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PubMed1999

[Drug resistance of Enterococcus species isolated from the urogenital system].

Despite low virulence of enterococci, they have become important nosocomial pathogens. This has been correlated with the increased use of broad-spectrum antibiotics, particularly cephalosporins. Many strains of enterococci exhibit multiple drug resistance; the most important being high-level resistance (HLR) to penicillin (MIC > 100 mg/l) and gentamicin (MIC > 500 mg/l and 2000 mg/l) and/or streptomycin (MIC > 2000 mg/l). The investigation was performed on 92 strains, isolated from genito-urinary tract and recognised as Enterococcus sp. All strains were obtained from several microbiological laboratories of Gdańsk, Gdynia and Tczew. On biochemical reaction profiles species of enterococci were identified as: E. faecalis (72.8%), E. faecalis varians (9.8%), E. durans (7.6%) and E. faecium (9.8%). The minimal inhibitory concentration (MICs) of penicillin, ampicillin, azlocillin, imipenem, gentamicin, amicacin, ciprofioxacin and vancomycin were determined by the agar dilution method. None of these 92 enterococcal strains was vancomycin resistant. 22.2% of E. faecium and 7.5% of E. faecalis showed high-level resistance to penicillin. None of these strains were produced beta-lactamase. High-level resistance to streptomycin and gentamicin was detected. Both--high-level resistance to streptomycin and gentamicin--were found in 6% E. faecalis; 11.1% E. faecalis varians and 22.2% E. faecium.

Drug Resistance, Microbial↗
PubMed2002

[Conjugative transfer of glycopeptide and macrolide resistant genes among Enterococci and from Enterococcus faecalis to Staphylococcus aureus].

The resistance determinants were transferred from clinical strains of enterococci to Staphylococcus aureus strains. As recipients methicillin-resistant and methicillin-susceptible strains were used and the filter-mating procedure was performed. The transconjugants resistant to erythromycin were obtained in the case of all recipients, in one case the vanA determinant conferring the resistance to vancomycin was transferred together with erythromycin resistance. However the resistance was very unstable and the level was not as high as in the case of Enterococcus faecalis donor strain. The vanA determinant was easily transferred between enterococcal strains by the conjugation and a transfer occurred of vanA alone or together with erythromycin resistance.

Anti-Bacterial Agents↗
PubMedDate not supplied

Resistance of Enterococcus strains isolated from pigs to gastrointestinal tract and antagonistic effect against Escherichia coli K88.

The intestinal flora plays an important role in health and wellbeing of different organisms. Indigenous microflora can be innocuous or pathogenic. Consumption of food supplemented with beneficial microorganisms as probiotics provides a good health state and this can be maintained and recovered. Currently, probiotic strains of Bifidobacterium and Lactobacillus are widely used in humans as well as animals. Swine industry would benefit with the application of probiotics, mainly to overcome diarrheal diseases produced by different causes, as a pathogenic E. coli K88. The aim of this work was to isolate strains of Enterococcus from gastrointestinal tract of pigs to use them as probiotic. Two strains of E. faecalis, 2 of E. mundii and 7 of E. faecium were isolated with characteristics of resistance to acid pH, tolerance to biliary salts and a high antagonistic activity (>80%) against E. coli K88. Based on their characteristics and species affinity, we believe that these strains could be administered to pigs as a probiotic.

Animals↗
PubMed1995

[Bactericidal activity of combinations of ticarcillin-clavulanic acid or other beta-lactams (amoxicillin, piperacillin-tazobactam, ticarcillin) with gentamicin against Enterococcus faecalis and E. faecium].

