Applications of fluorescent antibody for detecting capsular substances in Staphylococcus epidermidis

A fluorescent antibody technique was developed for the determination of the type of capsule of strains of Staphylococcus epidermidis. Many mouse virulent and avirulent strain populations were investigated. Of 300 fresh isolates of Staph. epidermidis, 27 were mouse virulent strains and of these 74.1% and 25.9% were mono- and polyvalent, respectively. The frequency of capsular type antigens I, II and III, produced by the 27 virulent strains was found to be 18.5%, 88.9% and 18.5%, the majority being capsular type II. In the mouse avirulent strains, capsular type antigen production was demonstrated in 263 out of 273 strains examined and mono- and polyvalent capsular types comprised 52.3% and 44.0%, respectively. Capsular type I, II, III strains and non-typable strains occurred at frequencies of 15.0%, 95.2%, 34.9% and 3.7% respectively, the majority of mouse avirulent strains also being capsular type II. These results indicate that a majority of ordinary Staph. epidermidis produced capsular type antigens although the capability is quantitatively different according to strain.     

表皮葡萄球菌 YycG单克隆抗体抗生物膜活性的研究

YycFG双组分信号转导系统调控葡萄球菌细胞壁合成、代谢及生物膜形成,PAS是组氨酸激酶YycG的胞外信号感应区域。本研究针对胞外PAS区域制备抗YycG‐PAS单克隆抗体（YycG‐PAS MAb ）。免疫鉴定结果表明,YycG‐PAS MAb可与重组YycG‐PAS蛋白和表皮葡萄球菌菌体 YycG蛋白结合,属于IgG2a亚型,效价为log 215。YycG‐PAS MAb（80μg／ml）与表皮葡萄球菌 RP62A菌株共培养24 h ,对细菌生物膜形成的抑制率达46．5％,与 mIgG （80μg／mL ）组相比有显著差异（ P＜0．05）。YycG‐PAS MAb （80μg／ml）与低浓度万古霉素（1μg／ml）联用可增强对24 h细菌生物膜的抑制作用,抑制率由57．6％提高至93．0％（P＜0．01）。YycG‐PAS MAb对浮游状态表皮葡萄球菌的生长及存活无显著影响。本研究为YycG‐PAS MAb在抗生物膜感染中的潜在应用价值奠定了一定基础。     

Phage typing set for differentiating Staphylococcus epidermidis

A phage typing set composed of 13 phages is described for characterizing Staphylococcus epidermidis. Isolates (372) from cases of bovine mastitis were used in this study. Of these, 350 or 94% were successfully delineated, and 63 phage types were observed. Twenty two cultures were not typeable.     

Mechanism of Chloramphenicol Resistance in Staphylococcus epidermidis

The mechanism of chloramphenicol resistance in several multiple-resistant Staphylococcus epidermidis strains has been studied and shown to be due to the presence of the enzyme, chloramphenicol acetyltransferase. As with S. aureus, the inactivating enzyme in S. epidermidis appears to be the product of a structural gene on the chloramphenicol plasmid because resistance and enzyme activity are concurcurrently lost after growth in acridine orange or at elevated temperatures. The synthesis of chloramphenicol acetyltransferase in S. epidermidis has been compared with the function of a similar enzyme in chloramphenicol-resistant S. aureus with the conclusion that the kinetics of induction, products of the reaction, and general properties of the enzymes are identical. The chloramphenicol acetylating enzyme from S. epidermidis has been purified to a state of homogeneity and compared with the analogous purified S. aureus enzyme. Both purified preparations consist of native enzymes with molecular weights of 80,000, and evidence is presented that is consistent with their being made up of four identical subunits of 20,000 each. The two staphylococcal enzymes are identical with respect to pH optimum, apparent affinity (K_m) for chloramphenicol, heat denaturation, and immunological reactivity, but they differ in electrophoretic mobility, chromatographic behavior, substrate specificity, and sensitivity to inhibition by mercuric ion.     

Monoclonal IgM antibody protection in mice against infection with an encapsulated strain of Staphylococcus epidermidis.

Passive protective activities of three different classes of monoclonal antibodies in mice against challenge with strain ATCC 31432 (capsular type I) of Staphylococcus epidermidis were examined. Monoclonal IgM antibody passively protected mice against challenge with the homologous strain, whereas monoclonal IgG1 and IgG2b antibodies did not. The protective activity of IgM was absorbed by the cell surface antigen extracted from the homologous strain but not by the antigen from heterologous strains. Rapid reduction of viable cells took place in the peritoneal cavity of mice immunized with monoclonal IgM as early as 6 h after the challenge with the homologous strain. An enzyme-linked immunosorbent inhibition assay showed there was remarkable inhibition with the homologous cell surface antigen but not with heterologous preparations from other strains. Results suggest that in the mouse the major passive protection against the S. epidermidis strain is provided by the IgM antibody to the cell surface antigen.     

Isolation of Staphylococcus epidermidis from Tobacco

Staphylococcus epidermidis has been isolated in significant numbers from growing tobacco leaves. The organism is also present on cured and aged tobacco.     

