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PubMed2005

Anaerobic co-reduction of chromate and nitrate by bacterial cultures of Staphylococcus epidermidis L-02.

Industrial wastewater is often polluted by Cr(VI) compounds, presenting a serious environmental problem. This study addresses the removal of toxic, mutagenic Cr(VI) by means of microbial reduction to Cr(III), which can then be precipitated as oxides or hydroxides and extracted from the aquatic system. A strain of Staphylococcus epidermidis L-02 was isolated from a bacterial consortium used for the remediation of a chromate-contaminated constructed wetland system. This strain reduced Cr(VI) by using pyruvate as an electron donor under anaerobic conditions. The aims of the present study were to investigate the specific rate of Cr(VI) reduction by the strain L-02, the effects of chromate and nitrate (available as electron acceptors) on the strain, and the interference of chromate and nitrate reduction processes. The presence of Cr(VI) decreased the growth rate of the bacterium. Chromate and nitrate reduction did not occur under sterile conditions but was observed during tests with the strain L-02. The presence of nitrate increased both the specific Cr(VI) reduction rate and the cell number. Under denitrifying conditions, Cr(VI) reduction was not inhibited by nitrite, which was produced during nitrate reduction. The average specific rate of chromate reduction reached 4.4 micromol Cr 10(10 )cells(-1 )h(-1), but was only 2.0 micromol Cr 10(10 )cells(-1 )h(-1) at 20 degrees C. The maximum specific rate was as high as 8.8-9.8 micromol Cr 10(10 )cells(-1 )h(-1). The role of nitrate in chromate reduction is discussed.

Anaerobiosis↗
PubMed1998

Effect of surface modifications of intraocular lenses on the adherence of Staphylococcus epidermidis.

The development of polymers with different surface properties and surface modifications of intraocular lenses (IOL) should reduce foreign body reactions after implantation by reducing the surface hydrophobicity of the lenses. It was examined how far such surface variations influenced the adhesiveness of bacteria. The most common organism isolated from cases of postoperative endophthalmitis is Staphylococcus epidermidis. For this reason, three strains of this species, the type strain ATCC 14990 and two clinical isolates (8687, 6579 I), with different hydrophobic surfaces, were studied. IOL made of PMMA, silicone, and a copolymer as well as PMMA lenses with modified surfaces (unpolished, polished, silanized, and heparinized) were used. Bacteria were radiolabelled with 3H-thymidine and the adherent bacteria were calculated per mm2 of lens surface. The three strains adhered better to the unpolished surface of silicone than to PMMA. Treatment of PMMA surface by polishing diminished the differences between the strains. An influence of hydrophobic interactions on the adherence of S. epidermidis ATCC 14990 was demonstrated. The adherence of this hydrophobic type strain was clearly reduced by heparinization of the PMMA surface. In contrast, the hydrophilic catheter isolate 6579 I adhered better to modified surfaces. This strain differed clearly in its PFGE pattern from both hydrophobic strains. Hydrophobic interactions play a role in the bacterial adherence to intraocular lenses in vitro and in vivo. Modifications of polymer surfaces, however, can result in rather different effects depending on the bacterial surface composition and properties.

Bacterial Adhesion↗
PubMed1969

Violagabriellae variant of Staphylococcus epidermidis on normal human skin.

Twenty-seven strains of a reddish violet pigment-producing variety of Staphylococcus epidermidis have been recovered from normal human skin. They closely resemble the previously unique Castellani strain, named Micrococcus violagabriellae, which was placed by K. J. Steel in S. epidermidis. These strains are classified as S. epidermidis by using the Baird-Parker schema; however, besides the pigment produced, they also differ from S. epidermidis in proteolytic activity and effect on litmus milk. The variety seems to be part of the normal flora of the human axilla.

Adult↗
PubMed2004

[Differences in antibiotic sensitivity in biofilm-positive and biofilm-negative strains of Staphylococcus epidermidis isolated from blood cultures].

