Co-occurrence of triple carbapenemase genes, blaVIM-2, blaNDM-1, and blaOXA-48 in Enterobacter hormaechei clinical isolates -first report from Croatia.

Two Enterobacter hormaechei isolates harbouring three carbapenemase genes each, were isolated from two patients from different ICUs at University Hospital Centre Zagreb, Croatia, which is to our knowledge, the first report of triple carbapenemase (blaVIM-2, blaNDM-1, and blaOXA-48) co-existence in E. hormachei strains and also among Enterobacterales members in Croatia. Antimicrobial susceptibility testing showed susceptibility only to colistin and amikacin. The production of carbapenemases was phenotypically tested by immunochromatographic assay and confirmed by PCR. Detailed analysis by Whole Genome Sequencing (WGS) of short reads by Illumina and long reads by Oxford Nanopore Technologies (ONT) was additionally performed and showed that both isolates belonged to ST200. They were separated by 98 Single Nucleotide Polymorphisms (SNPs) having variations in the number of blaVIM-2 genes on the chromosome, the number of blaNDM-1 genes on the plasmid, non-identical blaNDM-1 plasmids, different plasmid content in general, and only one isolate carried a 94 kb prophage.

Evaluation of Different Procedures for Titanium Dental Implant Surface Decontamination-In Vitro Study.

Polymicrobial biofilm removal and decontamination of the implant surface is the most important goal in the treatment of periimplantitis. The aim of this study is to evaluate the efficacy of four different decontamination methods for removing Acinetobacter baumannii and Staphylococcus aureus biofilms in vitro. Seventy-five dental implants were contaminated with a bacterial suspension and randomly divided into five groups (n = 15): the negative control group, which received no treatment; the positive control group, treated with 0.2% chlorhexidine; group 1, treated with a chitosan brush (Labrida BioCleanTM, Labrida AS, Oslo, Norway); group 2, treated with a chitosan brush and 0.2% chlorhexidine; and group 3, treated with a device based on the electrolytic cleaning method (GalvoSurge, GalvoSurge Dental AG, Widnau, Switzerland). The colony-forming unit (CFU) count was used to assess the number of viable bacteria in each sample, and statistical analyses were performed. When compared to the negative control group, all the decontamination methods reduced the CFU count. The electrolytic cleaning method decontaminated the implant surface more effectively than the other three procedures, while the chitosan brush was the least effective. Further research in more realistic settings is required to assess the efficacy of the decontamination procedures described in this study.

Enterobacterales carrying chromosomal AmpC ß-lactamases in Europe (EuESCPM): Epidemiology and antimicrobial resistance burden from a cohort of 27 hospitals, 2020-2022.

INTRODUCTION: The ESCPM group (Enterobacter species including Klebsiella aerogenes - formerly Enterobacter aerogenes, Serratia species, Citrobacter freundii complex, Providencia species and Morganella morganii) has not yet been incorporated into systematic surveillance programs. METHODS: We conducted a multicentre retrospective observational study analysing all ESCPM strains isolated from blood cultures in 27 European hospitals over a 3-year period (2020-2022). Diagnostic approach, epidemiology, and antimicrobial susceptibility were investigated. RESULTS: Our study comprised 6,774 ESCPM isolates. MALDI-TOF coupled to mass spectrometry was the predominant technique for bacterial identification. Susceptibility to new ß-lactam/ß-lactamase inhibitor combinations and confirmation of AmpC overproduction were routinely tested in 33.3% and 29.6% of the centres, respectively. The most prevalent species were E. cloacae complex (44.8%) and S. marcescens (22.7%). Overall, third-generation cephalosporins (3GC), combined third- and fourth-generation cephalosporins (3GC + 4GC) and carbapenems resistance phenotypes were observed in 15.7%, 4.6%, and 9.5% of the isolates, respectively. AmpC overproduction was the most prevalent resistance mechanism detected (15.8%). Among carbapenemase-producers, carbapenemase type was provided in 44.4% of the isolates, VIM- (22.9%) and OXA-48-enzyme (16%) being the most frequently detected. E. cloacae complex, K. aerogenes and Providencia species exhibited the most notable cumulative antimicrobial resistance profiles, with the former displaying 3GC, combined 3GC + 4GC and carbapenems resistance phenotypes in 15.2%, 7.4%, and 12.8% of the isolates, respectively. K. aerogenes showed the highest rate of both 3GC resistant phenotype (29.8%) and AmpC overproduction (32.1%), while Providencia species those of both carbapenems resistance phenotype (42.7%) and carbapenemase production (29.4%). ESCPM isolates exhibiting both 3GC and combined 3GC + 4GC resistance phenotypes displayed high susceptibility to ceftazidime/avibactam (98.2% and 95.7%, respectively) and colistin (90.3% and 90.7%, respectively). Colistin emerged as the most active drug against ESCPM species (except those intrinsically resistant) displaying both carbapenems resistance phenotype (85.8%) and carbapenemase production (97.8%). CONCLUSIONS: This study presented a current analysis of ESCPM species epidemiology in Europe, providing insights to inform current antibiotic treatments and guide strategies for antimicrobial stewardship and diagnostics.

