SAN DIEGO – The evidence-based treatment of diabetic foot osteomyelitis has jumped up to the next level as a result of two recent randomized clinical trials, the first-ever to address a couple of key contentious issues, experts agreed recently at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
Dr. Eric Senneville presented highlights of the two randomized trials, one of which examined the optimal duration of antibiotic therapy in patients with nonsurgically treated diabetic foot osteomyelitis. The other study was the first-ever head-to-head randomized comparison of antibiotics versus conservative surgery.
Dr. Eric Senneville
He also touched on another new development in the treatment of diabetic foot osteomyelitis: surgically implanted topical antibiotics, which show promise in specific situations.
Dr. Senneville of Gustave Dron Hospital in Tourcoing, France, was senior investigator in the prospective, randomized, multicenter comparison of outcomes with 6 versus 12 weeks of open-label antibiotic therapy in 40 patients. All participants had bone biopsy–confirmed osteomyelitis with no ischemia, and none underwent any bone resection during the treatment period.
The 6-week regimen proved to be the winning strategy. It resulted in remission in 12 of 20 patients, a result not significantly different from the 14 of 20 remission rate with 12 weeks of treatment. Moreover, significant drug-related gastrointestinal side effects occurred in only three patients in the 6-week-treatment arm, compared with nine patients treated for 12 weeks. There was no difference between the two groups in rates of relapse, need for later bone resection, or spread of osteomyelitis (Diabetes Care. 2015 Feb;38[2]:302-7).
In the surgery-versus-antibiotics trial, investigators at the University of Madrid prospectively randomized 52 patients with diabetic foot osteomyelitis to 90 days of antibiotics with no surgery or to conservative surgery with 10 days of postoperative antibiotics. Dr. Senneville emphasized that this was a select patient population and at this point the results apply only to similar groups; that is, all participants had forefoot osteomyelitis without ischemia or necrosis. There were six dropouts: one in the medically treated arm and five in the surgical group.
The key finding: At 12 weeks of follow-up, main outcomes were similar in the two groups. Eighteen of 24 patients in the medically managed group achieved primary healing, for a 75% cure rate, not significantly different from the 86% rate – 19 of 22 patients cured – in the surgical group. Median time to healing was 7 weeks with antibiotics only and similar at 6 weeks with surgery. Four patients in the antibiotic group worsened and required surgery, while three in the surgery group required reoperation (Diabetes Care. 2014 Mar;37[3]:789-95).
Dr. Senneville noted that the reulceration rate was 10% in the medically treated group and twice that in the surgical group. A higher reulceration rate has also been seen in retrospective studies. It’s thought to result from what has been termed pressure transfer syndrome, which is particularly common among patients who undergo surgery on the first metatarsal head.
Dr. Edgar J. G. Peters of VU Academic Medical Center, Amsterdam, commented that the Spanish randomized trial of antibiotics versus surgery in diabetic osteomyelitis was sorely needed. All too often, he observed, earlier retrospective studies conducted by surgeons concluded that surgery was best, while those carried out by infectious disease specialists found the antiobiotics-only strategy to be superior. Skeptical unbiased physicians were left in the dark.
He noted that this important clinical trial as well as the major randomized trial of 6 versus 12 weeks of antibiotic therapy were published too late for inclusion in the recently released systematic review of treatments for diabetic foot infections conducted by the International Working Group on the Diabetic Foot (Diabetes Metab Res Rev. 2015 Sep 7. doi: 10.1002/dmrr.2706), for which both Dr. Peters and Dr. Senneville were coauthors.
Turning to the novel use of topical antibiotics in patients with diabetic foot osteomyelitis, Dr. Senneville described several potential advantages, including the attainment of optimal drug levels in the presence of peripheral vascular disease and in avascular spaces.
The idea is to place antibiotic-impregnated beads or bone cement in the space created by debridement and removal of infected bone. By filling the dead space, the antibiotic-impregnated cement may control the infection simmering in any areas of infected bone unintentionally left behind, while also reducing the risk of pressure transfer syndrome. The use of antibiotic-eluting bone cement has recently been shown to reduce the need for reoperation (J Foot Ankle Surg. 2015 Jul-Aug;54[4]:536-40).
Dr. Senneville reported serving on speakers’ bureaus for Novartis and Merck and as an advisor to Pfizer.