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PubMed2005

Genetic relatedness of Staphylococcus epidermidis from infected infants and staff in the neonatal intensive care unit.

BACKGROUND: The genetic relatedness of Staphylococcus epidermidis associated with infections in infants and cultured from the hands of nurses was assessed. METHODS: From March 2001 to January 2002, infections caused by S. epidermidis were prospectively monitored. Participating nurses had hand cultures performed quarterly following hand hygiene. Pulsed-field gel electrophoresis was performed to determine genetic relatedness of strains from infants and nurses. RESULTS: During the study period, S. epidermidis caused 42 of 143 (29%) and 26 of 100 (26%) infant infections and was cultured from the clean hands of 51 of 61 (84%) and 53 of 58 (91%) nurses in neonatal intensive care unit (NICU)-1 and NICU-2, respectively. Fifty-eight clones of S. epidermidis were identified among 173 isolates typed: 38 of 173 isolates (22%) were unique clones detected in a single infant (n=10) or nurse (n=28); 42 of 173 (24%) isolates were defined as belonging to small cluster clones (n=15), ie, were detected in 2 to 4 nurses and/or infants; and 93 of 173 (54%) isolates belonged to large cluster clones (n=4), ie, detected in 7 to 64 nurses and/or infants. CONCLUSIONS: These data suggested that most S. epidermidis isolates were shared between infants and nurses. Hand hygiene alone is inadequate to prevent S. epidermidis infections, and additional strategies are needed to prevent cross transmission in NICU populations.

Carrier State↗

PubMed2004

Effect of growth medium on hydrophobicity of Staphylococcus epidermidis.

The present study was undertaken to evaluate the effect of growth medium on expression of hydrophobicity of Staphylococcus epidermidis. A total of 24 hydrophobic isolates of S. epidermidis, determined by n-hexadecane adherence assay (HAA) earlier were included. Five different growth media: horse blood agar (HBA), brain heart infusion agar (BHIA), brain heart infusion broth (BHIB), tryptic soy broth (TSB) and proteose peptone broth (PPB) were used. All 24 isolates exhibited the reproducible hydrophobicity when grown on HBA; however, 20 (83.33%), 19 (79.16%), 15 (62.50%) and 13 (54.16%) isolates were found to be hydrophobic when grown in BHIA, BHIB, TSB and PPB, respectively. HBA was found to be the most suitable medium for detection of hydrophobicity of S. epidermidis followed by BHIA or BHIB.

Animals↗

PubMed1994

In vitro adhesion of Staphylococcus epidermidis on heparin-surface-modified intraocular lenses.

This quantitative study assessed the in vitro adhesion of Staphylococcus epidermidis on two types of intraocular lenses: conventional poly(methyl methacrylate) (PMMA) and heparin-surface-modified PMMA. Level adhesion was measured by microbiological turbidimetry. We also measured modifications in the bacterium's structural fatty acids after adhesion using gas chromatography.

Bacterial Adhesion↗

PubMed1986

Opsonic activity of intravenous immunoglobulin preparations against Staphylococcus epidermidis.

Peritoneal dialysis effluent collected from patients undergoing continuous ambulatory peritoneal dialysis had no opsonic activity against Staphylococcus epidermidis and contained low concentrations of IgG and C3 (roughly equal to those found in 0.5% normal human serum). An intravenous immunoglobulin preparation that showed no opsonic activity against the same organism, on its own or when added to balanced salt solution or peritoneal dialysis fluid, showed good activity when combined with peritoneal dialysis effluent. This was probably due to the presence of low concentrations of C3 in the effluent as prior heat inactivation at 56 degrees C for 30 minutes eliminated any opsonic activity in the immunoglobulin-dialysis effluent mixture. Examination of a range of immunoglobulin preparations showed that their opsonic activity for S epidermidis in the absence of complement varied considerably. Luminol dependent chemiluminescence was unsatisfactory as a method for detecting complement independent immunoglobulin mediated opsonisation. Intravenous immunoglobulin preparations may be useful in boosting the peritoneal defences of those patients undergoing continuous ambulatory peritoneal dialysis (CAPD) who suffer from repeated intraperitoneal infections.

