OBJECTIVETo study the effect of calcium hydroxide solutions at different pH values on the cell-surface hydrophobicity of starved Enterococcus faecalis.

METHODSE. faecalis in starvation were harvested and incubated in freshly prepared calcium hydroxide solutions at the pH values ranging from 7.3 to 10.3 for 15 min or 60 min. The cell-surface hydrophobicity of the starved E. faecalis was evaluated by measuring microbial adhesion to hydrocarbons (MATH). Scanning electron microscopy was used to investigate the adhesion capability of starved E. faecalis cells incubated on human dentin at different pH levels.

RESULTSFor the same duration of treatment, increased pH value of calcium hydroxide solution significantly enhanced the cell-surface hydrophobicity of starved E. faecalis (P<0.01). At the same pH value, the cell-surface hydrophobicity of the bacterium increased significantly with time (P<0.05, 15 min vs 60 min). Scanning electron microscopy revealed a significantly increased adhesion of the starved cells on human dentin as the pH value and incubation time increased.

CONCLUSIONCalcium hydroxide solutions promote the adhesion of starved E. faecalis by modifying its cell-surface hydrophobicity.

Bacterial Adhesion ; Calcium Hydroxide ; pharmacology ; Enterococcus faecalis ; chemistry ; drug effects ; Hydrophobic and Hydrophilic Interactions ; Microbial Sensitivity Tests

OBJECTIVETo determine the antibiotics resistance, aminoglycoside-modifying enzymes and homology of high-level gentamycin resistant enterococcus in clinical specimens.

METHODSThe high-level gentamicin resistant (HLGR) isolates were screened by the agar method and the resistance of 14 antimicrobial agents was determined by K-B method. The aminoglycoside-modifying enzyme genes were detected by polymerase chain reaction (PCR). Pulsed-field gel electrophoresis (PFGE) was used to analyze the homology of HLGR isolates.

RESULTSThe ratio of HLGR was 64.2% (68/106). Among the HLGR,there were no isolates resistant to linezolid, vancomycin and tecoplanin, and Enterococcus faecium was more resistant to beta-lactam antibiotics and quinolone than Enterococcus faecalis. The positive rate of aac(6')-Ie-aph(2')-Ia was 92.6% and 3 isolates had the resistance gene mostly similar to aph(2')-Id. And among 51 HLGR isolates from the hospitalized patients, PFGE grouped 17 E. faecalis isolates into 4 clusters (A-D), and 33 E. faecium isolates into 8 clusters (A-H) with A cluster as predominant.

CONCLUSIONHLGR has become the important antibiotic resistance bacteria which results in nosocomial infection; and aac(6')-Ie-aph(2')-Ia is the main aminoglycoside-modifying enzyme gene which causes HLGR.

Drug Resistance, Bacterial ; genetics ; Electrophoresis, Gel, Pulsed-Field ; Enterococcus ; drug effects ; genetics ; Enterococcus faecalis ; drug effects ; genetics ; Enterococcus faecium ; drug effects ; genetics ; Gentamicins ; pharmacology ; Humans ; Kanamycin Kinase ; genetics ; Microbial Sensitivity Tests

OBJECTIVETo evaluate in vitro the antibacterial effectiveness of sodium hypochlorite on Enterococcus faecalis (E. faecalis) within root canals.

METHODSRoots inoculated with E. faecalis were divided into six groups, which underwent different root canal irrigation and treatment: Group 1: 5.25% NaOCl, Group 2: 2.5% NaOCl, Group 3: 0.9% NaCl, Group 4: root canal preparation + 5.25% NaOCl, Group 5: root canal preparation + 2.5% NaOCl, Group 6: root canal preparation + 0.9% NaCl. Microbiological samples were collected from root canals at three time points (before irrigation, immediately after irrigation and three days after irrigation).

