title_body: Anti-Bacteria properties of coffee?
upvoted_answer: The Following Abstract from this paper suggested that coffee has antibacterial properties 
  
  
    ABSTRACT The present study was carried out with water soluble portion
    and pure solvent of the acetone, ethanol, methanol, acetonit rile,
    water) extracts of leaves and leaf buds of Camellia sinensis (green
    tea), and beans of Coffea arabica (coffee) . Caffeine (3,7
    - dihydr o
    - 1, 3,7
    - trimethyl
    - 1H
    - purine
    - 2,6
    - dione) was isolated from both plants using a liquid
    - liquid extraction method, detected on thin layer chromatography (TLC) plates in comparison with standard caffeine, which served as a
    positive control. After performing the gross behavioral study, the
    Antibacterial activity was evaluated against Gram
    - negative bacteria included; Escherichia coli , Proteus mirabilis , Klebsiella pneumonia and Pseudomonas aeruginosa Both compounds at a
    concentration of 2 mg/ml showed similar anti bacterial activities
    against all tested bacteria, except for P. mirabilis , and the highest
    inhibitory effect was observed against P. aeruginosa using a modified
    agar diffusion method. The minimal inhibitory concentration (MIC) of
    caffeine was determined us ing a broth microdilution method in 96
    multi
    - well microtitre plates. MIC values ranged from 65.5 to
    250.0 μ g/ml for the caffeine isolated from coffee and 65.5 to 500.0 μ g/ml for green tea caffeine. Combination results showed additive
    effects against most p athogenic bacteria especially for P.
    aeruginosa, using both antibacterial assays. Key Words: Caffeine, MIC
    values, Antibacterial activity , Coffea arabica .