Learning from Nature: How Bacteria Become Resistant to Antibiotics

1. The bacteria may acquire an enzyme that that can either act like a pair of scissors, cutting the antibiotic into an inactive form or modify the drug's chemical structure so that it is no longer effective.
2. Pumps inside the antibiotic can spit out the drug once it penetrates the cell wall. This was discovered 30 years ago by Dr. Stuart Levy at Tufts University School of Medicine and greeted with profound skepticism at the time.
3. The bacteria may mutate its inner contents so that the drug can no longer inactivate its target.

Source: Superbugs, by Jerome Groopman, The New Yorker, August 11 & 18, 2008

HIV/AIDS in U.S. 40% Higher than Previously Reported

The CDC issued a report that says HIV/AIDS infections have been worse than previously reported in the U.S. Results indicate that approximately 56,300 new HIV infections occurred in the United States in 2006. This figure is roughly 40% higher than CDC’s former estimate of 40,000 infections per year, which was based on limited data and less precise methods (see “Historical Challenges in Tracking HIV Infections”). Because HIV/AIDS is usually detected years after being first contracted, tracking its real annual incidence has been challenging. Using new surveillance based on an approach known as STARHS (serologic testing algorithm for recent HIV seroconversion), researchers can differentiate new cases of HIV/AIDS within five months of contraction.

Source: Centers for Disease Control (CDC)

Salmonella Outbreak - The Shape of an Epidemic

Here from the CDC is the shape of what an epidemic looks like: