EDUCATIONAL WORKSHOPS 2009
KEYNOTE PRESENTATION
Management of the diabetic foot
Author: Paul Chadwick, Salford Royal Hospitals Trust
Sponsored through an unrestricted educational grant
from Novartis Pharmaceutical Ltd to help support the
cost of developing and hosting this educational
workshop series
Case History
 A 76 year old man was admitted as an emergency with a
red and swollen right foot
 Apyrexial and haemodynamically stable
 Diagnosed with type 2 diabetes two years earlier
 Oral hypoglycaemic therapy: blood sugar control
moderate
Author: Paul Chadwick, Salford Royal Hospitals Trust
Investigations
 X-ray of the foot showed changes consistent with both
osteomyelitis and soft tissue infection
 C-reactive protein 219 mg/l (<10mg/l)
 Neutrophils 19.2 x109/l (4-11 x109/l)
 Plasma glucose 24.6 mmol/l (3-6 mmo/l).
Author: Paul Chadwick, Salford Royal Hospitals Trust
Illustration reproduced with permission from Clinical Publishing Ltd, Oxford
Diagnosis & Initial management
 Moderate diabetic foot infection
 limb-threatening
 critical ischaemia not present
 Treated empirically with IV vancomycin and
piperacillin/tazobactam
Author: Paul Chadwick, Salford Royal Hospitals Trust
Microbiological investigation
 Polymicrobial infection
 Gram stain of showed neutrophils, Gram positive cocci
and Gram positive bacilli
 Enterocoocci and alpha-haemolytic Streptoccoci were
isolated from pus
 At least five different species comprising Gram positive
cocci and Enterobacteria were cultured from
superficial swabs.
Author: Paul Chadwick, Salford Royal Hospitals Trust
Surgical Intervention
 On day 4 debridement was undertaken to remove
infected bone and soft tissue
 Enterococcus faecalis, Propionobacterium sp. and
Escherichia coli were isolated from deep pus and tissue
samples.
Author: Paul Chadwick, Salford Royal Hospitals Trust
Further management
 On day 7 piperacillin-tazobactam was changed to oral
amoxicillin plus ciprofloxacin.
 4 weeks of antimicrobial therapy were given in total
 Ongoing wound and foot care was provided by the
Podiatry team
Author: Paul Chadwick, Salford Royal Hospitals Trust
Diabetic foot infection
 Most common reason for diabetes-related admission to
hospital
 High morbidity – may result in amputations
Author: Paul Chadwick, Salford Royal Hospitals Trust
Why does DFI occur?
 Foot ulceration is the major factor and occurs secondary
to peripheral neuropathy and/or vascular insufficiency
(neuro-ischaemic foot ulceration)
 Hyperglycaemia and other metabolic disturbances
contribute through immunological (e.g. neutrophil)
dysfunction and poor wound healing
Author: Paul Chadwick, Salford Royal Hospitals Trust
Prevention of DFI
 Appropriate foot care/pressure relief
 Podiatry services
 Good glycaemic control
 Specialist diabetes services
Author: Paul Chadwick, Salford Royal Hospitals Trust
CID 2004; 39:885-910
Multidisciplinary Foot-care Team
 Physician
 Podiatrist
 Medical Microbiologist/ID Physician
 Vascular surgeon
 Foot surgeon
 Radiologist
Author: Paul Chadwick, Salford Royal Hospitals Trust
Microbiological Samples
 Samples should be collected following cleansing and
debridement
 Tissue samples should be obtained from the base of an
ulcer by curettage, or at surgery
 Bone biopsy (including histopathological examination) is
important in establishing a diagnosis of osteomyelitis
 Samples should be transported without delay to the
laboratory and cultured under both aerobic and
anaerobic conditions.
Author: Paul Chadwick, Salford Royal Hospitals Trust
Microbiological pathogens
Infection is typically polymicrobial where ulceration is
present
 Aerobic Gram positive cocci
 Staphylococcus aureus
 Β-haemolytic streptococci
 Enterococci
 Enterobacteriaceae
 Obligate anaerobes
 (Nonfermentative Gram negative rods)
 (Candida spp.)
Author: Paul Chadwick, Salford Royal Hospitals Trust
Diagnosis and Assessment
 DFI is diagnosed clinically by signs and symptoms of
inflammation
 Infections are categorized as mild, moderate or severe, on
the basis of clinical and laboratory features
 Categorization helps to guide appropriate clinical
management
 Assessment made as to whether an episode is life or limb
threatening
Author: Paul Chadwick, Salford Royal Hospitals Trust
Mild infection
Purulent or inflamed wound present
 Limited to skin and superficial soft tissues
 Inflammation extends <2cm from wound
 Not systemically unwell
Treatment usually by oral route
e.g. flucloxacillin, doxycycline, clindamycin
Microbiological sampling not routinely required for mild
infection unless recent antimicrobial therapy or previous
antibiotic-resistant organisms
Author: Paul Chadwick, Salford Royal Hospitals Trust
Moderate infection
Purulent or inflamed wound present in a patient who is
systemically well and/or one of the following
 inflammation extends >2cm from wound
 lymphangitis
 spread beneath superficial fascia
 abscess formation
 necrosis or gangrene
 involvement of muscle, tendon, joint or bone
Treatment by oral or parenteral routes according to clinical
assessment and choice of agent
Author: Paul Chadwick, Salford Royal Hospitals Trust
Moderate infection
Treatment options include
 amoxicillin/clavulanate
 clindamycin + ciprofloxacin
 rifampicin + levofloxacin
 piperacillin/tazobactam
 ertapenem
NB. Choices influenced by local policy with consideration of
local issues such as C. difficile and MRSA incidence
Add glycopeptide, linezolid or daptomycin if MRSA infection
is suspected or infection is life/limb-threatening
Author: Paul Chadwick, Salford Royal Hospitals Trust
Severe infection
Infection in a patient with evidence of systemic
inflammatory response syndrome
IV treatment, at least initially, as an inpatient, e.g.
