Antimicrobial Activity and Antibiofilm of Epigallocatechin Galate in Staphylococcus Aureus
Name: CARINA KNIDEL
Publication date: 06/03/2018
Advisor:
Name |
Role |
|---|---|
| RICARDO PINTO SCHUENCK | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| ANDRÉ ROMERO DA SILVA | External Examiner * |
| DANIEL CLAUDIO DE OLIVEIRA GOMES | Internal Alternate * |
| RICARDO PINTO SCHUENCK | Advisor * |
Summary: Bacterial infections are among the major public health problems and the emergence of antimicrobial resistant bacteria becomes increasingly common. Staphylococcus aureus is an opportunistic pathogen, can cause a variety of infections, both hospital and community. Epigallocatechin gallate (EGCG), a flavonoid present in the leaves of the plant of Camelia sinensis, has different biological activities, including antimicrobial potential. The objective of the present study was to evaluate the antimicrobial, in vitro and in vivo, and antibiofilm potentials of EGCG in clinical S. aureus isolates with different genetic backgrounds. Nine strains isolated from different infections and with different antimicrobial susceptibilities were used. The antimicrobial activity was performed by broth microdilution test to determine the minimum inhibitory concentration (MIC) and the time-kill curve test. The MIC results ranged from 7.81 to 62.5 μg/mL and bactericidal activity was observed with 4 times the MIC. The activity of antibiofilm was evaluated after incubation of the isolates in the presence and absence of EGCG. Sub-inhibitory concentrations were able to significantly inhibit S. aureus biofilm production. The largest reduction in biofilm production was 100% and the smallest reduction among 50-60%. Cytotoxicity assays showed that concentrations ≤ 62.5 μg/mL EGCG were non-cytotoxic to murine macrophages. Regarding the in vivo test with G. mellonella larvae, EGCG significantly reduced the mortality of larvae infected by this pathogen (P = 0.0005) in only one isolate. In general, EGCG showed efficacy in inhibiting the growth of different clinical isolates of S. aureus and exhibited a relevant property of antibiofilm. Thus, EGCG is a promising substance for the treatment of infections caused by S. aureus.
