(AP) -- U.S. health officials are stepping up testing of swine
flu cases for Tamiflu resistance, now that an American has come
down with a resistant strain. A California teenager was
diagnosed with swine flu last month after arriving in Hong Kong
on June 11, and has since recovered. The 16-year-old is a San
Francisco resident and likely was infected in the United States,
health officials said Tuesday. Her illness was mild, but
noteworthy. She's just the third person in the world to be
diagnosed with a strain resistant to Tamiflu, the primary
pharmaceutical weapon against the new virus. The other two
resistant cases - patients in Denmark and Japan - had been
taking Tamiflu as a preventive measure after coming into contact
with someone with swine flu. The Californian girl had not taken
Tamiflu, meaning she apparently was infected by an already-
circulating resistant strain before she traveled to Hong Kong.
"It's a little more concerning" than the two previous cases,
said Dr. Tim Uyeki of the federal Centers for