The biggest public-health threat in the nation may be as close as your fingertips. Common bacteria increasingly are developing resistance to the most powerful antibiotics, making it more difficult to cure infections and reversing the half-century of progress made since the development of penicillin. In recent years, public-health officials have identified drug-resistant strains of pneumonia, gonorrhea, meningitis, tuberculosis and staph. Superbugs contribute to the nearly 90,000 deaths that occur each year due to hospital-acquired infections and add billions of dollars to the nation's health-care costs. Reasons for their rise include the overuse of antibiotics and, possibly, use of the drugs to promote growth in livestock. Government officials are divided over how to respond – and hampered by the lack of adequate surveillance systems.