RESULTSThe numbers of E. faecalis in root canal in each of the six groups were effectively reduced. Group 1 and 2 were statistically more effective than Group 3. Group 4 was statistically more effective than Group 5 and 6. Group 5 was statistically more effective than Group 6. Bacterial survival was observed in all canals of each group after a 3-day-incubation.

CONCLUSIONS2.5% NaOCl was highly effective for root canal irrigation. However residual bacteria remained in the root canals after chemical irrigation by NaOCl and mechanical preparation.

Dental Pulp Cavity ; microbiology ; Enterococcus faecalis ; drug effects ; Humans ; In Vitro Techniques ; Root Canal Irrigants ; pharmacology ; Sodium Hypochlorite ; pharmacology

OBJECTIVEThis study aims to compare and determine a kind of nano-hydroxyapatite composite material with good antibacterial efficacy on Enterococcusfaecalis (E. faecalis) in vitro.

METHODSWe investigated the antimicrobial activity of four kinds of nano-hydroxyapatite composites, namely, silver/hydroxyapatite composite nanoparticles (Ag/nHA), yttrium/hydroxyapatite composite nanoparticles (Yi/nHA), cerium/hydroxyapatite composite nanoparticles (Ce/nHA), and hydroxyapatite nanoparticles (nHA), against E. faecalis in vitro using the agar diffusion and broth dilution method by measuring the growth inhibition zone and the minimum inhibitory concentration (MIC), respectively.

RESULTSThe agar diffusion test results showed that Ag/nHA displayed an obvious growth inhibition zone, whereas Yi/nHA, Ce/nHA, and nHA showed no influence on E. faecalis. The MIC value of Ag/nHA was 1.0 g.L-1, and the three other materials had no effect on E.faecalis even at the high concentration of 32.0 g.L-1.

CONCLUSIONAg/nHA display a potential antimicrobial efficacy to planktonic E.faecalis. Whereas, the three other kinds of nano-hydroxyapatite composites (Yi/nHA, Ce/nHA, nHA) show no influence.

Anti-Bacterial Agents ; pharmacology ; Anti-Infective Agents ; Durapatite ; pharmacology ; Enterococcus faecalis ; drug effects ; Microbial Sensitivity Tests ; Nanocomposites ; toxicity ; Silver

The emergence of multi-drug resistant gram-positive cocci such as methicillin-resistant (MR) staphylococci, vancomycin-resistant (VR) enterococci, and vancomycin-intermediate resistant S. aureus (VISA) has given new urgency to the development of new antimicrobial agents. One of these is quinupristin/dalfopristin (Q/D). We decided to determine the susceptibility of gram-positive cocci isolated at two university hospitals in Seoul to Q/D and compare the results with eight other antimicrobial agents. We investigated 120 isolates of S. aureus including 49 MRSAs and one VISA, 120 isolates of coagulase negative staphylococci (CNS), 64 E. faecalis and 56 E. faecium, including seven strains of VR E. faecium. Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) for several antimicrobials, including vancomycin and Q/D, were determined by broth microdilution. All S. aureus including VISA were susceptible to Q/D. Q/D MIC90 for both methicillin-susceptible S. aureus (MSSA) and MRSA was 0.25 g/mL. 49 (87.5%) of 56 E. faecium including six of seven VR E. faecium were susceptible to Q/D. E. faecalis were not susceptible to Q/D (only 1.5% susceptible), but were inhibited by ampicillin (94% susceptible) or vancomycin (95%). CNS was susceptible to Q/D (96% susceptible) and vancomycin (100% susceptible). One of 38 staphylococci and two of 17 E. faecium were tolerant to Q/D. In conclusion, Q/D showed excellent activity against all species of gram-positive cocci including MRSA, VISA, and VR E. faecium except E. faecalis, and may provide a valuable option for the treatment of infections caused by these emerging nosocomial pathogens of gram-positive cocci.
Antibiotics/pharmacology* ; Antibiotics, Peptide/pharmacology* ; Coagulase/analysis ; Enterococcus faecalis/drug effects ; Enterococcus faecium/drug effects ; Human ; Korea ; Microbial Sensitivity Tests* ; Staphylococcus/enzymology ; Staphylococcus/drug effects ; Staphylococcus aureus/drug effects ; Support, Non-U.S. Gov'tn ; Virginiamycin/pharmacology* ; Virginiamycin/analogs & derivatives*

