1. 2 Overview of diabetic foot infections Masood Ziaee,MD Des,11, 2008.
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Transcript of 1. 2 Overview of diabetic foot infections Masood Ziaee,MD Des,11, 2008.
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Overview of diabetic foot infections
Masood Ziaee ,MD
Des ,11, 2008
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FOOT ULCERS IN DIABETES
“Rule of 15” 15% of diabetes patients Foot ulcer in lifetime
15% of foot ulcers Osteomyelitis
15% of foot ulcers Amputation
Clinical Care of the Diabetic Foot, 2005
©2006. American College of Physicians. All Rights Reserved.
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INTRODUCTION
Important factors for development of diabetic foot infections include
1. Neuropathy
2. Peripheral vascular disease
3. Hyperglycemia.
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INTRODUCTION (Neuropathy)
Autonomic neuropathy can cause diminished sweat secretion resulting in dry, cracked skin, facilitating microorganism entry.
Motor neuropathy can lead to foot deformities.
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INTRODUCTION
Peripheral arterial disease can lead to impaired blood supply needed for healing of ulcers and infections.
Hyperglycemia impairs neutrophil function and reduces host defenses.
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MICROBIOLOGY
Most diabetic foot infections are polymicrobial, with up to five or seven different specific organisms involved.
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MICROBIOLOGY
Superficial diabetic foot infections are likely to be due to Aerobic gram-positive cocci :
S. aureus, S. agalactiae, S. pyogenes, and coagulase-negative staphylococci
Methicillin-resistant S. aureus should be presumed and empiric antibiotic treatment should include activity against this organism, particularly for patients who are severely ill at the time of presentation.
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MICROBIOLOGY
Ulcers that are deep, chronically infected, and/or previously treated with antibiotics are more likely to be polymicrobial.
Such wounds may involve the above organisms in addition to Enterococci, Enterobacteriaceae, Pseudomonas Aeruginosa, and Anaerobes.
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MICROBIOLOGY
Wounds with extensive local inflammation, necrosis, or gangrene with signs of systemic toxicity should be presumed to have anaerobic organisms in addition to the above pathogens.
Potential pathogens include anaerobic streptococci,
Bacteroides species, and Clostridium species.
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CLASSIFICATION (Wagner )
Grade 0 — No ulcer in a high risk foot. Grade 1 — Superficial ulcer involving the full skin thickness but
not underlying tissues.
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CLASSIFICATION (Wagner )
Grade 2 — Deep ulcer, penetrating down to ligaments and muscle, but no bone involvement or abscess formation.
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CLASSIFICATION (Wagner )
Grade 3 — Deep ulcer with cellulitis or abscess formation, often with osteomyelitis.
Grade 4 — Localized gangrene. Grade 5 — Extensive gangrene involving the whole foot.
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DIAGNOSIS
Made on the basis of clinical manifestations :1. Erythema
2. Warmth
3. Tenderness
4. Swelling are observed
5. Pus is grossly visible at an ulcer site or sinus tract.
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Laboratory evaluation
Laboratory evaluation should include :
1. CBC
2. BS
3. Electrolytes
4. ESR
5. CRP
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Laboratory evaluation
Organisms cultured from superficial swabs are not reliable for predicting the pathogens responsible for deeper infection.
Deep tissue cultures are required; for evaluation of osteomyelitis, bone biopsy is needed.
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Laboratory evaluation
Risk for osteomyelitis
Evaluation for osteomyelitis is an important consideration in the management of diabetic foot infections.
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Factors increase the likelihood of osteomyelitis
Grossly visible bone or ability to probe to bone
Ulcer size larger than 2 x 2 cm Ulcer depth >3 mm Ulcer duration longer than 1 to 2 weeks ESR >70 mm/h
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Evaluation for osteomyelitis
Patients with diabetic foot infections should have initial evaluation with conventional radiographs.
