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Plasmids determining enzymatic inactivation of lincomycin in Staphylococcus epidermidis. A preliminary report.

Coagulase-negative staphylococcal strains isolated from immunocompromised patients harboured in 41% non-MLS type lincomycin resistance determinant. Two kinds of resistance plasmids were detected in Staphylococcus epidermidis isolates of this origin in connection with lincomycin resistance. One of them represented by pBI1 and pBI84 (1.4 Md in size) determines no other resistance marker. The pBI109PGL plasmid determines also penicillinase production and aminoglycoside resistance, its molecular mass is 31 Md. Hybridization using linA, linA' and linA-like specific gene probes suggested occurrence of genes of lincosamid-inactivating enzyme belonging to the lin gene family but differring from the previously characterized determinants.

Conjugation, Genetic↗

Changing resistance to antimicrobial drugs, and resistance typing in clinically significant strains of Staphylococcus epidermidis.

Resistance to 11 antimicrobial drugs was assessed in 532 clinically significant strains of Staphylococcus epidermidis received in the years 1978, 1979 and 1980 and compared with that of strains collected in 1976 and 1977 for an international study. Only 14% of strains were sensitive to all the drugs tested. Resistance to gentamicin increased significantly from 7% to 33% during the study period. The degree of association between pairs of drugs was assessed. There was strong association between resistance to methicillin, aminoglycosides and macrolide antibiotics and only weak association between resistance to novobiocin, tetracycline, chloramphenicol and penicillin. Patterns of resistance were complex and may be useful as an accessory typing system.

Aminoglycosides↗

Comparative radiolabel and ATP analyses of adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to hydrogel lenses.

PURPOSE: A comparative assessment of the relative primary adhesion of cells of Pseudomonas aeruginosa, its lux transformant, and of slime and non-slime producing strains of Staphylococcus epidermidis to various hydrogel lenses was conducted. METHODS: Hydrogel lenses were placed in cell suspensions with bacteria with or without a tritiated leucine label. After 2 hours exposure, the lenses were rinsed vigorously and densities of cells on the lenses were determined via scintillation counting or ATP analyses. RESULTS: The radiolabel procedure indicated greater numbers than the ATP analyses of adhered cells per lens per common inoculum of all strains. All strains exhibited greater primary adhesion to the 38% water content contact lens, with the lux transformant of P. aeruginosa showing the greatest degree of adhesion. Primary adhesion by P. aeruginosa was typically at least ten-fold greater per lens than that observed with S. epidermidis. CONCLUSIONS: Both a radiolabel-cell procedure and bioluminescent ATP analyses demonstrated similar patterns of primary adhesion of bacteria to hydrogel lenses. Generally the adhesion increased inversely to the water content of the lenses but the chemical composition of the lenses, particularly surface properties, altered this pattern for lenses of similar water content. The magnitude of primary adhesion varied with the species and strain of bacterium.

Adenosine Triphosphate↗

Multiple-locus variable-number tandem repeat analysis for typing of Staphylococcus epidermidis.

We applied a high-resolution PCR-based typing method, multiple-locus variable-number tandem repeat analysis (MLVA), for discrimination of 30 multidrug-resistant clinical isolates of Staphylococcus epidermidis. The results of MLVA were congruent with results obtained by pulsed-field gel electrophoresis (PFGE). MLVA generated discrete character data, and its discriminatory capacity was comparable to that of PFGE.

Bacterial Typing Techniques↗

Treatment and prevention of Staphylococcus epidermidis experimental biomaterial-associated infection by bactericidal peptide 2.

Biomaterial-associated infections (BAI) are the major cause of failure of indwelling medical devices and are predominantly caused by staphylococci, especially Staphylococcus epidermidis. We investigated the in vitro microbicidal activity of the synthetic antimicrobial peptide bactericidal peptide 2 (BP2) and its efficacy in a murine model of S. epidermidis BAI. BP2 showed potent microbicidal activity at micromolar concentrations against a broad spectrum of microorganisms, including antibiotic-resistant bacteria. The staphylocidal activity of BP2 was not affected by physiological salt concentrations and was only slightly affected by the presence of human plasma. In the BAI model, injection of BP2 (5 mg/kg of body weight) 1 h after challenge with S. epidermidis resulted in an 80% reduction in the number of culture-positive implants and a 100-fold reduction in survival of S. epidermidis in peri-implant tissue at 24 h postchallenge. When BP2 was injected along implants 3 h prior to bacterial challenge, the median numbers of CFU cultured from biomaterial implants and peri-implant tissue were reduced by 85% and 90%, respectively. In conclusion, BP2 has potent, broad-spectrum in vitro microbicidal activity and showed potent in vivo activity in a murine model of S. epidermidis biomaterial-associated infection.

