Use of antibiotics in people with diabetic foot disease: A consensus statement Article points 1. Narrow spectrum Graham Leese, Dilip Nathwani, antibiotics should be used where possible to reduce the risk of meticillin Matthew Young, Andrew Seaton, resistant Staphylococcus aureus and Clostridium difficile infection. Brian Kennon, Helen Hopkinson, 2. The choice of antibiotic agent, and route of Duncan Stang, Benjamin Lipsky, delivery used, in the treatment of the infected diabetic foot should William Jeffcoate, Tony Berendt reflect the severity of the infection. 3. Initial treatment of The authors, on behalf of the Scottish Diabetes Group and the infection of the diabetic Scottish Infectious Diseases Society, provide broad, practical foot is frequently based on targeting the pathogen guidance on the use of antibiotics in people with diabetic foot disease presumed involved. complicated by infection. Recommendations on the most appropriate 4. This guidance assists investigative techniques, antibiotics and likely infecting organisms healthcare professionals are provided. This guidance is dependent on local microbiological treating the infected diabetic foot until epidemiology and susceptibility patterns, and prescribing microbiological guidelines, and the authors encourage all those managing infection investigations and clinical in the diabetic foot to seek local specialist infection advice, where response shed further light on the nature of necessary, on the use of antibiotics. the infection. Key words: he following guidance aims to appropriate. Guidance about antibiotic - Antibiotic guidance help healthcare professionals make choice is dependent on local microbiological - Consensus statement decisions about antibiotic agents for epidemiology and susceptibility patterns. - Diabetic foot disease T - Infection the treatment of the infected diabetic foot in However, the consensus group felt that the order to improve patient outcomes. pathogens causing various diabetic foot This is a consensus document based on infections in Scotland are unlikely to vary limited available clinical trial evidence, substantially within Scotland. Therefore, Author details can be review of international guidelines and merit was seen in providing broad, practical found on the last page expert opinion. There may be circumstances guidance on antibiotic choice, subject to of this article. where alternative courses of action are local adaptation when necessary. 62 The Diabetic Foot Journal Vol 12 No 2 2009 General approach to diabetic foot ulcer management The multidisciplinary team Diabetic foot ulcers should be treated by a multidisciplinary footcare team as this managment strategy has been shown to reduce amputation rates. In addition, attention to aggressive treatment of macrovascular risk factors in people with diabetic foot ulcers has been shown to prolong survival. Re-ulceration Previous ulceration is the strongest predictor for recurrent ulceration and preventative measures need to be addressed following healing. Re-ulceration rates of up to 70% at 5 years have been reported. Specimens for culture There is some debate over when a culture is necessary. Clinically uninfected ulcers rarely need to be cultured. An acutely infected wound of mild or moderate severity in a person who has not recently been treated with antibiotics does not need to be cultured. Other wounds should almost always be cultured. If a specimen is not taken at presentation of clinical signs, then cultures should be taken if there is clinical failure of empirical antibiotics. Aspiration of purulent secretions, curettage of the post-debridement wound base, punch biopsy and extruded or biopsied bone are the best specimens for culture. Diagnosing bone infection Inability to touch bone when probing a wound with a sterile metal probe makes osteomyelitis unlikely, with a negative predictive value of approximately 90% (Jeffcoate and Lipsky, 2004). The positive predictive value of a positive probe-to-bone test is around 50%, meaning that half of all ulcers that probe to bone do not have osteomyelitis (Jeffcoate and Lipsky, 2004). If there is clinical suspicion of osteomyelitis plain X-ray is the usual initial investigation of choice. However, it can take 2 weeks before any changes of acute osteomyelitis are seen on plain radiograph and thus serial X-rays may be required to rule out osteomyelitis. If there is Use of antibiotics in people with diabetic foot disease: A consensus statement Page points ongoing concern of osteomyelitis and it cannot be Neuropathy, Bacterial Infection, and Depth) score 1. If you suspect diagnosed using X-ray, secondary investigations (Ince et al, 2008), the PEDIS (Perfusion, Extent/ osteomyelitis, plain of choice are (in order of preference): size, Depth/tissue