Staphylococcus epidermidis :: drug effects
Latest Paper:
Department of Pediatrics, University of Erlangen-Nuremberg, Germany. michael.groeschl@uk-erlangen.de
Adrenomedullin (ADM) promotes epithelial cell proliferation and antimicrobial activity in the gastrointestinal tract. Since ADM is also present in saliva, it was the objective of our study to investigate the role of salivary ADM in the maintenance of oral health. We found mRNA for ADM and the specific receptors CRLR-RAMP2 and CRLR-RAMP3 expressed by the salivary glands and by oral keratinocytes. The hormone was detected in the glandular tissues by western blot, being slightly bigger than the synthetic peptide, indicating a posttranslational modification. ADM was localized using immunohistochemistry and immunofluorescence. Staining specific for ADM was observed near the cell nuclei of the salivary ducts and acini. There was no correlation between ADM from matched saliva and serum of healthy volunteers. The physiological role of salivary ADM in the oral cavity was investigated by incubating buccal keratinocytes with ADM and measurement of the cell proliferation using bromodeoxyuridine (BrDU) assays. There was a significant, dose dependent increase (up to 5-fold; p< .001) of the BrDU incorporation after stimulation with ADM (1.5 to 50 ng/mL). The antibacterial properties of salivary ADM was studied by incubation of Gram+ and Gram- bacteria and yeast, isolated from human oral flora, with ADM ( .01-1000 ng/mL) for 24 h. Bacterial growth was inhibited dose dependently (p< .001), whereas the yeast was not affected. This finding was consistent when using radial growth inhibition test on agarose plates as well as photometric measurement in microtiter plates. Our findings suggest an important role of salivary ADM in the maintenance of oral health, being involved as well as in oral cell proliferation and anti-bacterial defense.
Mesh-terms: Adolescent; Adrenomedullin :: genetics; Adrenomedullin :: metabolism; Adrenomedullin :: pharmacology; Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents :: metabolism; Cell Proliferation :: drug effects; Cells, Cultured; Child; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Female; Fluorescent Dyes :: metabolism; Humans; Immunohistochemistry; Indoles :: metabolism; Keratinocytes :: cytology; Keratinocytes :: metabolism; Male; Microbial Sensitivity Tests; Middle Aged; Mouth Mucosa :: cytology; Mouth Mucosa :: metabolism; Pseudomonas :: drug effects; Rhodamines :: metabolism; Saliva :: chemistry; Salivary Glands :: metabolism; Staphylococcus epidermidis :: drug effects; Young Adult;
Most cited papers:
Peritonitis is a major complication of continuous ambulatory peritoneal dialysis. Relapsing peritonitis after the cessation of antimicrobial therapy is frequently reported and often involves Staphylococcus epidermidis. To investigate the potential role of catheter-associated biofilm in the pathogenesis of relapsing peritonitis, we describe an in vitro model permitting the development of an S. epidermidis biofilm on silicone elastomer biomaterial. This model has been used to investigate the ability of vancomycin hydrochloride to kill biofilm-encased organisms by using an antibiotic regimen typical of peritonitis therapy. No significant differences were seen between vancomycin-exposed and control groups in biofilm viable and total cell counts after 10 days. Vancomycin-exposed silicone-associated biofilm populations decreased by only .5 log10 CFU/cm2 over the study period. MICs and MBCs for the original S. epidermidis suspension were 3.125 and 6.25 micrograms/ml, respectively. For biofilm homogenate suspensions, MICs were 3.125 micrograms/ml, but MBCs were greater than 400 micrograms/ml. These data indicate that the biofilm organisms associated with an indwelling peritoneal catheter may display a form of tolerance, thereby suggesting one possible mechanism behind relapsing peritonitis.