The adhering capability and biofilm growth facilitate staphylococcal colonization of surfaces of damaged tissues and foreign bodies. Biofilm-forming bacteria are more resistant to immune system activities, mechanical effects of blood flow and other adverse effects, e.g. those due to antibiotics. Minimal inhibitory concentrations (MICs) were compared for two groups of Staphylococcus epidermidis strains isolated from blood cultures. Group 1 included biofilm positive strains whose biofilm-forming potential was revealed by both phenotypic and genotypic methods. Group 2 included strains without biofilm-forming potential. The comparison of MICs for selected antibiotics showed higher resistance of biofilm positive compared to biofilm negative strains. The difference was evident particularly for oxacillin, tetracycline, co-trimoxazole and gentamicin.

Biofilms↗
PubMed2005

Adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to silicone-hydrogel contact lenses.

PURPOSE: The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone-hydrogel lenses with those to a conventional hydrogel lens. METHODS: In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone-hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone-hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements. RESULTS: P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone-hydrogel lenses than to the daily wear silicone- and conventional hydrogel lenses (p < 0.05). No statistical differences were found between the adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone-hydrogel lenses than to the conventional hydrogel (p < 0.05), but in much lower amounts than the biofilm-positive strain. The water contact angle measurements revealed that the extended wear silicone-hydrogel lenses are hydrophobic, whereas the daily wear silicone- and conventional hydrogel lenses are hydrophilic. CONCLUSIONS: As a result of their hydrophobicity, the extended wear silicone-hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone-hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.

Bacterial Adhesion↗
PubMed2000

Slime production as a virulence factor in Staphylococcus epidermidis isolated from bacterial keratitis.

A total of 126 coagulase negative staphylococci (CONS) isolated from corneal scrapings of patients of bacterial keratitis and 50 isolates from healthy eyes (controls) were tested for slime production. Eighty eight (69.84%) of 126 isolates from patients and 11 (22%) of 50 isolates from controls were slime producing (P < 0.001). Of these 88 isolates, 42 were Staphylococcus epidermidis biotype II, 30 were S. epidermidis biotype I, 8 were S. epidermidis biotype III and the rest belonged to CONS other than S. epidermidis. Amongst the corneal ulcer isolates, multidrug resistance (resistance to 3 or more antibiotics) was observed in 82.9 per cent (73/88) slime producing organisms as against only 18.4 per cent (7/38) nonslime producing organisms (P < 0.001). Similarly, of the total 99 slime positive and 77 slime negative isolates, 79 (79.8%) and 22 (28.6%) respectively were multidrug resistant (P < 0.001). Although, slime production is known to be one of the major virulence factors of CONS in extraocular systemic staphylococcal infections, the present study detected slime in isolates from ocular infections. It was found that S. epidermidis I and II were the common biotypes associated with bacterial keratitis and, slime production and multidrug resistance were the two important virulence factors. These observations have clinical and therapeutic significance.

Eye Infections, Bacterial↗
PubMed2000

Origins of Staphylococcus epidermidis and Streptococcus oralis causing bacteraemia in a bone marrow transplant patient.

Coagulase-negative staphylococcal bacteraemia in immunocompromised patients is often associated with the use of central venous catheters, while the proposed origin of viridans streptococci causing bacteraemia in this patient group is the oral cavity. This report describes an episode of polymicrobial bacteraemia caused by Staphylococcus epidermidis and Streptococcus oralis followed by several further episodes of S. epidermidis bacteraemia in a 15-year-old boy after bone marrow transplantation. Pulsed-field gel electrophoresis (PFGE) of SmaI chromosomal DNA digests was used to compare blood culture and oral isolates of S. epidermidis and Str. oralis. The results indicated that the mouth was the source of both S. epidermidis and Str. oralis causing the first episode of bacteraemia. PFGE further demonstrated that the central venous catheter was the origin of a second strain of S. epidermidis responsible for subsequent episodes of staphylococcal bacteraemia. Both the oral mucosa and central venous lines should be considered as potential sources of organisms, including coagulase-negative staphylococci, associated with bacteraemia in immunocompromised patients.

Adolescent↗
PubMed1995

Effects of ciprofloxacin and vancomycin on physicochemical surface properties of Staphylococcus epidermidis, Escherichia coli, Lactobacillus casei and Lactobacillus acidophilus.