P31-A150†SARS-CoV-2 real time polymerase chain reaction testing of corneas from post-mortem SARS-CoV-2 positive donors.

PURPOSE: Possible transmission of SARS-CoV-2 from donors to recipients via cornea grafts is still a concern of the transplantation community. Current recommendations are to avoid corneal transplants from donors with ongoing SARS-CoV-2 infection or those recently exposed to it. During pandemic period in Croatia 21/1113; (1,9%) corneas were procured from donors positive for SARS-CoV-2 by postmortem nasopharyngeal swab tests. That tissue was discarded. Due to the lack of knowledge about the infectivity of such corneas, we started prospective study of SARS-CoV-2 presence in cornea tissue. Here we show our first results. METHODS: In the study period we had four corneas procured from two post-mortem SARS-CoV-2 positive donors. For the presence of SARS-CoV-2, analysis is performed on donor serum, hypothermic storage medium and cornea tissue lysate. Corneas were stored in hypothermic condition for 8 to 10 days, after which tissue was macerated and washed with PBS. The intracellular content was released by incubation with lysis buffer, followed by centrifugation. Next, tissue lysate, serum and hypothermic storage medium were in parallel subjected to fully automated nucleic acid isolation and RNA expression was analyzed by qRT-PCR. During isolation, RNasaP was used as internal control for successful nucleic acids isolation. RESULTS: No SARS-CoV-2 RNA was detected in the donors serum, storage medium and cornea tissue from donors who were SARS-CoV-2-positive upon tissue procurement. In nasopharyngeal swabs of post mortem positive donors cycle threshold values of viral copies were high (CT>34), indicating that there was small number of viral particles in infected donors that could have impact on negative results in tested tissue. CONCLUSION: Our data suggested that corneas may not be SARS-CoV-2 permissive if the donor was postmortem positive. Further research is required to gain more coherent insight into SARS-CoV-2 transmission via corneal transplantation.

Evaluation of the Photoactivation Effect of 3% Hydrogen Peroxide in the Disinfection of Dental Implants: In Vitro Study.

Photoactivation of 3% hydrogen peroxide with a 445 nm diode laser represents a relatively new, insufficiently researched antimicrobial method in the treatment of peri-implantitis. The purpose of this work is to evaluate the effect of photoactivation of 3% hydrogen peroxide with a 445 nm diode laser, and to compare the obtained results with 0.2% chlorhexidine treatment and 3% hydrogen peroxide treatment without photoactivation, in vitro, on the surface of dental implants contaminated with S. aureus and C. albicans biofilms. Previously, 80 infected titanium implants with S. aureus and C. albicans cultures were divided into four groups: G1-negative control (no treatment), G2-positive control (0.2% chlorhexidine), G3 (3% hydrogen peroxide), and G4 (photoactivated 3% hydrogen peroxide). The number of viable microbes in each sample was determined by the colony forming unit (CFU) count. The results were statistically processed and analyzed, showing a statistically significant difference across all groups compared to the negative control (G1), and the absence of a statistically significant difference between groups G1-G3. The new antimicrobial treatment, according to the results, could be worthy of further analysis and research.

Sepsityper® Kit versus In-House Method in Rapid Identification of Bacteria from Positive Blood Cultures by MALDI-TOF Mass Spectrometry.

