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PubMed2003

In vitro activity of allicin against Staphylococcus epidermidis and influence of subinhibitory concentrations on biofilm formation.

AIMS: The aim of this study is to determine the in vitro activity of allicin against Staphylococcus epidermidis and to evaluate the influence of allicin on biofilm formation. METHODS AND RESULTS: In vitro activity of allicin (diallyl thiosulphinate) against 38 strains of S. epidermidis was investigated. The activity of allicin was similar against S. epidermidis methicillin susceptible and methicillin resistant strains [minimum inhibitory concentration (MIC)90=8 mg l(-1)]. In general, subinhibitory concentrations (sub-MIC) of allicin diminished biofilm formation in the five strains analysed. CONCLUSION: The results confirm the antibacterial effect of allicin. Sub-MICs of allicin also diminished the biofilm formations by S. epidermidis. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study shows that allicin is active in vitro against S. epidermidis and that sub-MICs of allicin may play a role in the prevention of adherence of this bacteria to medical devices.

Anti-Infective Agents↗

PubMed1989

Response of chronic renal failure mice to peritoneal Staphylococcus epidermidis challenge: impact of repeated peritoneal instillation of dialysis solution.

The effect of repeated instillation of peritoneal dialysis (PD) solution on the peritoneal clearance of a Staphylococcus epidermidis challenge was investigated in a mouse model of surgically induced chronic renal failure. For periods of up to 2 weeks, mice bearing peritoneal catheter implants underwent daily (3 mL) or twice daily (1.5 mL) peritoneal instillation of PD solution (4.25% dextrose) by transcutaneous injection into the catheter lumen. Peritoneal instillation of PD solution did not have a significant influence on the microbiological status of peritoneal structures of renal failure or sham-operated mice following experimental intracatheter S epidermidis inoculation with 10(6) colony-forming units (CFU) (assessment 48 hours after inoculation) or 10(8) CFU (assessment 1 week after inoculation). Microbiological and scanning electron microscopy (SEM) assessments of recovered peritoneal catheters demonstrated that S epidermidis remained associated with the catheter site after other peritoneal structures had become culture negative. SEM of the parietal peritoneum revealed striking morphologic alterations of the mesothelial surface as a consequence of daily PD solution infusion. In the absence of S epidermidis inoculation, repeated instillation of PD solution caused a marked acute peritoneal inflammation without evidence of a concomitant systemic inflammatory response. Furthermore, peritoneal inflammatory response to S epidermidis challenge was augmented by the infusion procedure. Concurrent assessments of inflammatory response and microbiological status revealed that, in spite of heightened peritoneal inflammatory response with peritoneal infusion, bacterial clearance from the catheter site was not improved. Although the animal preparation was limited to peritoneal infusion without drainage, the influence of repeated peritoneal instillation of hyperosmolar, acidic PD solution on the response of mice to S epidermidis challenge was successfully addressed.

Animals↗

PubMed1992

Frequencies of subpopulations of aminoglycoside- and vancomycin-resistant variants in Staphylococcus aureus and Staphylococcus epidermidis.

Selection and regrowth of resistant variants, which are present in low frequencies in the initial inoculum, were seen when large inocula of five strains of Staphylococcus aureus and four strains of Staphylococcus epidermidis were incubated in broth with amikacin, gentamicin, netilmicin and tobramycin. Statistical analysis showed no significant difference between the aminoglycosides in the selective growth of resistant variants (P > 0.5). Vancomycin differed significantly from the aminoglycosides in both the frequency of, and selection of resistant variants (P < 0.001). No bacteria resistant to > 1 x MIC was seen in the vancomycin-exposed cultures of S. aureus and S. epidermidis, while in most aminoglycoside-exposed cultures, bacteria resistant to 4-16 x MIC were seen.

Aminoglycosides↗

PubMed1988

Saliva inhibits the chemiluminescence response, phagocytosis, and killing of Staphylococcus epidermidis by polymorphonuclear leukocytes.

