Antibacterial Activity of Various Morphologies of Films Based on Guanidine Derivatives of Pillar[5]arene: Influence of the Nature of One Substitute on Self-assembly.

The progress of the pillar[5]arene chemistry allowed us to set out a new concept on application of the supramolecular assemblies to create antimicrobial films with variable surface morphologies and biological activities. Antibacterial films were derived from the substituted pillar[5]arenes containing nine pharmacophoric guanidine fragments and one thioalkyl substituent. Changing the only thioalkyl fragment in the macrocycle structure made it possible to control the biological activity of the resulting antibacterial coating. Pretreatment of the surface with aqueous solution of the amphiphilic pillar[5]arenes reduced the biofilm thickness by 56 ± 10% of Gram-positive Staphylococcus aureus in the case of the pillar[5]arene containing a thiooctyl fragment and by 52 ± 7% for the biofilm of Gram-negative Klebsiella pneumoniae in the case of pillar[5]arene containing a thiooctadecyl fragment. Meanwhile, the cytotoxicity of the synthesized macrocycles was examined at a concentration of 50 µg/mL, which was significantly lower than that of bis-guanidine-based antimicrobial preparations.

Synergistic Effect of Silver Nanoparticles with Antibiotics for Eradication of Pathogenic Biofilms.

BACKGROUND: The increase in nosocomial multidrug resistance and biofilm-forming bacterial infections led to the search for new alternative antimicrobial strategies other than traditional antibiotics. Silver nanoparticles (AgNP) could be a viable treatment due to their wide range of functions, rapid lethality, and minimal resistance potential. The primary aim of this study is to prepare silver nanoparticles and explore their antibacterial activity against biofilms. METHODS: AgNPs with specific physicochemical properties such as size, shape, and surface chemistry were prepared using a chemical reduction technique, and then characterized by DLS, SEM, and FTIR. The activity of AgNPs was tested alone and in combination with some antibiotics against MDR Gram-negative and Gram-positive planktonic bacterial cells and their biofilms. Finally, mammalian cell cytotoxicity and hemolytic activity were tested using VERO and human erythrocytes. RESULTS: The findings of this study illustrate the success of the chemical reduction method in preparing AgNPs. Results showed that AgNPs have MIC values against planktonic organisms ranging from 0.0625 to 0.125 mg/mL, with the greatest potency against gram-negative bacteria. It also effectively destroyed biofilm-forming cells, with minimal biofilm eradication concentrations (MBEC) ranging from 0.125 to 0.25 mg/ml. AgNPs also had lower toxicity profiles for the MTT test when compared to hemolysis to erythrocytes. Synergistic effect was found between AgNPs and certain antibiotics, where the MIC was dramatically reduced, down to less than 0.00195 mg/ml in some cases. CONCLUSION: The present findings encourage the development of alternative therapies with high efficacy and low toxicity.

Triterpene Derivatives as Relevant Scaffold for New Antibiofilm Drugs.

New medicines for the treatment of bacterial biofilm formation are required. For thisreason, this study shows the in vitro activity of betulinic acid (BA), ursolic acid (UA) and their twentyderivatives against planktonic and biofilm cells (gram-positive bacterial pathogens: Enterococcusfaecalis, Staphylococcus aureus and Staphylococcus epidermidis). We evaluated the antibiofilm activity(through the crystal violet method), as well as the antibacterial activity via absorbance (OD600) atconcentrations of 5, 25 and 100 µM. Likewise, the cytotoxicity of all compounds was evaluated on akidney African green monkey (VERO) cell line at the same concentration, by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) methodology. We verified for the first timewhether different groups at carbon 3 (C-3) of triterpenes may interfere in the antibiofilm activity withminimal or no antibacterial effect. After the screening of 22 compounds at three distinctconcentrations, we found antibiofilm activity for eight distinct derivatives without antibiotic effect.In particular, the derivative 2f, with an isopentanoyl ester at position C-3, was an antibiofilm activityagainst S. aureus without any effect upon mammalian cells.

Microbial diversity in infections of patients with medication-related osteonecrosis of the jaw.

OBJECTIVES: A central role of infections in the treatment of MRONJ patients is widely accepted. An investigation of the MRONJ lesions' biofilms as potential pathogens seems logical. MATERIALS AND METHODS: We investigated the clinical data of our MRONJ patients who received surgery in advanced stage of the disease. Special attention was granted to the local colonizers harvested from osseous MRONJ specimens and submucosal putrid infections. RESULTS: Eleven out of 71 patients presented a spontaneous onset of the disease and for 60 out of 71 patients a trigger was detected. Breast cancer (29.6%) and prostate cancer (22.5%) were the most frequent underlying disease for prescription of an antiresorptive therapy, mostly zoledronate. Submucosal soft tissue biofilms significantly differed from biofilms harvested from the MRONJ lesions bottom, yet the most frequent bacteria were equally present in both groups: Streptococcus species (spp.), Prevotella spp., Actinomyces spp., Veillonella spp., and Parvimonas micra. The cephalosporins, cefuroxime and cefotaxime, and ß-lactam antibiotics with ß-lactamase inhibitor revealed the greatest susceptibility for the detected bacteria. CONCLUSION: The bacteria from the submucosal areas and the bottom of the infected bone presented comparable susceptibility to the common antibiotics regimes. Streptococcus spp., Prevotella spp., and Veillonella spp. present a high abundance in MRONJ lesions beside Actinomyces spp. The MRONJ lesions bottom is in many cases not infected by Actinomyces spp. CLINICAL RELEVANCE: The removal of the necrotic bone reduces the variety of bacteria found in MRONJ lesions, in particular at the bottom of the lesion.