In order to further accelerate pathogen identification from positive blood cultures (BC), various sample preparation protocols to identify bacteria with MALDI-TOF MS directly from positive BCs have been developed. We evaluated an in-house method in comparison to the Sepsityper® Kit (Bruker Daltonics, Bremen, Germany) as well as the benefit of an on-plate formic acid extraction step following positive signal by the BACTECTM FX system. Confirmation of identification was achieved using subcultured growing biomass used for MALDI-TOF MS analysis. A total of 113 monomicrobial positive BCs were analyzed. The rates of Gram-positive bacteria correctly identified to the genus level using in-house method and Sepsityper® Kit were 63.3% (38/60) and 81.7% (49/60), respectively (p = 0.025). Identification rates at species level for Gram-positive bacteria with in-house method and Sepsityper® kit were 30.0% (18/60) and 66.7% (40/60), respectively (p < 0.001). Identification rates of Gram-negative bacteria were similar with the in-house method and Sepsityper® Kit. Additional on-plate formic acid extraction demonstrated significant improvement in the identification rate of Gram-positive bacteria at both genus and species level for both in-house (p = 0.001, p < 0.001) and Sepsityper® Kit methods (p = 0.007, p < 0.001). Our in-house method is a candidate for laboratory routines with Sepsityper® Kit as a back-up solution when identification of Gram-positive bacteria is unsuccessful.

Search for new antimicrobials: spectroscopic, spectrometric, and in vitro antimicrobial activity investigation of Ga(III) and Fe(III) complexes with aroylhydrazones.

The in vitro antimicrobial activity of Fe(III) and Ga(III) complexes with N'-(2,3-dihydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (H2L1), N'-(2,4-dihydroxy-phenyl-methylidene)-3-pyridinecarbohydrazide (H2L2), N'-(2,5-dihydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (H2L3), N'-(2-hydroxy-3-methoxyphenyl-methylidene)-3-pyridine-carbohydrazide (H2L4), N'-(2-hydroxy-4-methoxyphenylmethyl-idene)-3-pyridine-carbohydrazide (H2L5), and N'-(2-hydroxy-5-methoxyphenylmethylidene)-3-pyridinecarbo-hydrazide (H2L6) toward several Gram-positive strains of Staphylococcus aureus, a Gram-negative strain of Escherichia coli, and a yeast Candida albicans were investigated. Fe(III)-complexes do not possess antimicrobial activity against all tested strains at concentrations up to 10 mg mL-1. Ga(III) complexes with dihydroxy derivatives showed selective activity, while the broadest range of antibacterial and antifungal activities was observed for complex with 2-hydroxy-3-methoxy-derivative, ligand H2L5. In addition, the coordination properties of ligands H2L1-H2L3 in solution were investigated by UV-Vis spectroscopy. The stability constants (logK) for Ga(III)-H2L 1:1 complexes in MeOH/H2O 1/1 at pH 2.52 were determined, and amounted to 5.8, 5.68, and 4.7, respectively. Detailed characterization of complexes was performed by high-resolution mass spectrometry. The fragmentation pathways for dimer [Fe2(L1)2]2+, [Fe(HL)2]+, [Ga(HL2)2]+ and adduct ions are given. The comparison with analogue Ga(III) and Fe(III) complexes with compounds H2L4-H2L6 was made as well.

Antimicrobial Efficacy and Permeability of Various Sealing Materials in Two Different Types of Implant-Abutment Connections.

The presence of a microgap along an implant-abutment connection (IAC) is considered the main disadvantage of two-piece implant systems. Its existence may lead to mechanical and biological complications. Different IAC designs have been developed to minimise microleakage through the microgap and to increase the stability of prosthodontic abutments. Furthermore, different sealing materials have appeared on the market to seal the gap at the IAC. The purpose of this study was to evaluate the antimicrobial efficacy and permeability of different materials designed to seal the microgap, and their behaviour in conical and straight types of internal IACs. One hundred dental implants with original prosthodontic abutments were divided into two groups of fifty implants according to the type of IAC. Three different sealing materials (GapSeal, Flow.sil, and Oxysafe gel) were applied in the test subgroups. The contamination of implant-abutment assemblies was performed by a joint suspension containing Candida albicans and Staphylococcus aureus. It was concluded that the IAC type had no significant influence on microleakage regarding microbial infection. No significant difference was found between the various sealing agents. Only one sealing agent (GapSeal) was found to significantly prevent microleakage. A complete hermetic seal was not achieved with any of the sealing agents tested in this study.