Saliva inhibited several functional properties of polymorphonuclear leukocytes (PMNs) from murine peritoneal exudate, namely, luminol-mediated chemiluminescence (CL) induced by either Staphylococcus epidermidis or formylmethionyl-leucyl-phenylalanine (FMLP), phagocytosis, and killing of bacteria in vitro. The concentration of saliva in the reaction mixture that caused a complete inhibition of the CL response of PMNs to both S. epidermidis and FMLP was 25%. However, there was no catalase or superoxide dismutase activity in saliva that could influence the CL response of PMNs. The production of superoxide by PMNs stimulated with S. epidermidis was assayed in the presence or absence of saliva by inhibition of the reduction of cytochrome c by superoxide dismutase. In the presence of 50% saliva, O2- generation by PMNs was only 7.3% of that observed in the absence of saliva. After gel filtration of salivary material through Sephadex G-25 or Sephacryl S-200, several fractions were obtained that inhibited the CL response of PMNs to either FMLP or S. epidermidis or to both. Two inhibitory fractions were analyzed. One contained immunoglobulin A, and the other contained a peptide which was composed of 14 different amino acids. The two fractions of high molecular weight included in the first protein peak of Sephacryl S-200 gel filtration were able to inhibit the CL response to S. epidermidis and to inhibit phagocytic activity, while fractions of low molecular weight (under 12,500 Mr) inhibited the CL response to FMLP and to S. epidermidis but did not inhibit phagocytic activity.

Catalase↗

PubMed2001

Biofilm formation by Staphylococcus epidermidis depends on functional RsbU, an activator of the sigB operon: differential activation mechanisms due to ethanol and salt stress.

Staphylococcus epidermidis is a common pathogen in medical device-associated infections. Its major pathogenetic factor is the ability to form adherent biofilms. The polysaccharide intercellular adhesin (PIA), which is synthesized by the products of the icaADBC gene cluster, is essential for biofilm accumulation. In the present study, we characterized the gene locus inactivated by Tn917 insertions of two isogenic, icaADBC-independent, biofilm-negative mutants, M15 and M19, of the biofilm-producing bacterium S. epidermidis 1457. The insertion site was the same in both of the mutants and was located in the first gene, rsbU, of an operon highly homologous to the sigB operons of Staphylococcus aureus and Bacillus subtilis. Supplementation of Trypticase soy broth with NaCl (TSB(NaCl)) or ethanol (TSB(EtOH)), both of which are known activators of sigB, led to increased biofilm formation and PIA synthesis by S. epidermidis 1457. Insertion of Tn917 into rsbU, a positive regulator of alternative sigma factor sigma(B), led to a biofilm-negative phenotype and almost undetectable PIA production. Interestingly, in TSB(EtOH), the mutants were enabled to form a biofilm again with phenotypes similar to those of the wild type. In TSB(NaCl), the mutants still displayed a biofilm-negative phenotype. No difference in primary attachment between the mutants and the wild type was observed. Similar phenotypic changes were observed after transfer of the Tn917 insertion of mutant M15 to the independent and biofilm-producing strain S. epidermidis 8400. In 11 clinical S. epidermidis strains, a restriction fragment length polymorphism of the sigB operon was detected which was independent of the presence of the icaADBC locus and a biofilm-positive phenotype. Obviously, different mechanisms are operative in the regulation of PIA expression in stationary phase and under stress induced by salt or ethanol.

Bacterial Proteins↗

PubMed2004

Structural elucidation of the extracellular and cell-wall teichoic acids of Staphylococcus epidermidis RP62A, a reference biofilm-positive strain.

The ability to adhere to artificial surfaces and form biofilms is considered as a virulence factor of Staphylococcus epidermidis, one of the major causes of nocosomial infections, especially those related to implanted medical devices. Cell-wall teichoic acid is known to play an important role in biofilm formation of staphylococci. The structure of the cell wall and extracellular teichoic acids of S. epidermidis RP62A, a reference biofilm-positive strain, was studied by NMR spectroscopy and capillary electrophoresis-mass spectrometry. Their structures were found to be a (1-->3)-linked poly(glycerol phosphate), substituted at the 2-position of glycerol residues with alpha-Glc, alpha-GlcNAc, D-Ala and alpha-Glc6Ala. D-Alanyl acylation of a sugar hydroxyl group seems to be a novel structural feature of teichoic acids from staphylococci.