Mesh-terms: Human; Microbial Sensitivity Tests; Microscopy, Electron, Scanning; Peritoneal Dialysis, Continuous Ambulatory :: adverse effects; Peritonitis :: microbiology; Peritonitis :: prevention & control; Silicone Elastomers; Staphylococcus epidermidis :: drug effects; Vancomycin :: pharmacology;
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
Indolicidin, an antimicrobial peptide with a unique amino acid sequence (ILPWKWPWWPWRR-NH(2)) is found in bovine neutrophils. A derivative of indolicidin, CP10A, has alanine residues substituted for proline residues and has improved activity against Gram-positive organisms. Transmission electron microscopy of Staphylococcus aureus and Staphylococcus epidermidis treated with CP10A showed mesosome-like structures in the cytoplasm. The peptide at 2-fold the minimal inhibitory concentration did not show significant killing of S. aureus ISP67 (a histidine, uridine, and thymidine auxotroph) but did show an early effect on histidine and uridine incorporation and, later, an effect on thymidine incorporation. Upon interaction with liposomes, detergents, and lipoteichoic acid, CP10A was shown by circular dichroism spectroscopy to undergo a change in secondary structure. Fluorescence spectroscopy indicated that the tryptophan residues were located at the hydrophobic/hydrophilic interface of liposomes and detergent micelles and were inaccessible to the aqueous quencher KI. The three-dimensional structure of CP10A in the lipid mimetic dodecylphosphocholine was determined using two-dimensional NMR methods and was characterized as a short, amphipathic helical structure, whereas indolicidin was previously shown to have an extended structure. These studies have introduced a cationic peptide with a unique structure and an ability to interact with membranes and to affect intracellular synthesis of proteins, RNA, and DNA.
Mesh-terms: Antimicrobial Cationic Peptides :: chemistry; Antimicrobial Cationic Peptides :: pharmacology; Bacterial Proteins :: metabolism; Cell Membrane :: drug effects; Circular Dichroism; DNA, Bacterial :: metabolism; Detergents :: metabolism; Gram-Positive Bacteria :: drug effects; Liposomes :: metabolism; Magnetic Resonance Spectroscopy; Microbial Sensitivity Tests; Microscopy, Electron; Models, Molecular; RNA, Bacterial :: metabolism; Research Support, Non-U.S. Gov't; Spectrometry, Fluorescence; Staphylococcus aureus :: drug effects; Staphylococcus aureus :: metabolism; Staphylococcus aureus :: ultrastructure; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: ultrastructure;
Department of Microbiology, University of Leeds, UK.
A Staphylococcus epidermidis plasmid conferring inducible resistance to 14-membered ring macrolides and type B streptogramins has been analysed and the DNA sequence of the gene responsible for resistance determined. A single open reading frame of 1.464 kbp, preceded by a complex control region containing a promoter and two ribosomal binding sites, was identified. The deduced sequence of the 488-amino-acid protein (MsrA) revealed the presence of two ATP-binding motifs homologous to those of a family of transport-related proteins from Gram-negative bacteria and eukaryotic cells, including the P-glycoprotein responsible for multidrug resistance. In MsrA, but not these other proteins, the two potential ATP-binding domains are separated by a Q-linker of exceptional length. Q-linkers comprise a class of flexible interdomain fusion junctions that are typically rich in glutamine and other hydrophilic amino acids and have a characteristic spacing of hydrophobic amino acids, as found in the MsrA sequence. Unlike the other transport-related proteins, which act in concert with one or more hydrophobic membrane proteins, MsrA appears to function independently when cloned in a heterologous host (Staphylococcus aureus RN4220). MsrA might, therefore, interact with and confer antibiotic specificity upon other transmembrane efflux complexes of staphylococcal cells. The active efflux of [14C]-erythromycin from cells of S. aureus RN4220 containing msrA has been demonstrated.
Mesh-terms: Adenosine Triphosphate :: metabolism; Amino Acid Sequence; Bacterial Proteins :: genetics; Bacterial Proteins :: metabolism; Base Sequence; Biological Transport; Drug Resistance, Microbial :: genetics; Erythromycin :: pharmacology; Gene Expression Regulation, Bacterial; Membrane Transport Proteins; Molecular Sequence Data; Multigene Family; Restriction Mapping; Sequence Homology, Nucleic Acid; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: genetics; Support, Non-U.S. Gov't;
Biofilms are communities of microorganisms attached to a surface. It has become clear that biofilm-grown cells express properties distinct from planktonic cells, one of which is an increased resistance to antimicrobial agents. Recent work has indicated that slow growth and/or induction of an rpoS-mediated stress response could contribute to biocide resistance. The physical and/or chemical structure of exopolysaccharides or other aspects of biofilm architecture could also confer resistance by exclusion of biocides from the bacterial community. Finally, biofilm-grown bacteria might develop a biofilm-specific biocide-resistant phenotype. Owing to the heterogeneous nature of the biofilm, it is likely that there are multiple resistance mechanisms at work within a single community. Recent research has begun to shed light on how and why surface-attached microbial communities develop resistance to antimicrobial agents.
