MRSA Linked To Increased Failure In Diabetic Foot

By Doug Brunk

SAN FRANCISCO -- The isolation of methicillin-resistant Staphylococcus aureus, either alone or as part of a polymicrobial infection, was associated with treatment failure in 35% of patients with a diabetic foot infection, Dr. Matthew E. Falagas reported during a poster session at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

The finding comes from an analysis of 15 randomized, controlled trials that compared the use of different antibiotics for treating diabetic foot infections.

The analysis showed that "a considerable proportion of patients with diabetes who have infection in their foot would not be treated effectively with current [antimicrobial] management," Dr. Falagas of the Alfa Institute of Biomedical Sciences in Athens, Greece, said in an interview.

"As a matter of fact, about one-fourth of all patients fail to be cured with the current antimicrobial regimens and treatment," he reported at the conference, which was sponsored by the American Society for Microbiology.

He and his associates found that different regimens of appropriate antibiotics--including penicillins, carbapenems, cephalosporins, and fluoroquinolones--were associated with similar treatment failures.

However, in the 68 patients whose infections were caused by methicillin-resistant Staphylococcus aureus (MRSA) alone or as part of a polymicrobial infection, treatment failure was 35%, compared with 23% in the 1,522 patients whose infections were caused by different bacteria.

In patients with infections caused by MRSA, the use of linezolid was not associated with a significantly lower failure rate, compared with the use of other antibiotics (32% vs. 37%, respectively).

The researchers also observed no significant differences in overall treatment failure when they compared patients who had osteomyelitis with those who did not (27% vs. 23%, respectively).

The treatment failures seen in the study were not a matter of patient compliance "because most of these patients were treated in the hospital with [intravenous] antimicrobial agents," according to Dr. Falagas, who is also with the department of medicine at Tufts University, Boston.

He added that, overall, patients who took carbapenems showed fewer treatment failures, which was a finding he did not expect.

When asked to comment on this article, Dr. George Andros, a vascular surgeon, stated: "MRSA remains a major culprit in diabetic foot infection and the principal cause for antibiotic failure. All too often antibiotic therapy is directed to the colonizing bacteria rather than focusing on MRSA and associated neuroischemia."

Dr. Andros is director of vascular services at the Diabetic Foot Center at Providence-Saint Joseph Medical Center in Burbank, Calif.