The purpose of this study was to assess the efficacy of alexidine (ALX), alone and combined with N-acetylcysteine (NAC), in eradicating two Enterococcus faecalis strain biofilms. The biofilms of E. faecalis ATCC 29212 and the clinical isolate E. faecalis D1 were grown in the MBEC-high-throughput device for 24 h and were exposed to five twofold dilutions of ALX (2%-0.007 8%) alone and combined with 100 mg⋅mL(-1) NAC, for 1 and 5 min. Eradication was defined as 100% kill of biofilm bacteria. The Student's t-test was used to compare the efficacy of the associations of the two irrigants. After 1-min contact time, ALX eradicated the biofilms at all concentrations except for 0.007 8% and 0.015 6%-0.007 8% with E. faecalis ATCC 29212 and E. faecalis D1, respectively. Similar results for eradication and concentration were obtained when it was combined with 100 mg⋅mL(-1) NAC. After 5 min of contact time, ALX alone and combined with NAC eradicated all enterococci biofilms. ALX showed antimicrobial properties against the two E. faecalis strain biofilms tested at very low concentrations, and its combined use with NAC was not seen to enhance its activity.
Acetylcysteine ; pharmacology ; Anti-Infective Agents, Local ; pharmacology ; Biguanides ; pharmacology ; Biofilms ; drug effects ; Dental Pulp Cavity ; microbiology ; Drug Combinations ; Enterococcus faecalis ; drug effects ; Humans

OBJECTIVETo study the changes of growth and biofilm formation capability of Enterococcus faecalis (Ef) in different stress conditions.

METHODSThe changes of growth of Ef in stress conditions were observed by measuring the A600 value with ultraviolet spectrophotometer. Ef was incubated on glass slide in stress conditions, biofilm formation capability of cells was investigated by colony-forming unit (CFU) counting of the culturable bacteria and fluorescence confocal laser scanning microscopy.

RESULTSEf couldn't growth under the conditions of 2%, 5%NaClO, pH = 11 and 12, the A600 value was unchanged in 96 hours. But the growth curve changed at different levels in other stress conditions: under 1%NaClO, the A600 value peaked at 1.461 at 16 hour (the peaked level was 1.238 at 6 hours in control group) ; under 0,0.05%,0.15% glucose, it peaked at 0.645,0.890, 1.173, respectively, at 6 hour (it was maximized to 1.195 at 6 hours in control group); the A600 value peaked at 1.704 at 6 hours at pH = 9 and 1.225 at 10 hours at pH = 10 (the peak level was 1.732 at 6 hours at pH = 7) . Biofilm assay showed that Ef were able to form biofilm in these stress conditions except 5%NaClO and pH = 12.

CONCLUSIONSEf could growth and form biofilms in energy starvation, low concentrations of sodium hypochlorite and weak alkaline stress.

Biofilms ; drug effects ; growth & development ; Colony Count, Microbial ; Enterococcus faecalis ; drug effects ; growth & development ; Glucose ; pharmacology ; Hydrogen-Ion Concentration ; Microscopy, Confocal ; Sodium Hypochlorite ; pharmacology

OBJECTIVETo analyze the infection status and the drug resistance of enterococci in patients with severe hepatitis to guide future treatment.

METHODSAll bacteria from infected patients with severe hepatitis were cultured with BacT/Alert120 automation instrument (Aksu) and identified with Vitek-AMS60 (Biomerieux). Drug sensitivities of the isolated enterococci were tested with 11 antibacterial agents.

