SA Forum is an invited essay from experts on topical issues in science and technology.

Antibiotics are a vital component of modern medicine. The introduction of penicillin in the 1940s dramatically reduced deaths from bacterial infections. Today antibiotics continue to save lives and make possible major treatments such as cancer therapy and organ transplants. We knew before penicillin was even on the market, however, that drug resistance could happen, and indeed it has.

When flooded with antibiotics, bacteria will evolve, become resistant to those drugs and even share their resistance mechanisms with one another. Now they are outsmarting our best antibiotics, and new drugs are years away. We are at the end of the current era of effective antibiotics to treat all bacterial infections. But can we change course?

A report released today by the U.S. Centers for Disease Control and Prevention shows that improving prescribing practices in hospitals can have a direct and almost immediate positive impact. But urgent action will have to be taken.

Antibiotics are among the most commonly prescribed drugs in medicine. Unfortunately, up to half of them are prescribed incorrectly or unnecessarily, helping spur drug resistance. CDC estimates that more than two million people in the U.S. are sickened every year with an antibiotic-resistant infection, and 23,000 will die as a result. Some studies have estimated that antibiotic resistance adds $20 billion in excess direct health care costs. Incorrect and unnecessary prescriptions also boost problems like Clostridium difficile infections—deadly diarrhea that is linked to 250,000 hospitalizations, 14,000 deaths and at least $1 billion in excess medical costs.

There are many areas for improvement: The new CDC report shows that some hospital clinicians prescribe three times as many antibiotics as others for patients in the same types of wards. In addition, about one in three antibiotic prescriptions written in hospitals for urinary tract infections and one in three prescriptions written for the drug vancomycin included a potential error, such as prescribing without proper evaluation.

The good news is we have ways to improve prescribing, known as antibiotic stewardship, that will preserve antibiotics and save lives. Stewardship programs help optimize antimicrobial therapy, ensuring that patients receive the correct antimicrobial and the right dose at the appropriate time for the best duration. Research shows that these programs can improve patient outcomes, reduce overall antimicrobial resistance within the facility and save health care facilities money.

Not only do stewardship programs reduce resistance, they can also decrease associated infections. According to today’s report, reducing antibiotic prescribing in hospitals by just 5 percent could lower C. diff infections 26 percent. Similarly, a six-year study in Northern Ireland found that restriction of antibiotics deemed “high-risk” for C. diff infections contributed to a significant drop in C. diff incidence.

Stewardship is just one strategy for combating resistance, but it is one that health care facilities and clinicians can implement immediately. Stewardship programs will vary from facility to facility, but every program should certain essential elements: The program should be supported by dedicated human, financial and information-technology resources. A single physician leader should be responsible for program outcomes, along with a pharmacist leader responsible for drug issues. The leaders will determine which resources, interventions and partners are needed to improve prescribing as well as monitor prescribing and resistance patterns. The program should regularly report prescribing and resistance information to clinicians and key staff as well as educate clinicians about these issues.

Whereas antimicrobial stewardship will require investments, the alternative could prove far more costly. Bacteria have developed resistance to every antibiotic currently available. Even when new drugs arrive, their effectiveness will quickly disappear if the prescribing doesn’t improve. Antimicrobial resistance is occurring in communities and individual hospitals, and it will take a widespread effort at the clinical, administrative and institutional levels to combat it