title: Green tea extract weakens the antibacterial effect of amoxicillin in methicillin-resistant Staphylococcus aureus infected mice.
abstract: Tea (Camellia sinensis) has been known for its modulation of resistance of methicillin-resistant Staphylococcus aureus (MRSA) to beta-lactam antibiotics in vitro. This study aimed to confirm the in vitro effect of green tea extracts with beta-lactams and to determine whether green tea extracts can reduce the minimum inhibitory concentrations (MICs) of amoxicillin in MRSA-infected mice. The catechins in the test tea that account for the reduced resistance to beta-lactams were quantitatively determined by high-performance liquid chromatography. The MICs of the ampicillin, cefazolin, amoxicillin, oxacillin, tea extract alone and tea extract in combination with beta-lactams were determined. Proportions of tea extracts and amoxicillin-tea extract combinations were administered to groups of mice enterally. The in vitro experiment showed that the MICs of four beta-lactams were greatly decreased in the presence of 0.25% tea extract. However, in an in vivo experiment, amoxicillin in combination with 5% tea extract conferred a higher ED(50) than that of antibiotic alone. Green tea extract, alone or in combination with amoxicillin, does not have protective benefits in MRSA-infected mice. This study concluded that tea extract weakened the antibacterial effect of amoxicillin in MRSA infected mice. Tea drinking is not recommended in combination with amoxicillin treatment.
authors: Pharmacology Department, Shantou University Medical College, Shantou, Guangdong, 515041, China.
authors: Qing
authors: Q
authors: Peng
authors: Yuanchun
authors: Y
authors: Huang
authors: Bing
authors: B
authors: Hou
authors: Dexing
authors: D
authors: Hua
authors: Fen
authors: F
authors: Yao
authors: Yuanshu
authors: Y
authors: Qian
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D028241:Camellia sinensis / Q000737:chemistry; D005260:Female; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D051379:Mice; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000188:drug therapy; D013662:Tea / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D013662:Tea; D000658:Amoxicillin