A Novel Technique for Disinfection Treatment of Contaminated Dental Implant Surface Using 0.1% Riboflavin and 445 nm Diode Laser-An In Vitro Study.

BACKGROUND: Antimicrobial photodynamic therapy (PDT) has been introduced as a potential option for peri-implantitis treatment. The aim of this study is to evaluate the antimicrobial effect of a novel technique involving a combination of 445 nm diode laser light with 0.1% riboflavin solution (used as a photosensitizing dye) as applied on a bacterial-fungal biofilm formed on implants and to compare the performance of this technique with that of the commonly used combination of 660 nm diode laser with 0.1% methylene blue dye. METHODS: An in vitro study was conducted on 80 titanium dental implants contaminated with Staphylococcus aureus (SA) and Candida albicans (CA) species. The implants were randomly divided into four groups: negative control (NC), without surface treatment; positive control (PC), treated with a 0.2% chlorhexidine (CHX)-based solution; PDT1, 660 nm (EasyTip 320 µm, 200 mW, Q power = 100 mW, 124.34 W/cm2, 1240 J/cm2) with a 0.1% methylene blue dye; and PDT2, 445 nm (EasyTip 320 µm, 200 mW, Q power = 100 mW, 100 Hz, 124.34 W/cm2, 1.24 J/cm2) with a 0.1% riboflavin dye. RESULTS: The PDT1 and PDT2 groups showed greater reduction of SA and CA in comparison to the NC group and no significant differences in comparison to the PC group. No statistically significant differences between the PDT1 and PDT2 groups were observed. CONCLUSIONS: A novel antimicrobial treatment involving a combination of 445 nm diode laser light with riboflavin solution showed efficiency in reducing SA and CA biofilm formation on dental implant surfaces comparable to those of the more commonly used PDT treatment consisting of 660 nm diode laser light with methylene blue dye or 0.2% CHX treatment.

Sealing Ability of Bioactive Root-End Filling Materials in Retro Cavities Prepared with Er,Cr:YSGG Laser and Ultrasonic Techniques.

The aim of this in vitro study was to compare the apical sealing ability of total fill bioceramic root repair material (BC-RRM) and mineral trioxide aggregate (MTA), regarding the retrograde preparation technique used: ultrasonic or erbium, chromium: yttrium, scandium, gallium, or garnet (Er,Cr:YSGG) laser. The study sample consisted of 48 human single-rooted teeth. After root-end resection, the samples were divided into two groups, according to the retrograde preparation technique used: Group 1: ultrasonic; Group 2: Er,Cr:YSGG laser. In each group, half of the retrograde cavities were filled with BC-RRM, and the other half were filled with MTA. The specimens were mounted in tubes and sterilized in plasma. The root canals were inoculated with Enterococcus faecalis, and the tubes were filled with fetal bovine serum, leaving the apical part of the root in the serum. After 30 days, the canals were sampled and cultured, and the colony forming units (CFUs) were counted with the additional polymerase chain reaction (PCR analysis). There was no significant difference between ultrasonic groups and the Er,Cr:YSGG-MTA group, regarding the number of CFUs (p > 0.05). The Er,Cr:YSGG-BC-RRM group showed the highest number of remaining viable bacteria (p < 0.001). Both filling materials filled in ultrasonic preparations presented similar sealing abilities. The BC-RRM showed more leakage when used in retro cavities prepared with the Er,Cr:YSGG laser.

Sealing Efficacy of the Original and Third-Party Custom-Made Abutments-Microbiological In Vitro Pilot Study.

Implant-abutment connection (IAC) is a key factor for the long-term success and stability of implant-supported prosthodontic restoration and its surrounding tissues. Misfit between prosthodontic abutment and implant at the IAC leads to technical and biological complications. Two kinds of prosthodontic abutments are currently available on the market: original and third-party abutments. The aim of this pilot study was to test and compare the internal fit (gap) at the implant-abutment interface depending on the abutment fabrication method based on microbial leakage in static conditions and the need for the use of gap sealing material. Two groups of 40 implants were formed on the basis of the type of abutment. In each of the groups of two implant systems, two subgroups of 10 implants were formed. The tested subgroups consisted of 10 implants with sealing material and a negative control subgroups consisting of 10 implants without any sealing material. The test material, GapSeal (Hager and Werken, Duisburg, Germany) was applied in the test subgroups. The implant-abutment assemblies were contaminated with a solution containing Staphylococcus aureus and Candida albicans for 14 days under aerobic conditions. Results showed that there was no statistically significant difference regarding the microbial leakage between the original and third-party custom-made abutments, regardless of the use of sealing material. It can be concluded that the abutment fabrication method has no significant influence on sealing efficacy regarding the bacterial and fungal leakage in static conditions.

