Background: Enterococci are intrinsically resistant/tolerant to various antimicrobial agents and can also acquire and combine different mechanisms of resistance, including quorum-sensing regulation, to most active compounds, which makes enterococcal infection treatment even more challenging. The aim of this study was to evaluate the pattern of antimicrobial resistance and to analyze the frequency of quorum-sensing asa1 and esp genes in clinical isolates representing the genus Enterococcus. Methods: Multiplex PCR assays were performed for the identification of 110 enterococcal isolates and the determination of their antibiotic susceptibility and the presence of asa1/esp genes. Additionally, the antibiotic resistance of the isolates was tested by the Kirby–Bauer disk diffusion method. Results: 90% of the isolates were identified as Enterococcus faecalis and 10% as Enterococcus faecium. Quorum-sensing regulation genes were present in 109 isolates. Aminoglycoside (aac(6′)/aph(2″)-, quinolone (emeA)-, β-lactams (TEM)-, and vancomycin (vanA)-resistance genes were detected in 108 isolates. All of the isolates tested were vanB negative. According to the Kirby–Bauer method, 39% of the isolates expressed multidrug resistance (MDR) and 33% of the MDR E. faecium were vancomycin-resistant. Conclusion: The large percentage of MDR enterococci possessing asa1/esp genes indicated a possible connection between quorum-sensing regulation and drug resistance. Therefore, the regular monitoring of the antimicrobial resistance of Enterococcus spp., and the identification of virulence factors are needed. It is also important to prevent host colonization through the elimination of factors leading to the expression of quorum-sensing genes.

Introduction: At the end of 2019, humanity faced a new strain of coronavirus, rapidly progressing to a global pandemic—a population threat and a public health challenge. The efforts of world scientists have led to the development of vaccines against COVID-19 in a short period of time. Aim: Survey of the opinion of students from different medical specialties from the Traкiа University, Stara Zagora and Burgas University "Prof. Asen Zlatarov” focused on COVID-19 vaccination and their willingness to be vaccinated has been conducted. Materials and Methods: Analysis of data from the online survey conducted in July 2021, on 11 questions aimed at the reasons for vaccination against COVID-19, its refusal, effectiveness of vaccines, possible risks, measures against the spread of the disease and personal contribution to public health has been carried out.Results: Of the 105 students surveyed, only 27 have been infected with COVID-19; high rates of unvaccinated (83%) and unconvinced (43%) who would not recommend vaccination to relatives and friends (36 %) are reported. The main reason for refusing vaccination is fear of side effects; 53% of respondents are not convinced of the safety and effectiveness of vaccines. The main reason for those vaccinated against COVID-19 (60%) is their own and their relatives' protection against infection; 48% of students support measures for stopping the spread of the disease.