PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Enterococcus faecalis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed2005

The susceptibility of starved, stationary phase, and growing cells of Enterococcus faecalis to endodontic medicaments.

The purpose of this investigation was to compare the susceptibility of cells of Enterococcus faecalis during exponential growth, stationary phase and starvation phase to three endodontic medicaments. E. faecalis strains VP3-80 and A197A in different growth phases were exposed to saturated calcium hydroxide solution, 0.05% chlorhexidine digluconate and 0.0001% sodium hypochlorite. Cells in the exponential growth phase were the most sensitive to all three medicaments and were killed between 3 s and 10 min. Cells in stationary phase were more resistant and living cells could be recovered at 10 min. However, cells in starvation phase were the most resistant and were not totally eliminated by the medicaments during the 10-min test period. Number of surviving cells of E. faecalis cells to the tested medicaments increased 1000- to 10,000-folds in aging cultures.

Calcium Hydroxide↗
PubMed1997

Relationship between the thermotolerance and the increase of DnaK and GroEL synthesis in Enterococcus faecalis ATCC19433.

Relationship between intrinsic thermal resistance, thermotolerance and heat shock proteins (hsp) synthesis is studied in Enterococcus faecalis. We showed that an impressive phenotypic heat resistance was induced by mild heat and a slight thermotolerance was developed by various sublethal pretreatments such as NaCl, SDS and bile salts. Hydrogen peroxide, acid and alkaline shifts or "thermomimetic" agent such as ethanol, did not enhance the survival of adapted cells against the lethal thermal shock (62 degrees C). The inhibition of protein synthesis by chloramphenicol or rifampin abolished thermotolerance. The immunological identification of the DnaK and GroEL proteins in E. faecalis allowed to study induction of these molecular chaperones under various conditions. Heat was the most efficient inductor of DnaK and GroEL synthesis. However, it was surprising that ethanol did not strongly induce these proteins. We also show that amplification of these hsp is not correlated to acquired thermotolerance with a linear relationship. A weak thermotolerance is not coupled from increased synthesis of DnaK and GroEL. So, we postulate that the high synthesis of the major hsp is not obligatory in the thermal cross-protection but that de novo protein synthesis is an absolute necessity in E. faecalis. Activation of preformed hsp or other factors depending or not on protein synthesis may be also necessary to enhance thermal resistance.

Chaperonin 60↗
PubMed1996

Comparative intravitreal antibiotic therapy for experimental Enterococcus faecalis endophthalmitis.

OBJECTIVE: To evaluate the most effective intravitreal antibiotic treatment of vancomycin-sensitive and -resistant Enterococcus faecalis endophthalmitis. DESIGN: Animal experiment. SETTING: Seventy-eight New Zealand white rabbits received an intravitreal injection of 10(5) vancomycin-sensitive or -resistant E faecalis organisms in one eye. Infections were allowed to proceed 3 hours before dividing animals randomly into the following treatment groups (n = 6, each): the vancomycin-sensitive E faecalis model--(1) vancomycin (1 mg/0.1 mL), (2) combined vancomycin (1 mg/0.1 mL) and amikacin (0.4 mg/0.1 mL), (3) combined vancomycin (1 mg/0.1 mL) and gentamicin (0.1 mg/0.1 mL), (4) combined vancomycin (1 mg/0.1 mL) and ceftazidime (2 mg/0.1 mL), (5) combined ampicillin (5 mg/0.1 mL) and gentamicin (0.1 mg/0.1 mL), and (6) pristinamycin (1 mg/0.1 mL); and the vancomycin-resistant E faecalis model--(1)same as above, excluding group 4. Control groups received sterile balanced salt solution. Twenty-four hours following intravitreal treatment, vitreous humor was collected for quantitative bacteriological studies. RESULTS: Intravitreal therapy with combined vancomycin and amikacin provided the most effective reduction of vancomycin-sensitive E faecalis organisms compared with combined vancomycin and gentamicin therapy (P =.10, Wilcoxon's rank sum test) or any other treatment group (P < .01, Wilcoxon's rank sum test). For vancomycin-resistant E faecalis endophthalmitis model, the combined ampicillin and gentamicin therapy was the most effective, followed by the combined vancomycin and amikacin therapy (P < .01, Wilcoxon's rank sum test). CONCLUSIONS: Treatment with intravitreal vancomycin plus amikacin and with intravitreal ampicillin plus gentamicin provide an effective bactericidal therapy for severe experimental vancomycin-sensitive and -resistant E faecalis endophthalmitis, respectively.

