Cath Lab Digest

Given the challenges of selecting appropriate empiric therapy with the rise of antibiotic resistance, these authors offer a review of the literature in regard to diabetic foot infections. They offer pertinent insights on infection severity, common pathogens and other factors in choosing the right agent.

   While antibiotic therapy for infection is typically empiric at the outset, making the right call is not easy. If physicians make a too narrow selection in terms of antibiotic coverage, they may miss the offending organism. Conversely, choosing a too broad antibiotic can lead to antibiotic resistance.

   The most difficult thing about antibiotic selection is the lack of culture and sensitivity results at the time of treatment initiation. Certainly, a key to effective treatment of diabetic foot infections is obtaining good wound and tissue cultures in an expedited manner. One should obtain all cultures before initiating empiric antibiotic therapy.

   In selecting empiric antibiotic therapy, it is imperative first to consider the severity of the infection. Guidelines from the Infectious Disease Society of America (IDSA) outline the criteria for determining the severity of an infection. ¹ By first establishing the severity of the infection, one can ascertain the appropriate route of antibiotic administration.

   Uninfected ulcers, ulcers that lack purulence or inflammation, do not usually require antibiotic treatment. ^1,2 Antibiotic treatment of these wounds can be expensive and promote antibiotic resistance. There may be drug-related toxicity as well. ¹

   Mild diabetic foot infections have at least two of the following characteristics: purulence, erythema (extending less than 2 cm around the wound), pain, tenderness, warmth or induration. There are no local complications or systemic illness. ¹ One can usually treat mild infections with an antibiotic that has a narrower spectrum of activity. Generally, these are oral antibiotics. ^3,4 This allows for treatment to take place on an outpatient basis. For mild soft tissue infections, treatment duration typically lasts for one to two weeks but may go up to four weeks if required. ¹

   For mild infections, the IDSA recommends using dicloxacillin (Dynapen), clindamycin (Cleocin, Pfizer), cephalexin (Keflex, MiddleBrook), trimethoprim-sulfamethoxazole (TMP-SMZ) (Bactrim, Roche), amoxicillin/clavulanate (Augmentin, GlaxoSmithKline), or levofloxacin (Levaquin, Ortho-McNeil) as oral agents.

Keys To Treating Moderate DFIs

   Patients with moderately infected diabetic foot ulcers are systemically well and metabolically stable. These ulcers have at least one of the following qualities: cellulitis extending more than 2 cm from the wound, lymphangitic streaking, spread beneath the superficial fascia, deep tissue abscess, gangrene and involvement of the muscle, bone or joint. ¹

   One can generally treat these infections with oral antibiotics. Alternatively, physicians may initially start patients on parenteral antibiotics and transition them to oral antibiotics. Patients can undergo therapy on either an inpatient or outpatient basis, and the treatment regimen routinely lasts two to four weeks. ¹ Note that antibiotic therapy is not a substitute for surgical debridement when there is suspected abscess or bone or joint involvement. ⁵