The summary of article:

Salmonella more virulent in space, study suggests
James Randerson
The Guardian
Tuesday September 25 2007

Salmonella was the first pathogen in space-flight.
It's the first study about changes in salmonella virulence in 12 days with zero gravity or low gravity in september of last year.
This experiment is a 'first of its kind' in space-flight biological study.
The pathogen is more virulent in the space, and this is a strong alert for future space flight missions, as the lunar colonisation and the mission to Mars. Moreover, this study found that the expression level in 167 different genes had been altered, it is likely a mechanism of defense or adaptation.
I think that is dangerous this experiments, forexample, if a bacteria come at earth without know the experts, but it is benefitial as well, because if an ill astronaut travel to space, he can to cause a great disaster in the base or spacial population.