Mesh-terms: Anti-Bacterial Agents :: pharmacology; Bacterial Proteins :: metabolism; Biofilms :: drug effects; Biofilms :: growth & development; Drug Resistance, Microbial; Drug Resistance, Multiple; Klebsiella pneumoniae :: drug effects; Klebsiella pneumoniae :: growth & development; Klebsiella pneumoniae :: metabolism; Phenotype; Polysaccharides, Bacterial :: chemistry; Polysaccharides, Bacterial :: metabolism; Pseudomonas aeruginosa :: drug effects; Pseudomonas aeruginosa :: growth & development; Pseudomonas aeruginosa :: metabolism; Research Support, Non-U.S. Gov't; Sigma Factor :: metabolism; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: growth & development; Staphylococcus epidermidis :: metabolism;
Spinal Service and Spinal Injuries Unit, Royal Adelaide Hospital, South Australia.
Discitis after discography is due to bacterial penetration into the intervertebral disc by a contaminated needle and has an incidence of 1% to 4%. We have examined the prophylactic role of cephazolin administered at the time of discography. An experimental study in sheep using radiographic contrast containing Staphylococcus epidermidis showed that either adding the antibiotic to the intradiscal suspension or giving it intravenously 30 minutes before intradiscal inoculation of bacteria prevented any radiographic, macroscopic or histological signs of discitis; all the intervertebral disc cultures were negative. In a prospective clinical study of 127 consecutive patients having lumbar discography, the injected contrast contained cephazolin 1 mg per ml. None of the patients developed clinical or radiographic signs of discitis. We recommend the use of a suitable broad spectrum antibiotic in a single prophylactic dose whenever the intervertebral disc is entered.
Mesh-terms: Animals; Cefazolin :: administration & dosage; Cefazolin :: pharmacology; Cefazolin :: therapeutic use; Contrast Media :: administration & dosage; Discitis :: etiology; Discitis :: pathology; Discitis :: prevention & control; Human; Injections, Intravenous; Intervertebral Disk :: pathology; Intervertebral Disk :: radiography; Lumbar Vertebrae; Prospective Studies; Radiography :: adverse effects; Sheep; Staphylococcal Infections :: etiology; Staphylococcal Infections :: pathology; Staphylococcal Infections :: prevention & control; Staphylococcus epidermidis :: drug effects; Support, Non-U.S. Gov't;
Division of Infectious Diseases, Children's Hospital, Boston, Massachusetts 02115.
To assess long-term nosocomial transmission, trends in antibiotic resistance, and expression of potential virulence factors, 86 randomly selected Staphylococcus epidermidis bloodstream isolates obtained from 80 patients in a neonatal intensive care unit (NICU) over a 10-year period were studied. Pulsed-field gel electrophoresis (PFGE) analysis of SmaI-digested whole chromosomal DNA revealed distinctive banding patterns that persisted in the NICU over long periods. Pattern A included 22 isolates (26%) obtained during 1983-1990, and pattern B included 24 isolates (28%) from 1983 to 1991. All 10 isolates examined in 1984 fell into one of these two patterns. Isolates with either pattern expressed polysaccharide/adhesin (PSA) and slime; 90% and 87% were resistant to oxacillin and gentamicin, respectively, with no trends over time. These findings suggest that distinct clones of S. epidermidis can become endemic in NICUs over periods as long as a decade and that nosocomial transmission plays an important role in neonatal S. epidermidis bacteremia.
Mesh-terms: Bacteremia :: epidemiology; Bacteremia :: microbiology; Bacteremia :: transmission; Cross Infection :: epidemiology; Cross Infection :: microbiology; Drug Resistance, Microbial; Electrophoresis, Gel, Pulsed-Field; Human; Infant, Newborn; Intensive Care Units, Neonatal; Massachusetts :: epidemiology; Staphylococcal Infections :: epidemiology; Staphylococcal Infections :: microbiology; Staphylococcal Infections :: transmission; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: isolation & purification; Staphylococcus epidermidis :: pathogenicity; Support, U.S. Gov't, Non-P.H.S. ; Virulence;
Antibiotic Research Unit, Department of Infectious Diseases and Clinical Microbiology, University Hospital, Uppsala, Sweden.