Animals↗
PubMed2004

Molecular detection of linezolid resistance in Enterococcus faecium and Enterococcus faecalis by use of 5' nuclease real-time PCR compared to a modified classical approach.

A nucleotide transversion from guanine to uracil in the 23S rRNA confers linezolid resistance. We describe a real-time PCR using two Taqman probes that detects a single mutated allele among the genomes of Enterococcus faecium and Enterococcus faecalis. Results were confirmed by a classical approach involving LabChip technology assayed with an Agilent Bioanalyzer 2100.

Acetamides↗
PubMed2005

Enterococcal surface protein Esp does not facilitate intestinal colonization or translocation of Enterococcus faecalis in clindamycin-treated mice.

Enterococcal surface protein (Esp) is a cell wall-associated protein of Enterococcus faecalis that has been identified as a potential virulence factor. We used a mouse model to examine whether Esp facilitates intestinal colonization or translocation of E. faecalis to mesenteric lymph nodes. After clindamycin treatment, similar levels of high-density colonization were established after orogastric inoculation of an E. faecalis isolate containing the esp gene within a large pathogenicity island and an isogenic mutant created by allelic replacement of the esp gene with a chloramphenicol resistance cassette (P=0.7); translocation to mesenteric lymph nodes was detected in 3 of 12 (25%) mice in both groups. Isogenic mutants of FA2-2 (a plasmid-free derivative of E. faecalis strain JH2) with or without the esp gene failed to establish colonization of clindamycin-treated mice. These results suggest that Esp does not facilitate intestinal colonization or translocation of E. faecalis.

Animals↗
PubMed1999

Characterization of Enterococcus faecalis alkaline phosphatase and use in identifying Streptococcus agalactiae secreted proteins.

We have identified and characterized an Enterococcus faecalis alkaline phosphatase (AP, encoded by phoZ). The predicted gene product shows homology with alkaline phosphatases from a variety of species; it has especially high similarity with two alkaline phosphatases from Bacillus subtilis. Expression of phoZ in Escherichia coli, E. faecalis, Streptococcus agalactiae (group B streptococcus [GBS]), or Streptococcus pyogenes (group A streptococcus [GAS]) produces a blue-colony phenotype on plates containing a chromogenic substrate, 5-bromo-4-chloro-3-indolylphosphate (XP or BCIP). Two tests were made to determine if the activity of the enzyme is dependent upon the enzyme's subcellular location. First, elimination of the signal sequence reduced AP activity to 3% of the wild-type activity (or less) in three species of gram-positive bacteria. Restoration of export, using the signal sequence from C5a peptidase, restored AP activity to at least 50% of that of the wild type. Second, we engineered two chimeric proteins in which AP was fused to either a periplasmic domain or a cytoplasmic domain of lactose permease (a membrane protein). In E. coli, the periplasmic fusion had 17-fold-higher AP activity than the cytoplasmic fusion. We concluded that AP activity is export dependent. The signal sequence deletion mutant, phoZDeltass, was used to identify random genomic fragments from GBS that encode exported proteins or integral membrane proteins. Included in this set of fragments were genes that exhibited homology with the Rib protein (a cell wall protein from GBS) or with DppB (an integral membrane protein from GAS). AP acts as a reporter enzyme in GBS, GAS, and E. faecalis and is expected to be useful in a variety of gram-positive bacteria.

