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Background and aim: Infections caused by pathogenic bacteria increase patient morbidity and mortality and significantly raise treatment costs. The use of silver nanoparticles as an alternative treatment for S aureus, E coli, MRSA, E faecalis, K pneumoniae and P aeruginosa indicates their antibacterial effect and prompts medical research to consider the next generation of antibacterial drugs that could change antibiotic therapy. By combining silver nanoparticles with different classes of antibiotics, the antibacterial effect is evidenced by increased values of the inhibition zone compared to the values obtained for some antibiotics commonly used in the treatment of bacterial infections. This study focuses on comparing the antibacterial activity of antibiotics versus antibiotics combined with silver nanoparticles against various bacteria, by comparing inhibition zones obtained for both. We aim to prove that the size of the inhibition zone for antibiotics combined with silver nanoparticles is greater, thus confirming the improved antibacterial effect. Metods: In this study we tested the antibacterial activity of solutions of silver nanoparticles alone or in combination with different antibiotics. We used standard bacterial strains, ATCC, both Gram positive bacteria Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, as well as Gram negative bacteria Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, but also on clinical isolates: a strain MRSA (Methicillin Resistant Staphylococcus aureus) and a PDR strain (pan drug resistant) of Klebsiella pneumoniae. Bacterial identification was performed using Vitek MS analyzer (bioMerieux). Antibiotic susceptibility determination was performed with VITEK2 COMPACT SYSTEM (bio Merieux, Inc Durham NC) with ready to use VITEK AST cards. The interpretation of the results was done in compliance with EUCAST 2023-2024 standards. Testing was performed for several classes of antibiotics, silver nanoparticle solutions in 2 concentrations (10 µg/mL and 100 µg/mL) and for combinations of antibiotics with silver nanoparticle solutions. The diameter of the inhibition zone (ZOI) for silver nanoparticles, antibiotics and silver nanoparticles combined with antibiotic against each bacterium was expressed in millimeters. The Kirby-Bauer disk-diffusion method, in accordance with current EUCAST standards, was used to analyze the antibacterial effect of antibiotics, silver nanoparticles, and antibiotics combined with silver nanoparticles at biocompatible doses of 10 and 100 µg/mL. The experiments were conducted in triplicate, and the results were almost identical. Results: The results of this study show that the silver nanoparticles displayed antibacterial activity, proven by the appearance of the inhibition zone, in various sizes, for all bacteria studied. The antibiotic classes tested were beta-lactamins, first, second, third and fourth generation cephalosporins, macrolides, fluoroquinolones, lincosamides, aminoglycosides, glycopeptides, tetracyclines, oxazolidinones, sulfonamides, rifamycins, amphenicols. Testing S aureus ATCC 29213, the highest zone of inhibition was demonstrated for cephalosporins (32.6667 ± 0.701 mm), macrolides (31.6667 ± 0.701 mm, and lincosamides (29.6667 ± 0.701 mm). Testing MRSA (internal code GR0333), the highest zone of inhibition for combination of silver nanoparticles and antibiotics was demonstrated for fluoroquinolones (36.3333 ± 0.701 mm), lincosamides (32.3333 ± 0.701 mm), Fusid acid (32.3333 ± 0.701 mm) and aminoglicosides (31.3333 ± 0.701 mm). Testing E coli ATCC 25922 the highest zone of inhibition was for Fosfomycine, 39 mm and for E faecalis ATCC 29212 for aminoglicosides was 19 mm. For K pneumoniae (internal code GQ8575) the inhibition zone for silver nanoparticles 100 µg/mL was 12.3333 ± 0.701 mm and for P aeruginosa ATCC 27253 was 16 ± 1.214 mm. Conclusions: The use of metallic nanoparticles, especially silver ones, as antimicrobial agents with definite bactericidal activity has led medical specialists to consider this new treatment which may change antibacterial therapy. Studies of in vitro combinations between silver nanoparticles and different classes of antibiotics represent a highly efficient and effective new antibacterial treatment against multidrug-resistant bacteria. To avoid the problem of antimicrobial resistance associated with conventional antibiotics, it is necessary to understand the adaptive mechanisms of bacteria under the action of metal nanoparticles, which could be exploited in future studies. Further in vitro and in vivo studies that would assess specify the biocompatibility and toxicity of silver nanoparticles will make these super nanomaterials the medicines of the future.
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The article presents a synthetic molecular characterization of the methicillin-resistant Staphylococcus aureus and describes the most important community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clones that circulate nowadays in the world: the main molecular and epidemiological characteristics, as well as notions related to the clinic of infections produced by these clones and their antibiotic resistance spectrum. The predominant clone of CA-MRSA in North America is USA300 - ST8-IV in North America, in Australia - Queensland (Qld) MRSA (ST93-IV), in Europe - ST80-IV, in Asia there is a high heterogeneity of clones population, in Africa the distribution of CA-MRSA clones is unclear, and in South America - USA 1100 and USA300-Latin American variant are predominant. The molecular diagnosis is performed by highly specialized institutions. The knowledge of clones allows the study of antibiotic resistance spectrum for each one, a fact of great importance for medical practice. Molecular epidemiology of the CA-MRSA shows that lowly restricted sales of antibiotics in shops and pharmacies, as well as medical prescribing practices without a laboratory investigation, especially in Eastern Europe and Asia, contribute to the development of new MRSA clones with increased resistance to antibiotics.
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The loss of teeth is largely caused by supporting tissue damage, because of bacterial invasion from the infected root canals. Sixty patients with periapical lesions (PLs) of endodontic origin were included in the study. Clinical and radiological examination was performed. Periapical radiographs were analyzed by two independent observers to determine the size and severity of PLs, using Periapical Index (PAI) scores. The tissue samples collected by periapical curettage during apicoectomy or after dental extractions by alveolar curettage were histologically and immunohistochemically analyzed. The PLs were histologically diagnosed as: periapical granulomas (PGs), granulomas with cystic potential and radicular cysts (RCs) with various degrees of inflammation. Capillary density was evaluated using the angiogenic index after immunohistochemical staining with CD34 monoclonal antibody. A statistically significant correlation was observed between PAI scores and the size of the lesions. 68.33% of cases were PGs, 18.33% PGs with cystic potential and 18.33% RCs with different degrees of inflammation. Seventy-five percent PLs had an angiogenic index 1 and 25% had an angiogenic index 2. Statistically significant differences were obtained between the angiogenic index and lesion size (p<0.05). Capillary density within PLs did not influence the severity scores of lesions detected on radiographs. The angiogenic index appeared not to be associated with the histological lesion type and the intensity of inflammation, but was more likely correlated with the degree of granulation tissue maturation and the size of PLs.