MICs of amoxicillin, piperacillin-tazobactam, ticarcillin and ticarcillin-clavulanic acid were determined against 52 clinical strains of E. faecalis and E. faecium. Modal MICs (mg/l) of these antibiotics were 1, 4, 64 and 64, respectively. Bactericidal activity of the beta-lactams was tested at two concentrations (1/2 MIC and 100 mg/l) alone or combined with gentamicin (4 mg/l) against 10 clinical strains of Enterococcus spp. Activity of ticarcillin was not modified by the addition of clavulanic acid (4 mg/l). Time-kill curves showed that all beta-lactams at 100 mg/l were bactericidal after 18 h of incubation (decrease in bacterial counts > or = 3 log10 CFU/ml) against 6 strains of E. faecalis, with MICs of amoxicillin at 1 mg/l and 2 strains of E. faecium with MICs of amoxicillin at 1 and 2 mg/l. Addition of gentamicin resulted in a bactericidal effect at 3 or 6 hours for the great majority of the combinations studied, except against the two strains highly resistant to gentamicin. Combination of every beta-lactam at 1/2 MIC with gentamicin was synergistic (except in case of high level resistance to gentamicin) and prevented bacterial growth but was not bactericidal. Against two strains of E. faecium with high MICs of amoxicillin (8 mg/l), piperacillin-tazobactam (64 mg/l) and ticarcillin-clavulanic acid (512 mg/l), only combinations of amoxicillin 100 mg/l and gentamicin were always bactericidal. In conclusion, against E. faecalis strains, ticarcillin-clavulanic acid tested at 100 micrograms/ml had a bactericidal activity similar to that of the other beta-lactams tested, alone or combined with gentamicin.(ABSTRACT TRUNCATED AT 250 WORDS)

Amoxicillin↗
PubMed1998

[Vancomycin resistant enterococcus in France. High prevalence in a young ambulatory care patient population].

OBJECTIVE: Assess the prevalence of asymptomatic carriage of vancomycin-resistant Enterococci in a population of healthy young French subjects. METHODS: Stool samples obtained from 100 persons living in south-eastern France (20 sampling sites) were directly seeded on enriched selective media containing 6 mg/l vancomycin. Bacterial species and their resistant gene were identified with classical methods and multiplex genomic amplification. RESULTS: The incidence of asymptomatic carriage was 17% with a homogeneous geographic distribution of the resistant strains. Nine Enterococcus faecium van A strains and 8 E. gallinarum van C1 strains were isolated. CONCLUSION: These findings demonstrate carriage of vancomycin-resistant Enterococci in a population of young ambulatory subjects in France. The incidence observed was much higher than in an earlier study conducted in France. These results might be explained by a much more sensitive detection technique. Care should be taken to avoid dissemination in hospital settings.

Adult↗
PubMed1998

Enterococcus faecium bacteremia: does vancomycin resistance make a difference?

BACKGROUND: Enterococcus faecium has received increased attention, primarily due to the emergence of vancomycin resistance. The purpose of this investigation was to study the epidemiological characteristics of vancomycin-resistant E faecium (VRE) bacteremia and to determine the clinical impact of vancomycin resistance on the outcome of patients with this infection. METHODS: We retrospectively analyzed the clinical features and outcome of 53 patients with E faecium bacteremia. RESULTS: From January 1992 until December 1995, there were 32 episodes of bacteremia caused by vancomycin-susceptible E faecium (VSE) and 21 caused by VRE. An intra-abdominal site was the most common source of bacteremia in both groups. All of the VRE and 78% of VSE bacteremia cases were nosocomially acquired. Previous administration of vancomycin was associated with VRE bacteremia (P<.001), as were indwelling bladder catheters (P=.01). Fifty-nine percent of the patients with VSE bacteremia survived vs 24% with VRE (P=.009), despite similar severity-of-illness scores. In 62% of the patients with VRE sepsis, death was related to the bacteremia (P=.01). Patients infected with VRE had longer hospitalizations than those with VSE (34.8 vs 16.7 days, respectively) (P=.004), were more likely to be on the medical service (P=.03), and on the average, had hospitalization costs of more than $27,000 per episode than did patients with VSE bloodstream infection ($83,897 vs $56,707, respectively) (P=.04). CONCLUSIONS: Vancomycin-resistant E faecium bacteremia is a complication of prolonged hospitalization in debilitated patients. Vancomycin resistance has a negative impact on survival in patients with E faecium bacteremia and leads to higher health care costs.