Biofilms↗

PubMed1992

The effects of magnesium, calcium, EDTA, and pH on the in vitro adhesion of Staphylococcus epidermidis to plastic.

The effects of increasing concentrations of magnesium (Mg2+), calcium (Ca2+) or EDTA, and pH on the adhesion of five slime-positive strains of Staphylococcus epidermidis (Se+) to plastic were examined using an in vitro microwell assay. The addition of Mg2+ (as either MgSO4 or MgCl2) to the bacterial suspension in concentrations as low as 16 microM significantly enhanced the adhesion of all test strains to plastic (P < 0.001). Similarly, the addition of Ca2+ (as CaCl2) in concentrations exceeding 128 microM produced a significant increase in the adhesion of all test strains, but not to the extent observed with Mg2+. In contrast, the adhesion of all test strains to plastic was significantly reduced in the presence of EDTA at concentrations greater than 8 mM. However, EDTA in concentrations as low as 0.25 mM caused a significant decrease in the adhesion of two strains of Se+. The effect of pH was variable, but at a pH of 5.0 and 6.0, the adhesion of all test strains was significantly reduced compared to control values at a pH of 7.0. Two strains showed a significant increase in adhesion at a pH of 8.0. We also compared the effects of these variables on the adherence of a slime-negative phase variant derived from a slime-positive parent strain. With the exception of pH, the adhesion of both strains in response to increasing divalent cations or EDTA was similar. These data indicate that, in addition to hydrophobic interactions, ligand-specific binding, and slime production, pH and divalent cations, especially Mg2+, are important determinants of the adhesion of S. epidermidis to plastic surfaces in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Adhesion↗

PubMed2004

Temporin A soaking in combination with intraperitoneal linezolid prevents vascular graft infection in a subcutaneous rat pouch model of infection with Staphylococcus epidermidis with intermediate resistance to glycopeptides.

The efficacy of linezolid and temporin A in the prevention of prosthetic graft infection due to methicillin-resistant Staphylococcus epidermidis with intermediate resistance to glycopeptides was investigated in a subcutaneous rat pouch model. Linezolid and temporin A, alone or combined, greatly reduced the bacterial numbers compared to the effect with control drugs.

Acetamides↗

PubMed1977

Evaluation of a new bacteriophage set for typing of Staphylococcus epidermidis strains.

A new set of typing phages was evaluated for typing 821 Staphylococcus epidermidis strains isolated from normal human skin and from acne lesions. This method was compared with two different systems for biochemical differentiation of S. epidermidis. Distinct subgroups of cocci, which differed in phage susceptibility as well as in biochemical properties, were found. A tentative subdivision of S. epidermidis strains by use of 16 phages arranged into four groups is proposed, together with additional biochemical differentiation of non-typable strains.

Acne Vulgaris↗

PubMed2004

Penetration of fusidic acid and rifampicin into cerebrospinal fluid in low-grade inflammatory meningitis caused by Staphylococcus epidermidis.

Cerebrospinal fluid (CSF) concentration-time curves of rifampicin and fusidic acid were studied in a patient with post-operative meningitis caused by Staphylococcus epidermidis. The patient was treated with this combination of antimicrobial agents because of a severe hypersensitivity reaction to vancomycin. Peak CSF concentrations of rifampicin exceeded the MIC by > 60-fold, while those of fusidic acid just reached the MIC. CSF concentrations of fusidic acid were relatively stable within the range reported for patients with uninflamed meninges, but serum levels were surprisingly low. An increase in the metabolism of fusidic acid induced by rifampicin cannot be excluded.

Anti-Bacterial Agents↗

PubMed1993

[Absence of distinctive characteristics between Staphylococcus epidermidis strains responsible of non-hospital infectious endocarditis and commensal strains].

In order to recognize particular characteristics of pathogenic strains, epidemiologic markers of 27 Staphylococcus epidermidis strains (9 pathological and 18 commensal) were studied. Nine strains were responsible of infective endocarditis (8 on native valves, and 1 on prosthetic valve). No case occurred after admission to hospital or surgery. Eighteen commensal strains were isolated from control subjects who had had no contact with the hospital environment and who had not received a recent antibiotic treatment. The microbiological characteristics were so diverse that no differentiation between the pathogenic strains and commensal strains could be done and no particular pathogenic clone was recognized.

