Transcript Important factors for development of diabetic foot

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Overview of diabetic foot
infections
Masood Ziaee ,MD
Des ,11, 2008
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FOOT ULCERS IN DIABETES
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“Rule of 15”
15% of diabetes patients
Foot ulcer in lifetime
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15% of foot ulcers
Osteomyelitis
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15% of foot ulcers
Amputation
Clinical Care of the Diabetic Foot, 2005
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©2006. American College of Physicians. All Rights Reserved.
INTRODUCTION
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Important factors for development of
diabetic foot infections include
Neuropathy
Peripheral vascular disease
Hyperglycemia.
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INTRODUCTION (Neuropathy)
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Autonomic neuropathy can cause diminished
sweat secretion resulting in dry, cracked skin,
facilitating microorganism entry.
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Motor neuropathy can lead to foot deformities.
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INTRODUCTION
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Peripheral arterial disease can lead to
impaired blood supply needed for healing of
ulcers and infections.
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Hyperglycemia impairs neutrophil function
and reduces host defenses.
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MICROBIOLOGY
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Most diabetic foot infections are polymicrobial,
with up to five or seven different specific
organisms involved.
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MICROBIOLOGY
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Superficial diabetic foot infections are likely to be
due to Aerobic gram-positive cocci :
S. aureus, S. agalactiae, S. pyogenes, and coagulasenegative staphylococci
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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
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Ulcers that are deep, chronically infected, and/or
previously treated with antibiotics are more likely
to be polymicrobial.
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Such wounds may involve the above organisms
in addition to Enterococci, Enterobacteriaceae,
Pseudomonas Aeruginosa, and Anaerobes.
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MICROBIOLOGY
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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.
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Potential pathogens include anaerobic streptococci,
Bacteroides species, and Clostridium species.
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CLASSIFICATION (Wagner )
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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 )
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Grade 2 — Deep ulcer, penetrating down to ligaments and
muscle, but no bone involvement or abscess formation.
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CLASSIFICATION (Wagner )
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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
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Made on the basis of clinical manifestations :
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Erythema
Warmth
Tenderness
Swelling are observed
Pus is grossly visible at an ulcer site or sinus
tract.
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Laboratory evaluation
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Laboratory evaluation should include :
CBC
BS
Electrolytes
ESR
CRP
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Laboratory evaluation
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Organisms cultured from superficial swabs are
not reliable for predicting the pathogens
responsible for deeper infection.
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Deep tissue cultures are required; for
evaluation of osteomyelitis, bone biopsy is
needed.
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Laboratory evaluation
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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
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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
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Patients with diabetic foot infections should
have initial evaluation with conventional
radiographs.
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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
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1.
If the patient is diabetic and has symptoms referable to the foot,
MRI is the test of choice.
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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
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Evidence of osteomyelitis by these imaging
modalities should prompt a bone biopsy to confirm
the diagnosis and to guide antimicrobial therapy.
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In the absence of osteomyelitis by these alternative
imaging modalities, osteomyelitis is unlikely.
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MANAGEMENT
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Management of diabetic foot infections requires
Attentive wound management
Good nutrition
Antimicrobial therapy
Glycemic control
Fluid and electrolyte balance.
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CLASSIFICATION OF INFECTION
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Mild infection
Moderate infection
Severe infection
Mild infection
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Presence of 2 manifestations of
1.
Inflammation (purulence, or erythema, pain,
tenderness, warmth, or induration),
Any Cellulitis/erythema extends 2 cm around the
ulcer,
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Infection is limited to the skin or superficial subcutaneous
tissues
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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Oral agents for empiric treatment of mild to moderate diabetic foot infections
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
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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
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Oral antibiotic therapy in conjunction with attentive
wound care until there is evidence that the infection
has resolved (usually about 1 to 2 weeks).
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Antibiotics need not be administered for the entire
duration that the wound remains open.
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Moderate infection
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Infection in a patient who is
1.
Systemically well and metabolically stable
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
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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
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Aztreonam
2 g every 6 to 8 hours
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Duration of therapy
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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
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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.
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Empiric therapy should include activity against
streptococci, MRSA, aerobic gram negative bacilli
and anaerobes.
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Duration of therapy
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Patients requiring amputation of the involved limb
should receive intravenous antibiotic therapy
perioperatively.
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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
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Duration of antibiotic therapy in the setting of
osteomyelitis
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Antibiotic therapy for osteomyelitis
Antibiotic
Dosing
Nafcillin
1-2 g intravenously every 6 hours
Oxacillin
1-2 g intravenously every 6 hours
Cefazolin
1 g intravenously every 8 hours
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
Infectious agent
MSSA
MRSA*
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 2-4 wks
soft tissue
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Non-ablative bony resection back
to viable but potentially or
definitely infected bone
4-6 wks
Retained dead bone
min 3 months
Duration of therapy
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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
Adjunctive therapies
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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
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2008
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