Anti-Bacterial Agents↗
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↗
PubMed1996

Surgical Infection Society position on vancomycin-resistant Enterococcus.

The risk of transfer of vancomycin resistance to staphylococci is a real possibility and has been achieved in the laboratory. Prolonged colonization occurs with vancomycin-resistant Enterococcus (VRE), and many more patients are colonized than infected. The failure to identify, isolate, and adhere to infection control measures when caring for VRE-colonized patients dooms to failure any means to control its spread. Control of vancomycin use alone is unlikely to greatly affect the number of patients at risk for VRE colonization. The global spread of VRE may be impossible to stop, but infection control measures are the most important line of defense inside hospitals.

Anti-Bacterial Agents↗
PubMed2000

Morphologic changes correlating to different sensitivities of Escherichia coli and enterococcus faecalis to Nd:YAG laser irradiation through dentin.

BACKGROUND AND OBJECTIVE: Previous studies demonstrated the disinfecting potential of Nd:YAG laser irradiation on the root canal system from an overall quantitative viewpoint. The aim of this study was to evaluate the specific effect of irradiation through dentin on gram-negative and gram-positive bacteria with regard to their cell structure. STUDY DESIGN/MATERIALS AND METHODS: Sterile dentin samples of standardized size were divided into two sets of four groups with eight samples each. The first set was inoculated with Escherichia coli as the gram-negative test strain, the second set was inoculated with Enterococcus faecalis, which served as the gram-positive test organism. The samples were then irradiated on the bacteria-free side in contact mode under constant scanning movement at an angle of 10 degrees by use of the fiber optic of the Nd:YAG laser. Upon laser treatment they were critical point dried and subjected to SEM investigation. Another two sets of samples were prepared and irradiated in the same manner and evaluated by standard microbiological procedures to verify whether the observed morphologic alterations correlated to cell death. RESULTS: SEM investigations revealed damage pattens that increased with the amount of energy applied. Whereas the gram-negative test organism showed immediate structural injury, the gram-positive test organism required repeated application of irradiation. The microbiological examination showed reduction of both bacterial strains, yet to different extents. CONCLUSION: Our study demonstrates the different morphologic impact of Nd:YAG laser irradiation through dentin on representatives of the two main groups of bacteria. It shows that the construction of the cell wall is crucial for their individual sensitivity to laser treatment.

Colony Count, Microbial↗
PubMed2000

NF-kappaB activation mediates the response of a subpopulation of basal uroepithelial cells to a cell wall component of Enterococcus faecalis.

Earlier in vitro studies revealed that treatment of basal urothelial cells (UT) with lipoteichoic acid, a cell wall component of Enterococcus faecalis (LT-2), stimulated a subpopulation of quiescent cells with high proliferative potential to divide (Elgavish et al., 1996b, J Cell Physiol 169:42-51). Studies were consistent with the possibility that NO-mediated mechanisms were involved (Elgavish et al., 1996c, J Cell Physiol 169:66-77). We postulated that LT-2 may upregulate expression of iNOS. Promoters of the gene encoding iNOS, as well as genes encoding many cytokines, contain elements homologous to consensus sequences for the binding of the transcription factor NF-kappaB. Based on this, we postulated that: (1) NF-kappaB activation is an early event following exposure of basal UT to LT-2 and (2) NF-kappaB activation mediates basal UT proliferation triggered by LT-2. To test these hypotheses, UT maintained for 3 days under growth-restricting conditions, were treated with or without 25 microg/ml LT-2. Nuclear distribution of NF-kappaB, that is, activated NF-kappaB, was detected by immunofluorescence microscopy in a subpopulation of basal UT as early as 5-10 min after the beginning of the treatment. In contrast, LT-2 had no effect on cultures containing more differentiated UT. NF-kappaB activation preceded production of NO, since treatment with 25 microM hemoglobin, a potent inactivator of NO, did not prevent LT-2-triggered NF-kappaB activation. Treatment with 10 microM pyrrolidine dithiocarbamate (PDTC) inhibited LT-2-triggered activation of NF-kappaB and prevented the stimulatory effect of LT-2 on proliferation of basal UT. These findings support the possibility that NF-kappaB activation mediates basal UT proliferation triggered by LT-2.