Those with one or more of the above factors whose radiographs are indeterminate for osteomyelitis should undergo magnetic resonance imaging (MRI).
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The following concepts may help guide radiographic modality selection
1. If the patient is diabetic and has symptoms referable to the foot, MRI is the test of choice.
2. If the patient has symptoms referable to the spine, MRI is the test of choice to evaluate for vertebral osteomyelitis.
3. If MRI is not available, CT is the alternative test of choice.
4. If metal hardware precludes MRI or CT, a nuclear study is the test of choice.
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Osteomyelitis
Evidence of osteomyelitis by these imaging modalities should prompt a bone biopsy to confirm the diagnosis and to guide antimicrobial therapy.
In the absence of osteomyelitis by these alternative imaging modalities, osteomyelitis is unlikely.
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MANAGEMENT
Management of diabetic foot infections requires
1. Attentive wound management
2. Good nutrition
3. Antimicrobial therapy
4. Glycemic control
5. Fluid and electrolyte balance.
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CLASSIFICATION OF INFECTION
Mild infection Moderate infection Severe infection
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Mild infection
Presence of 2 manifestations of 1. Inflammation (purulence, or erythema, pain,
tenderness, warmth, or induration),
2. Any Cellulitis/erythema extends 2 cm around the ulcer,
3. Infection is limited to the skin or superficial subcutaneous tissues
4. No other local complications or systemic illness.
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Mild infection
1. Treated with outpatient oral antimicrobial therapy.
2. Empiric therapy include activity against skin flora including streptococci and methicillin-resistant S. aureus (MRSA).
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Oral agents for empiric treatment of mild to moderate diabetic foot infections
Regimens with activity against streptococci and MRSA
1-Clindamycin
2-Linezolid
3-Penicillin + Trimethoprim-sulfamethoxazole or doxycycline
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Mild infection
3.Patients who fail to respond to treatment with agents active against streptococci and MRSA should receive extended antimicrobial coverage to include activity against aerobic gram negative bacilli and anaerobes.
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Oral agents for empiric treatment of mild to moderate diabetic foot infections
Regimens with activity against streptococci, MRSA, aerobic
gram negative bacilli and anaerobes
Trimethoprim-sulfamethoxazole +Amoxicillin-clavulanate
Clindamycin+Ciprofloxacin or levofloxacin or moxifloxacin
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Antibiotic dosing
Clindamycin 300 to 450 mg every 6 to 8 hours
Linezolid 600 mg every 12 hours
Penicillin 500 mg every 6 hours
Trimethoprim-sulfamethoxazole 2 double strength tablets every 12 hours
Doxycycline 100 mg orally every 12 hours
Amoxicillin-clavulanate 2000/125 mg every 12 hours
Ciprofloxacin 750 mg every 12 hours
Levofloxacin 750 mg every 24 hours
Moxifloxacin 400 mg every 24 hours
Oral agents for empiric treatment of mild to moderate diabetic foot infections
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Mild infection
4.If infection in a clinically stable patient fails to respond to more than one antibiotic course, some favor discontinuing antimicrobial therapy to optimize the yield of culture specimens obtained a few days later .
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Duration of therapy
Oral antibiotic therapy in conjunction with attentive wound care until there is evidence that the infection has resolved (usually about 1 to 2 weeks).
Antibiotics need not be administered for the entire duration that the wound remains open.
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Moderate infection
Infection in a patient who is1. Systemically well and metabolically stable
2. Which has 1 of the following characteristics: cellulitis extending >2 cm, lymphangitic streaking, spread beneath the superficial fascia, deep-tissue abscess, gangrene, and involvement of muscle, tendon, joint or bone.
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Moderate infection
Empiric therapy of deep ulcers with extension to fascia should include activity against streptococci, MRSA, aerobic gram negative bacilli and anaerobes.
