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 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.

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.

Mechanism of Mechanochemical C-H Bond Activation in an Azobenzene Substrate by PdII Catalysts.

Mechanism of C-H bond activation by various PdII catalysts under milling conditions has been studied by in situ Raman spectroscopy. Common PdII precursors, that is PdCl2 , [Pd(OAc)2 ]3 , PdCl2 (MeCN)2 and [Pd(MeCN)4 ][BF4 ]2 , have been employed for the activation of one or two C-H bonds in an unsymmetrical azobenzene substrate. The C-H activation was achieved by all used PdII precursors and their reactivity increases in the order [Pd(OAc)2 ]3

Reversible Gas-Solid Ammonia N-H Bond Activation Mediated by an Organopalladium Complex.

N-H bond activation of gaseous ammonia is achieved at room temperature in a reversible solvent-free reaction using a solid dicyclopalladated azobenzene complex. Monitoring of the gas-solid reaction in real-time by in situ solid-state Raman spectroscopy enabled a detailed insight into the stepwise activation pathway proceeding to the final amido complex via a stable diammine intermediate. Gas-solid synthesis allowed for isolation and subsequent structural characterization of the intermediate and the final amido product, which presents the first dipalladated complex with the PdII-(µ-NH2)-PdII bridge. Gas-solid reaction is readily followed via color changes associated with conformational switching of the palladated azobenzene backbone. The reaction proceeds analogously in solution and was characterized by UV-vis and NMR spectroscopies showing the same stepwise route to the amido complex. Combining the experimental data with density functional theory calculations we propose a stepwise mechanism of this heterolytic N-H bond activation assisted by exogenous ammonia.

First report on PVL-positive methicillin-resistant Staphylococcus aureus of SCCmec type V, spa type T441 in Croatia.

The aim of the study was to investigate the molecular epidemiology of community- associated MRSA in Primorsko-Goranska County of Croatia during a six-year period(2001-2007). In period from 2001 and 2007, 46 MRSA isolates were collected in Rijeka, strains were subjected to susceptibility testing according to CLSI guidelines, mecA gene detection and SCCmec typing as well as detection of PVL. Strains were typed by Pulse Field Gel Electrophoresis (PFGE) and spa typing. All isolates were susceptible to vancomycin, linezolid, mupirocin, nitrofurantoin, only one strain was resistant to fusidic acid and co-trimoxazole. Results of SCCmec typing showed the presence of SCCmec type IV in 26 MRSA strains, SCCmec type V in three strains, and 13 strains comprised SCCmec I. SCCmec type II and III were not observed. Four MRSA strains were non-typeable by applied SCCmec typing methods. PVL was detected in 4 strains, two SCCmec IV and two SCCmec V. PFGE analysis, grouped MRSA strains into six similarity groups and 18 singletons. Dominating spa types in this collection of strains were t015, with 15 strains, followed by t041(N=7), t051,(N=2 ), t2850(N=2), t008(N=2)and single isolates t441, t002, t448, t018, t019, t355, t390, t026, t449, t148. We also detected two new spa types, t3510 and t3509, respectively. This is the first report on SCCmec type V in Croatia, and, to our knowledge, first report of PVL-positive mehicillin-resistant Staphylococcus aureus SCCmec type V and t441(ST59-MRSA-V) in this part of Europe.

Nationwide Survey of Klebsiella Pneumoniae Strains Producing CTX-M Extended-spectrum ß-lactamases in Croatia.

Extended-spectrum ß-lactamases (ESBL) producing bacteria have been increasingly reported in both hospital and community patients. Production of ESBLs is the major mechanism of resistance to oxymino-cephalosporins and aztreonam in Gram-negative bacteria. Recently a new family of ESBLs with predominant activity against cefotaxime (CTX-M ß-lactamases) has been reported. Over 80 CTX-M enzymes have been described so far, which can be grouped into five main subgroups according to amino acid sequence identity (CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9 and CTX-M-25). In some countries, CTX-M ß-lactamases are the most prevalent types of ESBLs, for instance in Russia, Greece, Spain, Switzerland, Japan, Taiwan, China and Argentina. These enzymes have been identified in countries near Croatia such is Italy, Hungary and Austria. The aim of this study was to determine the prevalence and the types of CTX-M ß lactamases produced by Klebsiella pneumoniae clinical isolates collected from October 2006 to January 2007 from both community- and hospital-based isolates were included (Figure 1.). 128 ESBL isolates were subjected to further analysis: screening with double disc diffusion test and confirmed by ESBL E test.

First Report of NDM-1-Producing Acinetobacter guillouiae.

BACKGROUND: Acinetobacter spp. is an opportunistic pathogen that has demonstrated increasing relevance in nosocomial infections. Carbapenem-resistant strains have been reported worldwide. METHODS: Since 2014, screening for metallo-ß-lactamases (MBLs) in all Acinetobacter spp. isolates using phenotypic methods and PCR has been implemented at the University Hospital Center Zagreb. RESULTS: The bacterial strain was isolated from the drain of a child hospitalized in a paediatric intensive care unit and identified as Acinetobacter guillouiae using a MALDI TOF automated system. The strain was resistant to meropenem, ceftazidime, cefotaxime, ceftriaxone, cefepime, sulbactam/ampicillin, gentamicin and ciprofloxacin, intermediately susceptible to piperacillin/tazobactam and imipenem, and susceptible to amikacin and colistin. The Hodge test and combined disk test with EDTA were positive. The MICs of meropenem and imipenem were not reduced by cloxacillin, but a small reduction of two dilutions was observed following the addition of sodium chloride, which indicated that OXA-58 was produced. PCR and sequencing of chromosomal DNA from boiled colonies revealed blaOXA-58 and blaNDM-1 genes. CONCLUSION: This is the first report of NDM-1 in Acinetobacter spp. in Croatia. The early detection of these genes will aid in the prevention and in the achievement of adequate infection control by limiting the spread of these organisms.

