BOSTON – Overuse of antibiotics and resulting antibiotic-resistant infections are taking an estimated $20 billion toll on the U.S. pocketbook, according to a new study.

The study, released Monday by the Boston-based Alliance for the Prudent Use of Antibiotics (APUA) and John H. Stroger, Jr. Hospital of Cook County in suburban Chicago, was based on a review of 1,391 patients hospitalized in 2000, 13 percent of whom had antibiotic resistant infections (ARIs).

The study found the medical cost of ARIs ranged from $18,588 to $29,069 per patient, while the duration of hospital stay was extended 6.4 to 12.7 days for affected patients. The study estimated the costs incurred at the study hospital as a result of the ARIs to be between $10.7 million and $15 million.

The study also found that the excess mortality attributed to ARIs alone was 6.5 percent – a death rate two times higher than in patients without ARIs.

The study was sponsored by a grant from bioMerieux and the Centers for Disease Control and Prevention and is titled "Hospital and Societal Costs of Antimicrobial Resistant Infections in a Chicago Teaching Hospital: Implications for Antibiotic Stewardship."

According to APUA, antibiotic resistance is fueled by misuse and overuse of antibiotics. ARIs include methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and a growing number of  pathogens that are developing resistance to many common antibiotics.

"The findings indicate that significant health and economic benefits could be realized through effective interventions to reduce antimicrobial-resistant and healthcare-associated infections," said Rebecca Roberts, MD, the lead author and a member of the Department of Emergency Medicine at Cook County (Stroger) Hospital.

Stuart Levy, professor of medicine at the Tufts University School of Medicine in Boston, as well as a senior author of the paper and co-founder and president of the APUA, said the study shows the costs ARIs are exacting on the nation in terms of human suffering and financially.

"At a time when our country is debating how to deliver better, more affordable care, this study demonstrates the enormous cost savings that could be realized for both the healthcare system and to individuals and their families," he said. "These costs will only continue to increase if we don't amend our behavior and practice a more prudent usage of antibiotics."

Levy said further study is required to discover how much could be saved on a national level if the country took basic steps to halt the development of resistant infections and their spread in hospitals.

The study is published in an Oct. 15 issue of Clinical Infectious Diseases.