Anti-Bacterial Agents↗

PubMed1983

Population analysis in strains of Staphylococcus aureus and Staphylococcus epidermidis. II. Cefuroxime and cefotaxime.

Population analyses of susceptibility to cefuroxime and cefotaxime in penicillin-susceptible, penicillin-resistant, and methicillin-resistant strains of Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) were carried out. All strains were clinical isolates. Both antibiotics were shown to be more penicillinase-stable than cephalothin in studies of the penicillin-resistant strains of S. aureus, but less stable than methicillin. The studies of penicillin-resistant strains of S. epidermidis showed no differences in penicillinase-stability between cephalothin and the new cephalosporins. From the methicillin-resistant strains of S. aureus and S. epidermidis it was possible to select highly-resistant mutants against both antibiotics with a frequency of c. 10(-5) although MIC determinations had shown the strains to be susceptible.

Cefotaxime↗

PubMed2005

The product of the qacC gene of Staphylococcus epidermidis CH mediates resistance to beta-lactam antibiotics in gram-positive and gram-negative bacteria.

We have characterized a natural isolate of Staphylococcus epidermidis resistant to heavy metals that carries a small 2391-bp plasmid, pSepCH, encoding the qacC gene. The S. epidermidis qacC gene confers resistance to a number of beta-lactam antibiotics and to ethidium bromide in its natural host and in Escherichia coli K12 and Salmonella enterica sv. Typhimurium. This is the first communication of a small multidrug resistance (SMR) pump involved in resistance to beta-lactam antibiotics. Experiments using tolC, ompW and ompD mutant strains of S. Typhimurium demonstrated that the beta-lactam antibiotic resistance conferred by this pump does not depend on these outer membrane proteins.

Anti-Bacterial Agents↗

PubMed1987

Rapid identification of Staphylococcus epidermidis.

A panel of Minitek sugar disks, consisting of trehalose, mannitol, xylose, and sucrose, was evaluated for its ability to identify blood culture isolates of Staphylococcus epidermidis (SE). Using a heavy suspension of organism in Mueller-Hinton broth, 50 microL was pipetted onto each disk in wells of a flat-bottomed microtiter tray. The tray was covered, incubated in a moist chamber in non-CO2 at 35 degrees C, and examined after 5 and 24 hours. A color change of yellow or orange was positive; no color change (red) was negative. Expected reactions for SE were as follows: negative trehalose, mannitol, and xylose; positive, sucrose. On evaluation of 227 coagulase-negative staphylococci (CNS) at 5 and 24 hours, the panel had a sensitivity of 94 and 96%, specificity of 92 and 89%, predictive value of positive tests of 97 and 96%, and predictive value of negative tests of 84 and 87%. This panel offered an inexpensive and convenient method for differentiating SE from the other CNS in five hours.

Alkaline Phosphatase↗

PubMed1999

Identification and partial characterisation of an extracellular activator of fatty acid modifying enzyme (FAME) expression in Staphylococcus epidermidis.

Fatty acid modifying enzyme (FAME) is an extracellular enzyme that inactivates bactericidal fatty acids by esterifying them to cholesterol. Inactivation of these fatty acids may allow Staphylococcus epidermidis to live for long periods of time on the skin. This study describes the identification and partial characterisation of an extracellular activator of FAME production. Addition of FAME-free concentrated culture filtrate (activator) to S. epidermidis cultures (OD600 = 0.05) caused a 3-5-fold increase in FAME activity. Addition of the activator did not increase the amount of exopolysaccharide produced by S. epidermidis. The mol. wt of this activator was <3000 kDa and it was quite resistant to boiling. Treatment of the activator with proteinase K did not destroy its ability to induce FAME expression. Addition of S. aureus activator to S. epidermidis cultures also increased FAME expression. However, when S. epidermidis activator was added to S. aureus cultures no increase or inhibition in FAME production was observed.