Complement C3↗

PubMed1988

Comparison of cefazolin, cefamandole, vancomycin, and LY146032 for prophylaxis of experimental Staphylococcus epidermidis endocarditis.

We evaluated antibiotic prophylaxis in the rabbit model of experimental endocarditis with three strains of Staphylococcus epidermidis of differing susceptibility patterns. For the first strain, which was highly susceptible to methicillin and cephalosporins, vegetations grew S. epidermidis for all 15 untreated rabbits compared with 1 of 20 rabbits receiving cefazolin, 3 of 20 receiving cefamandole, none of 20 receiving vancomycin, and none of 20 receiving LY146032. For the second strain, which was methicillin resistant but cephalosporin susceptible, vegetations were positive for 14 of 15 untreated controls, 4 of 20 receiving cefazolin, 5 of 22 receiving cefamandole, none of 20 receiving vancomycin, and none of 20 receiving LY146032. For the third strain, which was methicillin resistant and only intermediately susceptible to cephalosporin antibiotics, vegetation cultures were positive for 15 of 17 untreated controls, 14 of 21 receiving cefazolin, 11 of 20 receiving cefamandole, 5 of 20 receiving vancomycin, and 0 of 22 receiving LY146032. In conclusion, these studies in the endocarditis model indicate that cefazolin and cefamandole have some protective value against certain strains of S. epidermidis. Vancomycin and LY146032, however, were more active than cephalosporins for all three strains included in this analysis. These findings support the need for trials of vancomycin and LY146032 prophylaxis in patients undergoing placement of prosthetic heart valves.

Animals↗

PubMed1986

Mucin production by Staphylococcus epidermidis. A virulence factor promoting adherence to vascular grafts.

The production of an exopolysaccharide (mucin) by some Staphylococcus epidermidis strains facilitates bacterial adhesion to prosthetic vascular grafts and may play an important role in adherence-mediated growth. An in vitro model was developed to measure the differential adherence of mucin-producing (RP-12) and nonmucin-producing (SP-2) S epidermidis strains onto expanded polytef and velour knitted Dacron graft material. After incubation in a 10(7)/mL suspension of organisms, graft specimens were repeatedly washed to remove nonadherent organisms and then sonicated to dislodge adherent organisms. Bacterial adherence was calculated from a quantitative culture of the sonication effluent. Both S epidermidis strains adhered in ten to 100 times greater numbers to the knitted Dacron graft material than to expanded polytef. The production of an exopolysaccharide by the RP-12 strain significantly increased adherence to both graft types compared with the SP-2 strain. The increased adherence of the RP-12 strain was inhibited by adding D-mannosamine to the inoculum. The in vitro model developed is well suited for further study of the mechanisms by which bacteria adhere to and colonize vascular grafts.

Adhesiveness↗

PubMed1980

Staphylococcus epidermidis endophthalmitis following intraocular lens implantation.

A 90-year-old man developed a hypopyon following cataract extraction with intraocular lens implantation. The hypopyon cleared with topical corticosteroid therapy but recurred whenever the corticosteroid therapy was reduced. At surgery for the removal of the intraocular lens an opaque anterior vitreous membrane was excised. Cultures of the anterior vitreous grew Staphylococcus epidermidis. The diagnosis was further confirmed by the histology of the anterior vitreous membrane, which showed Gram-positive cocci in the macrophages and polymorphonuclear leucocytes. This case shows that corticosteroids may completely mask an endophthalmitis from an organism of low virulence such as Staphylococcus epidermidis. Endophthalmitis from an organism of low virulence should be considered in any case of persistent postoperative inflammation.

Aged↗

PubMed1986

In vitro activity of coumermycin alone or in combination against Staphylococcus aureus and Staphylococcus epidermidis.

The in vitro activity of coumermycin was tested against oxacillin-susceptible and resistant strains of Staphylococcus aureus and Staphylococcus epidermidis, and compared with that of penicillin G, oxacillin, minocyclin, erythromycin, vancomycin, teicoplanin, rifampicin and LM 427. The MICs were measured using the agar dilution method with an inoculum of 10(5) cfu/spot. Coumermycin was the most active antibiotic with MIC90 of 0.025-0.2 mg/l. The MICs of coumermycin remained unchanged by further incubation for 48 h. The combination of coumermycin with ciprofloxacin, an inhibitor of subunit A of the DNA gyrase, was studied by the time-kill curve method and resulted in a synergistic effect when subinhibitory concentrations of either antibiotic were used. The combination of coumermycin with rifampicin or LM 427 was antagonistic.