Evaluation of Antimicrobial Efficacy and Permeability of Various Sealing Materials at the Implant-Abutment Interface-A Pilot In Vitro Study.

The microenvironment of the oral cavity is altered when an implant, a biocompatible foreign body, is inserted into the mouth. Bacteria settle in the tissues in and around the implant due to the passage of microorganisms through the microgap at the connection of the implant and prosthetic abutment. To prevent colonization of the implant by microorganisms, one idea is to use sealing and antimicrobial materials to decontaminate the implant-abutment interface and close the microgap. The purpose of this study is to evaluate the antimicrobial efficacy and permeability of different types of sealing materials at the implant-abutment interface, under static conditions. Three different sealing material (GapSeal gel, Oxysafe gel and Flow.sil) were used for sealing the implant-abutment interfaces in 60 titanium dental implants, which were first contaminated with a solution containing Staphylococcus aureus and Candida albicans for 14 days under an aerobic condition. Results showed that a complete seal against bacterial infection was not formed at the implant-abutment interface, while for fungal infections, only GapSeal material helped to prevent microleakage. Findings of this in vitro study reported that application of sealing material before abutment connection may reduce peri-implant bacterial and fungal population compared with the interface without sealing material.

A Detailed Kinetico-Mechanistic Investigation on the Palladium C-H Bond Activation in Azobenzenes and Their Monopalladated Derivatives.

Palladium C-H bond activation in azobenzenes with R1 and R2 at para positions of the phenyl rings (R1 = NMe2, R2 = H (L1); R1 = NMe2, R2 = Cl (L2); R1 = NMe2, R2 = I (L3); R1 = NMe2, R2 = NO2 (L4); R1 = H, R2 = H (L5)) and their monopalladated derivatives, using cis-[PdCl2(DMF)2], has been studied in detail by in situ 1H NMR spectroscopy in N,N-dimethylformamide-d7 (DMF-d7) at room temperature; the same processes have been monitored in parallel via time-resolved UV-vis spectroscopy in DMF at different temperatures and pressures. The final goal was to achieve, from a kinetico-mechanistic perspective, a complete insight into previously reported reactivity results. The results suggest the operation of an electrophilic concerted metalation-deprotonation mechanism for both the mono- and dipalladation reactions, occurring from the coordination compound and the monopalladated intermediates, respectively. The process involves deprotonation of the C-H bond assisted by the presence of a coordinated DMF molecule, which acts as a base. For the first time, NMR monitoring provides a direct evidence of all the intermediate stages: that is, (i) coordination of the azo ligand to the PdII center, (ii) formation of the monopalladated species, and (iii) coordination of the monopalladated species to another PdII unit, which finally result in the (iv) formation of the dipalladated product. All of these species have been identified as intermediates in the dipalladation of azobenzenes, evidenced also by UV-vis spectroscopy time-resolved monitoring. The data also confirm that the cyclopalladation of asymmetrically substituted azobenzenes occurs by two concurrent reaction paths. In order to identify the species observed by NMR and by UV-vis spectroscopy, the final products, intermediates, and the PdII precursor have been prepared and characterized by X-ray diffraction and IR and NMR spectroscopy. DFT calculations have also been used in order to explain the isomerism observed for the isolated complexes, as well to assign their NMR and IR spectra.

Short-Term Antibacterial Efficacy of Three Bioceramic Root Canal Sealers Against Enterococcus Faecalis Biofilms.