Cell Wall↗
PubMed2000

Isolation of an 1,3-1,4-beta-glucan degrading Enterococcus faecium strain from the intestinal tract of chicken and partial characterization of its novel 1,3-1,4-beta-glucanase.

An Enterococcus faecium strain with a novel endo 1,3-1,4-endo-beta-glucanase (lichenase, E.C. 3.2.1.73) was isolated from the intestinal tract of broiler chicken. The enzyme was secreted into the culture medium and acted exclusively on mixed linked 1,3-1,4-beta-glucans as determined with a reducing sugar assay. The purified enzyme has its isoelectric point at pI 4.8, maximum activity was determined at pH 6.5 and 40 degrees C. Thermal stability of the enzyme was low, but high pH stability and high residual activity was observed after incubation in digesta samples from the chicken intestine. Multiple lichenase activities were obtained from culture supernatants on SDS/PAGE and native zymograms, but it is concluded that the lichenase consists of one active protein at 30.5 kD and additional polypeptides of unknown function.

Animals↗
PubMed2001

The stress proteome of Enterococcus faecalis.

Enterococcus faecalis is a resident bacterium of the intestinal tract of humans and animals. This bacterium can be responsible for serious diseases and is one of the largest causes of hospital-based infections. This hardy organism resists many kinds of stresses and is used as a major indicator of the hygienic quality of food, milk, and drinking water. On the other side, enterococci seem to have beneficial role in the development of cheese aroma and are added in certain starter cultures. Since ten years, our laboratory has used the two-dimensional electrophoresis (2-DE) technique to study the response of E. faecalis to physical or chemical stresses as well as to glucose and total starvation. Twenty-seven protein spots on 2-D gels have been identified by N-terminal sequencing or Western blotting which make up the first proteome database of this species. The proteins were classified in four different groups according to their function and their regulation. The first group comprises well-characterized proteins with known protective functions towards stresses. The second group contains enzymes of catabolic pathways. Their implication in stress resistance seems not obvious. A third group are proteins induced in glucose-starved cells belonging to the CcpA regulon. Induction of these enzymes under starvation may serve to increase the scavenging capacity of the cells for nutrients or may be important to mobilize endogenous energetic reserves. Lastly, nine N-terminal amino acid sequences or open reading frames (ORF) showed no homologies with sequences in databases. A comprehensive description of stress proteins of E. faecalis and analysis of their patterns of expression under different environmental conditions would greatly increase our understanding of the molecular mechanisms underlying the extraordinary capacity of this bacterium to survive under hostile conditions.

Acids↗
PubMed1991

Factors influencing the synthesis of an extracellular proteinase by Enterococcus faecalis subsp. liquefaciens.

Studies were conducted on optimum temperature, pH and the requirement for an energy source, amino acids, casein, Zn2+ and Ca2+ during the synthesis of an extracellular acid proteinase by Enterococcus faecalis var. liquefaciens. Synthesis was monitored using cells grown to mid-logarithmic phase and resuspended at high density in fresh growth medium. Proteinase production was optimal at 30 degrees C and pH 7.0. Proteinase synthesis, being energy-dependent, occurred only in glycolysing cells. The synthesis was high when lactose but not glucose was utilized as a source of energy, indicating that phospho-beta-galactosidase gene might probably be located directly upstream the proteinase gene on a plasmid. Good induction of proteinase synthesis could be achieved by 0.2-0.5% of either yeast extract or tryptic digested casein, perhaps due to its content of a wide variety of free amino acids. Casein was essential for preventing proteinase autolysis and sustaining the enzyme production. Zn2+ and Ca2+ were required for the formation of an active extracellular proteinase. The synthesis immediately ceased after addition of chloramphenicol or EDTA. EDTA inactivated the preformed proteinase as well. Sodium chloride at a concentration of 6.5% inhibited both proteinase synthesis and glycolysis.

