Bacteria strains and flu virus strains are not examples of evolution. They are simply variation within a kind. Also, none of the examples in that article that bazmerelda posted the link to are cases of evolution, either. Most people don't know this fact: speciation is not evolution. Most people also don't know that creationists believe that different species arise by natural selection. Speciation and natural selection are different from Darwinian evolution. Darwinian evolution is the creation of a completely new "kind" of creature. The term "kind" fits mostly with the taxonomic "Family" group (roughly: bears, cats, dogs, whales, etc.). A change from one Family group to another has never been observed, thus, evolution has never been observed.