OBJECTIVES: The aim of the study was to evaluate the antimicrobial efficacy of three bioceramic root canal sealers against Enterococcus faecalis (E. faecalis) biofilm. MATERIAL AND METHODS: E. faecalis bacterial suspension was grown on filter paper discs on agar plates. After the incubation period, the discs were covered with four different root canal sealers: 1) Premixing bioceramic root canal sealer (TotalFill BC Sealer); 2) Dual component bioceramic sealer (BioRoot RCS); 3) Mineral trioxide agreggate based sealer (MTA Fillapex); 4) Epoxy resin-based selar (AH Plus). After contact time of 60 minutes, the sealers were removed, and the discs were transferred into sterile tubes containing phosphate buffered saline. After serial dilutions, the aliquots of the suspension were cultivated for 24 hours. After the incubation period, the colony forming units (CFUs) were counted. RESULTS: There were no significant differences in antibacterial efficacy between the Total Fill BC Sealer and the AH Plus sealer (p=0.386). Both sealers showed better antibacterial efficacy compared to the BioRoot RCS and the MTA Fillapex (p<0.001). CONCLUSION: The Total Fill BC Sealer and AH Plus had better antibacterial efficacy than the BioRoot RCS and the MTA Fillapex sealers.

Clinical and Salivary Findings in Patients with Metal and Crystalline Conventional and Self-Ligating Orthodontic Brackets.

AIM: Data regarding different types of orthodontic brackets and ligation and various clinical and salivary findings are scarce. Therefore, the aim of this study was to compare clinical and salivary findings in patients with different types of fixed orthodontic appliances. SUBJECTS AND METHODS: Decayed, missing and filled teeth index (DMFT) and plaque index, salivary flow rate, salivary pH and prevalence of white spot lesions were determined in 83 patients with different types of orthodontic brackets and ligation (metal passive self-ligating brackets, conventional metal brackets, mono-crystal brackets and polycrystalline active self-ligating brackets), before and six months after the beginning of fixed orthodontic treatment. The patients were recruited in a private dental office, in the period of two years. The group comprised 83 patients (mean age: 15.14 ± 1.66 years), including 52 women (mean age: 15.08 ± 1.68) and 31 men (15.24 ± 1.64). Statistical analysis was performed by use of dependent and independent samples t-test as well as one way ANOVA, Wilcoxon signed rank test and the Kruskal Wallis test. P-values below 0.05 (p<0.05) were considered significant. RESULTS: DMFT and salivary flow have shown a significant increase, while salivary pH has shown a significant decrease in the observed time interval, in all patients irrespective of type of brackets and ligation. Among patients with different bracket material, no significant differences were found in any of the observed parameters. CONCLUSION: Although salivary flow rate is increased in patients with fixed orthodontic appliances which can have caries-protective effect, DMFT also increases and salivary pH decreases six months after the beginning of the treatment independently of bracket material or ligation type. All patients should receive instructions for precise oral hygiene and dietary habits before the beginning of fixed orthodontic therapy and at every dental check-up.

Antimicrobial assesment of aroylhydrazone derivatives in vitro.

Aroylhydrazones 1-13 were screened for antimicrobial and antibiofilm activities in vitro. N'-(2-hydroxy-phenylmethylidene)-3-pyridinecarbohydrazide (2), N'-(5-chloro-2-hydroxyphenyl-methylidene)-3-pyridinecarbohydrazide (10), N'-(3,5-chloro-2-hydroxyphenylmethylidene)-3-pyridinecarbohydrazide (11), and N'-(2-hydroxy-5-nitrophenylmethylidene)-3-pyridinecarbohydrazide (12) showed antibacterial activity against Escherichia coli, with MIC values (in µmol mL-1) of 0.18-0.23, 0.11-0.20, 0.16-0.17 and 0.35-0.37, resp. Compounds 11 and 12, as well as N'-(2-hydroxy-3-methoxyphenylmethylidene)-3-pyridinecarbohydrazide (6) and N'-(2-hydroxy-5- methoxyphenylmethylidene)-3-pyridinecarbohydrazide (8) showed antibacterial activity against Staphylococcus aureus, with the lowest MIC values of 0.005-0.2, 0.05-0.12, 0.06-0.48 and 0.17-0.99 µmol mL-1. N'-(2-hydroxy-5-methoxyphenylmethylidene)-3-pyridinecarbohydrazide (7) showed antifungal activity against both fluconazole resistant and susceptible C. albicans strains with IC90 range of 0.18-0.1 µmol mL-1. Only compound 11 showed activity against C. albicans ATCC 10231 comparable to the activity of nystatin (the lowest MIC 4.0 ×10-2 vs. 1.7 × 10-2 µmol mL-1). Good activity regarding multi-resistant clinical strains was observed for compound 12 against MRSA strain (MIC 0.02 µmol mL-1) and compounds 2, 6 and 12 against ESBL+ E. coli MFBF 12794, with the lowest MIC for compound 12 (IC50 0.16 µmol mL-1). Anti-biofilm activity was found for compounds 2 (MBFIC 0.015-0.02 µmol mL-1 against MRSA) and 12 (MBFIC 0.013 µmol mL-1 against EBSL+ E. coli). In the case of compound 2 against MRSA biofilm formation, MBFIC values were comparable to those of gentamicin sulphate, whereas in the case of compound 12 and EBSL+ E. coli even more favourable activity compared to gentamicin was observed.