Caseins↗
PubMed2006

Enterococcus faecalis-mediated biomineralized biofilm formation on root canal dentine in vitro.

Enterococcus faecalis is the most predominant bacteria in teeth with failed root canal therapy and is found to survive harsh conditions prevailing in the root canals of endodontically treated teeth. This study aims to investigate the interaction between E. faecalis and root canal dentine substrate. Towards this end, tooth specimens were prepared and divided into two groups. The tooth specimens in group 1 were incubated with E. faecalis for periods of 2-, 4-, and 6-week intervals and the chemical composition of the biofilm was determined using X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy. The tooth specimens in group 2 were incubated with E. faecalis for a period of 6 weeks and the topography and ultrastructure of the biofilm were examined using scanning electron microscopy (SEM), light microscopy, and laser confocal scanning microscopy. The sediments formed from the bacterial interaction on the dentine (in group 1) were also examined by SEM and FTIR. These experiments highlighted different stages in the interaction of E. faecalis with root canal dentine. Further, a bacterial-induced apatite reprecipitation on mature biofilm was also observed. This ability of E. faecalis to form such calcified biofilm on root canal dentine may be a factor that contributes to their persistence after endodontic treatment.

Biocompatible Materials↗
PubMed2005

Growth of Enterococcus mundtii ST15 in medium filtrate and purification of bacteriocin ST15 by cation-exchange chromatography.

Bacteriocin ST15 (bacST15), produced by Enterococcus mundtii ST15, inhibited the growth of a variety of bacteria, including exopolysaccharide (EPS)-producing strains isolated from biofilms in stainless steel pipes. Maximal production of bacST15 (51200 AU/ml) was recorded after 20 h of growth in MRS broth (Biolab), which was maintained throughout fermentation. Only 12800 AU/ml bacST15 has been recorded in MRS filtrate with components smaller than 8000 Da, suggesting that nutrients larger than 8000 Da are required for optimal bacST15 production. Cation-exchange chromatography yielded an active peptide, which is 3944.00 Da, according to electron-spray mass spectrometry and tricin-SDS PAGE. BacST15 is smaller than the 4287 Da reported for bacteriocins ATO6 and KS produced by E. mundtii . The iso-electric point of bacST15 is between 7 and 9, and similar to that reported for pediocin PD-1.

Anti-Bacterial Agents↗
PubMed1996

Molecular analysis of the rpoD gene of Enterococcus faecalis.

The complete nucleotide sequence of the rpoD gene of Enterococcus faecalis ATCC19433 has been determined. This gene encodes a putative 368 amino acids (aa) polypeptide of a predicted Mr of 41842 named sigma 42. Upstream of the rpoD gene and beginning from the end of the cloned chromosomal fragment is an open reading frame encoding a putative 264-aa polypeptide. It is reminiscent of the C-terminal domain of known DNA primase from Gram-positive bacteria indicating that the E. faecalis rpoD gene is included in a macromolecular synthesis (MMS) operon, as it was described for Escherichia coli, Bacillus subtilis and Lactococcus lactis rpoD gene.

Amino Acid Sequence↗
PubMed1996

Unusual resistance and acquired tolerance to cadmium chloride in Enterococcus faecalis.

Enterococcus faecalis exhibits an extremely high natural resistance to cadmium which can be even raised by a conditioning treatment at a lower cadmium concentration as well as by a previous exposure to a sublethal temperature. By contrast, thermotolerance is not significantly induced by previous exposure to low cadmium concentration. The synthesis of several proteins is markedly enhanced by a low concentration of the chemical agent.

Adaptation, Biological↗
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↗