Alkaline Phosphatase↗
PubMed1999

Analysis of cross infection using genomic fingerprinting in nosocomial urinary tract infection caused by Enterococcus faecalis.

To evaluate cross infection and a possible outbreak of Enterococcus faecalis urinary tract infection (UTI) in our urology ward, we studied the DNA fingerprinting of E. faecalis strains isolated from nosocomial UTI patients, in the period 1982-1996, using arbitrarily primed polymerase chain reaction (AP-PCR) analysis. The serovar and amplified products of DNA extracted from clinically isolated urinary E. faecalis strains by the AP-PCR method were analyzed, and the respective isolation periods of E. faecalis-positive UTI patients were investigated. There were nine patients with E. faecalis UTI between March and May 1994 and all strains isolated from their urine specimens were serovar type 7. AP-PCR revealed that five of the nine isolates had the same pattern. It appeared that these strains had caused the outbreak of E. faecalis UTI. Cross-infection between patients with E. faecalis UTI was demonstrated by genomic fingerprinting, suggesting that cross infection had occurred via urinary catheters or by hand contact in our ward. We may, therefore, reasonably conclude that we should beware of the transmission of urinary E. faecalis and take countermeasures against its dissemination.

Journal Article↗
PubMed1989

Molecular epidemiology of nosocomial, multiply aminoglycoside resistant Enterococcus faecalis.

The prevalence of high-level aminoglycoside resistance among Enterococcus faecalis at the Memphis VA Medical Center was 23.6% (59 of 250 isolates) from October to December 1986. Hybridization to a probe cloned from Ent. faecalis pIP1800 for 6' acetyltransferase-2" phosphotransferase (AAC6'-APH2") was observed in 55 (93.2%) of the resistant isolates and was associated with gentamicin resistance. Hybridization to a probe cloned from Ent. faecalis pJH1 for 3', 5" phosphotransferase type III (APH3', 5" III) was observed in 28 (47.4%) and was associated with streptomycin resistance. Twenty-five of the 32 isolates which were resistant to both gentamicin and streptomycin hybridized to both probes. Cell mating in conjunction with hybridization indicated that the AAC6'-APH2" gene is transferred separately from that for APH3', 5" (III), and the streptomycin resistant gene is cotransferred with the latter. The gentamicin-streptomycin resistant isolates therefore contain genes from two Ent. faecalis plasmids, and resistance to these two antibiotics appears to transfer separately. The genetic homogeneity of these isolates suggests nosocomial transmission of enterococci.

Aminoglycosides↗
PubMed2005

Enterococcus faecalis divIVA: an essential gene involved in cell division, cell growth and chromosome segregation.

Enterococcus faecalis divIVA (divIVAEf) is an essential gene implicated in cell division and chromosome segregation. This gene was disrupted by insertional inactivation creating E. faecalis JHSR1, which was viable only when a wild-type copy of divIVAEf was expressed in trans, confirming the essentiality of the gene. The absence of DivIVAEf in E. faecalis JHSR1 inhibited proper cell division, which resulted in abnormal cell clusters possessing enlarged cells of altered shape instead of the characteristic diplococcal morphology of enterococci. The lower viability of the divIVAEf mutant is caused by improper nucleoid segregation and impaired septation within the numerous cells generated in each cluster. Overexpression of DivIVAEf in Escherichia coli KJB24 resulted in enlarged cells with disrupted cell division, suggesting that this round E. coli mutant strain could be used as an indicator for functionality of DivIVAEf. A Bacillus subtilis divIVA mutant was not complemented by DivIVAEf, indicating that this protein does not recognize DivIVA-specific target sites in B. subtilis, or that it does not interact with other proteins of the cell division machinery of this micro-organism. DivIVAEf also failed to complement a Streptococcus pneumoniae divIVA mutant, supporting the phylogenetic distance between Enterococcus and Streptococcus. Our results indicate that DivIVA is a species-specific multifunctional protein implicated in cell division and chromosome segregation in E. faecalis.

