The first choice oral antibiotic recommended by NICE for mild diabetic foot infection in adults is flucloxacillin 500mg to 1g four times daily for 7 days. Alternatives for people with penicillin allergy or in whom flucloxacillin is unsuitable are clarithromycin, doxycycline or (in pregnancy) erythromycin.
According to NICE, these antibiotics 'have good activity against many of the pathogens that cause diabetic foot infection, have good penetration for skin and soft tissue infections, and can be used in the different settings where treatment may take place, including ambulatory care'. The guideline committee noted that flucloxacillin has poor oral bioavailability and a higher (off-label) dose of up to 1g four times a day may be needed in people with impaired circulation.
For adults with moderate or severe diabetic foot infections, the recommended antibiotics are flucloxacillin, co-amoxiclav, co-trimoxazole and ceftriaxone. In some cases these may be combined with gentamicin and/or metronidazole. Other options are advocated if the presence of Pseudomonas aeruginosa or MRSA is suspected or confirmed.
The choice of agent should be guided by individual patient factors, likely pathogens, and microbiological results where available. In moderate or severe infection, broader cover is needed because aerobic and anaerobic bacteria may be present. Severe infections can become limb-threatening quickly so an antibiotic with the broadest possible cover is appropriate; this can be changed to a narrower-spectrum antibiotic based on culture results when available.
The guideline says patient preference is important in the choice of antibiotic, particularly for treatment that will involve a hospital stay or be prolonged. People may have had previous foot infections, with previous courses of antibiotics, that will influence their preferences.
The guideline committee agreed that a shorter course of antibiotics was generally as effective as a longer course for adults with a mild diabetic foot infection, and a 7-day course was sufficient for most people. For adults with moderate or severe diabetic foot infection, a 7-day course is advised as a minimum, with treatment recommended for up to 6 weeks in osteomyelitis.