Oligomerization of RNAIII-Inhibiting Peptide Inhibits Adherence and Biofilm Formation of Methicillin-Resistant <i>Staphylococcus aureus In Vitro</i> and <i>In Vivo</i>

Abstract

Biofilm formation enhances bacterial resistance and complicates treatment. Therefore, an innovative strategy is urgently needed for the treatment of Staphylococcus aureus biofilm infectious diseases. RNAIII-inhibiting peptide (RIP), as a quorum-sensing inhibitor, inhibits S. aureus biofilm formation. However, RIP possesses poor antibiofilm activity when used alone or at a low dose in vivo. The activity and stability of RIP can be enhanced by designing its derivatives through amino acid substitution, terminal modification, or oligomerization. Among the derivatives, 16P-AC significantly decreased the biofilm formation and adherence of methicillin-resistant S. aureus (MRSA) on polystyrene material by inhibiting the expression level of four biofilm formation-related genes in vitro. Moreover, 16P-AC showed excellent protective effects by decreasing the bacterial titers in the urine, kidney, stent, and bladder, as well as by inhibiting intercellular adhesion on the implanted stent, in a rat urinary tract infection model induced by MRSA. This derivative also exhibited a relatively good stability in rat plasma. Therefore, 16P-AC is a potential drug candidate to treat biofilm-associated infections caused by MRSA. The present modification strategy is feasible to improve the metabolic stability and activity of RIP in vivo.