The photo-activated and photo-thermal effect of the 445/970 nm diode laser on the mixed biofilm inside root canals of human teeth in vitro: A pilot study.

AIMS: 1) Evaluation of the photo-thermal (PT) and photo-activated (PAD) antibacterial effect of the 445/970 nm diode laser on E. faecalis, S. aureus and C. albicans mixed biofilms grown together inside root canals of human teeth. 2) Defining a potentially efficient clinical protocol for safe and predictable usage in endodontic procedures. METHODOLOGY: The root canals of 100 extracted human teeth with single straight canals were prepared with ProTaper NEXT files, sterilized, contaminated with a combination of three cultures (E. faecalis, S. aureus, C. albicans) and incubated for 15 days. The samples were randomly distributed into three groups (n = 20) and treated as follows: Group 1 (G1) - the 445 nm photo-thermal (PT) effect, Group 2 (G2) - a combination of the 445 nm and 970 nm PT effect, Group 3 (G3) - the 445 nm photo-activated (PAD) effect with 0.1% riboflavin, Group 4 (G4) - a combination of 3% sodium hypochlorite (NaOCl) and the 445 nm PAD effect. Four samples were used as positive control (non-treated) and four as a negative control. 12 aditional samples were used as a control for the G4 (3% NaOCl rinse without the laser). The number of viable microbes in each canal was determined by the colony forming unit (CFU) count. RESULTS: A statistically significant reduction in the microbial population after all treatments was observed (P < 0.001). Groups 2 and 3 showed similar results, both better than Group 1. Group 4 produced the best results. CONCLUSIONS: The 445 nm PAD protocol has a stronger antimicrobial effect than the 445 nm PT protocol. Prolonged exposure time to laser light and a combination of wavelengths (445/970 PT protocol) helps in the reduction of microbes. C. albicans appears to be more sensitive to laser irradiation than the other bacteria tested in this study. Following current results, tested laser protocols could be recommended for clinical usage but only as an adjunct to "classic" NaOCl rinse since alone they are not able to completely eradicate all microorganisms.

Panton-Valentine leukocidin and staphylococcal cassette chromosome mec characterization of community acquired methicillin-resistant Staphylococcus aureus.

OBJECTIVES: Staphylococcus aureus (SA) represents one of the most important microorganism that is part of the normal microflora of humans, but in certain conditions can cause very serious infections. Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a wide spectrum of nosocomial and community associated infections worldwide. The aim of this study was to determine community acquired MRSA (CA-MRSA), as well as the frequency of Panton-Valentine leukocidin (PVL) genes and staphylococcal cassette chromosome mec (SCCmec) types in isolates obtained from outpatients in the region of 700,000 people (Canton Sarajevo, Bosnia and Herzegovina) Methods: Our investigation included phenotypic and genotypic markers such as antimicrobial resistance, pulsed-field gel electrophoresis (PFGE), SCC typing, and PVL detection. RESULTS: Antimicrobial susceptibility: all MRSA isolates were resistant to the ß-lactam antibiotics tested, and all isolates were susceptible to trimethoprim sulphamethoxazole, rifampicin, fusidic acid, linezolid, and vancomycin. After the PFGE analysis, the isolates were grouped into five similarity groups: A-E. The largest number of isolates belonged to one of two groups: C - 60% and D - 27%. In both groups C and D, SCCmec type IV was predominant (60% and 88.8%, respectively). A total of 24% of the isolates had positive expression of PVL genes, while 76% showed a statistically significantly greater negative expression of PVL genes. CONCLUSIONS: Using combination techniques, we were able to investigate the origin and genetic background of the strains. PFGE analysis revealed two large, genetically related groups of strains consisting of 87 isolates. Our results suggest failure to apply the screening policy, and a lack of knowledge about multiresistant MRSA strains. This study showed the local epidemiological situation which should be the basis of antimicrobial empiric therapy for non-hospitalized patients.

