Infection of the Foot - Appendix Infection of the foot Is antibiotic therapy really necessary ? If a foot, with or without an ulcer, is showing signs of infection (red, hot, swollen), there is really no question that antibiotic therapy is required. What is controversial is whether an uninfected foot ulcer should be treated with antibiotics. Recently, Edmonds et al had conducted a clinical trial which showed clinically uninfected foot ulcers may nevertheless benefit from antibiotic therapy. In any case, very few ulcers are truly uninfected. Therefore we tend to err on the cautious side and use antibiotics if we are in any doubt at all. How long should antibiotic therapy be continued ? This depends on the severity of the infection. If it is superficial and localized, treat until infection has resolved and then a few more days to give a safety margin. If the infection involves an ulcer, treatment may need to continue until the ulcer has healed. If the infection involves underlying bone, treatment needs to continue for several months, even after superficial signs of infection and ulcer have resolved. What oral antibiotic therapy should be used ? Staphylococci aureus is the usual bacteria involved. Choice of therapy is based on this assumption and modified according to response. If the wound is dirty and smelly, it is worthwhile also treating for anaerobic organisms. Swabs are usually not of great use but should be performed if a wound is not responding to treatment. Particular emphasis is on looking for multi-resistant staphylococci. The choice of antibiotics is often restricted by cost, availability and government regulations. The following are commonly used regimens: Dicloxacillin or flucloxacillin 250mg to 1gm 6 hrly. Use the higher dose if infection is severe or involves bones. Absorption can be erratic, so if there is any doubt use a higher dose. Dicloxacillin is less likely to cause hepato-toxicity. Augmentin. Dosage depends on whether it is Augmentin or Augmentin Forte or Augmentin Duo. The clauvulinic acid makes this agent active against staphylococci. It is also active against anaerobic organisms. Clindamycin. 150mg 6 hrly. A very good and probably under-used antibiotic. It is well tolerated. The main drawback is that it can cause pseudo-membranous colitis, especially in elderly people. Ask the patient to stop treatment if there is diarrhoea more than 5-6 times a day. In severe infection, especially if osteomyelitis is suspected, can be used in combination with ciprofloxacin. Ciprofloxacin. 250-750mg bd. Just about the only oral agent effective against the occasional pseudomona infection. For this purpose the 750mg bd dosage is required. Can be used in combination with clindamycin. In Australia, an Authority Script is required. Keflex. 500mg 6 hrly. A good antibiotic for superficial and minor infection. Not all that effective for severe infection and when used, a high dosage should be prescribed. Rifampicin 450mg mane and Fucidin 500mg bd. This is a good combination for patients with multi-resistant staphylococci infection. A combination is required to prevent development of resistance. Warn the patient that Rifampicin may turn the tears and urine pinkish in colour. Rifampicin can also increase the metabolism of many other drugs. When should a patient be admitted to hospital ? This will depend on bed availability and social and geographical situation of the patient. Generally, if the foot is very swollen or the patient is systemically unwell, then hospital admission is advisable. When this is not possible, we sometimes use 'Hospital in the Home' type of arrangement and give antibiotics such as Rociphen or Vancomycin which can be administered intravenously once daily. How is osteomyelitis diagnosed ? Osteomyelitis should be suspected whenever there is a big or deep foot ulcer, especially when healing is slow. It is also likely to be present if bones can be probed at the bottom of the ulcer. X-ray should be the first test requested. It is quite specific but not very sensitive. In other words, if osteomyelitis is seen, the diagnosis is reasonably well established. However, if it is not seen, it may still be present. The next test we usually then rely on is a white cell scan. White cells are obtained from the patient's blood, labelled with radioactive isotope and reinjected. They localize at the site of infection and an area of discrete uptake in the bone is good evidence of osteomyelitis. Sometimes it is useful to do an ordinary bone scan at the same time. It helps to tell whether the uptake of white cells is specific. How would the presence of osteomyelitis affect the treatment ? If osteomyelitis is present, antibiotic therapy needs to be given for a much longer time and usually in a higher dosage. Intravenous administration is sometimes required. Decision must also be made whether it is necessary to surgically remove the infected bone. Last-Modified: Thursday, 15 October 2003 10:19:26 GMT