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.

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.

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.

Dicyclopalladated complexes of asymmetrically substituted azobenzenes: synthesis, kinetics and mechanisms.

Two series of new dicyclopalladated complexes {(DMF)PdCl(µ-R(1)C6H3N═NC6H3R(2))PdCl(DMF)} of 4,4'-functionalized azobenzenes with substituents of varying electron-donating or electron-withdrawing strength (R(1) = H, NMe2; R(2) = H, Cl, Br, I, OMe, PhNH, CO2H, SO3Na, or NO2) have been synthesized and fully characterized. (1)H NMR spectroscopy along with the ESI mass spectrometry unambiguously identified the new complexes in the solution, and their solid-state structures were determined by X-ray crystallography. The presence of easily exchangeable solvent ligands was confirmed by (1)H NMR spectroscopy, X-ray experiments, and ESI mass spectrometry. The complexes were additionally characterized by UV-vis and fluorescence spectroscopies. The effect of different 4,4'-substituents on the formation rate of mono- and dicyclopalladated azobenzenes was studied by UV-vis spectroscopy. The experimental results are complemented by the quantum-chemical (DFT) calculations in order to rationalize the kinetic results as well as substituent effects on the reaction rates. It was found that the mono- and dicyclopalladation reactions of azobenzenes proceed in two consecutive processes, adduct formation and palladation steps. The rate-determining step in both palladations is the breaking of the ortho C-H bond, which has been confirmed as an electrophilic substitution process by Hammett correlations and DFT calculations.

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.

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.

The screening of methicillin-resistant staphylococcus aureus in vascular surgery patients: a comparison of molecular testing and broth-enriched culture.

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is a major global health care-associated pathogen. This study sought to examine the prevalence of MRSA in patients who were admitted to a vascular surgery ward during a 3-month period. METHODS: MRSA screening was accomplished through the acquisition of nasal, throat and perineal swabs. These swabs were placed in tryptic soy broth that had been supplemented with 6.5% NaCl and incubated for 24 h. The resulting isolates were subcultured on agar plates containing 5% sheep blood. The BD GeneOhm MRSA assay for screening swabs was performed in accordance with the manufacturer's instructions. RESULTS: A total of 58 patients were included in the study and swabs from 232 sites were obtained during the sampling period. MRSA was detected in 33 samples of 12 patients during the study period; thus, there was a 20.6% prevalence of patients who were recognized as MRSA carriers. There were discrepancies between the results of classical bacteriological screening and molecular MRSA detection methods in 8 of the patients. CONCLUSIONS: Nasal, throat and perineal MRSA screening can detect the carriage of this pathogen and allow for the timely use of appropriate infection control measures. The choice of screening techniques poses a challenge; it has been demonstrated that molecular detection methods should be performed with great sensitivity, specificity and, most importantly, speed. The cost of the PCR screening method is the only disadvantage of this approach.

Value of rapid aetiological diagnosis in optimization of antimicrobial treatment in bacterial community acquired pneumonia.

In 80 adult patients with community acquired pneumonia (CAP) conventional microbiological methods, polymerase chain reaction (PCR) and serum C-reactive protein (CRP) levels were performed and the appropriateness of the empirical antimicrobial treatment was evaluated according to bacterial pathogen detected. The aetiology was determined in 42 (52.5%) patients, with Streptococcus pneumoniae as the most common pathogen. PCR applied to bronchoalveolar lavage (BAL) provided 2 and PCR on sputum samples 1 additional aetiological diagnosis of CAP The mean CRP values in the S. pneumoniae group were not significantly higher than in the group with other aetiological diagnoses (166.89 mg/L vs. 160.11 mg/L, p = 0.457). In 23.8% (10/42) of patients with determined aetiology, the empirical antimicrobial treatment was inappropriate. PCR tests need further investigation, particularly those for the atypical pathogens, as they are predominant in inappropriately treated patients. Our results do not support the use of CRP as a rapid test to guide the antimicrobial treatment in patients with CAP.

[Comparative urinary bactericidal activity of oral antibiotics against gram-positive pathogens]. / Usporedna urinarna baktericidna aktivnost oralnih antibiotika prema gram-pozitivnim urinarnim patogenima.

In routine bacteriological laboratories the antibacterial activity of antibiotics is determined by in vitro testing, usually by disk-diffusion test. However, in vitro testing does not always reflect antibacterial efficiency of antibiotics in vivo. In this investigation, the urine samples obtained in a single oral dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant Gram-positive urinary tract pathogens. Urinary bactericidal activity of linezolid had been previously compared with ciprofloxacin but not with other oral antibiotics such as beta-lactams. Linezolid showed satisfactory urinary bactericidal titres throughout the whole testing period against all Gram-positive cocci. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against staphylococci, but their activity against enterococci was weaker. According to the results of ex-vivo testing amoxycillin could be recommended only for infections caused by E. faecalis. Amoxycillin combined with clavulanic acid can be considered as a therapeutic option for infections caused by S. saprophyticus and E. faecalis. Older cephalosporins had high titres only against S. saprophyticus. Their drawback is a short elimination half-time in urine resulting in rapid decrease of urinary bactericidal titers during dosing interval. Furthermore, they do not show activity against enterococci due to their intrinsic resistance to cephalosporins.

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.