Under clinical conditions, during antibiotic treatment, micro-organisms often grow at sub-inhibitory concentrations. This may lead to altered adhesive cell surface properties and to a disruption of the indigenous microflora, in addition to the creation of a more pathogenic biofilm. The effects of growing Staphylococcus epidermidis, Escherichia coli and lactobacilli in the presence of sub-inhibitory concentrations of ciprofloxacin and vancomycin were determined. Growing the cells under antibiotic burden sometimes led to altered cell surface hydrophobicity (by adhesion to hexadecane), changes in the pH-dependence of zeta potentials, and elemental surface compositions or in different SDS-PAGE protein profiles. For several isolates only one of the surface properties was altered by the presence of an antibiotic in the growth medium and no systematic effects were observed for all isolates representing a certain species or even strain. The important conclusion to be drawn from the results of this study is that the effects of growing cells under antibiotic burden on their adhesive cell surface properties can only be established when using a variety of techniques.

Alkanes↗
PubMed2003

Stimulation of Staphylococcus epidermidis growth and biofilm formation by catecholamine inotropes.

BACKGROUND: Bacterial colonisation of indwelling medical devices by coagulase-negative staphylococci is a prevalent risk in intensive-care units. Factors determining biofilm formation and progression to catheter- related infection are incompletely understood. We postulated that administration of inotropic agents via indwelling intravenous catheters may stimulate growth and formation of biofilms by Staphylococcus epidermidis. METHODS: Inocula representing physiologically relevant infecting doses of S epidermidis were incubated in a minimum medium supplemented with fresh human plasma in the presence or absence of pharmacological concentrations of norepinephrine or dobutamine. Biofilm formation on polystyrene and medical-grade silicone was examined. After incubation, cultures were assessed for growth and formation of biofilms by colony counting and scanning electronmicroscopy. The production of exopolysaccharide, a major constituent of S epidermidis biofilms, was also assessed by use of immunofluorescence microscopy. FINDINGS: Incubation of S epidermidis with catecholamine inotropes in the presence of human plasma resulted in a significant increase in growth compared with control on both polystyrene and silicone surfaces, with pronounced increases in biofilm formation as visualised by scanning electronmicroscopy. Experiments with transferrin labelled with radioactive iron showed the ability of catecholamine inotropes to facilitate acquisition of iron by S epidermidis. Immunofluorescence microscopy revealed extensive exopolysaccharide production associated with S epidermidis biofilms. INTERPRETATION: The ability of catecholamine inotropic drugs to stimulate bacterial proliferation and biofilm formation may be an aetiological factor in the development of intravascular catheter colonisation and catheter-related infection. The removal of iron from transferrin for subsequent use by S epidermidis is a possible mechanism by which catecholamine inotropes stimulate bacterial growth as biofilms.

Adult↗
PubMedDate not supplied

In vitro and in vivo effects of rifampin on Staphylococcus epidermidis graft infections.

Rifampin, bound in high concentrations to prosthetic grafts, has been proposed for the treatment of vascular graft infections. The optimum antibiotic concentration and duration of treatment for infected grafts is not known. This study compared the in vitro and in vivo efficacy of varying concentrations of rifampin against three different strains of slime producing Staphylococcus epidermidis (RP62A, KC2, and KB1) bound to the knitted Dacron at high and low concentrations at 10(4) and 10(7) CFU/cm2 of prosthetic. Time kill experiments were performed at 4, 18, and 42 hr, in which each Dacron bound bacterial strain was exposed in vitro to 4X, 64X, 100X, and 1,000X minimum inhibitory concentration (MIC) of rifampin. In vitro, the Dacron bound laboratory strain RP62A was implanted subcutaneously in the backs of male Swiss-Webster mice and exposed to 4X, 100X, and 1,000X the MIC of rifampin for similar time periods. In addition, systemic vancomycin (10 mg/kg) was assessed for synergy and prevention of rifampin resistance. In vitro, all concentrations of rifampin showed near total killing (< 1 log) of all bacterial strains at low initial concentrations (10(4) CFU/cm2) but not high (10(7) CFU/cm2) to 42 hr. Importantly, resistance was shown to develop in all three strains of S. epidermidis with high initial bacterial biofilm concentrations. In vivo, rifampin concentrations between 4X MIC and 100X MIC achieved a balance between optimal killing and prevention of resistance. Systemic vancomycin slightly improved bacterial clearance but did not alter the development of rifampin resistance at high local concentrations. Caution is advised with the use of antibiotic bonded grafts because resistance may develop even with the addition of systemic antibiotics.

