Trimethoprim Resistance and Susceptibility Genes in Staphylococcus epidermidis

Genes encoding trimethoprim (TMP)-resistant and -susceptible dihydrofolate reductases (DHFR) in Staphylococcus epidermidis isolated in Saitama Prefecture were compared with the TMP-resistant DHFR gene of S. aureus, dfrA. The nucleotide sequences of TMP^r and TMP^S genes in five S. epidermidis isolates tested could be divided into three types: type 1, identical with the TMP^r gene dfrA that had been found in S. aureus; type 3, identical with the TMP^s gene dfrC in S. epidermidis; and type 2, having only two nucleotide substitutions to dfrC with no amino acid change. TMP^r isolates carried either one of the type 2 or type 3 sequences in addition to the type 1 sequence. A Southern hybridization analysis revealed that, in TMP^r S. epidermidis, the type 1 sequence was located on a 5.5 kb EcoRI-EcoRV restriction fragment together with the sequence for the gentamicin (GM)-resistant gene, while the type 2 or type 3 sequence was located on the 1.0 kb EcoRI-EcoRV fragment. No plasmid-carrying dfrA-homologous sequence was detected in the S. epidermidis isolates we tested. These results suggest that the TMP^r and GM^r genes are closely linked and located on the chromosome in S. epidermidis isolated in Japan.     

Partial Purification and Some Properties of the Uridine Diphospho-N-Acetylglucosamine-Enolpyruvate Reductase from Staphylococcus epidermidis

A method for the partial purification of the uridine diphospho-N-acetylglucosamine-enolpyruvate reductase from Staphylococcus epidermidis is presented. Some properties of the enzyme, including its dependence on monovalent cation and flavine adenine dinucleotide, are discussed.     

Nature and Properties of a Staphylococcus epidermidis Bacteriocin

Staphylococcin 1580, produced by Staphylococcus epidermidis 1580, consisted of 41.8% protein, 34% carbohydrate, and 21.9% lipid. In the protein fraction, the acidic amino acids, glutamic and aspartic acid, and the neutral amino acids, glycine and alanine, predominated. Neutral sugars consisted of glucose, galactose, and fucose in a molar ratio of 6:3:1. The purified bacteriocin was not inactivated by heating for 15 min at 120 C in the presence of 0.5% serum albumin and was stable in the pH range from 3.5 to 8.5. The compound was sensitive to the action of the proteolytic enzymes trypsin, Pronase, and chymotrypsin. All gram-negative bacteria tested were resistant; a large number of gram-positive bacteria were sensitive to staphylococcin 1580 action. Growth of stable staphylococcal L-forms was inhibited by the bacteriocin to the same extent as their parent strains. The staphylococcin was adsorbed to cell walls, cell membranes, and resistant cells. The effect of staphylococcin 1580 appeared to be bactericidal but not bacteriolytic.     

Staphylococcus epidermidis infections

The opportunistic human pathogen Staphylococcus epidermidis has become the most important cause of nosocomial infections in recent years. Its pathogenicity is mainly due to the ability to form biofilms on indwelling medical devices. In a biofilm, S. epidermidis is protected against attacks from the immune system and against antibiotic treatment, making S. epidermidis infections difficult to eradicate.     

Phosphatase-negative Staphylococcus epidermidis

As a result of the study of a number of additional characteristics, more than a half of the cultures, formerly identified as phosphatase-negative S. epidermidis according to the scheme of the International Subcommittee on the Taxonomy of Staphylococci and Micrococci, have been shown to be more similar to S. Hominis and S. captis on account of their properties. The study of correlation between the main differentiating characteristics of S. epidermidis has shown that it is poorly pronounced. For this reason the decision to classify a phosphatase-negative culture with S. epidermidis should be based on the study of additional characteristics which differentiate this species not only from S. saprophyticus, but also from other phosphatase-negative staphylococci.     

Partial Purification and Properties of the Pyruvate-Uridine Diphospho-N-Acetylglucosamine Transferase from Staphylococcus epidermidis

A method for the partial purification of the pyruvate-uridine-diphospho-N-acetylglucosamine transferase from Staphylococcus epidermidis is presented. Some properties of the enzyme are discussed.     

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.     

Deoxyribonuclease-Positive Staphylococcus epidermidis Strains

Use of the agar plate test for the enzyme deoxyribonucleate 3′-nucleotidohydrolase (deoxyribonuclease) can result in frequent misdiagnosis of Staphylococcus epidermidis as S. aureus.     

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.     

Formation and Properties of Persister Cells of Staphylococcus capitis and Staphylococcus epidermidis,Bacteria Inhabiting Human Skin

Microbiology - Persisters (P) are the cells surviving, but not reproducing in the presence of lethal doses of antibiotics (AB). These are the cells of a scarce (0.001–1.0%) subpopulation,...     

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.     

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.