Screening of Chinese medicinal plants for inhibition against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).
BACKGROUND
Traditional herbs are a valuable source of novel antibacterials in combating pathogenic isolates of methicillin-resistant Staphylococcus aureus (MRSA), a global nosocomial problem.


OBJECTIVE
To assess in vitro anti-MRSA activity of extracts from Chinese herbs. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined in the setting of clinical MRSA isolates.


METHODS
A collection of 19 plant extracts were obtained and bioassay-guided phytochemical analysis performed. Antibacterial susceptibilities were screened for inhibitory zone and MICs/MBCs determined by serial dilution with a standardized microdilution broth methodology. 9 MRSA isolates and a standard control strain (ATCC 25923) were cultured and exposed to the plant extract and isolated compound. Vancomycin was used as a positive control agent.


RESULTS
All the presented 19 plants showed anti-MRSA activity with MIC of 1.25-3.07mg/ml. The most active antimicrobial plants were Dendrobenthamia capitata, Elsholtzia rugulosa, Elsholtzia blanda, Geranium strictipes and Polygonum multiflorum (MIC< or =1.43mg/ml), and betulinic acid isolated from the active ethyl acetate fraction of Dendrobenthamia capitata extract was determined with MIC/MBC values as 62.5/125.0mg/ml.


CONCLUSIONS
Dendrobenthamia capitata, Elsholtzia rugulosa, Elsholtzia blanda, Geranium strictipesPolygonum multiflorum and betulinic acid demonstrate promising anti-MRSA potential.
Zuo
G Y
GY
Research Center for Natural Medicines, Kunming General Hospital, PLA, Kunming, China. zuoguoying@263.net
Wang
G C
GC
Zhao
Y B
YB
Xu
G L
GL
Hao
X Y
XY
Han
J
J
Zhao
Q
Q
D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000302:isolation & purification; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage* / Q000737:chemistry / Q000302:isolation & purification; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000008:administration & dosage* / Q000737:chemistry; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; D014640:Vancomycin