Aminocoumarins↗

PubMed2002

Adherence of two strains of Staphylococcus epidermidis to contact lenses.

PURPOSE: To compare the adherence of biofilm-producer and nonbiofilm-producer Staphylococcus epidermidis in vitro to different soft contact lenses (CLs) to study its possible contribution to the pathogenesis of keratitis. METHODS: Strains of S. epidermidis slime-positive ATCC 35984 (biofilm-producer) and slime-negative ATCC 12228 (nonbiofilm-producer) were used with eight types of soft CLs from the four groups determined by the United States Food and Drug Administration (FDA), according to the ionicity and water content. The lenses were incubated overnight with the 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 were able to adhere to all CLs but at a lower level than slime-positive strains. There were significant differences in bacterial attachment among the four FDA groups. On the whole, there was higher bacterial adhesion to nonionic and low-water content materials. Contact lenses produced by soft molding were less adherent than CLs produced by either lathe-cutting or spin-casting. CONCLUSIONS: Bacterial biofilm favors bacterial adhesiveness and colonization of soft CLs. Bacterial attachment was less in soft molding CLs (etafilcon A), which provide a more homogeneous and smoother surface.

Bacterial Adhesion↗

PubMed1984

Staphylococcus epidermidis bacteremia in neonates: further observations and the occurrence of focal infection.

The frequency and clinical significance of Staphylococcus epidermidis isolates from blood cultures of neonates collected during a 17-month period in The New York Hospital neonatal intensive care unit (NICU) were reviewed. Twenty-three episodes of clinically significant S epidermidis bacteremia were detected using the criteria of isolation from 3/3 blood culture bottles from a single culture, or isolation from two or more blood cultures taken at different times, or simultaneous isolation from blood and fluid, pus or vascular catheter. Of these 23 episodes of S epidermidis bacteremia, ten were associated with colonized vascular catheters, and four episodes occurred in infants with necrotizing enterocolitis. Focal S epidermidis infection occurred in ten episodes, and persistent bacteremia occurred frequently in this setting. S epidermidis was the most frequent cause of bacteremia in the Neonatal Intensive Care Unit during the period reviewed. Of the isolates determined to be clinically significant, 74% were resistant to methicillin and cephalothin and 91% were resistant to gentamicin. All isolates were sensitive to vancomycin. In addition to removing vascular catheters suspected of being colonized and searching for potential sites of focal infection, an antibiotic regimen that includes vancomycin should be initiated once significant S epidermidis bacteremia has been recognized in the neonate.

Catheters, Indwelling↗

PubMed1993

Interleukin-8 production by human peritoneal mesothelial cells in response to tumor necrosis factor-alpha, interleukin-1, and medium conditioned by macrophages cocultured with Staphylococcus epidermidis.

Patients treated with continuous ambulatory peritoneal dialysis (CAPD) may suffer from recurrent peritonitis episodes caused by Staphylococcus epidermidis. Early recruitment of granulocytes from the peripheral blood is important for the peritoneal antibacterial defense of CAPD patients. In this study, human peritoneal mesothelial cells were shown to produce high levels of interleukin-8 (IL-8) in response to IL-1 beta and tumor necrosis factor-alpha (TNF alpha) but not lipopolysaccharide or S. epidermidis. Coculture of peritoneal macrophages with S. epidermidis induced high levels of IL-1 alpha, IL-1 beta, and TNF alpha in 24-h-conditioned medium. Preincubation of this medium with anti-TNF alpha, anti-IL-1 alpha, or anti-IL-1 beta partially blocked stimulation of IL-8 production by mesothelial cells. Added together, these antibodies abolished IL-8 production to a level just above background. Migration of granulocytes to the stimulated mesothelial cell-conditioned medium could be totally blocked with rabbit polyclonal anti-IL-8 antibody. Thus, mesothelial cells are important for the recruitment of granulocytes into the peritoneal cavity.

Cells, Cultured↗

PubMed1985

Effect of the imidazole derivative lombazole on the ultrastructure of Staphylococcus epidermidis and Candida albicans.