Acyltransferases↗

PubMed1996

Use of cleaved amplified polymorphic sequences to distinguish strains of Staphylococcus epidermidis.

We examined the utility of a PCR-based method termed cleaved amplified polymorphic sequences (CAPS) to type 35 well-characterized isolates of Staphylococcus epidermidis. The results were compared with detailed epidemiologic information and typing obtained by using pulsed-field gel electrophoresis (PFGE). To identify CAPS markers for this study, eight pairs of oligonucleotide primers corresponding to five previously sequenced S. epidermidis genes were synthesized and then used to amplify DNA sequences from the S. epidermidis strains by using PCR. Amplified products were reproducibly obtained for seven of eight primer pairs from chromosomal DNA of 33 of the 35 isolates. Seven restriction site polymorphisms were found in five of the amplified products when they were subjected to digestion with a panel of restriction endonucleases. Each fragment-enzyme combination that was polymorphic demonstrated only two alleles in the 33 S. epidermidis isolates analyzed, corresponding to the presence or absence of a single restriction site. Overall, five distinct combinations of alleles were detected and were designated CAPS types A through E. There was a close correlation between the CAPS grouping, the epidemiologic information for the strains, and grouping by PFGE following SmaI digestion of chromosomal DNA. Although PFGE analysis was more discriminatory than typing based on the limited number of CAPS markers used in this study (isolates from the same CAPS group were sometimes distributed into more than one PFGE group), no isolates from the same PFGE group were found in more than one CAPS group. The CAPS procedure was highly reproducible, in contrast to published experience with arbitrarily primed PCR. These preliminary data suggest that CAPS represents a PCR-based technique for strain typing that is highly reproducible, rapid, utilizes widely available technologies, and provides results that are relatively easy to interpret and express.

Bacterial Typing Techniques↗

PubMed2000

Identification of three essential regulatory gene loci governing expression of Staphylococcus epidermidis polysaccharide intercellular adhesin and biofilm formation.

The formation of adherent multilayered biofilms embedded into a glycocalyx represents an essential factor in the pathogenesis of Staphylococcus epidermidis biomaterial-related infections. Using biofilm-producing S. epidermidis 1457 and transposon Tn917 carried on plasmid pTV1ts, we isolated nine isogenic biofilm-negative transposon mutants. Transduction by S. epidermidis phage 71 was used to prove the genetic linkage of transposon insertions and altered phenotypes. Mapping of the different transposon insertions by Southern hybridization and pulsed-field gel electrophoresis indicated that these were inserted in four unlinked genetic loci. According to their phenotypes, including quantitative differences in biofilm production in different growth media, in the amount of the polysaccharide intercellular adhesin (PIA) produced, in the hemagglutination titers, and in the altered colony morphology, the mutants could be separated into four phenotypic classes corresponding with the genetic classes. Synthesis of PIA was not detectable with class I and II mutants, whereas the amount of PIA produced reflected the residual degree of biofilm production of class III and IV mutants in different growth media. Chromosomal DNA flanking the transposon insertions of five class I mutants was cloned and sequenced, and the insertions were mapped to different locations of icaADBC, representing the synthetic genes for PIA. Expression of icaADBC from a xylose-dependent promoter in the different isogenic mutant classes reconstituted biofilm production in all mutants. In a Northern blot analysis no icaADBC-specific transcripts were observed in RNA isolated from mutants of classes II, III, and IV. Apparently, in addition to icaADBC, three other gene loci have a direct or indirect regulatory influence on expression of the synthetic genes for PIA on the level of transcription.

Adhesins, Bacterial↗

PubMed1993

Anomalous growth of Staphylococcus epidermidis in the presence of Silastic and glycopeptide antibiotics.

In the presence of supra-inhibitory concentrations of the glycopeptide antibiotics vancomycin and teicoplanin, biofilms of Staphylococcus epidermidis on a Silastic surface produce anomalous growth. This takes the form of macroscopic, cohesive aggregates of cocci bound together with slime. This phenomenon was intermittent, independent of antibiotic concentrations between 20 and 50 micrograms ml-1, occurred more often with teicoplanin, and was found both with slime-positive and slime-negative strains.

Microscopy, Electron, Scanning↗