Now, according to a study published in the Annals of Internal Medicine, a new variant of the strain is resistant to even more antibiotics and it's spreading among gay and bisexual populations in San Francisco, Boston, New York and Los Angeles.

NPR: Tracking a New Strain of Drug-Resistant Staph

Some doctors paint a scary worst-case scenario: A flu pandemic breaks out and beats down the immune systems of millions of people, and then staphylococci--the hospital strain and the nastier variant in the community--run wild on a killing spree.

FORBES: Germ Warfare