Tea Catechin Inhibits Biofilm Formation of Methicillin-Resistant S. aureus

Staphylococcus aureus (S. aureus) is the most common pathogen causing infections from skin to systemic infections. The success of S. aureus infections can partially be attributed to its antibiotic resistance and to its ability to form biofilm. An increasing prevalence of methicillin-resistant S. aureus (MRSA) becomes a global public health problem in recent decades. Here, the effects of tea catechin extracts on the growth and biofilm formation of three MRSA strains were investigated. The results revealed that tea catechin extracts potently suppressed MRSA growth, and the minimal inhibitory concentration of tea catechin extracts against these MRSA strains was 0.1 g/L. Then, tea catechin extracts inhibited biofilm formation of these strains in a dose-dependent manner measured with a colorimetric method, and the inhibitory effect was also demonstrated by scanning electron microscopy assay. Moreover, adhesin genes biofilm-associated protein (bap), bone sialoprotein-binding protein (bbp), collagen-binding protein (cna), clumping factors A (clfA), fibronectin binding protein A and B (fnbA and fnbB), and intercellular adhesion gene BC (icaBC) were scanned, and the results shown that fnbA and icaBC were present in these three strains. Furthermore, tea catechin extracts depressed fnbA and icaBC expression in the strains. Therefore, inhibition of biofilm formation by tea catechin extracts probably was associated with downregulation of fnbA and icaBC expression in these strains