Despite a decrease in MRSA infection rates, the CDC director says we need to preserve antibiotic effectiveness for the future.

Reported cases of methicillin-resistant Staphylococcus aureus (MRSA) infections have fallen by 30,800 over a six-year period in the U.S., health officials announced Monday.

While the numbers look promising, Tom Frieden, director of the U.S. Centers for Disease and Control and Prevention (CDC), said the numbers are “a bare bones estimate” of the antimicrobial threat facing the United States.

Every year, more than two million Americans are infected with some form of antibiotic-resistant bacteria, resulting in 23,000 deaths annually.

While the reduction is promising, Frieden warned that we’re currently buying time on the biological clock as more antibiotic medications are outsmarted by evolving bacteria.

“Many people see antimicrobial resistance as a threat to someone else,” he said. “Without more action now, more patients will be thrust back to… a post-antibacterial era.”

A major component in antibiotic resistance is the overuse of common antibiotics in both humans and livestock. This can endanger humans when they eat meat. The CDC and other health organizations have documented numerous strains of bacteria that have evolved resistance to modern medicine.

Frieden spoke with reporters Monday regarding the findings of a new study in the journal JAMA Internal Medicine, a first-ever snapshot of the microbial threat facing the U.S.

The study found that of the 80,461 MRSA infections that occurred in 2011, 60 percent were related to outpatient hospital procedures, 17 percent occurred during hospital stays, and 20 percent occurred in the general community. These numbers show a 27.7 percent decrease for outpatient infections, a 54.2 percent decrease in hospital infections, and a five percent decrease in community-related infections since 2005.

Frieden said that progress in reducing hospital-related infections is key because the effectiveness of major surgeries like joint replacements and organ transplants are dependent on a person’s ability to fight off infection.

One “nightmare bacteria” on the CDC’s urgent list is carbapenem-resistant Enterobacteriaceae (CRE), which is fatal in half of all cases. Another is Clostridium difficile (C. diff.), which caused 14,000 deaths and 250,000 hospitalizations from 2005 to 2011, along with drug-resistant gonorrhea, which can cause infertility in young women.

Reducing antibiotic resistance further will depend on success in curtailing the inappropriate use of antibiotics, Frieden said. More than half of the antibiotics prescribed today are used improperly, he said.

“We’ve been trusted with these antibiotics that have been developed over decades and we need to preserve their effectiveness for the future,” he said.

One significant problem is that doctors sometimes prescribe antibiotics for things like the common cold, which is spread by a virus, not bacteria.

Compounding the problem is the fact that creating new antibiotics to combat threats that have evolved due to the overuse of current medications is costly and time-consuming.

“More medication isn’t better. The right medications are better,” Frieden said. “It is not too late. If we’re not careful, the medicine chest will be empty.”