Source: Leukemia  |  Posted 7 years ago

New antibiotics, such as linezolid and levofloxacin, have advanced the treatment of diabetic foot infections, concludes a recent review article on the subject.

Among the complications of diabetes, none is more "common, costly, and complex than foot infections," note David G. Armstrong, DPM, and Benjamin A. Lipsky, MD, with the Department of Surgery, at the Southern Arizona Veterans Affairs Medical Center, in Tucson, United States.

These infections typically result from foot deformities and sensory neuropathy. Once the skin barrier is impaired, bacteria can reach subcutaneous tissues. The most common pathogens are aerobic gram-positive cocci, mainly []Staphylococcus Aureus[], including methicillin-resistant []S. Aureus[] (MRSA). Gram negative bacteria also play a role, predominantly in chronic or resistant infections.

Currently, no specific antibiotic regimen has proven superior for treating these diabetic foot infections, the authors note. Clinical trials suggest that fluoroquinolones, cephalosporins, beta-lactam inhibitor penicillins, and carbapenems are effective. However, concern about the rising rates of resistance of gram-positive cocci to the fluoroquinolones has prompted the need to use these agents in combination with other antibiotics that target gram-positive organisms, such as rifampin.

Linezolid is a recently developed agent active against all gram-positive organisms including MRSA and vancomycin-resistant Enterococcus faecium. The antibiotic is the first in a new class of oxazolidinones that inhibit bacterial synthesis early in replication; consequently, bacterial resistance is infrequent. In addition, linezolid achieves high concentrations in bone, muscle, and fat, making it promising for lower extremity diabetic ulcerations, including osteomyelitis.

Linezolid was initially approved for several types of infections, including skin and soft tissue infections, and was approved for treating diabetic foot infections in July 2003. Approval was given on the basis of a trial that compared linezolid to ampicillin/sulbactam and oral amoxicillin/clavulanate in 371 patients with various types of infections.

In the 317 patients that were clinically evaluable, 83% of the linezolid-treated patients were cured compared with 73% of patients receiving an aminopenicillin agent [95% confidence interval -0.006 to 0.197]. Furthermore, in patients with an infected ulcer, the largest subset of patients, the clinical cure rate for patients taking linezolid was significantly higher than for the patients treated with aminopenicillins (81.4% vs. 67.9%; 95% confidence interval 1.9 to 25.2).

"Creative routes of antibiotic administration and new antibiotics are helping practitioners to manage these infections more effectively and to minimize the physical, emotional, and financial complications that result from diabetic foot infections," the authors conclude.