| Congresso Brasileiro de Microbiologia 2023 | Resumo: 192-2 | ||||
Resumo:Introduction: Hospital-acquired infections are worrisome infections. Moreover, bacteria can undergo selection when exposed to antibiotics, acquiring resistance to antimicrobials used. Klebsiella pneumoniae stands out for of hospital-acquired infections and your main resistance mechanism is to New Delhi Metallobetalactamase (NDM) production, an enzyme that highly potentiates multi-drug resistance in bacteria. The search for an alternative treatment is necessary to control such pathogen. In that view, antimicrobial peptides (AMPs) are an attractive alternative due to their distinctive modes of action at the bacterial membrane level, or through interaction with intracellular targets. Thus, the combination of AMPs and antibiotics can decreased costs, improved efficacy, and reduced side effects. Objective: This work aims to evaluate a novel alternative for NDM-producing K. pneumoniae treatment, using the potential AMPs 2FLY - 2FLY-V8 proadrenomedullin-derived. Methods: The parental AMP 2FLY and its variants were synthesized by using N-9-fluorenylmethyloxycarbonyl (FMOC) technology at 95% purity, while maintaining the C-terminal in the acidic (-OH) form. CFU values were determined, based on the optical density (OD) that corresponds to half of log phase. In order to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), the broth microdilution method was used according to M7- A6 of the National Committee for Clinical Laboratory Standards. At combinations between peptides and antibiotic were performed in a 96-well microdilution microplate. The peptide and antibiotic were diluted from 1 to 64 µM. The results were expressed as fractional inhibitory concentration index (FICI). Finally, the hemolytic assay was performed. The red blood cells were plated together at 1 to 128 µM. Statistical analyses were performed using the program "GraphPad Prism version 8.0.1". Results: The variants 2FLY-V3, 2FLY-V5, 2FLY-V7 and 2FLY presented no activity against K. pneumoniae in the MIC and MBC assays. FLY-V1 and 2FLY-V8 had MIC at 128 µM, and 2FLY-V4 had MIC at 32 µM. The two peptides that showed promising results against this strain were 2FLY-V6 and 2FLY-V2, with MICs of 16 and 8 µM, respectively. 2FLY-V6 was selected for the synergism assay, in combination with meropenem (MIC 32 µM). Among all combinations tested in the synergism test, the concentration of 16 µM of meropenem with 4 µM of the peptide obtained the smaller FICI. Hemolytic activity results shows that 2FLY-V7 was hemolytic at 32 µM. 2FLY and 2FLY-V1 and 2FLY-V3 showed a considerable hemolysis rate starting at 64 µM, being 57%, 68% and 49%, respectively. The 2FLY-V2 variant is hemolytic and its rate starts to rise from 8 µM. The 2FLY-V4 and 2FLY-V6 variants are the two peptides that showed high hemolytic potential at the lowest concentrations (4 µM). Conclusion: In summary, 2FLY-V6 has synergistic potential with meropenem, decreasing both AMP and antibiotic concentrations. Otherwise, this same peptide may show deleterious effects to erythrocytes. In that view 2FLY-V6 could be topically used to treat cutaneous infectious. Palavras-chave: antimicrobial peptides, bacterial infection , meropenem Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq | |||||