Comparison of final disinfection protocols using antimicrobial photodynamic therapy and different irrigants after single-file reciprocating instrumentation against intracanal bacterial biofilm - An in vitro study.

BACKGROUND: The aim of the study was to compare the efficacy of antimicrobial photodynamic therapy (aPDT) with irrigation protocols that include sodium hypochlorite (NaOCl), ethylenediaminotetraacetic acid (EDTA) or QMiX (combined irrigant: EDTA, chlorhexidine, detergent) solution after single-file reciprocating root canal instrumentation. METHODS: The study sample included 68 extracted mandibular human single canal teeth. The canals were inoculated with bacterial suspension made of wild strain of Enterococcus faecalis. After 17 days of incubation, the samples were assigned to experimental groups according to the final disinfection protocol and a control group. The root canals in all groups were, firstly, instrumented with Wave One Gold reciprocating system. Then the canals were disinfected as follows: Group 1. 2.5% NaOCl and EDTA followed by the application of the aPDT; Group 2. 2.5% NaOCl, EDTA and 2.5% NaOCl; Group 3. 2.5% NaOCl and QMIX solution; Group 4. 2.5% NaOCl and EDTA. In the control group, the canals were irrigated with saline solution. Microbiological samples were collected at baseline, after single-file instrumentation and after the final disinfection protocols. The samples were plated onto Mitis Salivarius agar plates for incubation. The colony forming units (CFUs) were counted, and the final number was determined based on the dilution factor. RESULTS: Reciprocating single-file instrumentation reduced CFUs significantly in all groups (p<0.05). No significant difference between Group 1 and Group 2 was observed (p=0.178). Irrigation with the QMiX was more efficient than the aPDT (p=0.02). CONCLUSIONS: The aPDT used after irrigation with NaOCl and EDTA demonstrated similar antimicrobial efficacy as conventional irrigation with NaOCl.

Antimicrobial Efficacy of Photodynamic Therapy and Light-Activated Disinfection Against Bacterial Species on Titanium Dental Implants.

PURPOSE: The aim of this study was to evaluate the efficacy of photodynamic therapy (PDT) and light-activated disinfection (LAD) against a 3-day-old bacterial suspension prepared from three different bacterial species present on titanium dental implants, and to analyze the possible alterations of the implant surfaces as a result of the PDT and LAD. MATERIALS AND METHODS: The study was conducted on 72 titanium dental implants contaminated with a bacterial suspension prepared from three bacterial species: Prevotella intermedia, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. The contaminated implants were incubated under anaerobic conditions for 72 hours and then were randomly divided into four experimental groups and two control groups (n = 12 each), according to the following treatment protocols: group 1 (PDT1): PDT (660 nm, 100 mW, 60 seconds) with toluidine blue; group 2 (PDT2): PDT (660 nm, 100 mW, 60 seconds) with phenothiazine chloride dye; group 3 (LAD): light-emitting diode (LED) with toluidine blue; group 4 (toluidine blue): treatment with only toluidine blue for 60 seconds. In the positive control group, the implants were treated with a 0.2% chlorhexidine-based solution for 60 seconds, and in the negative control group, no treatment was used. RESULTS: The highest bacterial reduction was recorded in the PDT1 (98.3%) and PDT2 (97.8%) groups. The results of this study showed that there was a statistically significant reduction of bacteria in the PDT1 and PDT2 groups compared with the negative control group (P < .05), individually for each bacterial species as well as for all three species together. LAD was less effective than PDT1 and PDT2, and did not show a statistically significant difference compared with the negative control or any other treatment group. Toluidine blue was the least effective treatment in terms of both the total bacterial count and the individual count for each bacterial species. CONCLUSION: Both PDT1 and PDT2 protocols showed a high efficacy against a 3-day-old bacterial biofilm on dental implants and were more effective compared with LAD.