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Background and purpose: Multi-resistant enterococci are important nosocomial pathogens that are shown to have high prevalence in recent years. Knowledge of antimicrobial resistance pattern is essential to formulate treatment guidelines for infections caused by enterococci. The aim of this study was to investigate the antimicrobial resistance among enterococci isolated from Hamedan hospitals. Material and methods: The study was carried out during 2012-2014 in 242 Enterococcus faecalis and Enterococcus faecium Strains isolated from clinical specimens of teaching inpatients and outpatients hospitals in Hamedan. Identified species by biochemical methods were confirmed by PCR. Antibiotic resistance was performed by disk diffusion. MIC (Minimum Inhibitory Concentration) of vancomycin and Teicoplanin were determined by Microdilution Broth method. Results: A total of 280 enterococcal isolates were studied of which, 175 (62.5%) were identified as Enterococcus faecalis, 67(24%) as Enterococcus faecium, and 38(13.5%) as Enterococcus spp. No resistance to Linezolid and Nitrofurantoin was detected among E.faecalis isolates. All isolates of E. faecium were susceptible to Linezolid. Resistance rates to ampicillin, Vancomycin, Teicoplanin, ciprofloxacin, erythromycin, Norfloxacin, gentamicin and Nitrofurantoin were found higher in E.faecium isolates than those of the E.faecalis group. Conclusion: Due to the high prevalence of Vancomycin-resistant enterococci and also increasing resistance of enterococcus to most common antibiotics, there is a need for preventive and control measurements. Therefore, antibiotic susceptibility testing is recommended for all patients before prescription of appropriate antibiotics.

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Background and purpose: Mechanical and chemical canal preparations are not capable of eliminating all microorganisms from dentinal tubules, so using medical intervention is necessary to fulfill this task. The aim of this study was to compare the antimicrobial effect of Carvacrol and Calcium hydroxide against Enterococcus faecalis in different layers of dentin and different time intervals.

Materials and methods: An experimental study was performed in which 70 upper anterior single-rooted teeth were extracted and after separating middle of roots, the inner diameter of canals was equalized. After sterilization the specimens were subjected to Enterococcus faecalis suspension and then randomly divided into four groups of 15 each and one control group including 10 samples. Carvacrol was placed in canals for 5 minutes, 48 hours and one week and Calcium hydroxide was placed in canals for one week. Finally, dentinal debris obtained from canal preparation were incubated in culture medium and presence of Enterococcus faecalis was assessed. Statistical analysis was performed using Chi-square test in SPSS.

Results: In the inner layer of dentin, success rate of Enterococcus faecalis elimination was 100% for Carvacrol at all time intervals and 80% for Calcium hydroxide after one week. In the middle layer of dentin, the success rate of Carvacrol was 93% after 5 minutes and 87% after 48 hours and one week, but success rate of Calcium hydroxide after one week was 73%. There were no significant differences in antimicrobial effect between the groups (P>0.05).

Conclusion: Carvacrol can eliminate Enterococcus faecalis in shorter time intervals compared with Calcium hydroxide.

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Background and purpose: Calcium hydroxide and Chlorhexidine are among common intracanal medications. Recently an herbal composition named Carvacrol has been suggested as an intracanal medication. The purpose of this study was to compare antimicrobial effect of Carvacrol, Chlorhexidine and Calcium hydroxide on Enterococcus faecalis.

Materials and methods: In this experimental study, 56 single-rooted teeth were extracted and after canal preparation, they were randomly divided into three groups (n= 16) and 2 positive and negative control groups (n= 4 per group). After sterilization by autoclave, all samples except negative control group were contaminated with Enterococcus faecalis. The root canals in group 1 were filled by Calcium hydroxide paste. Paper cones impregnated by 0.2% Chlorhexidine and 94% Carvacrol were placed in working length of root canals in group 2 and 3, respectively. Negative control group was assessed without contamination and no medication was used in positive control group. After incubation of specimens for 48 hours and canal irrigation, a sample was taken from each canal and bacterial colony growth was assessed in BHI agar. Data analysis was done in SPSS ver.20 applying Chi-square and Fishers exact test.

Results: All three groups were found effective in eliminating Enterococcus faecalis and there were no significant differences in antibacterial effect between these groups (P= 0.99).

Conclusion: Carvacrol can be recommended as an effective herbal medication for intracanal irrigation.