 clindamycin + ciprofloxacin
 piperacillin/tazobactam
 meropenem or imipenem/cilastatin
Add glycopeptide, linezolid or daptomycin if MRSA infection
is suspected or infection is life/limb-threatening
Author: Paul Chadwick, Salford Royal Hospitals Trust
Diagnostic Imaging
 Imaging should always be considered to identify soft
tissue abscesses or osteomyelitis
 Osteomyelitis is present in 30% DFI
 It is important to identify underlying osteomyelitis as this
influences the choice, dose, route and duration of
antimicrobial therapy, however
 There is no single, non-invasive, highly sensitive and
specific test for osteomyelitis
 MRI can help to identify bone involvement (marrow
oedema) and define its extent.
Author: Paul Chadwick, Salford Royal Hospitals Trust
Clinical signs of osteomyelitis
The following are associated with osteomyelitis
 Inflamed, swollen (‘sausage’) toe
 Presence of exposed bone
 Positive ‘probe-to-bone’ test
Author: Paul Chadwick, Salford Royal Hospitals Trust
‘Sausage toe’
Osteomyelitis of hallux
Probe to bone?
X-rays and DFI
 Plain X-rays can be negative during the first 2-3 weeks of
osteomyelitis
 Charcot neuroarthropathy & gout may produce similar
appearances
 Pragmatic approach where osteomyelitis is suspected but
X-rays are negative
 treat for osteomyelitis for two weeks then re-Xray
 extend the course of therapy if new changes become
apparent.
Author: Paul Chadwick, Salford Royal Hospitals Trust
Osteomyelitis distal phalanx
MR imaging and DFI
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Marrow oedema
Cortical discontinuity
periosteal reaction
debris
sequestra
soft tissue oedema/induration
joint involvement
ulceration
sinus formation
abscess collection
Author: Paul Chadwick, Salford Royal Hospitals Trust
Osteomyelitis of calcaneum, T1 image
Marrow
oedema
Sinus
Image courtesy of Dr J Harris, Radiology Department, Salford Royal Hospital
Osteomyelitis of 1st metatarsal head, STIR image
Soft tissue
oedema
Marrow
oedema
Image courtesy of Dr J Harris, Radiology Department, Salford Royal Hospital
Does the patient require surgery?
Surgical intervention is often required. Urgent assessment is
needed by a surgeon with expertise in foot surgery where
the infection is life- or limb-threatening. Vascular surgery
may be needed where there is critical ischaemia.
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Excision & drainage
Debridement
Resection +/- reconstruction
Revascularisation
Amputation
Author: Paul Chadwick, Salford Royal Hospitals Trust
Wound Care Issues
 Ongoing debridement of non-viable tissue as required
 Dressings to allow daily inspection of wound and to
encourage a moist wound-healing environment
 Remove pressure from the wound (off-loading)
Author: Paul Chadwick, Salford Royal Hospitals Trust
Larval (Maggot) Therapy
 Useful for some sloughy wounds
 Feed by extra-corporeal digestion, secreting collagenases
 Enzymes break down necrotic tissue into a semi-liquid
form that the maggots can ingest
Author: Paul Chadwick, Salford Royal Hospitals Trust
Contra-indications to larvae
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Metronidazole
Do not use in abdominal cavity
Do not use in fistulae
Not recommended near major blood vessels
Anti-coagulant therapy in the community setting
Dry necrotic wounds (need to be softened)
Author: Paul Chadwick, Salford Royal Hospitals Trust
Sloughy wound before
Maggot therapy
Maggot Therapy
Glucose Control
Good blood glucose control should be achieved
 To manage the acute infection
 To reduce the risk of future foot problems
Author: Paul Chadwick, Salford Royal Hospitals Trust
Duration of Antimicrobial Therapy
 Continued until the signs and symptoms of infection have
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resolved (ulcer may persist)
May be longer than for skin and soft tissue infections in nondiabetic patients
Mild soft tissue infections 1-2 weeks
Moderate-severe soft tissue 3-4 weeks
Osteomyelitis typically 6 weeks, unless all affected bone is
completely removed by surgery (1-2 weeks)
Therapy ≥3 months sometimes required for extensive bone
infection e.g. calcaneum
NB. Courses may need to be longer than for non-diabetic
patients with cellulitis
Author: Paul Chadwick, Salford Royal Hospitals Trust
Antibiotics in DFI
 Antimicrobial therapy can be challenging!
 Consider patient factors (e.g. age, renal function,
peripheral vascular disease)
 Side effects are common
 Gastrointestinal intolerance of oral antibiotics, often to
multiple agents
 Hypersensitivity reactions (typically skin rashes)
 Deterioration in renal function may occur
Author: Paul Chadwick, Salford Royal Hospitals Trust
OHPAT and DFI
Outpatient or home parenteral antimicrobial therapy may
be appropriate as prolonged IV therapy often needed for
 Severe infection
 Osteomyelitis
 MRSA infection
 Intolerance of oral agents
 No response to oral agents
Author: Paul Chadwick, Salford Royal Hospitals Trust