methacrylate) (PMMA), PMMA with polypropylene haptics, silicone, hydrogel, acrylic, heparin-surface-modified (HSM) PMMA, and fluorine-surface-modified PMMA. The lenses were incubated overnight with bacteria, then sonicated and vortexed to separate the adhered bacteria. Quantitative cultures were performed and the results statistically analyzed. RESULTS: Slime-negative strains of S epidermidis adhered to all IOLs but at a lower level than slime-positive strains. The most adherent lenses were acrylic with the positive strain and PMMA with the negative strain. The least adherent IOLs were PMMA with the positive strain and hydrogel with the negative strain. There were no significant differences between rigid and foldable lenses. Polypropylene was significantly more adherent than PMMA to the slime-positive strain. The acrylic and the HSM PMMA IOLs were significantly more adherent to the positive strain. CONCLUSIONS: In vitro, there were significant differences in bacterial adhesion among IOL materials. Slime-positive strains of S epidermidis were more adherent than slime-negative ones.

Bacterial Adhesion↗

PubMed1995

Characterization of the hemagglutinin of Staphylococcus epidermidis.

Adherence to biomaterials and production of biofilm is thought to be pivotal in the pathogenesis of prosthetic device infection by Staphylococcus epidermidis. In this study a strong association (P < .001) of hemagglutination with adherence and biofilm production was observed. Hemagglutination was not associated with cell surface hydrophobicity (P = .906). Hemagglutination inhibition studies revealed that hemagglutination was not affected by heat, pH, cation concentration, proteolytic enzymes, biologic detergent, serum proteins, or subinhibitory antibiotics. Hemagglutination was abolished by periodate oxidation and digestion with glycosidases. It was markedly inhibited by beta-lactose and its monosaccharide constituents in a concentration-dependent fashion. Hemagglutinin expression depended on the presence of glucose. Chemical analysis of a partially purified hemagglutinin preparation and cell-free hemagglutinating supernatants revealed little or no protein and small quantities of reducing sugars, pentose, ketose, hexosamine, uronic acid, and phosphate. Hemagglutinin of S. epidermidis appears to be a polysaccharide distinct from other known adhesins of S. epidermidis.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1970

Mechanism of Chloramphenicol Resistance in Staphylococcus epidermidis.

The mechanism of chloramphenicol resistance in several multiple-resistant Staphylococcus epidermidis strains has been studied and shown to be due to the presence of the enzyme, chloramphenicol acetyltransferase. As with S. aureus, the inactivating enzyme in S. epidermidis appears to be the product of a structural gene on the chloramphenicol plasmid because resistance and enzyme activity are concurcurrently lost after growth in acridine orange or at elevated temperatures. The synthesis of chloramphenicol acetyltransferase in S. epidermidis has been compared with the function of a similar enzyme in chloramphenicol-resistant S. aureus with the conclusion that the kinetics of induction, products of the reaction, and general properties of the enzymes are identical. The chloramphenicol acetylating enzyme from S. epidermidis has been purified to a state of homogeneity and compared with the analogous purified S. aureus enzyme. Both purified preparations consist of native enzymes with molecular weights of 80,000, and evidence is presented that is consistent with their being made up of four identical subunits of 20,000 each. The two staphylococcal enzymes are identical with respect to pH optimum, apparent affinity (K(m)) for chloramphenicol, heat denaturation, and immunological reactivity, but they differ in electrophoretic mobility, chromatographic behavior, substrate specificity, and sensitivity to inhibition by mercuric ion.

Journal Article↗

PubMed1985

Instability of antibiotic resistance in a strain of Staphylococcus epidermidis isolated from an outbreak of prosthetic valve endocarditis.

Plasmid profiles, phage typing, antibiograms, and biotyping were used to characterize Staphylococcus epidermidis isolated from multiple cultures of blood of four patients with prosthetic valve endocarditis. Epidemiological evidence implicated a common source for these infections. Of 20 clinically significant isolates, 14 exhibited variations from the prototype pattern of multiple resistance to five antibiotics. All isolates tested appeared to be the same strain by phage typing. Of 18 isolates available for plasmid analysis, 10 contained six plasmids of identical size, whereas eight differed from the prototype profile in the loss of one to three plasmids. Loss of resistance to gentamicin, chloramphenicol, erythromycin, and clindamycin but not to methicillin was associated with the loss of specific plasmids. Because antibiotic resistance in this strain of S. epidermidis was unstable, the use of antibiograms alone was not a reliable means of evaluating the relatedness of these multiple isolates.

Anti-Bacterial Agents↗