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Background and purpose: Decrease in the number of oral microorganisms leads to reduction in caries score. Bacterial therapy, such as using probiotic bacteria, is an alternative procedure in treatment of infections caused by microorganisms. The purpose of this study was to compare the effect of probiotic and non-probiotic yogurt-drink on two common oral microorganisms.
Materials and methods: In this experimental study, the minimum inhibitory concentration (MIC) of yogurt drinks and diameter of the growth inhibition zone of Streptococcus mutans and Enterococcus faecalis in probiotic and non-probiotic yogurt drinks were measured using micro broth dilution and disk agar diffusion methods, respectively. Data analysis was done in SPSS V22 applying Mann-Whitney test.
Results: The MIC of non-probiotic yogurt drink against Enterococcus faecalis and Streptococcus mutans was significantly higher than the probiotic yogurt drink (P= 0.002). The two yogurt drinks did not show any significant differences in the diameter of growth inhibition zone for S. mutans (P= 0.061) and E. faecalis (P= 0.99).
Conclusion: The study showed that probiotic yogurt drink can inhibit E. faecalis and S. mutans more than the non-probiotic yogurt drink, and it may be considered as a preventive agent for oral and dental diseases.

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Background and purpose: Contamination of swimming beaches in north of Iran has caused environmental problems in recent years. Mahmoudabad is exposed to these dangers due to having the longest coastline in the country.  The aim of this study was to determine microbial water quality of swimming beaches in Mahmoudabad.
Materials and methods: In a descriptive-analytical study, we analyzed microbial water quality from 15 different sites in 2019 (monthly). Microbial tests were carried out according to the standard methods for Coliform group and Enterococcus faecalis. Data analysis was performed in SPSS software.
Results: The average total coliforms in all sampling sites exceeded 1000 MPN/100 ml in summer, autumn and winter. In all seasons, E. faecalis were detected at highest levels in most of the swimming sites. Other sites had standard fecal coliform microbial quality for swimming beaches.
Conclusion: Microbial quality of natural swimming beaches in Mahmudabad was not favorable which could pose health risks to swimmers and travelers.
 

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 Background and purpose: Glycopeptide resistance genes can be transmitted to clinical strains from gram-positive environmental bacteria and the normal flora. The aim of this study was to evaluate the prevalence of vancomycin and teicoplanin-resistant Enterococcus faecalis and Enterococcus faecium isolates in hospital environment and fecal samples of healthy individuals.
Materials and methods: Human stool and hospital environment samples were collected and inoculated on selective M-enterococcus agar medium. Then, E. faecalis and E. faecium were identified using phenotypic and molecular methods. Antibiotic susceptibility pattern of the isolates against teicoplanin and vancomycin was determined by micro-broth dilution method. Data were analyzed in SPSS applying Chi-square test.
Results: From 145 isolates, E. faecalis and E. faecium were detected in 84 (54.93%) and 61 (42.07%) isolates, respectively. One (1.19%) E. faecalis isolate and 4 (6.56%) E. faecium isolates were resistant to vancomycin, while 4 (6.56%) E. faecium isolates were found to be resistant to teicoplanin. The minimum inhibitory concentrations of 50 (MIC₅₀) and 90 (MIC₉₀) for vancomycin and teicoplanin in E. faecalis and E. faecium were 4 and 16 μg/ml, respectively.
Conclusion: The MIC results of vancomycin and teicoplanin showed that most of enterococci isolates studied were sensitive to these two antibiotics. Therefore, their use should be closely monitored to prevent resistance.

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 Background and purpose: Antimicrobial property is one of the important features of sealers, which plays an essential role in limiting microorganisms from the root canal system. This study was conducted to investigate the antimicrobial properties of EndosealMTA, Sure seal root, and AH26 sealers on Enterococcus faecalis bacteria.
Materials and methods: In this study, ceramic sealers Endoseal MTA, suersealroot, and resin sealer AH26 were used. Each of these sealers was placed in wells in the agar medium for 10-15 minutes to spread and then immediately incubated at 35±2°C for 24 hours. Statistical analysis was performed using SPSS (V.22), with the application of Shapiro-Wilk, Kruskal-Wallis, and ANOVA tests.
Results: The highest mean halo of non-growth was related to the Endoseal MTA group. The antimicrobial property of Suresealroot sealer was lower compared to AH26 sealer, but this difference was not statistically significant. (P=0.368). The antimicrobial property of Endoseal MTA sealer was higher compared to AH26 sealer, but this difference was not statistically significant (P=0.368). The antimicrobial properties of Suresealroot sealer were lower compared to Endoseal MTA, but there was no statistically significant difference (P=0.48).
Conclusion: Ceramic sealers Suresealroot, Endo seal MTA and AH26 resin sealer showed antimicrobial properties against Enterococcus faecalis; But the antimicrobial properties of Ceramic Sealers were not different from resin sealer on Enterococcus faecalis