Bacterial Proteins↗
PubMed1997

Cloning and genetic and sequence analyses of the bacteriocin 21 determinant encoded on the Enterococcus faecalis pheromone-responsive conjugative plasmid pPD1.

The pheromone-responsive conjugative plasmid pPD1 (59 kb) of Enterococcus faecalis encodes the bacteriocin 21 (bac21) determinant. Cloning, transposon insertion mutagenesis and sequence analysis of the bac21 determinant showed that an 8.5-kb fragment lying between kb 27.1 and 35.6 of the pPD1 map is required for complete expression of the bacteriocin. The 8.5-kb fragment contained nine open reading frames (ORFs), bacA to bac1, which were oriented in the same (upstream-to-downstream) direction. Transposon insertions into the bacA to bacE ORFs, which are located in the proximal half of bac21, resulted in defective bacteriocin expression. Insertions into the bacF to bac1 ORFs, which are located in the distal half of bac21, resulted in reduced bacteriocin expression. Deletion mutant analysis of the cloned 8.5-kb fragment revealed that the deletion of segments between kb 31.6 and 35.6 of the pPD1 map, which contained the distal region of the determinant encoding bacF to bac1, resulted in reduced bacteriocin expression. The smallest fragment (4.5 kb) retaining some degree of bacteriocin expression contained the bacA to bacE sequences located in the proximal half of the determinant. The cloned fragment encoding the 4.5-kb proximal region and a Tn916 insertion mutant into pPD1 bacB trans-complemented intracellularly to give complete expression of the bacteriocin. bacA encoded a 105-residue sequence with a molecular mass of 11.1 kDa. The deduced BacA protein showed 100% homology to the broad-spectrum antibiotic peptide AS-48, which is encoded on the E. faecalis conjugative plasmid pMB2 (58 kb). bacH encoded a 195-residue sequence with a molecular mass of 21.9 kDa. The deduced amino acid sequence showed significant homology to the C-terminal region of HlyB (31.1% identical residues), a protein located in the Escherichia coli alpha-hemolysin operon that is a representative bacterial ATP-binding cassette export protein.

Amino Acid Sequence↗
PubMed2003

Structures, locations, and transfer frequencies of genetic elements conferring high-level gentamicin resistance in Enterococcus faecalis isolates in Greece.

The elements conferring high-level gentamicin resistance in 64 clinical isolates of Enterococcus faecalis were characterized by PCR and by restriction enzyme hybridization analysis of genomic and plasmid DNA. There was a strong association between gentamicin resistance and the aac(6')-aph(2") gene carried on IS256-based elements with different structures, locations, and transfer characteristics.

Acetyltransferases↗
PubMed2003

Plasmid content of a vancomycin-resistant Enterococcus faecalis isolate from a patient also colonized by Staphylococcus aureus with a VanA phenotype.

Vancomycin-resistant Enterococcus faecalis coisolated with vancomycin-resistant (VanA) Staphylococcus aureus was found to contain two plasmids, designated pAM830 (45 kb) and pAM831 (95 kb). pAM830, found to be conjugative and closely related to the Inc18 family of broad-host-range conjugative plasmids, encodes resistances to vancomycin (via a Tn1546-like element) and erythromycin; pAM831 encodes resistances to gentamicin, streptomycin, and erythromycin.

Bacterial Proteins↗
PubMed2004

Biotechnological production of L(+)-lactic acid from wood hydrolyzate by batch fermentation of Enterococcus faecalis.

The inhibition of lactic acid fermentation by wood hydrolyzate was decreased (approx. 20%) by adaptation of Enterococcus faecalis RKY1 to wood hydrolyzate-based medium whereby lactic acid productivity and cell growth were enhanced by 0.5 g l(-1) h(-1) and 2.1 g l(-1), respectively. When the diluted or concentrated wood hydrolyzate (equivalent to 25-100 g glucose l(-1)) was supplemented with 15 g yeast extract l(-1), 24-93 g lactic acid l(-1) was produced at a rate between 1.7 g l(-1) h(-1) and 3.2 g l(-1) h(-1).

