title: Inhibition of methicillin-resistant Staphylococcus aureus by the compound Qingre granules.
abstract: BACKGROUND
  The infection rate of methicillin-resistant Staphylococcus aureus (MRSA) is increasing yearly due to the overprescription of antibiotics. Traditional Chinese compound medicines are less inclined to induce bacterial resistance in the clinical setting because of their multi-acting mechanisms. However, most current research is limited to bacteriostasis in vitro using single extracts or formulations. Plasma pharmacology is an in vitro method, using what is called "medicine serum". The aim of this study was to investigate whether the medicine serum of compound Qingre granules (QRKL) alone or in combination with antibiotics may treat MRSA infection in the clinic.
  
  
  METHODS
  An animal model of MRSA resistance was created by injecting rabbits with the standard strain of MRSA ATCC43300. Infected rabbits were treated with QRKL by intragastric administration. Sixty minutes after the last intragastric administration, serum was obtained from the rabbits by heart puncture to obtain what is termed "medicine serum". The minimum inhibitory concentration (MIC) of QRKL, medicine serum alone, or serum combined with antibiotics was assessed by agar dilution.
  
  
  RESULTS
  were compared with the growth of sixteen isolates of MRSA.
  
  
  RESULTS
  The MIC of QRKL to the standard strain ATCC43300 was 10.00 mg/ml. The MIC(90) of vancomycin was 1.00 microg/ml, which, when combined with QRKL, dropped to 0.50 microg/ml. The MIC(90) of cefuroxime alone was 512.00 microg/ml. This level also decreased to 256.00 microg/ml when combined with QRKL. The addition of QRKL thus significantly reduced the MIC of both cefuroxime and vancomycin compared with antibiotics alone (P < 0.01). The MIC(90) of vancomycin with medicine serum decreased to 0.50 microg/ml, and the MIC of vancomycin with medicine serum also descended compared with using vancomycin alone (P < 0.01).
  
  
  CONCLUSIONS
  The growth of MRSA can be inhibited by QRKL or medicine serum of QRKL in vitro. The addition of QRKL results in increased sensitivity of MRSA to vancomycin and this may provide a novel treatment for patients with MRSA infection.
authors.affiliation: Department of Infectious Diseases, Beijing Friendship Hospital, Capital Medical University, China.
authors.forename: Yi-yun
authors.initials: YY
authors.lastname: Yu
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Shu-wen
authors.initials: SW
authors.lastname: Zhang
authors.forename: Bao-en
authors.initials: BE
authors.lastname: Wang
mesh_terms: D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D004365:Drugs, Chinese Herbal; D014640:Vancomycin