loss, Infection, Sensation) score X-ray is the usual initial l Magnetic resonance imaging (MRI). (Schaper, 2004). The Scottish Care Information investigation of choice. l Isotope white cell scan. – Diabetes Collaboration electronic ulcer 2. The presence and severity l Triple phase bone scan (highly sensitive at management programme is based on the Texas of infection should be diagnosing osteomyelitis, but is not specific, classification system. classified according to one and can remain positive for >1 year). of the recognised systems. Imaging options may be dictated by the local Classification of infection 3. Antibiotic choice is availability of imaging equipment. It is recommended that the presence and severity dependent on local of infection be classified according to the IDSA microbiological Loose bone system (Table 1) or the PEDIS system developed susceptibility and epidemiology. Loose bone extruded from an ulcer, or any bone by the International Working Group for the debrided, should be sent for bone culture and Diabetic Foot. 4. Initial antibiotic microbiological assessment. The extrusion of a treatment is frequently General principles of antibiotic use empirical, based on the bone fragment (sequestrum) is highly suggestive presumed pathogen. of underlying osteomyelitis, although the Antibiotic choice is primarily dependent on infection may have arrested coincident to the causative pathogens and epidemiology. However, 5. In light of international concerns over Clostridium passage of the sequestrum. treatment with antibiotics often needs to be difficileand meticillin- commenced before culture and sensitivity results resistant Staphylococcus “Sausage” digit are available. Thus initial therapy is usually aureus, narrow-spectrum The presence of a red, swollen “sausage”-shaped empirical, and based on the local epidemiological antibiotic therapy should digit is suggestive of osteomyelitis, but can be the information and local susceptibility data. As the be used wherever possible. result of other foot problems (e.g. fracture). pathogens in diabetic foot infections do not vary significantly in different parts of Scotland, the Differential diagnosis authors offer practical guidance on antibiotic use. Differentiating between osteomyelitis and Charcot These recommendations are, however, subject foot can be difficult. Diagnosis is based on a good to circumstances related to local epidemiology history and physical examination, and is assisted and prescribing policy. Direct contact with by obtaining supplementary investigations such local specialists may be necessary for advice on as X-ray, MRI, and possibly isotope white cell and specialised use of these, or other, antibiotics. triple phase bone scans. It is important to note Initial antibiotic treatment is frequently that osteomyelitis and Charcot foot frequently empirical, based on the presumed pathogen occur simultaneously. Osteomyelitis most often (Table 2). This guidance is of value until affects the forefoot and heel, while Charcot neuro- microbiological investigations and clinical arthropathy usually affects the forefoot or ankle. response shed further light on the nature of the infection, where available. In light of international Prophylactic antibiotic use concern over Clostridium difficile infection Antibiotics should be used only in those who associated with certain antibiotics (especially have clinical signs of infection (i.e. “mild”, clindamycin, co-amoxiclav, cephalosporins “moderate” or “severe” in the Infectious Disease and quinolones) and the risk of meticillin- Society of America [IDSA] infection grading resistant Staphylococcus aureus (MRSA) infection system; see Table 1). (associated with co-amoxiclav, cephalosporins, quinolones and macrolides), narrow-spectrum Foot ulcer classification antibiotic therapy should be used wherever Various ulcer classification schemes are used. possible. C. difficile is a particular risk for people The primary ones are the Wagner score (Wagner, aged >65 years and for inpatients. Adjustment 1981), the University of Texas system (Lavery of therapy based on microbiology results, et al, 1996), the SINBAD (Site, Ischaemia, when available and clinical response to 64 The Diabetic Foot Journal Vol 12 No 2 2009 Use of antibiotics in people with diabetic foot disease: A consensus statement Page points empirical therapy is important in the Specific antibiotic guidance 1. This guidance is management of these risks. Specific clinical symptoms identified during categorised by the severity The choice of antibiotic and the route of careful examination shed light on the likely of infection, and by delivery should reflect the severity of infection microbiology of a diabetic foot ulcer. From whether the person is, or (Table