Lombazole, an antimicrobial agent of the imidazole class, induced profound ultrastructural changes in Staphylococcus epidermidis and Candida albicans, as observed by freeze fracture electron microscopy. In S. epidermidis cells, the primary effect on ultrastructure was characterized by a distinct change in the morphology of the plasma membrane. Secondary effects of lombazole were cell wall thickening, accumulations of lipidlike material, abnormal cell division, severe change of shape, separation of the plasma membrane from the cell wall, and disruption of cells. The alterations in C. albicans were characterized by the deformation of and a decrease in the number of invaginations in the protoplasmic fracture face and corresponding ridges on the exoplasmic fracture face and by separation of the plasma membrane from the cell wall, leaving a gap which frequently contained small vesicles. Moreover, a considerable thickening of the cell wall occurred at localized regions. These structural alterations are discussed in relation to biochemical changes which may correlate with these phenomena.

Candida albicans↗

PubMed1994

Antibiotic treatment of experimental endocarditis due to methicillin-resistant Staphylococcus epidermidis.

The natural history and treatment of experimental endocarditis due to heterogeneous and homogeneous methicillin-resistant Staphylococcus epidermidis was investigated. Amoxicillin/clavulanate or vancomycin were administered for 3 days via a computerized pump to mimic human drug kinetics in animals. After challenge with the minimum inoculum producing 90% of infections (ID90), bacteria in the vegetations grew logarithmically for 16 h. Then, bacterial densities stabilized (at approximately 10(8) cfu/g) and growth rates sharply declined. Both regimens cured > or = 60% of endocarditis (due to heterogeneous or homogeneous bacteria) when started 12-16 h after infection, although the bacterial densities in the vegetations had increased by 20 times in between. In contrast, treatment started after 24 h failed in most animals, while bacterial densities had not increased any more. Thus, while both regimens were equivalent, the therapeutic outcome was best predicted by growth rates in the vegetations, not by bacterial densities. These observations highlight the importance of phenotypic tolerance developing in vivo.

Amoxicillin↗

PubMed1992

Osteomyelitis experimentally induced with Bacteroides thetaiotaomicron and Staphylococcus epidermidis. Influence of a foreign-body implant.

Experimental osteomyelitis was induced in the rabbit tibia with Staphylococcus epidermidis alone, with Bacteroides thetaiotaomicron alone, and with both bacteria as etiologic agents, in the presence or absence of a foreign-body implant. Animals were monitored by clinical observation and roentgenographic, microbiologic, histologic, immunofluorescent microscopic, and electron microscopic methods. Scanning and transmission electron microscopy showed masses of coccoid and rod-shaped bacteria embedded in a matrix of exopolysaccharide and adhered to bone, marrow, and the foreign-body implant (when present). Of the 58 rabbits receiving an implant, osteomyelitis developed in 48 (83%), and bacteria were recovered by culture from 56 (97%). Of the 31 animals without the implant, osteomyelitis developed in 18 (58%), but no bacteria were recovered by culture. Bacterial recovery appeared to be dependent on the presence of the implant. The rate of induction and the severity of osteomyelitis were enhanced by the presence of the foreign-body implant and by the polymicrobic infection.

Animals↗

PubMed2002

Detection of biofilm-forming strains of Staphylococcus epidermidis and S. aureus.

The formation of biofilm represents an important virulence factor of certain strains of Staphylococcus epidermidis and S. aureus. The ability of bacteria to aggregate, forming biofilms, is strictly related to the capacity of producing an extracellular mucoid substance often referred to as slime, whose main component is of polysaccharidic nature and consists of glycosaminoglycans. In recent years, new molecular techniques based on PCR have come alongside more traditional methods for identification of virulent biofilm-forming strains. The detection of the genes governing the production of such extracellular polysaccharide and, in particular, the icaA, the icaC and the icaD genes, provides us with a rapid and accurate technique for strain characterization. However, well-established methods, such as the Congo red agar test are still needed in order to confirm the phenotypic expression in the case of possible phase-variant strains. In future, the complete knowledge of the genetic mechanisms of phenotype modulation, comprehending all regulatory genes, could permit the characterization of the isolates just by molecular means in a single step.

