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PubMed2005

Bacterial insertion sequence IS256 as a potential molecular marker to discriminate invasive strains from commensal strains of Staphylococcus epidermidis.

The skin commensal Staphylococcus epidermidis has become one of the most important causative agents of nosocomial infections associated with medical devices. Differentiation between invasive S. epidermidis and its commensal counterpart is crucial for clinical decision making. The ica gene locus, which codes for production of polysaccharide intercellular adhesion (PIA), represents a frequently suggested molecular marker for infectivity. Our data demonstrated that production of PIA was not significantly increased among clinical strains, which may explain the controversial results obtained previously on the correlation of ica presence with origin from infection. Therefore, in this study, we attempted to identify novel genes discriminating between invasive and commensal strains based on the comparison of genome sequences. Our results indicated that the bacterial insertion sequence element IS256 occurred significantly more frequently in strains of clinical origin. Importantly, IS256 might thus constitute a molecular marker to discriminate invasive strains from commensal strains of S. epidermidis.

Carrier State↗
PubMed1990

Immunochemical analysis of the extracellular slime substance of Staphylococcus epidermidis.

To analyze immunochemically the extracellular slime substance of Staphylococcus epidermidis, rabbits were repeatedly immunized with the crude slime extract isolated from an adherent, slime-producing clinical Staphylococcus epidermidis strain. Immunoelectron microscopy demonstrated that the target antigens of the resulting antibodies were located in the extracellular slime-like layer of bacterial cells. When these target antigens were characterized by immunoblotting, a variety of antigens were detected, including many with molecular masses higher than 80 kilodaltons and also a predominant one with a molecular mass of 30 kilodaltons. No characteristic differences were observed between the tube adherence test positive and negative Staphylococcus epidermidis isolates. Although there was variation in the number and intensity of high molecular mass antigens, such variations did not correlate with the tube adherence test. Of the 110 Staphylococcus epidermidis isolates studied, 106 (96%) expressed the 30-kilodalton antigen. This component was found in no other Staphylococcus spp. examined in the study. The bacterial component was not only easily detached from bacterial cells but also water-soluble, characteristics implicating a slime-like nature. Further studies are needed to definitively establish the origin and nature of the 30-kilodalton Staphylococcus epidermidis-specific component, and determine its potential benefit as a diagnostic tool.

Antibodies, Bacterial↗
PubMed1992

Purification and characterisation of elastase from Staphylococcus epidermidis.

An elastase of Staphylococcus epidermidis was purified by ion exchange chromatography on CM-Sepharose and characterised. Its M(r) is c. 21 kDa, its optimal temperature for activity is 42 degrees C and the pH optimum is 6.8. The enzyme is activated by cysteine and other SH-donators and inhibited by L-trans-epoxy-succinylleucylamido-(4-guanidino)butane (E64), an inhibitor of cysteine proteases, but not by 3,4-dichloroisocoumarin (3,4-DCI), an inhibitor of serine proteases. This finding suggests that the elastase of S. epidermidis is a cysteine protease. Because S. epidermidis elastase degrades human sIgA, IgM, serum albumin, fibrinogen, and fibronectin, this enzyme may be regarded as a virulence factor.

Chromatography, Ion Exchange↗
PubMed2001

Binding of human clusterin by Staphylococcus epidermidis.

To hypothesise that Staphylococcus epidermidis may possess clusterin receptor(s), bacterial binding of human clusterin was determined. In a fluid phase, the binding was markedly influenced by culture medium and three out of 12 S. epidermidis strains grown on ISO-sensitest agar expressed clusterin-binding ability. S. epidermidis J9P, selected for further study, showed saturable binding of iodine-labelled clusterin, and the binding was only inhibited by unlabelled clusterin. The binding was sensitive to protease treatment. Scatchard plot indicated one single class of binding sites (K(d)=104.2 nM). None of the S. epidermidis strains bound immobilised clusterin. These data imply that ligand-receptor interaction exists between S. epidermidis and clusterin in fluid phase, but the domain(s) recognised by bacteria may have been occluded when clusterin was adsorbed on a surface.

Clusterin↗
PubMed1999

Molecular characterization and antibiotic susceptibilities of ocular isolates of Staphylococcus epidermidis.

Nineteen isolates of Staphylococcus epidermidis from patients with ocular infections were analyzed. Patients were selected in retrospect, by choosing cases in which S. epidermidis was the sole isolate. Twelve different patterns were obtained after hybridization with a probe with high-level homology to insertion sequences found in S. epidermidis. Susceptibilities to penicillin, methicillin, gentamicin, tetracycline, erythromycin, ciprofloxacin, vancomycin, and teicoplanin were determined. Six strains were resistant to three or more antibiotics.

