Transcript Diagnosis and treatment of DM foot infections

Diagnosis and treatment of DM foot
infections
(2012 IDSA Clinical Practice
Guidelines)
Moon Soo-youn
Division of Infectious Diseases
Kyung Hee University Hospital at Gangdong
• Diabetic foot infections (DFI)
– Improper diagnosis and therapeutic approaches
 amputations
• Infected diabetic foot or not?
– Antibiotics?
– Surgical interventions?
I.
In which diabetic patients with a foot wound should I
suspect infection, and how should I classify it?
II. How should I assess a diabetic patient presenting
with a foot infection?
III. When and from whom should I request a
consultation for a patient with a diabetic foot
infection?
IV. Which patients with a diabetic foot infection should I
hospitalize, and what criteria should they meet before
I discharge them?
V. When and how should I obtain specimen(s) for
culture from a patient with a diabetic foot wound?
VI. How should I initially select, and when should I
modify, an antibiotic regimen for a diabetic foot
infection?
VII. When should I consider imaging studies to evaluate a
diabetic foot infection, and which should I select?
VIII. How should I diagnose and treat osteomyelitis of the
foot in a patient with diabetes?
IX. In which patients with a diabetic foot infection should
I consider surgical intervention, and what type of
procedure may be appropriate?
X. What types of wound care techniques and dressings
are appropriate for diabetic foot wounds?
I. In which diabetic patients with a foot
wound should I suspect infection, and
how should I classify it?
• Possibility of infection occurring in any foot wound in a
patients with diabetes
– Classic signs of inflammation: redness, warmth, swelling,
tenderness, or pain
– Purulent secretions
– Additional or secondary signs: nonpurulent secretions,
friable or discolored granulation tissue, undermining of
wound edges, foul odor
– ≥2 of the classic findings of inflammation  infected
(2004)
• Factors increasing the risk for DFI
–
–
–
–
–
–
–
–
–
Positive probe-to-bone (PTB) test
Ulceration >30 days
History of recurrent foot ulcers
Traumatic foot wound
Peripheral vascular disease
Previous lower extremity amputation
Loss of protective sensation
Renal insufficiency
History of walking bare foot
Perfusion
Extent
Depth
Infection
Sensation
• Other classification systems
– Meggitt-Wagner: ulcer depth, presence of infection and
gangrene
– S(AD)/SAD: size, (area, depth), sepsis (infection),
arteriopathy, and denervation
– University of Texas (UT) ulcer classification: combined
matrix of 4 grades and 4 stages
– Ulcer Severity Index: 20 clinical parameters
– Diabetic Ulcer Severity Score (DUSS) and MAID: specific
wound characteristics associated with stages of wound
repair
– DFI Wound Score: semiquantitative assessment of the
presence of signs and symptoms of inflammation,
combined with measurements of wound size & depth
II. How should I assess a diabetic
patient presenting with a foot infection?
• The patient as a whole
– Complications of diabetes: peripheral neuropathy,
peripheral vascular disease, neuro-osteoarthropathy,
impaired wound healing
– Various patients comorbidities
– Maladaptive behaviors
– Immunologic perturbations – reduced PMN function,
impaired humoral and cell-mediated immunity
• The affected foot or limb
– Vascular supply: arterial ischemia, venous insufficiency
• Ankle-Brachial Index
– Presence of protective sensation
– Biomechanical problems
• The infected wound
– Debride any wound with necrotic tissue or surrounding
callus
– Microorganisms colonize all wounds  clinical diagnosis!
III. When and from whom should I
request a consultation for a patient
with a diabetic foot infection?
• Multidisciplinary diabetic foot care team
– Endocrinology, dermatology, podiatry, general surgery,
vascular surgery, orthopedic surgery, plastic surgery,
wound care, psychology or social work
– Specialists in infectious diseases or clinical microbiology
• Ischemia – revascularization
– Peripheral arterial disease
– ABI <0.40
• Pressure off-loading, dressing techniques
IV. Which patients with a diabetic foot
infection should I hospitalize, and what
criteria should they meet before I
discharge them?
• Hospitalization
– All patients with a severe infection
– Selected patients with a moderate infection with
complicating features (sever PAD, lack of home support)
– Any patient unable to comply with an appropriate
outpatient treatment regimen
– Patient failing to improve with OPD therapy
• Discharge
–
–
–
–
–
Clinically stable
Any urgently needed surgery performed
Acceptable glycemic control
Able to manage at discharge location
Well-defined plan including appropriate antibiotic
regimen, off-loading scheme, wound care and OPF f/u
V. When and how should I obtain
specimen(s) for culture from a patient
with a diabetic foot wound?
• Infected wound culture prior to empiric antibiotic
therapy
VI. How should I initially select, and
when should I modify, an antibiotic
regimen for a diabetic foot infection?