Animals↗

Alteration of organized structure of biofilm formed by Staphylococcus epidermidis on soft contact lenses.

The effect of a nonsteroidal antiinflammatory drug commercially available in eye drop form (sodium diclofenac) was assayed for its ability to affect biofilms formed by clinical Staphylococcus epidermidis isolates. Biofilms produced by one strain positive for a slime-associated antigen, suggested to be expressed by more virulent strains, was not affected by sodium diclofenac treatment. On the other hand, biofilm produced by the slime-positive, antigen-negative strain showed dramatic alterations already after short treatments with sodium diclofenac as reported for salicylate and other nonsteroidal drugs. Such results suggest further investigation of the possible use of sodium diclofenac drops in the treatment of ophthalmic infections in soft contact lens wearers.

Anti-Bacterial Agents↗

Activity of eight antibacterial agents on Staphylococcus epidermidis attached to Teflon catheters.

The presence of a Teflon catheter had no effect on the in-vitro activity of a range of antibacterial agents against slime producing and non-producing Staphylococcus epidermidis strains as determined by a microdilution assay. The susceptibility of S. epidermidis attached to Teflon catheters for 6, 24 and 48 h was also evaluated. MICs for planktonic and attached bacteria were similar. When bacteria attached to Teflon for 6 h were used as inocula, MBC values increased 32-8192-fold for the antibacterial agents tested. Similar results were observed when bacteria attached for 24 and 48 h were used as inocula. The activity of a high concentration (16 x MBC) of these antimicrobial agents against S. epidermidis biofilms in Teflon catheters was evaluated; for five slime non-producing strains, the highest reduction (around 99%) in bacterial viability was produced by cloxacillin and teicoplanin; for the slime producers, the highest effect (99.5% reduction) was shown by amikacin, clindamycin cloxacillin and ciprofloxacin but all cases still showed bacterial counts higher than 10(3) cfu/catheter segment. It is concluded that adherence of S. epidermidis to Teflon catheters decreases the bactericidal activity of the antibacterial agents tested in vitro.

Anti-Bacterial Agents↗

Efficacy of ampicillin/sulbactam combination in experimental shunt infections caused by Staphylococcus epidermidis. A light and scanning electron microscope study.

In this study, the efficacy of ampicillin/sulbactam combination in reactions of periventricular tissue of the lateral ventricle induced by the presence of infected (Staphylococcus epidermidis) silicone rubber shunt tubing was examined by using light and scanning electron microscopy. It was demonstrated that reactive changes to implants had occurred in periventricular tissue in the control group. In infected shunt tubing without given prophylactic antibiotic group, generalized meningitis and ventriculitis, loss of integrity of ependymal cells, numerous inflammatory cells, bacterial colonies, exuda and even pus were seen. It was also shown that rarely inflammatory reactions, minimal disintegration of ependymal cells, no bacterial colonies, and phagocytes were present in the group which was given prophylactic ampicillin/sulbactam combination per and postoperatively. We think that ampicillin/sulbactam combination is very effective in prevention and treatment of shunt infections.

Ampicillin↗

Effect of subinhibitory concentrations of cefamandole and cefuroxime on adherence of Staphylococcus aureus and Staphylococcus epidermidis to polystyrene culture plates.

The ability of cefamandole and cefuroxime to inhibit adherence of staphylococci to polystyrene culture plates was tested in an in vitro assay using eight strains each of Staphylococcus aureus and Staphylococcus epidermidis. The results indicated that subinhibitory concentrations of cefamandole and cefuroxime altered the adherence ability of both staphylococcal species, inhibition of adherence being more marked in the presence of cefamandole. It may be important to consider antiadherence properties in association with bactericidal activity when selecting agents for antibiotic prophylaxis.

Bacterial Adhesion↗

Efficacy of polycationic peptides in preventing vascular graft infection due to Staphylococcus epidermidis.

A rat model was used to investigate the efficacy of two polycationic peptides, ranalexin and buforin II, in the prevention of vascular prosthetic graft infection due to methicillin-resistant Staphylococcus epidermidis with intermediate resistance to glycopeptides. The in vitro activity of the peptides was compared with those of vancomycin and teicoplanin by MIC determination and time-kill study. Moreover, the efficacy of collagen-sealed peptide-soaked Dacron was evaluated in a rat model of graft infection. Graft infections were established in the dorsal subcutaneous tissue of 120 adult male Wistar rats. The in vivo study included a control group, one contaminated group that did not receive any antibiotic prophylaxis and four contaminated groups that received an antibiotic-soaked graft. Experiments demonstrated that the activities of buforin II and ranalexin were greater than those of vancomycin and teicoplanin. Particularly, rats with buforin II-coated Dacron grafts showed no evidence of staphylococcal infection while, for the rats with ranalexin-, vancomycin- and teicoplanin-coated Dacron grafts, the quantitative graft cultures demonstrated bacterial growth (1.9 x 10(2) +/- 0.6 x 10(2) cfu/mL, 6. 2 x 103 +/- 1.9 x 10(3) cfu/mL and 5.1 x 10(4) +/- 4.8 x 10(3) cfu/mL, respectively). The study demonstrated that the use of peptide-soaked Dacron graft can result in significant bacterial growth inhibition and indicates that these compounds may be potentially useful in prosthetic surgery.