Anti-Bacterial Agents↗
PubMed2000

Molecular characterization and LD(50) identify virulent isolates of Staphylococcus epidermidis from adult sepsis.

Staphylococcus epidermidis plays an important role in infections of patients with implanted prosthetic devices. The exact clinical significance of recovered S. epidermidis from clinical specimens is difficult to assess, as they are inhabitants of the normal skin. In this study, 11 adults with clinical sepsis and blood cultures that grew only S. epidermidis were the host population. Bacterial virulence in vivo was determined by using the mouse LD(50) assay where the intravenous lethality was determined for each patient isolate. Bacterial dose (CFU x 10(9)) that produced lethality in 50% of the animals at 12 h was the value used for comparison. Restriction fragment length polymorphism (RFLP) analysis of chromosomal DNA by pulsed-field gel electrophoresis (PFGE) was used for identification of individual strains and their clonal organization. Confirmation of species assignment was done by RFLP analysis of 16S + 23S rRNA gene regions (ribotyping). Plasmid profile analysis was also conducted. Four of 11 blood isolates from adults with S. epidermidis sepsis had indistinguishable or closely related DNA patterns and were considered clone A. The same clone was previously seen to account for the majority of sepsis in a neonatal intensive care unit. There were significant differences in virulence characteristics of the S. epidermidis isolates. Clone A isolates produced lethality by LD(50) in mice at a dose averaging 2.35; clone B isolate at a dose of 2.54, and the remaining isolates, representing six distinct clones, were lethal to mice at significantly larger doses (3.51-5.17, average 4.16). These data suggest that individual clones of S. epidermidis isolated from septic adults have detectable differences in virulence as defined by an animal bioassay, and the more virulent clone is widespread.

APACHE↗
PubMed2004

Impact of surface coating on the adherence of slime producing and nonproducing Staphylococcus epidermidis.

The ability of Staphylococcus epidermidis to grow in the form of a biofilm not only facilitates its persistence in the host, but also allows it to survive at antibiotic concentrations several orders higher than the Minimum Inhibitory Concentration (MIC). We evaluated different surface treatments of hardened polystyrene in order to develop a model system for growth of S. epidermidis as a biofilm. We assayed for biofilm growth of S. epidermidis clinical isolates on unmodified polystyrene, on polystyrene modified by chemical abrasion and on polystyrene modified by sulfonation, using either Tryptic Soya Broth or Brain Heart Infusion as a growth medium. We concluded that sulfonated polystyrene and Brain Heart Infusion provided the best growth system for predicting the ability of a clinical isolate to form biofilm (Akaike value 23.680). Using this method, biofilm formation was detected in 14 (70%) of ica-positive strains and negative in 16 (80%) of ica-negative strains.

Bacterial Adhesion↗
PubMed1988

Current thoughts on Staphylococcus epidermidis in vascular surgery.

Staphylococcus epidermidis (CNS) is a major cause of infection in peripheral vascular surgery. It occurs as commonly in vascular prostheses as in orthopaedic, cardiac and neurosurgical implants. Greater awareness of the possible presence of CNS in initially indolent infections, particularly in the groin, is necessary. More rapid isolation and identification techniques to separate the contaminant from the pathogenic CNS are needed. It seems that better preoperative antiseptic care of vascular patients may reduce the tendency for even 24 h cephalosporin prophylaxis to encourage the emergence of resistant CNS strains.

Anti-Bacterial Agents↗
PubMed2002

Combinations of lysostaphin with beta-lactams are synergistic against oxacillin-resistant Staphylococcus epidermidis.

Oxacillin-resistant Staphylococcus aureus is rapidly killed by the endopeptidase lysostaphin, and the addition of beta-lactam antibiotics provides synergistic killing. We investigated the possibility that beta-lactams given in combination with lysostaphin would improve the activity of lysostaphin against oxacillin-resistant Staphylococcus epidermidis (ORSE), which is normally less susceptible to lysostaphin. Checkerboard synergy testing was performed for lysostaphin given in combination with oxacillin against 10 ORSE isolates for which the lysostaphin MICs were > o r= 8 microg/ml. The fractional inhibitory concentration index ranged from 0.0234 to 0.2656, indicating synergy, which was confirmed in growth curve experiments. In the rabbit model of experimental aortic valve endocarditis using an ORSE strain, the combination of lysostaphin and nafcillin was as effective as vancomycin alone and significantly better than lysostaphin or nafcillin alone. We conclude that beta-lactam antibiotics given in combination with lysostaphin are synergistic against many strains of ORSE.

Animals↗
PubMed1993

[Experimental studies on urinary tract infection--bladder and kidney lodgement in mice by strains of Staphylococcus epidermidis].