Bacterial Adhesion↗

PubMed1993

An electronmicroscope study of glycopeptide antibiotic-resistant strains of Staphylococcus epidermidis.

Ultra-thin section transmission electronmicroscopy revealed that two of three glycopeptide-resistant strains of Staphylococcus epidermidis had abnormally thick cell walls, a finding consistent with the view that the reduction in susceptibility may result from the overproduction of glycopeptide binding sites within the cell-wall peptidoglycan. The third resistant strain had a slightly thickened cell wall with an irregular, roughened outline; this strain also underwent autolysis on prolonged incubation on blood agar and the resistance may be associated with abnormal cell-wall synthesis. Sub-MIC concentrations of vancomycin and teicoplanin caused surface damage to a proportion of cocci able to grow in the presence of antibiotic. Exposure to teicoplanin was additionally associated with the formation of filamentous forms and variable amounts of extracellular material. Transmission electronmicroscopy showed that both antibiotics exerted effects within the bacterial cytoplasm of the resistant strains that were not seen in an NCTC control strain: intracellular lamellae and structures resembling mesosomes were observed in the former. These effects were more noticeable in cocci exposed to vancomycin. Bacteria exposed to teicoplanin often showed abnormal septation and, in some preparations, a double-layered cell wall.

Cell Wall↗

PubMed1989

The activity of rifampin and analogs against Staphylococcus epidermidis biofilms in a CAPD environment model.

Rifampin has been noted to exhibit exceptional antimicrobial activity against Staphylococcus epidermidis biofilms as compared to commonly used antibiotics. To further explore this unique effect of rifampin, we evaluated the antimicrobial activity of three commercially available preparations of rifampin, two rifampin analogs (CGP29861 and rifapentine) and the parent compound rifamycin SV. These were tested against standardized S. epidermidis biofilms in various milieus. All six members of the rifamycin group tested demonstrated marked antimicrobial activity but with minor foci of resisters when tested in a peptone water environment. The microscopy of the exposed biofilms showed profound lysis and morphological distortion of the remaining cells. The synergistic elimination of the foci of resistance was achieved in an environment of fresh peritoneal dialysis (PD) solution or by the addition of vancomycin. Neither vancomycin nor fresh PD solution demonstrated significant antimicrobial activity when tested alone with biofilm preparations. Spent PD fluid markedly antagonized the activity of the rifamycins with the exception of the rifampin analogs, an effect primarily of pH. The synergistic effect of vancomycin with the rifamycins was not affected either by protein content or pH, leaving the antagonistic properties of spent PD fluid unexplained. The variable activity of the different members of the rifamycin group underlines the importance of structural differences in determining their interaction with bacterial biofilms. Further precision of the nature of these structural interactions is seen to have considerable potential for therapeutic advancement of catheter-associated sepsis.

Anti-Bacterial Agents↗

PubMed1986

Novel mechanism for plasmid-mediated erythromycin resistance by pNE24 from Staphylococcus epidermidis.

We describe an unusual type of erythromycin resistance (Emr) mediated by a plasmid designated pNE24 from Staphylococcus epidermidis. This 26.5-kilobase plasmid encodes resistance strictly to 14-membered macrolide antibiotics, erythromycin, and oleandomycin. Resistance to other macrolide-lincosamide-streptogramin B (MLS) antibiotics was not observed even after a prior induction stimulus with various MLS antibiotics. Plasmid pNE24 was found to express resistance constitutively and manifested a low to intermediate MIC (62.5 micrograms/ml) for erythromycin. The resistance gene, designated erpA, appears to mediate resistance by altering the permeability of the host cell for erythromycin, because the measured uptake of 14C-labeled erythromycin by strain 958-2 (containing pNE24) was lower than for the erythromycin-susceptible, isogenic strain 958-1. No inactivation of erythromycin in overnight broth culture supernatants could be detected. In addition, no significant loss in binding affinity between [14C]erythromycin and ribosome could be detected for ribosomes isolated from strain 958-2 relative to 958-1, indicating that pNE24 probably does not produce a modification of the bacterial ribosome. No other selectable marker was found associated with pNE24; however, a 60,000-dalton protein was present only in the membrane fractions of cells (958-2) containing pNE24 and may play a role in mediating resistance to erythromycin.

Bacterial Proteins↗