Potentiating activity of Norfloxacin by synthetic chalcones against NorA overproducing Staphylococcus aureus.

Staphylococcus aureus is responsible for a series of infections occurring in both human and animal hosts. S. aureus SA1199B is a strain resistant to hydrophilic fluoroquinolone due to overproduction of the NorA efflux pump that has been used as a microbial model to evaluate if a compound act as efflux pump inhibitor. Finding substances from natural or synthetic origin able to reverse resistance mechanisms like those of efflux pumps is a challenge. The use of Chalcones and their derivatives is of great chemical and pharmacological interest, as they present a simple structure and several pharmacological activities. This study aims to evaluate the antibacterial potential of 4 synthetic chalcones, as well as to evaluate their action in the modulation of Norfloxacin resistance against the strain SA1199B strain. Microdilution assays were performed for evaluation of the antimicrobial activity. For evaluation of the modulating effect on resistance to Norfloxacin or EtBr, MIC values of these compounds were determined in the absence or presence of subinhibitory concentrations used of each chalcone. MICs values of both Norfloxacin and EtBr were significantly reduced in the presence of all tested chalcones, indicating that inhibition of the active efflux of these compounds by NorA could be a possible mechanism of action of the chalcones. These results show that the compounds studied have a high potential as a NorA inhibitor, with the best modulating effect verified for the compound 3. Pharmacokinetic and toxicity predictive studies indicated a high intestinal absorption and good volume of distribution for chalcones by oral administration, activity in the central nervous system and ease to be transported between biological membranes. Emphasizing that analogs 1 and 4 were easily metabolized by CYP3A4 enzyme, constituting a pharmacological active ingredient without toxic risk due to metabolic activation. These chalcones combined with Norfloxacin could be a promise technological strategy to be applied in the treatment of infections caused by S. aureus overproducing NorA.

Reliability of qualitative occlusal tooth wear evaluation using an intraoral scanner: A pilot study.

Dental wear analysis through the use of an intraoral scanner is a reality of modern dentistry. This study aimed to investigate the reliability of qualitative tooth wear evaluation through three-dimensional images captured with an intraoral scanner and compared to clinical and photographic examinations. Eighteen adult volunteers of both genders (18 to 55 years old) were submitted to clinical exams, intraoral photographs and intraoral scanning protocol using an optical scanner (TRIOS® Pod, 3Shape, Copenhagen, Denmark). Occlusal tooth wear, from second to second premolars, was measured by two evaluators and reevaluated after 30 days, according to a slight modification of the method described by Mockers et al. Weighted Kappa was used to measure intra and inter-examiner agreement. The Friedman test was used to verify the differences among methods. Random and systematic errors were assessed using Bland-Altman plots. All statistical analysis was performed with p<0.05. There was a substantive agreement for clinical (K = 0.75) and photographic exams (K = 0.79) and a moderate agreement for intraoral scanner analysis (K = 0.60) for inter-examiner evaluation. A substantial intra-examiner agreement was obtained for both evaluators. No significant difference between the methods was observed (p = 0.7343 for examiner 1 and 0.8007 for examiner 2). The Bland-Altman plot confirmed no systematic errors between the methods and a random error of 0.25 with the scanner method when compared to clinical assessment. All three methods showed reliability in qualitative occlusal tooth wear evaluation. Intraoral scanning seems to be a sound and reliable tool to evaluate tooth wear when compared to traditional methods, considering the lower inter-examiner agreement and the inherent limitations of this pilot study. Further research will be necessary in order to achieve more robust evidence.