Garlic extract and two diallyl sulphides inhibit methicillin-resistant Staphylococcus aureus infection in BALB/cA mice.

OBJECTIVES: The inhibitory effect of garlic extract, diallyl sulphide and diallyl disulphide against methicillin-resistant Staphylococcus aureus (MRSA) infection in BALB/cA mice was studied. The influence of these agents upon the levels of fibronectin, interleukin-6 and lipid oxidation in MRSA-infected mice was examined.

METHODS: Garlic extract at 100% and 50%; diallyl sulphide (DAS) at 10% and 5%; diallyl disulphide (DADS) at 1% and 0.5% were used in this study. Sixteen clinical MRSA isolates obtained from infected patients were used in this study (n=16). Mice were infected by injecting 200 microL MRSA-PBS solution, which contained 10(7) cfu, via the tail vein. At 16 h post-infection (p.i.), garlic extract, DAS or DADS at 200 microL was administrated orally. At 24 h p.i., mice were killed and blood, liver, kidney and spleen of each mouse were collected. Plasma and the filtrate from each organ and serial dilutions were used to determine colony count. Plasma fibronectin level was determined by rabbit anti-rat fibronectin antibody and quantified by ELISA. Interleukin-6 levels were determined by commercial kit. Lipid oxidation was determined by measuring malondialdehyde levels.

RESULTS: The oral administration of these agents significantly decreased the viability of MRSA, in plasma, liver, kidney and spleen (P<0.05). MRSA infection significantly increased fibronectin and interleukin-6 levels in plasma of MRSA-infected mice (P<0.05); however, the oral administration of garlic extract and two diallyl sulphides significantly reduced both fibronectin and interleukin-6 levels (P<0.05). MRSA infection also significantly enhanced lipid oxidation in plasma and three organs (P<0.05). The treatments of garlic extract and two diallyl sulphides significantly decreased the malondialdehyde level and showed antioxidant protection (P<0.05).

CONCLUSIONS: These data strongly supported the conclusion that garlic extract, diallyl sulphide and diallyl disulphide possessed multiple protective functions against MRSA infection, in which diallyl sulphide and diallyl disulphide could be considered as novel therapeutic agents for the treatment of MRSA infection.