Adaptation, Physiological↗
PubMed1989

Identification of aggregation substances of Enterococcus faecalis cells after induction by sex pheromones. An immunological and ultrastructural investigation.

The sex pheromone system of Enterococcus faecalis is responsible for the clumping response of a plasmid carrying donor strain with a corresponding plasmid free recipient strain due to the production of sex pheromones by the recipient strain. The clumping response is mediated by a surface material (called aggregation substance) which is synthesized upon addition of sex pheromones to the cultures. Here we show that after induction a dense layer of "hairlike" structures is formed on the cell wall of the bacteria. These hairlike structures are responsible for the cell-cell contact which leads to the aggregation of cells. Formation of these structures was specific, only occurring after the addition of homologous sex pheromone.

Biological Factors↗
PubMed1991

Inducible transfer of conjugative transposon Tn1545 from Enterococcus faecalis to Listeria monocytogenes in the digestive tracts of gnotobiotic mice.

Transfer of conjugative transposon Tn1545 from Enterococcus faecalis to Listeria monocytogenes was studied in vitro and in vivo. Tn1545 transferred following filter mating at a frequency of 2.5 x 10(-7) transconjugants per donor colony. A 20-fold increase in transfer frequency was observed when matings were performed in the presence of a subinhibitory concentration of tetracycline. The frequency of in vivo transfer of Tn1545, expressed as the number of transconjugants per donor cell extracted from the intestines of the gnotobiotic mice after 35 days of experiment, was 1.1 x 10(-8). Presence of a low concentration of tetracycline in the drinking water increased this frequency 10-fold.

Animals↗
PubMed2003

EfrAB, an ABC multidrug efflux pump in Enterococcus faecalis.

A DNA fragment responsible for resistance to antimicrobial agents was cloned from the chromosomal DNA of Enterococcus faecalis ATCC 29212 by using drug-hypersensitive mutant Escherichia coli KAM32 as a host cell. Cells of E. coli KAM32 harboring a recombinant plasmid (pAEF82) carrying the DNA fragment became resistant to many structurally unrelated antimicrobial agents, such as norfloxacin, ciprofloxacin, doxycycline, acriflavine, 4',6-diamidino-2-phenylindole, tetraphenylphosphonium chloride, daunorubicin, and doxorubicin. Since the sequence of the whole genome of E. faecalis is known, we sequenced several portions of the DNA insert in plasmid pAEF82 and identified two open reading frames within the insert. We designated the genes efrA and efrB. A search of the deduced amino acid sequences of EfrA and EfrB revealed that they are similar to each other and that they belong to the ATP-binding cassette (ABC) family of multidrug efflux transporters. Transformed E. coli KAM32 cells harboring efrAB showed energy-dependent efflux of acriflavine. The efflux activity was inhibited by reserpine, verapamil, and sodium-o-vanadate, known inhibitors of ABC efflux pumps.

ATP-Binding Cassette Transporters↗
PubMed2000

Bactericidal activity of gentamicin against Enterococcus faecalis in vitro and in vivo.

The activity of gentamicin at various concentrations against two strains of Enterococcus faecalis was investigated in vitro and in a rabbit model of aortic endocarditis. In vitro, gentamicin at 0.5 to 4 times the MIC failed to reduce the number of bacteria at 24 h. Rabbit or human serum dramatically increased gentamicin activity, leading to a >/=3-log(10) CFU/ml decrease in bacterial counts when the drug concentration exceeded the MIC. Susceptibility testing in the presence of serum was predictive of in vivo activity, since gentamicin alone significantly reduced the number of surviving bacteria in the vegetations if the peak-to-MIC ratio was greater than 1. However, gentamicin selected resistant mutants in rabbits. The intrinsic activity of gentamicin should be taken into account in evaluation of combinations of gentamicin and cell wall-active agents against enterococci.

Animals↗