Eight strains of Staphylococcus epidermidis were isolated from clinical specimens and were subjected to the tests for encapsulation, slime-production, mouse-virulence, capsular-typing and adherence to the plastic surface, the renal cells and the bladder epithelial cells. With the intraperitoneal injection of these strains into mice, three encapsulated strains were observed in mouse-virulent, while two slime-producing and three unencapsulated strains were mouse-avirulent. In ultra-thin sections of mouse-virulent strains, capsules were demonstrated by electron microscopy, however no capsule was seen around the walls of mouse-avirulent strains. On the other hand, slime-producing strains were shown to have higher adherence rate to plastic surface, compared to encapsulated strains. The direct adherence rate to the bladder epithelial cells was greater in the encapsulated strains than the slime-producing strains, although there was no difference to the renal cells. Also, cell suspension containing 10(7) colony forming units of these strains were injected intravenously or intravesically into mice. Of these encapsulated strains showed kidney and bladder lodgement with in 28 and 21 days after intravesical injection, respectively, although slime-producing and unencapsulated strains could only be obtained for 7 days in the kidney and 3 days in the bladder. However, there was no difference in the internal organs lodgement of the strains after intravenous injection into mice. These experimental results suggested that the encapsulation of the strains would be an important factor for bladder lodgement, however, significant effects were not observed with the slime-producing and unencapsulated strains.

Animals↗
PubMed2002

icaR encodes a transcriptional repressor involved in environmental regulation of ica operon expression and biofilm formation in Staphylococcus epidermidis.

Biofilm formation in Staphylococcus epidermidis is dependent upon the ica operon-encoded polysaccharide intercellular adhesin, which is subject to phase-variable and environmental regulation. The icaR gene, located adjacent to the ica operon, appears to be a member of the tetR family of transcriptional regulators. In the reference strain RP62A, reversible inactivation of the ica operon by IS256 accounts for 25 to 33% of phase variants. In this study, icaA and icaR regulation were compared in RP62A and a biofilm-forming clinical isolate, CSF41498, in which IS256 is absent. Predictably, ica operon expression was detected only in wild-type CSF41498 and RP62A but not in non-IS256-generated phase variants. In contrast, the icaR gene was not expressed in RP62A phase variants but was expressed in CSF41498 variants. An icaR::Em(r) insertion mutation in CSF41498 resulted in an at least a 5.8-fold increase in ica operon expression but did not significantly alter regulation of the icaR gene itself. Activation of ica operon transcription by ethanol in CSF41498 was icaR dependent. In contrast, a small but significant induction of ica by NaCl and glucose (NaCl-glucose) was observed in the icaR::Em(r) mutant. In addition, transcription of the icaR gene itself was not significantly affected by NaCl-glucose but was repressed by ethanol. Expression of the ica operon was induced by ethanol or NaCl-glucose in phase variants of CSF41498 (icaR+) but not in RP62A variants (icaR deficient). These data indicate that icaR encodes a repressor of ica operon transcription required for ethanol but not NaCl-glucose activation of ica operon expression and biofilm formation.

Biofilms↗
PubMed2000

Rapid identification of Staphylococcus epidermidis.

During the collection of airborne bacteria in a museum in England some bacterial strains were isolated which due to their fatty acid profiles were clearly identified as members of the genus Staphylococcus. As fatty acid compositions of coagulase-negative staphylococci are very similar, differing only in quantities but not in qualities, further identification at the species level without a fatty acid database was not achieved. Investigation of the isolates using the Staph ID 32 API system resulted in an identification of the isolates as Staphylococcus epidermidis (probabilities of 79.7-95.5%). For further genotypic characterization of these isolates, some Staphylococcus epidermidis strains from different sources and the type strains of Staphylococcus aureus, Staphylococcus capitis, Staphylococcus epidermidis, Staphylococcus gallinarum, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus warneri and Staphylococcus xylosus were subjected to repetitive-sequence PCR, including enterobacterial repetitive intergenic consensus (ERIC) PCR, BOX-PCR and repetitive extragenic palindromic unit sequence (REP) PCR. ERIC- and BOX-PCR yielded a species-specific banding pattern for all Staphylococcus epidermidis strains. Furthermore, all staphylococcal reference strains investigated exhibited distinct banding patterns, clearly distinguishable from that of Staphylococcus epidermidis. No species-specific banding patterns could be observed after REP-PCR. As species identification of coagulase-negative staphylococci by fatty acid analyses and biochemical tests is known to be difficult ERIC- and BOX-PCR seem to be excellent tools for the identification of Staphylococcus epidermidis isolates.