Mouse Virulent Strain of Staphylococcus epidermidis

Using 10⁹ or 10⁷ colony-forming units of a strain of Staphylococcus epidermidis (strain 1142) in saline or 5% mucin, respectively, 90 to 100% of mice died within 24 to 48 hr after intraperitoneal challenge infection. These organisms gradually multiplied in the peritoneal cavity when injected intraperitoneally into mice, while the mouse avirulent strain (strain 1124) rapidly decreased and no organisms were found there 20 hr after injection. This strain was capable of inducing resistance against challenge with homologous strains. The resistance appeared as early as the first week and disappeared the 4th week after the immunization. However, no resistance was induced with strain 1124 against challenge with strain 1142. Also, hyperimmune rabbit serum prepared with strain 1142 passively protected against challenge with homologous strain in mice. The protective antibody was absorbed out with homologous organisms but not with strain 1124. Subsequently, a surface substance was obtained from strains 1142 or 1124 by the method of Morse. The 1142 surface substance was capable of inducing a resistance against challenge with the homologous strain but not with the 1124 surface substance. Also, this substance absorbed the protective antibody in hyperimmune rabbit serum prepared with the homologous strain but not with the 1124 surface substance nor with the Smith surface antigen extracted from the Smith strain of Staphylococcus aureus. Conversely, the protective antibody in rabbit anti-Smith strain serum against challenge with the homologous strain was absorbed with the Smith surface antigen but not with the 1142 surface substance. In the agar diffusion test, the 1142 surface substance and the Smith surface antigen produced single precipitin lines only against homologous antisera. Biochemical analysis of the 1142 surface substance showed that the substance contained neither nucleic acids nor proteins but is composed of hexosamine, glycerol, phosphorus, alanine, glycine and phenylalanine.     

MicroDSC study of Staphylococcus epidermidis growth

Background  

A microcalorimetric study was carried out using a Staphylococcus epidermidis population to determine the reproducibility of bacterial growth and the variability of the results within certain experimental parameters (temperature, bacterial concentration, sample thermal history). Reproducibility tests were performed as series of experiments within the same conditions using either freshly prepared populations or samples kept in cold storage. In both cases, the samples were obtained by serial dilution from a concentrated TSB bacterial inoculum incubated overnight.     

Staphylococcus epidermidis role in the skin microenvironment

Wound healing is a complex dynamic physiological process in response to cutaneous destructive stimuli that aims to restore the cutaneous’ barrier role. Deciphering the underlying mechanistic details that contribute to wound healing will create novel therapeutic strategies for skin repair. Recently, by using state‐of‐the‐art technologies, it was revealed that the cutaneous microbiota interact with skin immune cells. Strikingly, commensal Staphylococcus epidermidis‐induced CD8+ T cells induce re‐epithelization of the skin after injury, accelerating wound closure. From a drug development perspective, the microbiota may provide new therapeutic candidate molecules to accelerate skin healing. Here, we summarize and evaluate recent advances in the understanding of the microbiota in the skin microenvironment.     

Dependence of Staphylococcus epidermidis on non-transferrin-bound iron for growth

The ability of Staphylococcus epidermidis strains to grow in the presence of human transferrin and varying amounts of ferric iron was studied. At initial bacterial densities up to 10(4) cfu ml(-1), none of the three strains grew when transferrin iron saturation was below the full saturation point, whereas the bacteria grew consistently when transferrin was fully iron-saturated and there was non-transferrin-bound iron in the medium. Precultivation of the bacteria under iron-restricted conditions to induce siderophore production did not abolish the growth dependence on non-transferrin-bound iron. At initial bacterial densities of 10(6) cfu ml(-1), the bacteria proliferated consistently also in the presence of partially saturated transferrin. The results indicate that at low bacterial densities, S. epidermidis cannot utilise transferrin-bound iron for growth and that its proliferation is dependent on non-transferrin-bound iron.     

Plasmid-mediated resistance to fosfomycin in Staphylococcus epidermidis

Staphylococcus epidermidis strain BM2641, isolated from a patient, was resistant to penicillin G, methicillin, aminoglycosides, chloramphenicol, macrolide, lincosamide and streptogramin B-type (MLS) antibiotics, and to high levels of fosmycin. Resistance to forsfomycin and/or to MLS was lost at low frequencies either spontaneously or after curing with novobiocin. The plasmid DNA from BM2641 and its cured derivatives was purified, analyzed by agarose gel electrophoresis and transferred to a nitrocellulose sheet. Comparative analysis of the resistance phenotypes with the plasmid content of the strains indicated that fosfomycin and MLS resistance were encoded by plasmids pIP1842 (2.5 kb) and pIP1843 (2.6 kb), respectively. Southern hybridization with a probe specific for gene fosA of Serratia marcescens showed that the fosfomycin resistance determinant in Staphylococcus is not homologous to that of Gram-negative bacteria.     

Significance of Staphylococcus epidermidis in the Clinical Laboratory

Susceptibility to 11 antibiotics was determined for 63 cultures of Staphylococcus aureus and 63 cultures of Staphylococcus epidermidis obtained at random from the clinical laboratory. The incidence of resistance to nine of these antibiotics was greater for S. epidermidis than for S. aureus. Studies of the minimal inhibitory concentration of these cultures to clindamycin showed that 61 cultures of S. aureus were susceptible whereas only 46 cultures of S. epidermidis were susceptible to this antibiotic. Although cultures of S. aureus were more active in the production of seven virulence factors, some cultures of S. epidermidis produced virulence factors. By successive cultivation in increasing concentrations of clindamycin, resistant variants were obtained for 10 cultures of S. aureus and 3 cultures of S. epidermidis. The presence of subinhibitory concentrations of clindamycin inhibited the production of some virulence factors by the resistant variants. In view of the greater resistance of S. epidermidis to antibiotics and its ability to produce virulence factors, its isolation in the clinical laboratory should not be regarded lightly.