Animals↗
PubMed1993

Analysis of pristinamycin-resistant Staphylococcus epidermidis isolates responsible for an outbreak in a Parisian hospital.

In 1990, over a 6-month period, an increase from 1 to 10% in the incidence of pristinamycin resistance among coagulase-negative staphylococci was observed in four intensive care units of a Parisian hospital. Twenty-three such isolates, as well as 25 pristinamycin-susceptible Staphylococcus epidermidis isolates, were collected and typed by analyzing various bacterial constituents. Two structurally related plasmids of 7.3 and 14.3 kb, carrying the gene vga encoding resistance to pristinamycin, were detected in the 23 pristinamycin-resistant coagulase-negative staphylococci which were identified as S. epidermidis. Although related by numerous common characteristics, 20 of these 23 isolates could be divided into two types, A (17 isolates) and B (three isolates). These types were characterized on the basis of their plasmid contents and hybridization patterns obtained when the EcoRI-digested DNA was probed with plasmid pIP1551 containing an internal fragment of the insertion sequence IS256. These findings suggest that the dissemination of type A epidemic strains was, in large part, responsible for the outbreak.

Base Sequence↗
PubMed2002

In catheter infections by Staphylococcus epidermidis the intercellular adhesion (ica) locus is a molecular marker of the virulent slime-producing strains.

Recently, it has been shown that S. epidermidis includes the ica operon responsible for slime production. In the operon, coexpression of icaA and icaD genes is required for full slime synthesis. In this study, the presence of icaA and icaD genes was searched for in a collection of 100 Staphylococcus epidermidis strains from catheter-associated infections by an original PCR method. Another 51 strains of S. epidermidis isolated from the skin or mucosa of healthy volunteers (26 of which derived from the hospital staff) were also investigated. Slime-forming ability was phenotypically tested on Congo red agar plates. Sixty-one percent of the strains isolated from catheters were icaA- icaD-positive and produced slime. The results indicate that detection of ica genes by a PCR method is a useful tool for prompt identification of S. epidermidis slime-forming strains isolated from catheter-related infections. Also, three saprophytic strains from the hospital staff were positive for slime synthesis and presence of ica genes, suggesting a potential diffusion of slime-forming strains in hospital personnel.

Biomarkers↗
PubMed1991

Antibiotic susceptibility of coagulase-negative staphylococcal blood isolates with special reference to adherent, slime-producing Staphylococcus epidermidis strains.

The epidemiologic relationship between slime-producing coagulase-negative staphylococci and antibiotic resistance was evaluated by analyzing the in vitro susceptibility of 278 blood isolates to 10 different antimicrobial agents. The strain collection consisted of 60 coagulase-negative staphylococcal septicemia isolates, recovered from at least 2 successive blood cultures from 59 septicemia patients and 218 single blood isolates defined as insignificant. When the slime-producing Staphylococcus epidermidis isolates were compared with all non-slime-producing S. epidermidis isolates, the slime-producing isolates exhibited higher MIC50 and/or MIC90 values than the non-slime-producing isolates, and were also more commonly resistant against many of the antimicrobials tested. The association between slime production and resistance against tobramycin, gentamicin and rifampicin was statistically significant (p less than 0.05). A similar finding was observed among the S. epidermidis septicemia isolates when they were analyzed separately from the single (suspected blood contaminant) S. epidermidis isolates. Further characterization of the septicemia isolates revealed that the positive correlation between slime production and antibiotic resistance reflected, to some extent, multiresistance of 1 epidemic slime-producing S. epidermidis strain. No difference in resistance was observed between the slime-producing and non-slime-producing single S. epidermidis blood isolates.

Anti-Bacterial Agents↗
PubMed1975

New bacteriophages of Staphylococcus epidermidis.