• Route of therapy
– All severe and some moderate DFIs: IV therapy, at least
initially
– Most mild, and in many moderate infections: Highly
bioavailable oral antibiotics
– Selected mild superficial infection: Topical therapy
• Duration of therapy
– Until, but NOT beyond resolution of findings
infections
– NOT through complete healing of the wound
– 1-2 weeks for mild infections
– 2-3 weeks for moderate to severe infections
of
Gram positive cocci
History of previous MRSA infection or colonization within the past year
Local prevalence of MRSA is high enough (50% for mild and 30% for
moderate SSTI)
Severe infection – failing to empirical coverage for MRSA 
unacceptable risk of treatment failure
Most severe
Chronic, previously
treated, or severe
infections
In countries where P. aeruginosa is a frequent isolate
In patients who have been soaking their feet
In patients who have failed therapy with non-pseudomonal
therapy
In patients with severe infection
VII. When should I consider imaging
studies to evaluate a diabetic foot
infection, and which should I select?
• Plain radiographs for all patients with new DFI
– Bony abnormality, soft tissue gas and radio-opaque
foreign bodies
• MRI
– Study of choice for additional imaging
– Soft tissue abscess, osteomyelitis
• Combination of radionuclide bone scan and a labeled
WBC scan
– Best alternative
contraindicated
when
MRI
is
unavailable
or
VIII. How should I diagnose and treat
osteomyelitis of the foot in a patient
with diabetes?
• Diagnosis
– PTB test for any DFIs with an open wound
– Plain X-ray
• relatively low sensitivity and specificity
• Serial X-ray
– MRI
– Leukocyte or antigranulocyte scan + bone scan
– Bone culture and histology  definitive diagnosis
• Treatment
– Microbiology
• S. aureus, S. epidermidis
• E. coli, K. pneumoniae, Proteus species, P. aeruginosa
• Peptostreptococcus, Peptococcus, Finegoldia magna
– Surgical treatment or medical treatment?
– Adjunctive treatment
• Hyperbaric oxygen therapy
– Cochrane review – reduced risk of major amputation
(2004)
• Growth factors (granulocyte colony stimulating factor)
– No accelerated resolution of infection but reduced
need for operative procedures (2004)
• Maggots (larvae)
• Topical negative pressure therapy (Vacuum-assisted closure)
• No persuasive evidence
IX. In which patients with a diabetic
foot infection should I consider
surgical intervention, and what type of
procedure may be appropriate?
• Urgent surgical intervention
4-7 compartments
– Gas in the deeper tissues, abscess, necrotizing fasciitis
• Less urgent surgery
– Wounds with substantial nonviable tissue or extensive
bone or joint involvement
• Early, evolving infection
– Best to delay surgery in an attempt to avoid the
consequent scarring and deformity
• Key element to any surgical approach
– To reach the appropriate foot compartment(s) and
extend the exploration and debridement to healthy
tissue
• Revascularization
– Ischemia secondary to larger-vessel atherosclerosis rather
than to “small-vessel disease”
– Angioplasty or vascular bypass
X. What types of wound care
techniques and dressings are
appropriate for diabetic foot wounds?
• Appropriate wound care
– Debridement
•
•
•
•
•
•
Removing colonizing bacteria
Granulation tissue formation and re-epithelialization
Reducing pressure at callused sites
Collection of appropriate specimens for culture
Examination for the presence of deep tissue involvement
Relatively contraindicated in wounds primarily ischemic
– Redistribution of pressure off the wound to the entire
weight-bearing surface of the foot (“off-loading”)
• Vital part of wound care
• Total contact cast: often considered “gold standard” device
– Caution in patients with severe PAD or active infection
• Other devices
– Removal, especially at home
– Wound dressing
• Optimal healing environment
• Moist wound environment  granulation, autolytic
processes, angiogenesis, more rapid migration of epithelial
cells across the wound base
• Continuously moistened saline gauze: dry/necrotic wounds
• Hydrogels: dry/necrotic wounds facilitate autolysis
• Films: occlusive/semi-occlusive, moistening dry wounds
• Alginates: drying exudative wounds
• Hydrocolloids: absorbing exudate & facilitate autolysis
• Foams: exudative wounds
– Topical antimicrobials – not advocated
• Topical antiseptics and silver-based dressings
– Little evidence
– Expense, potential for local adverse effects
– Emergence of bacterial resistance
– Adjunctive therapy – no supportive data
•
•
•
•
•
Hyperbaric oxygen therapy
Platelet-derived growth factors
G-CSF
Bioengineered skin equivalents
Topical negative pressure
• Infection should be suspected in all DM foot
– PEDIS grade
• Treatment
– OFF-LOADING
– Debridement, dressing
– Antibiotics
• Until infection is controlled, NOT until wound healing
– Vascularity - revascularization
• Osteomyelitis
– X-ray, MRI
– Longer antibiotics
– Surgical treatment
• Prevention (2004 guidelines)
–
–
–
–
–
Detection of neuropathy before its complication ensue
Optimizing glycemic control
Appropriate footwear
Avoiding foot trauma
Daily self-examination of the feet