The bactericidal activities of vancomycin against two reference strains and two clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis were studied with five different concentrations ranging from 2x to 64x the MIC. The decrease in the numbers of CFU at 24 h was at least 3 log10 CFU/ml for all strains. No concentration-dependent killing was observed. The postantibiotic effect (PAE) was determined by obtaining viable counts for two of the reference strains, and the viable counts varied markedly: 1.2 h for S. aureus and 6. h for S. epidermidis. The determinations of the PAE, the postantibiotic sub-MIC effect (PA SME), and the sub-MIC effect (SME) for all strains were done with BioScreen C, a computerized incubator for bacteria. The PA SMEs were longer than the SMEs for all strains tested. A newly developed in vitro kinetic model was used to expose the bacteria to continuously decreasing concentrations of vancomycin. A filter prevented the loss of bacteria during the experiments. One reference strain each of S. aureus and S. epidermidis and two clinical isolates of S. aureus were exposed to an initial concentration of 10x the MIC of vancomycin with two different half-lives (t1/2s): 1 or 5 h. The post-MIC effect (PME) was calculated as the difference in time for the bacteria to grow 1 log10 CFU/ml from the numbers of CFU obtained at the time when the MIC was reached and the corresponding time for an unexposed control culture. The difference in PME between the strains was not as pronounced as that for the PAE. Furthermore, the PME was shorter when a t1/2 of 5 h (approximate terminal t1/2 in humans) was used. The PMEs at t1/2s of 1 and 5 h were 6.5 and 3.6 h, respectively, for S. aureus. The corresponding figures for S. epidermidis were 10.3 and less than 6 h. The shorter PMEs achieved with a t1/2 of 5 h and the lack of concentration-dependent killing indicate that the time above the MIC is the parameter most important for the efficacy of vancomycin.
We determined the ability of Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli to survive and grow in peritoneal dialysis fluids from patients undergoing chronic ambulatory peritoneal dialysis. Staphylococci did not survive in commercially available dialysis solutions but grew readily in peritoneal effluents obtained from patients after the dialysis dwell time. The number of CFU doubled 6 and 13 times in 24 h for S. epidermidis and S. aureus, respectively. E. coli grew well in both the pre- and postdialysis peritoneal fluid. Peritoneal macrophages as well as peripheral blood leukocytes inhibited bacterial growth in peritoneal dialysis fluid. However, 10(6) phagocytes per ml were minimally required to obtain a bacteriostatic effect. The addition of serum to peritoneal dialysis fluid increased the antibacterial activity of macrophages and blood leukocytes. The capacity of the aminoglycoside antibiotic tobramycin to reduce bacterial CFU in peritoneal dialysis fluid was only 10% of its bactericidal capacity in standard Mueller-Hinton brush. Peritoneal dialysis fluid had no effect on the antibacterial activity of imipenem.
Mesh-terms: Blood Bactericidal Activity; Escherichia coli :: drug effects; Escherichia coli :: growth & development; Human; Imipenem; Peritoneal Dialysis; Peritoneal Dialysis, Continuous Ambulatory; Peritoneum :: microbiology; Phagocytes :: physiology; Staphylococcus :: growth & development; Staphylococcus aureus :: drug effects; Staphylococcus aureus :: growth & development; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: growth & development; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S. ; Thienamycins :: pharmacology; Tobramycin :: pharmacology;
Department of Health and Preventive Sciences, University "Federico II," 80131 Naples, Italy. pvillari@napoli.peoples.it
Coagulase-negative staphylococci, especially Staphylococcus epidermidis, are increasingly important nosocomial pathogens, particularly in critically ill neonates. A 3-year prospective surveillance of nosocomial infections in a neonatal intensive care unit (NICU) was performed by traditional epidemiologic methods as well as molecular typing of microorganisms. The aims of the study were (i) to quantify the impact of S. epidermidis on NICU-acquired infections,(ii) to establish if these infections are caused by endemic clones or by incidentally occurring bacterial strains of this ubiquitous species,(iii) to evaluate the use of different methods for the epidemiologic typing of the isolates, and (iv) to characterize the occurrence and the spread of staphylococci with decreased glycopeptide susceptibility. Results confirmed that S. epidermidis is one of the leading causes of NICU-acquired infections and that the reduced glycopeptide susceptibility, if investigated by appropriate detection methods such as population analysis, is more common than is currently realized. Typing of isolates, which can be performed effectively through molecular techniques such as pulsed-field gel electrophoresis but not through antibiograms, showed that many of these infections are due to clonal dissemination and, thus, are potentially preventable by strict adherence to recommended infection control practices and the implementation of programs aimed toward the reduction of the unnecessary use of antibiotics. These strategies are also likely to have a significant impact on the frequency of the reduced susceptibility of staphylococci to glycopeptides, since this phenomenon appears to be determined either by more resistant clones transmitted from patient to patient or, to a lesser extent, by strains that become more resistant as a result of antibiotic pressure.
