Recent studies indicated dangerous bacteria are multiplying so fast, doctors are having trouble keeping up.

Researchers at Harvard Medical School exposed common antibiotics to bacteria similar to those that cause infections in humans. They found the bacteria could literally eat most of the drugs considered the main line of defense. Some of the drugs were even tested at levels 50 times higher than normal use.

According to researchers, the resistance problem occurs because bacteria are constantly mutating, and if even just a few cells survive an antibiotic attack, they can multiply again. Some of the bad bugs that are spreading include MRSA and new, lethal form of tuberculosis called XDRTB.

The strain of TB has mainly affected foreign countries, but four cases have been reported in the U.S..