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Parenteral agents for empiric treatment of moderate to severe diabetic foot infections
Vancomycin +regimens active against aerobic gram negative bacilli and anaerobes:
Beta-lactam/beta-lactamase inhibitors
Ampicillin-sulbactam 3 g every 6 hours
Piperacillin/tazobactam 4.5 g every 8 hours
Ticarcillin-clavulanate 3.1 g every 4 hours
Carbapenems
Imipenem 500 mg every 6 hours
Meropenem 1 g every 8 hours
Alternative regimens
Metronidazole PLUS one of the following : 500 mg IV every 8 hours
Ceftazidime 2 g every 8 to 12 hours
Cefepime 2 g every 12 hours
Ciprofloxacin 400 mg IV every 12 hours
Aztreonam 2 g every 6 to 8 hours
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Duration of therapy
1. Patients with infection also requiring surgical debridement should receive intravenous antibiotic therapy perioperatively.
2. In the absence of osteomyelitis, antibiotic therapy should be administered in conjunction with attentive wound care until signs of infection appear to have resolved (2 to 4 weeks of therapy is usually sufficient).
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Duration of therapy
3.If there is a good response to parenteral therapy, oral agents can be used to complete the course of treatment.
4.If clinical evidence of infection persists beyond the expected duration, consider issues of patient adherence to therapy, development of antibiotic resistance, an undiagnosed deep abscess, or ischemia
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Severe infection
Infection in a patient with Limb threatening diabetic foot infections.
Systemic toxicity or metabolic instability (eg, fever, chills, tachycardia, hypotension, confusion, vomiting, leukocytosis, acidosis, severe hyperglycemia, or azotemia).
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Severe infection
Limb threatening diabetic foot infections should be treated with parenteral antibiotic therapy and, in most cases, surgical debridement.
Empiric therapy should include activity against streptococci, MRSA, aerobic gram negative bacilli and anaerobes.
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Duration of therapy
Patients requiring amputation of the involved limb should receive intravenous antibiotic therapy perioperatively.
If the entire area of infection is fully resected, a brief course of oral antibiotic therapy (about a week) following surgery is usually sufficient
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Duration of therapy
Duration of antibiotic therapy in the setting of osteomyelitis
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Antibiotic therapy for osteomyelitis
Infectious agent
Antibiotic Dosing
MSSA
Nafcillin 1-2 g intravenously every 6 hours
Oxacillin 1-2 g intravenously every 6 hours
Cefazolin 1 g intravenously every 8 hours
MRSA* Vancomycin
30 mg/kg intravenously every 24 hours in 2 equally divided doses; not to exceed 2 g/24 hours unless concentrations in serum are inappropriately low
Coagulase negative staphylococci Vancomycin
30 mg/kg intravenously every 24 hours in 2 equally divided doses; not to exceed 2 g/24 hours unless concentrations in serum are inappropriately low
Gram negative organisms (including Pseudomonas)
Ciprofloxacin 750 mg orally twice daily
Levofloxacin 750 mg orally once daily
Ceftazidime 2g intravenously every 8 hours
Cefepime 2 g intravenously every 12 hours
Empiric therapy Vancomycin PLUS an agent with activity against gram negative organisms
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Duration of therapy in osteomyelitis
Bony ablation with no residual infected soft tissue
24-72 hrs
Bony ablation with residual infected soft tissue
2-4 wks
Non-ablative bony resection back to viable but potentially or definitely infected bone
4-6 wks
Retained dead bone min 3 months
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Duration of therapy
Mild infection : 1-2 weeks Moderate infection : 2 to 4 weeks, unless
osteomyelitis Severe infection : soft tissue up to 4 weeks
unless osteomyelitis Osteomyelitis: depends on degree of resection
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Adjunctive therapies
Adjunctive therapies for treatment of diabetic foot infections include
1. Vacuum assisted wound closure
2. Hyperbaric oxygen
3. Granulocyte colony-stimulating factor (G-CSF).
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Reference
November 2008
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