Friday, September 01, 2006
Bacterial Infection of the Foot
Infection of the Foot - Diabetic Foot Disease Article
People with diabetes, especially those with very high blood glucose levels, have poorer defence against infection. Minor cuts and abrasions to the foot that we all get from time to time can turn into infection. So protect the feet with appropriate footwear. If there is a foot ulcer, the break in skin would also make infection much more likely to occur.It is essential to distinguish between localized versus generalized foot infection because they require different intensity of treatment.
Localized foot infection is recognized by redness, heat and swelling confined to an area. Note the foot as a whole is not swollen. Oral antibiotics for a few days can usually eliminate the infection.
Generalized foot infection. Note the whole foot is red and swollen. Oral antibiotics in higher dosage can be tried but if there is no rapid response (eg. within 24 hours), intravenous antibiotics and sometimes surgical intervention are urgently required because there is likely to be infected tissue deep inside the foot.
Infection of the Foot
People with diabetes, especially those with very high blood glucose levels, have poorer defence against infection. Minor cuts and abrasions to the foot that we all get from time to time can turn into infection. So protect the feet with appropriate footwear. If there is a foot ulcer, the break in skin would also make infection much more likely to occur.It is essential to distinguish between localized versus generalized foot infection because they require different intensity of treatment.
Localized foot infection is recognized by redness, heat and swelling confined to an area. Note the foot as a whole is not swollen. Oral antibiotics for a few days can usually eliminate the infection.
Localized foot infection associated with a neuropathic ulcer. Due to the neuropathy, the patient may not feel any pain or discomfort. Oral antibiotics are usually satisfactory but may need to be continued until the ulcer has healed.
Generalized foot infection. Note the whole foot is red and swollen. Oral antibiotics in higher dosage can be tried but if there is no rapid response (eg. within 24 hours), intravenous antibiotics and sometimes surgical intervention are urgently required because there is likely to be infected tissue deep inside the foot.
Foot infection complicated by osteomyelitis. In the presence of a foot ulcer there is a risk of the underlying bones being involved. X-ray may show bone destruction. Once there is osteomyelitis, a much higher dose of antibiotics and for a longer period (eg. several months) is often required to eradicate the infection. Quite often, intravenous antibiotic therapy is required. Sometimes the infected bones need to be surgically removed to help the foot heal.
Osteomyelitis in the early phase does not show up on X-ray but can be detected as a hot spot on a technetium bone scan, confirmed by a similar uptake in a white cell bone scan. MRI scan has emerged as the most sensitive and specific test for osteomyelitis and should be performed if the diagnosis is in doubt. If an ulcer is big (> 2cm) or so deep that bone can be probed at the bottom of the ulcer, one should suspect that osteomyelitis is present.
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
Diabetic Foot Problems
People with diabetes, especially those with very high blood glucose levels, have poorer defence against infection. Minor cuts and abrasions to the foot that we all get from time to time can turn into infection. So protect the feet with appropriate footwear. If there is a foot ulcer, the break in skin would also make infection much more likely to occur.It is essential to distinguish between localized versus generalized foot infection because they require different intensity of treatment.
Localized foot infection is recognized by redness, heat and swelling confined to an area. Note the foot as a whole is not swollen. Oral antibiotics for a few days can usually eliminate the infection.
Generalized foot infection. Note the whole foot is red and swollen. Oral antibiotics in higher dosage can be tried but if there is no rapid response (eg. within 24 hours), intravenous antibiotics and sometimes surgical intervention are urgently required because there is likely to be infected tissue deep inside the foot.
Infection of the Foot
People with diabetes, especially those with very high blood glucose levels, have poorer defence against infection. Minor cuts and abrasions to the foot that we all get from time to time can turn into infection. So protect the feet with appropriate footwear. If there is a foot ulcer, the break in skin would also make infection much more likely to occur.It is essential to distinguish between localized versus generalized foot infection because they require different intensity of treatment.
Localized foot infection is recognized by redness, heat and swelling confined to an area. Note the foot as a whole is not swollen. Oral antibiotics for a few days can usually eliminate the infection.
Localized foot infection associated with a neuropathic ulcer. Due to the neuropathy, the patient may not feel any pain or discomfort. Oral antibiotics are usually satisfactory but may need to be continued until the ulcer has healed.
Generalized foot infection. Note the whole foot is red and swollen. Oral antibiotics in higher dosage can be tried but if there is no rapid response (eg. within 24 hours), intravenous antibiotics and sometimes surgical intervention are urgently required because there is likely to be infected tissue deep inside the foot.
Foot infection complicated by osteomyelitis. In the presence of a foot ulcer there is a risk of the underlying bones being involved. X-ray may show bone destruction. Once there is osteomyelitis, a much higher dose of antibiotics and for a longer period (eg. several months) is often required to eradicate the infection. Quite often, intravenous antibiotic therapy is required. Sometimes the infected bones need to be surgically removed to help the foot heal.
Osteomyelitis in the early phase does not show up on X-ray but can be detected as a hot spot on a technetium bone scan, confirmed by a similar uptake in a white cell bone scan. MRI scan has emerged as the most sensitive and specific test for osteomyelitis and should be performed if the diagnosis is in doubt. If an ulcer is big (> 2cm) or so deep that bone can be probed at the bottom of the ulcer, one should suspect that osteomyelitis is present.
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
Diabetic Foot Problems
# posted by Pat O'Connor @ 5:13 AM 