RESULTSAmong the 112 isolated enterococci, Enterococcus faecalis was the most preponderant bacterium, and the second was E. faecium. Their isolation rates were 79.5% and 14.3%, respectively. 57.1% of all the enterococci were found in the ascetic fluid of patients with severe hepatitis. Fifty-eight (51.8%) isolated enterococci were found to be high level aminoglycoside resistant (HLAR), 19 (17.0%) enterococci were ampicillin-resistant enterococcus (ARE) and 7 (6.3%) were both HLAR and ARE. The susceptive rates of the enterococci to vancomycin and teicoplanin were very high, namely 96.4% and 100%, respectively. No vancomycin or teicoplanin resistant enterococci were found, but 4 enterococci were mildly sensitive to vancomycin.

CONCLUSIONEnterococcus faecalis is the most prevalent species isolated in severe hepatitis patients infected with enterococcal infection. From our study, vancomycin and teicoplanin are the drugs of first choice to treat those infections.

Aminoglycosides ; pharmacology ; Ampicillin Resistance ; Drug Resistance, Bacterial ; Enterococcus faecalis ; drug effects ; Gram-Positive Bacterial Infections ; complications ; microbiology ; Hepatitis ; microbiology ; Humans ; Microbial Sensitivity Tests ; Teicoplanin ; pharmacology ; Vancomycin ; pharmacology

OBJECTIVETo compare the antimicrobial efficacy of four endodontic irrigants using an in vitro model infected by Enterococcus faecalis (Ef).

METHODSThe root canals of fifty extracted teeth were infected by Ef in vitro. The test groups were irrigated with 3% H(2)O(2), 2.5% sodium hypochlorite (SH), 2% chloramine-T (CR), and 2% chlorhexidine (CHX), respectively, and the control group was irrigated with 0.9% NaCl. The concentration of Ef in canals of each group was calculated before and after irrigation. The residual bacteria within the dentinal tubules and vitalities of the residual bacteria were also examined.

RESULTSAll chemical irrigants were significantly more effective than 0.9% NaCl (P < 0.05); 2.5% SH and 2% CHX were statistically more effective than 3% H(2)O(2) (P < 0.05). Residual bacteria could be found in the dentinal tubules and propagated 72 h after.

CONCLUSIONS2% CR and 2% CHX had almost the equivalent antimicrobial effect as 2.5% SH, but 3% H(2)O(2) was less effective.

Chloramines ; pharmacology ; Chlorhexidine ; pharmacology ; Dental Pulp Cavity ; microbiology ; Enterococcus faecalis ; drug effects ; Humans ; Hydrogen Peroxide ; pharmacology ; In Vitro Techniques ; Root Canal Irrigants ; pharmacology ; Sodium Hypochlorite ; pharmacology ; Tosyl Compounds ; pharmacology

A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine. The aim of this study was to compare the antimicrobial activity of 1% alexidine with that of 2% chlorhexidine using Enterococcus faecalis-infected dentin blocks. Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each. E. faecalis was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2% chlorhexidine or 1% alexidine solutions for 5 and 10 min, respectively. Sterile saline was used as a control. The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope. Significantly fewer bacteria were observed in the 2% chlorhexidine- or 1% alexidine-soaked groups than in the control group (P<0.05). However, there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups (P>0.05). Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups. In conclusion, 10-min soaking with 1% alexidine or 2% chlorhexidine can be effective against E. faecalis infection.
Animals ; Anti-Bacterial Agents ; pharmacology ; Bacterial Adhesion ; drug effects ; Bacterial Load ; drug effects ; Biguanides ; pharmacology ; Cattle ; Cell Membrane ; drug effects ; Chlorhexidine ; pharmacology ; Dentin ; microbiology ; Enterococcus faecalis ; drug effects ; Microscopy, Electron, Scanning ; Random Allocation ; Time Factors