Mesh-terms: Birth Weight; Candidiasis :: epidemiology; Cross Infection :: epidemiology; Cross Infection :: microbiology; Cross Infection :: transmission; Drug Resistance, Microbial; Epidemiology, Molecular; Human; Incidence; Infant, Low Birth Weight; Infant, Newborn; Infant, Very Low Birth Weight; Intensive Care Units, Neonatal :: statistics & numerical data; Italy :: epidemiology; Klebsiella Infections :: epidemiology; Klebsiella pneumoniae; Pneumonia :: epidemiology; Staphylococcal Infections :: epidemiology; Staphylococcal Infections :: transmission; Staphylococcus aureus; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: genetics; Teicoplanin :: pharmacology; Time Factors; Vancomycin :: pharmacology;
Mikrobielle Genetik, Universität Tübingen, Federal Republic of Germany.
The lantibiotic epidermin is produced by Staphylococcus epidermidis Tü3298. The known genes involved in epidermin biosynthesis and regulation are organized as operons (epiABCD and epiQP) that are encoded on the 54-kb plasmid pTü32. Here we describe the characterization of a DNA region that mediates immunity and increased epidermin production, located upstream of the structural gene epiA. The sequence of a 2.6-kb DNA fragment revealed three open reading frames, epiF,-E, and -G, which may form an operon. In the cloning host Staphylococcus carnosus, the three genes mediated an increased tolerance to epidermin, and the highest level of immunity (sevenfold) was achieved with S. carnosus carrying epiFEG and epiQ. The promoter of the first gene, epiF, responded to the activator protein EpiQ and contained a palindromic sequence similar to the EpiQ binding site of the epiA promoter, which is also activated by EpiQ. Inactivation of epiF,-E, or -G resulted in the complete loss of the immunity phenotype. An epidermin-sensitive S. epidermidis Tü3298 mutant was complemented by a DNA fragment containing all three genes. When the epiFEG genes were cloned together with plasmid pTepi14, containing the biosynthetic genes epiABCDQP, the level of epidermin production was approximately fivefold higher. The proteins EpiF,-E, and -G are similar in deduced sequence and proposed structure to the components of various ABC transporter systems. EpiF is a hydrophilic protein with conserved ATP-binding sites, while EpiE and -G have six alternating hydrophobic regions and very likely constitute the integral membrane domains. When EpiF was overproduced in S. carnosus, it was at least partially associated with the cytoplasmic membrane. A potential mechanism for how EpiFEG mediates immunity is discussed.
Mesh-terms: ATP-Binding Cassette Transporters :: biosynthesis; ATP-Binding Cassette Transporters :: chemistry; ATP-Binding Cassette Transporters :: genetics; Amino Acid Sequence; Antibiotics, Peptide :: biosynthesis; Antibiotics, Peptide :: pharmacology; Bacterial Proteins :: biosynthesis; Bacterial Proteins :: chemistry; Bacterial Proteins :: genetics; Base Sequence; Cloning, Molecular; Drug Resistance, Microbial :: genetics; Genes, Bacterial :: genetics; Genes, Bacterial :: physiology; Membrane Proteins :: genetics; Microbial Sensitivity Tests; Molecular Sequence Data; Molecular Weight; Operon :: genetics; Peptides; Promoter Regions (Genetics):: genetics; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Staphylococcus :: drug effects; Staphylococcus epidermidis :: drug effects; Staphylococcus epidermidis :: genetics; Support, Non-U.S. Gov't;
