New-generation biofilm effective antimicrobial peptides and a real-time anti-biofilm activity assay: CoMIC.

Nowadays, it is very important to produce new-generation drugs with antimicrobial properties that will target biofilm-induced infections. The first target for combating these microorganisms, which are the source itself. Antimicrobial peptides, which are more effective than antibiotics due to their ability to kill microorganisms and use a different metabolic pathway, are among the new options today. The aim of this study is to develop new-generation antibiotics that inhibit both biofilm-producing bacteria and the biofilm itself. For this purpose, we designed four different peptides by combining two amino acid forms (D- and L-) with the same sequence having alpha helix structures. It was found that the combined use of these two forms can increase antimicrobial efficacy more than 30-fold. These results are supported by molecular modeling and scanning electron microscopy (SEM), at the same time cytotoxicity (IC50) and hemotoxicity (HC50) values remained within the safe range. Furthermore, antibiofilm activities of these peptides were investigated. Since the existing biofilm inhibition methods in the literature do not technically simulate the exact situation, in this study, we have developed a real-time observable biofilm model and a new detection method based on it, which we call the CoMIC method. Findings have shown that the NET1 peptide with D-leucine amino acid in its structure and the NET3 peptide with D-arginine amino acid in its structure are effective in inhibiting biofilm. As a conclusion, our peptides can be considered as potential next-generation broad-spectrum antibiotic molecule/drug candidates that might be used in biofilm and clinical important bacteria. KEY POINTS: • Antimicrobial peptides were developed to inhibit both biofilms producing bacteria and the biofilm itself. • CoMIC will fill a very crucial gap in understanding biofilms and conducting the necessary quantitative studies. • Molecular modelling studies, NET1 peptide molecules tends to move towards and adhere to the membrane within nanoseconds.

Simple concentration method enables the use of gargle and mouthwash instead of nasopharyngeal swab sampling for the diagnosis of COVID-19 by PCR.

Since its emergence in December 2019, SARS-CoV-2 is causing one of the most devastating pandemics in human history. Currently, the most important method for definitive diagnosis of COVID-19 is identification of SARS-CoV-2 RNA in nasopharyngeal swab samples by RT-PCR. Nasopharyngeal swab sampling is a discomforting procedure sometimes with adverse effects, which also poses a risk for infection for the personnel performing the sampling. We have developed a new method for concentrating biological samples, which enabled us to use gargle and mouthwash samples to be used in RT-PCR, for the diagnosis of COVID-19, as an alternative to nasopharyngeal swab samples. We have analyzed nasopharyngeal and gargle and mouthwash samples, before and after concentration, of 363 patients by RT-PCR for the presence of SARS-CoV-2. Among 114 patients in which SARS-CoV-2 was identified in at least one of their samples, the virus was identified in 76 (66.7%), 67 (58.8%), and 101 (88.6%) of nasopharyngeal swab, gargle, and mouthwash samples before and after concentration, respectively. When concentrated by our new method, gargle and mouthwash samples can be used instead of nasopharyngeal samples in identification of SARS-CoV-2 by RT-PCR, with the same or better sensitivity. Eliminating the need for nasopharyngeal sampling will save the patients from an invasive and painful procedure and will lower the risk of infection for the healthcare personnel taking the sample. This easy sampling procedure may decrease the workload of hospitals, shorten the turnaround time of obtaining test results, and thus enable rapid isolation of infected patients.