Animals↗

Commensal isolates of methicillin-resistant Staphylococcus epidermidis are also well equipped to produce biofilm on polystyrene surfaces.

OBJECTIVES: To study biofilm production and to detect icaAD, atlE and aap genes in 137 isolates of methicillin-resistant Staphylococcus epidermidis (MRSE) obtained from healthy individuals from the community (35 isolates), from hospitalized patients at the Antônio Pedro University Hospital (25 isolates) and from individuals from a home-care system (HCS; 77 isolates). METHODS: Biofilm production was determined in vitro using polystyrene inert surfaces. icaAD, atlE and aap genes were detected using PCR. Hybridization experiments were also carried out to confirm some PCR results. Antimicrobial susceptibility testing was carried out using the NCCLS methods. RESULTS: Although many of the commensal MRSE isolates produced biofilms, the percentage of biofilm producers was significantly higher (P = 0.0107) among hospital isolates (76%) than among isolates from the community (60%) and from the HCS (57%). An association was observed between multiresistance and biofilm production for isolates obtained from healthy individuals from the community and from household contacts from the HCS (P < 0.0001). The concomitant presence of the ica operon and atlE and aap genes was associated with the strong biofilm-producer phenotype (P < 0.0001). CONCLUSION: Because many of the commensal MRSE isolates obtained from nares produced biofilms and carried icaAD, aap and atlE genes, biofilms or such genetic elements should not be used as markers for clinical significance. The biofilm environment seems to increase genetic exchanges and hence may contribute to multiresistance phenotypes.

Anti-Bacterial Agents↗

Evidence for autolysin-mediated primary attachment of Staphylococcus epidermidis to a polystyrene surface.

Biofilm formation on a polymer surface which involves initial attachment and accumulation in multilayered cell clusters (intercellular adhesion) is proposed to be the major pathogenicity factor in Staphylococcus epidermidis foreign-body-associated infections. We have characterized two distinct classes of biofilm-negative Tn917 mutants in S. epidermidis affected in initial attachment (class A) or intercellular adhesion (class B). mut1 (class A mutant) lacks five surface-associated proteins with molecular masses of 120, 60, 52, 45 and 38 kDa and could be complemented by transformation with a 16.4 kb wild-type DNA fragment. The complemented mutant was able to attach to a polystyrene surface, to form a biofilm, and produced all of the proteins missing from mut1. Subcloning experiments revealed that the 60 kDa protein is sufficient for initial attachment. Immunofluorescence microscopy using an antiserum raised against the 60 kDa protein showed that this protein is located at the cell surface. DNA-sequence analysis of the complementing region revealed a single open reading frame which consists of 4005 nucleotides and encodes a deduced protein of 1335 amino acids with a predicted molecular mass of 148kDa. The amino acid sequence exhibits a high similarity (61% identical amino acids) to the atl gene product of Staphylococcus aureus, which represents the major autolysin; therefore the open reading frame was designated atlE. By analogy with the S. aureus autolysin, AtlE is composed of two bacteriolytically active domains, a 60 kDa amidase and a 52 kDa glucosaminidase domain, generated by proteolytic processing. The 120 kDa protein missing from mut1 presumably represents the unprocessed amidase and glucosaminidase domain after proteolytic cleavage of the signal- and propeptide. The 45 and 38kDa proteins are probably the degradation products of the 60 and 52 kDa proteins, respectively. Additionally, AtlE was found to exhibit vitronectin-binding activity, indicating that AtlE plays a role in binding of the cells not only to a naked polystyrene surface during early stages of adherence, but also to plasma protein-coated polymer surfaces during later stages of adherence. Our findings provide evidence for a new function of an autolysin (AtlE) in mediating the attachment of bacterial cells to a polymer surface, representing the prerequisite for biofilm formation.

Adhesins, Bacterial↗

In vitro synergy between cefepime and vancomycin against methicillin-susceptible and -resistant Staphylococcus aureus and Staphylococcus epidermidis.