Fifty-six phages designated the U-series and 34 phages designated the Ph-series were carefully examined. The spectrum of activity was established for 183 strains of Staphylococcus epidermidis from different countries and for 258 strains of Staphylococcus aureus. All 90 phages were active against strains of both species, but some differences in sensitivity were noted. Sixteen of the 90 phages were selected for phage typing of S. epidermidis. With use of a routine test dilution of phage (the highest dilution that yields confluent lysis of the propagation strain), 71.6% of 183 coagulase-negative staphylococci tested were sensitive to the phages; 42 phage patterns were observed. The results indicate that phage typing of S. epidermidis can be recommended for epidemiological and ecological purposes.

Humans↗
PubMed1995

Elucidation of the primary structure of the lantibiotic epilancin K7 from Staphylococcus epidermidis K7. Cloning and characterisation of the epilancin-K7-encoding gene and NMR analysis of mature epilancin K7.

Lantibiotics are bacteriocins that contain unusual amino acids such as lanthionines and alpha, beta-didehydro residues generated by posttranslational modification of a ribosomally synthesized precursor protein. The structural gene encoding the novel lantibiotic epilancin K7 from Staphylococcus epidermidis K7 was cloned and its nucleotide sequence was determined. The gene, which was named elkA, codes for a 55-residue preprotein, consisting of an N-terminal 24-residue leader peptide, and a C-terminal 31-residue propeptide which is posttranslationally modified and processed to yield mature epilancin K7. In common with the type-A lantibiotics nisin A and nisin Z, subtilin, epidermin, gallidermin and Pep5, pre-epilancin K7 has a so-called class-Al leader peptide. Downstream and upstream of the elkA gene, the starts of two open-reading-frames, named elkP and elkT, were identified. The elkP and elkT genes presumably encode a leader peptidase and a translocator protein, respectively, which may be involved in the processing and export of epilancin K7. The amino acid sequence of the unmodified pro-epilancin K7, deduced from the elkA gene sequence, is in full agreement with the amino acid sequence of mature epilancin K7, determined previously by means of NMR spectroscopy [van de Kamp, M., Horstink, L. M., van den Hooven, M. W., Konings, R. N. M., Hilbers, C. W., Sahl, H.-G., Metzger, J. W. & van de Ven, F. J. M. (1995) Eur. J. Biochem. 227, 757-771]. The first residue of mature epilancin K7 appears to be modified in a way that has not been described for any other lantibiotic so far. NMR experiments show that the elkA-encoded serine residue at position +1 of pro-epilancin K7 is modified to a 2-hydroxypropionyl residue in the mature protein.

Amino Acid Sequence↗
PubMed2005

Subclinical mastitis and antimicrobial susceptibility of Staphylococcus caprae and Staphylococcus epidermidis isolated from two Italian goat herds.

A total of 156 goats from 2 commercial dairy goat farms were monitored for intramammary infections during an entire lactation. Most of the infections (80.7%) observed were due to coagulase-negative staphylococci (CNS) species. In herd 1, nearly all of the infections (96%) were due to CNS species, with Staphylococcus caprae (SCAP) being the most common specific pathogen observed, accounting for about 43% of the infections. In herd 2, the proportion of the infections due to CNS was 67% and Staphylococcus epidermidis (SEPI) was the most common pathogen (48% of infections) and SCAP was not present. Linear somatic cell scores (SCS) were greater in milk from infected udder halves, with an average difference of 0.78 SCS. The SCS for infected udder halves was greater than noninfected for all CNS species, although differences among species were observed. The ranking across CNS species was SCAP > other CNS > SEPI > no infection. However, infections by SEPI tended to be more persistent. Increased SCS was associated with a statistically significant decrease in milk yield, but no effect was observed for intramammary infections (IMI). Ninety-seven isolates of CNS (53 SCAP and 44 SEPI) were investigated for in vitro susceptibility to several antimicrobial agents. Benzylpenicillin was the most effective antimicrobial agent against SCAP and SEPI. A concentration of 0.05 microg/mL was sufficient to inhibit growth of 90% of SCAP colonies, and 0.10 microg/mL yielded a similar effectiveness for SEPI. Amoxicillin and the combination of amoxicillin and clavulanic acid were only slightly less effective. Tetracycline (62.5 microg/mL) and tilmicosin (500 microg/mL) were the least effective treatments for SEPI and SCAP, respectively.

Amoxicillin↗