Air Microbiology↗
PubMed1982

Common R-plasmids in Staphylococcus aureus and Staphylococcus epidermidis during a nosocomial Staphylococcus aureus outbreak.

During a 7-month period in 1978 to 1979, 31 patients and personnel at a Kentucky hospital were colonized or infected with a Staphylococcus aureus strain resistant to clindamycin, erythromycin, gentamicin, methicillin, penicillin, and tetracycline. S. epidermidis with similar antibiotic resistance patterns had been isolated in this hospital in the year before the S. aureus outbreak. A 32-megadalton R-plasmid, pUW3626, mediating resistance to penicillin and gentamicin, was present in these isolates and in coisolated S. epidermidis from the same outbreak. By colony hybridization, pUW3626 was homologous to gentamicin R-plasmids from staphylococci isolated in other geographic areas. Our studies suggest that the emergency of antibiotic resistance in S. Aureus may result from genetic transfer from S. epidermidis as well as from the interhospital spread of resistant staphylococci.

Anti-Bacterial Agents↗
PubMed1990

Neutrophil chemotactic activity of peptidoglycan. A comparison between Staphylococcus aureus and Staphylococcus epidermidis.

The ability of peptidoglycan from Staphylococcus epidermidis and Staphylococcus aureus to generate in human serum chemoattractant for peripheral blood neutrophils was studied. It was shown that PG from the two bacteria was able to induce chemotactic activity in normal human serum. Sonication of PG was required to generate this activity. Very little or no activity was generated in heat-treated or C5-deficient human serum by PG, indicating that PG treatment of serum resulted in generation of chemoattractants by activation of complement. Kinetics studies employing C2-deficient or MgEGTA-chelated serum revealed that S. epidermidis induced chemotactic activity by activating the alternative complement pathway. The alternative complement activation induced by S. epidermidis occurred rapidly and was completed after 15 min, whereas S. aureus activated the alternative pathway much more slowly, with activation reaching a maximum at 60 min. The rapid activation of the alternative complement pathway by S. epidermidis PG may partly explain why this bacterium does not normally cause infections in healthy individuals.

Antigens, Bacterial↗
PubMed2005

Effects of controlled fibronectin surface orientation on subsequent Staphylococcus epidermidis adhesion.

Several bacterial species, including Staphylococcus aureus and Staphylococcus epidermidis (SE) are known to express cell receptors that bind specifically to surface immobilized or extracellular matrix ligands, such as the protein fibronectin (FN). Yet, few existing studies have examined the effect of protein surface orientation on bacterial adhesion. We report here a substratum modification protocol that allows for the specific orientation of FN molecules on a surface at known levels of surface coverage. Monoclonal antibodies (Mabs), specific to either the COOH-terminus or NH3-terminus of FN, are conjugated to biotin, then immobilized to streptavidin-coated glass substrata. Specific orientation of the bound FN molecules is verified using the same Mabs in an ELISA. Bacterial adhesion of Staphylococcus epidermidis (SE) to FN bound by either its C-terminus or its NH3-terminus was quantified in batch static adhesion assays. Results indicate an increase in SE adhesion to FN-coated surfaces when the FN is bound by its C-terminus (NH3-terminus free), indicating SE receptor-specific adhesion to the FN NH3-terminus. These studies demonstrate that antifibronectin monoclonal antibodies can be used to specifically bind and orient fibronectin on a surface. In addition, adhesion of SE to these model substrata can be controlled by the orientation of the protein.

Antibodies, Monoclonal↗
PubMed1984

Staphylococcus epidermidis septicemia in children with leukemia and lymphoma.

Staphylococcus epidermidis is emerging as a cause of morbidity and mortality in immunocompromised patients. From January 1980 through June 1982, there were 150 episodes of septicemia in 92 children with leukemia and lymphoma at Memorial Sloan-Kettering Cancer Center, New York. Staphylococcus epidermidis was the fourth most common organism isolated, responsible for 12.7% of all septicemic episodes. Only nine of 53 isolates were sensitive to methicillin; all were sensitive to vancomycin. Staphylococcus epidermidis septicemia was associated with immunosuppressive chemotherapy (94.7%); broad-spectrum antibiotics (79.0%); catheters and drains (73.7%); neutropenia (63.2%); skin or soft-tissue infections (42.1%); prior septicemia (42.1%); concurrent polymicrobial septicemia (21.1%); and prolonged hospitalization (mean, 39 days). Of 19 patients, two died. Increased awareness of the pathogenic potential of S epidermidis in children with hematologic malignancies and prompt alteration of therapy to an effective antimicrobial agent, in most cases vancomycin hydrochloride, is required when the organism is isolated in patients known to be at risk with clinical evidence of septicemia.

Adolescent↗