Anti-Bacteria properties of coffee? Does coffee have any known anti-bacteria properties? Is it more immune to be consumed by bacteria than other food products? Does it kill bacteria in mouth when drunk by infected people?

I'm interested if there are any scientific research on that matter.
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 .