| Congresso Brasileiro de Microbiologia 2023 | Resumo: 398-1 | ||||
Resumo:Staphylococcus pseudintermedius is the most common cause of pyoderma and otitis in dogs, and studies have shown that it is zoonotic. Due to the lack of new antimicrobials and the emergence of resistant strains, over the last few years, there has been an increase in investment in vivo and in vitro studies on antimicrobial properties found in plants as a possible alternative to the problem. Several species of the plant genus Hypericum have been shown to have antimicrobial activity, including Hypericum brasiliense, which has shown promising results in previous studies against Staphylococcus aureus. This study seeks to evaluate the potential bactericidal, and bacteriostatic activity of H. brasiliense fraction Uliginosin B against S. pseudintermedius clinical isolates. Firstly, the Minimal Inhibitory Concentration (MIC) and the Minimal Bactericidal Concentration (MBC) were assessed. After 24h incubation at 37 °C, two colonies of S. pseudintermedius LB 16100 and LB1633 from trypticase soy agar medium (TSA) plate were transferred into BHI medium (5 ml-1), followed by shaking incubation at 37 °C with for 24h. The suspension was adjusted to 0.5 McFarland standard turbidity. The fraction of extract was diluted in a 10% dimethyl sulfoxide (DMSO) and applied in a 96-well plate. Serial dilution was performed, reaching concentrations between 128 μg ml-1and 0,25 μg ml-1, following the application of bacterial suspension. The plate was incubated at 37 °C for 24 h and dyed with 20 µl -1 of 0,01% resazurin. The MIC is the lowest concentration extract that inhibits the visible growth of bacterial culture (CLSI 2015). We used vancomycin at concentrations between 8 μg ml-1 and 0,0625 μg ml-1 as a positive control. We performed tests in triplicate. For MBC, 1 μl-1 of each serial dilution obtained at the MIC wells was removed after the incubation period and before adding the Resazurin solution. Spots were sown in a petri dish with TSA and incubated at 37 °C for 24 h, followed by observing the presence or absence of bacterial growth. The spot with no bacterial growth was the value of the MBC. Before, growth curves of S. pseudintermedius were obtained by turbidity measurements. Specifically, cells were cultivated, with and without concentrations of Uliginosin B fraction, as described above in 96-well microtiter plates, and the optical density of each of the samples was recorded at 37 °C for 24 hours. The data presented represent the mean±SD of at least three-independent curves obtained from different cultures. The MIC value for Uliginosin B against S.pseudintermedius LB 16100 and LB 1633 planktonic cells was 1 μg ml-1, while the MBC was 8 μg ml-1. By contrast, the antimicrobial vancomycin (control) showed MIC and MBC values at 2 and 8 μg ml-1, respectively. The growth curves obtained were affected by the presence of the Uliginosin B fraction. In all cases there is a low and continuous growth during the measure times compared to the control group, without the presence of the extract. H. brasiliense Uliginosin B fraction showed antimicrobial activity indicates that it is a promising antimicrobial agent candidate. In vivo activity must be evaluated in the future to confirm the in vitro,/i> results. Palavras-chave: Staphylococcus pseudintermedius, Hypericum brasiliense, Uliginosin B, MIC, Growth Kinects Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPQ | |||||