The in vitro activity of cefepime combined with vancomycin was assessed by the chequerboard method against 35 clinical isolates of methicillin-susceptible (MSSA, n = 8) or -resistant (MRSA, n = 10) Staphylococcus aureus and methicillin-susceptible (MSSE, n = 9) or -resistant (MRSE, n = 8) Staphylococcus epidermidis and S. aureus ATCC 25923 (MSSA). The combination was synergic against 16 isolates and additive/indifferent against 20. For 10 of the clinical isolates (two MSSA, three MRSA, two MSSE, three MRSE) and the reference strain, the interaction of cefepime and vancomycin was also determined by the time-kill method. Except for one MRSA isolate, synergic killing was demonstrated with clinically achievable concentrations of vancomycin (0.5-1 mg/L) and cefepime (methicillin-susceptible isolates: 0.5-1 mg/L; methicillin-resistant isolates: 2-64 mg/L).

Anti-Bacterial Agents↗

A dual fluorescence technique for visualization of Staphylococcus epidermidis biofilm using scanning confocal laser microscopy.

A new dual fluorescence technique is described which, when combined with scanning confocal laser microscopy (SCLM), can be used to visualize the components of biofilm produced by Staphylococcus epidermidis. Chemostat cultures of RP62A (a well-characterized slime-producing strain of S. epidermidis) were used to produce mature biofilm on polyvinylchloride (PVC) disks immobilized in a modified Robbins device using a 'seed' and 'feed' model system. Serial horizontal and vertical optical thin sections, as well as three-dimensional computer reconstructions, were obtained on in situ biofilm using the dual fluorescence procedure. Bacteria were visualized by green autofluorescence excited at 488 nm with an Argon laser. Cell-associated and exocellular matrix material (slime) was visualized by red fluorescence excited at 568 nm with a Krypton laser after interaction of the biofilm with Texas Red-labeled wheat germ agglutinin which is a slime-specific lectin marker. Structural analysis revealed that the cocci grew in slime-embedded cell clusters forming distinct conical-shaped microcolonies. Interspersed open channels served to connect the bulk liquid with the deepest layers of the mature, hydrated biofilm which increased overall surface area and likely facilitated the exchange of nutrients and waste products throughout the biofilm. The combined dual fluorescence technique and SCLM is potentially useful as a specific noninvasive tool for studying the effect of antimicrobial agents on the process of biofilm formation and for the characterization of the architecture of S. epidermidis biofilm formed in in vivo and in vitro on medical grade virgin or modified inert polymer surfaces.

Biofilms↗

[Dose-dependent effect of penicillin on activity of metabolic enzymes in Staphylococcus epidermidis].

The study was concerned with investigation of the biochemical properties, antibiotic resistance and the effect of various doses of penicillin on the activity of metabolic enzymes in the bacterial cells of Staphylococcus epidermidis isolated from the pharynx mucosa of healthy subjects. The study revealed an increase in the aggressive properties of the representatives of the mouth normal microflora. It was also observed that the highest percentage of the staphylococcal isolates was resistant to beta-lactam antibiotics. The effect of various concentrations of penicillin on the microbial metabolism was shown to be directed at different targets. Penicillin intensified the aerobic processes and lipid synthesis in the bacterial cells. The reactions of the processes of the amino acid metabolism proceeded in different directions. Some concentrations of penicillin inhibited such processes.

Anti-Bacterial Agents↗

An in vitro model for studying the effects of slime and nonslime-forming Staphylococcus epidermidis contamination of intravenous catheters.

An in vitro model was developed to study the relationship between intravenous catheters, bacteria, and the subcutaneous tunnel. Studies of both slime-forming and nonslime-forming coagulase negative Staphylococcus epidermidis show that slime formation enhances capillary action of coagulase negative S. epidermidis. This offers a possible explanation of the increased virulence associated with slime-forming coagulase negative S. epidermidis in the clinical situation.

Agar↗

Levels of antibody to Staphylococcus epidermidis in patients with acne vulgaris.

Sera from 23 patients with acne vulgaris of varying degrees and sera from 15 patients with skin diseases other than acne were tested for antibody levels to Staphylococcus epidermidis by use of bacterial agglutination and agar-gel immunodiffusion. Antibody levels to S epidermidis varied from 0 to 1:160 in both the patients with acne and in the control groups. There was no correlation between the antibody level to S epidermidis and the degree of acne. In a previous investigation it was found that antibody levels to Corynebacterium acnes are significantly increased in serum from patients with papulopustular and cystic acne. Both S epidermidis and C acnes can frequently be isolated from lesions in acne. The fact that antibody levels are increased to C acnes but not to S epidermidis may indicate that the mere presence of an organism in the acne lesion is not sufficient stimulation for antibody formation. The increase of antibody to C acnes which was demonstrated previously in patients with severe acne vulgaris may therefore reflect a direct involvement of the organism in the acne process.

Acne Vulgaris↗