Diabetic foot infection

Dr Aurélien DINH, MD

Pr Louis BERNARD, MD, PhD

Infectious Diseases, University Hospital Tours, France

Corresponding author: louis.bernard@univ-tours.fr

Meeting of the Lebanese Society of Rheumatology

6th of November 2009, Beyruth

Definition

• Infection is due– to tissue infestation – by micro organisms – with inflammatory response

• Diabetic foot infection (DFI) is due to foot ulceration

• Colonization should be distinguish from infection

• Colonization is continuous on wound

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No infection !

Infection !

Diagnosis

• Diagnosis of infection is clinical (not bacteriological):– Induration– Warmth– Erythema– Local tenderness– Purulence discharge

• DFI involve soft tissue with or wthout bone tissue (osteitis)

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Are all diabetics equal for foot infection ?

• NO !!• Diabetic foot infection is mostly

due to peripheral neuropathy• Mainly because of

– deformation (neuroarhropathy) – insensitiveness

Deformation

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Sensitive neuropathy

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Peripheral neuropathy• Lack of protective sensation• Cracking skin>>Neuropathy is favourable to

wound• Neuropathy delays diagnosis and

treatment of wound• Neuropathy does’nt help to take

care (no pain, no care)

Physiopathology of DFI

• Foot wound and infection are more frequent in diabetic population

• Risks factors are subject to debate but :– Deficit of cellular mechanism of defense (hyperglycemia)– Peripheral neuropathy– Hyperpressure– No off-loading– Chronicity of wound– Hypoxy– Vascular disease– Anatomic deformation

Predictive factors of outcome

• Peripheral vascular disease– restrict debridment– Reduce antibiotic efficacy – Encourage gangrene

• No off-loading– Encourage by insensitivity to pain– Refrain from wound healing – Encourage infection and osteitis

Clinical classification (staging in DFI)

• UT (University of Texas) Classification– Easy to use, based on : depth of wound/

infection/ vascular disease

• IWGDF-IDSA classification (International working group on the diabetic foot classification) focus on infection stage

• Others classifications : Wagner, Lipsky, PEDIS

UT Classification

Wound prevalence by grade and stage

Prevalence of amputation within each wound category

IDSA-IWGDF classification

Lavery, CID 2007

How to collect specimens for microbiological

diagnosis ?• Bacteriological samples :

– should be performed • Only in case of clinical infection • Before antibiotic therapy

– Several methods exists

How to get reliable microbiological data ?

• How to get bacteriological specimens ?• There is no consensus to distinguish the best

method• Local protocols should be done by clinicians

and microbiologists• They should specify: objective of analysis,

method of taking specimens, transport, culture…

• The goal is to identify micro organisms involve in bacterial invasion and to avoid colonization

General principles

• Wound should be cleanse and debride before obtaining specimens for culture

• Samples should – be clearly identified – and promtly send to laboratory

Microbiological evaluation

• Generally : blood cultures or cultures of deep tissue biopsy specimen>>more clinically significant

• Superficial swab: easy to perform, not invasive

• Scraping with a curette• Needle Aspiration• Soft tissue biopsy• Bone biopsy (osteomyelitis)

Superficial swab

Needle aspiration

Soft tissue biopsy

Bone biopsy

62

65

68???

Sapico 1984, Lavery 1995, Slater 2004, Kessler 2006, Senneville 2006

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Microbiological correlation between superficial sample and deep tissue

biopsy (from E. Senneville)

Microbiological correlation (between kind of wound and germs involved)

Lipsky CID 2004

Bone biopsy

• Gold-standard test for diagnosis osteo myelitis (histological analysis should be performed)

• Usefulness reliably recovering the pathogens responsible for bone infection

• It should be performed passing through a clean zone

Concordance between superficial swabs and bone biopsy

Senneville CID 2006

Recommanded wash out period before bone biopsy :

+15 days

0

1

2

3

4

5

6

7

1 5 9 13 17 21

pénicilline

céfalotine

netilmycine

clindamycine

ciprofloxacine

rifampicine

Witso et al. Acta Orthop Scand, 1999

Bone biopsy

Which relevance for other laboratory investigations ?

• Limited interest • No biological markers can help to

make difference between infection and colonization

• Kinetic of the value of C Reactive protein could be interesting to estimate response to treatment

Assess risk factors

• Mechanical factors• Vascular factors

– Clinical data– Systolic index pressure– Doppler – Transcutaneous oxygen pressure– others

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DFI management

• Multidiscplinary team• Management

– Strict glycemic control – Strict off-loading– Medical debridment– Wound care plan– Edema controll– Tetanos vacinal status

Glycemia/off loading

• Glycemia – should be strictly controlled:

• close monitoring, • insulinotherapy

• Off loading : – The major factor !!– It should be total and continuous

Atherosclerosis/Debridment

• Seek for vascular disease to correct

• Mechanical debridment to clean tissue– Physically excise dead and unhealthy

tissues– Reduces bacterial burden– Removes reservoir of potential pathogens

>> help to heal

Local therapy

• Local antiseptic : – No Proof of effectiveness !!

• Local antibiotherapy : – No Proof of effectiveness !!

Wound care

• Wound dressing – should be performed daily, – no adhesive or occlusive devices

• But there is:

– No good trials– No consensus– No study cost/effectiveness

Others

• Tetanos vaccine status : YES

• Hyperbaric oxygenia : no proof of effectiveness

• Growth factors: no proof of effectiveness

Antibiotherapy

• Indication: when there is infection and after microbiological sample performed

• Empirical antibiotic regimen: – Effective against staphylococcus aureus– Decrease with bacteriological results– Depending on severity of infection– Depending of diagnosis of osteitis– Mostly parenteral at the beginning– With good biodisponibility and penetration

Complex choice of antibiotherapy

• Bacterial spectra >> effective on Staphylococcus• Biodisponibility >> intra veinous ?• Penetration >> high dose ?• Tolerance >> visceral failure• Interaction• Bitherapy >> to prevent resistance• High dose >> because of atherosclerosis

Treatment duration

Lipsky, CID 2004

Surgical strategies

• Vascular surgeryVascular surgery– by pass

– Percutaneous transluminal angioplasty

• Orthopedic surgery– To control infection

– To attempt to salvage limb

Vascular surgery (1)

• Vascular disease exacerbate infection>> revascularization

• Revascularisation can be realise – to save the limb – or to help healing

Vascular surgery (2)

• In case of critical ischemia– revascularization should be perform when

sepsis is controlled– In case of emergency: revascularization

should be performed close or at the same time

• When ischemia is less critical: revascularization should always be discussed

Before

After

Benefit of revascularization (1)

Jacqueminet Diabetes care 2005

Jacqueminet Diabetes care 2005

Benefit of revascularization (2)

Methods for local treatment

• Most important !!• Excision of infected tissues• Limited debridment of necrotic tissues• Drainage of deep abscess and deep space

infection• In some cases : amputation = the only option• Surgery should attempt to preserve the

integrity of walking surface

Indications for surgery

• Urgent surgical consultation:– Fasciitis and necrosis– Gangrene/abscess

• Delay surgery : – cellulitis not responding after 3 days of efficient

antibiotic therapy

• Indications for amputation:– If vascular disease: state on vascularization

possible procedure– If non vascular disease: if extensive soft tissue lost

or fasciitis with life or limb-threatening infection

Osteitis in DFI

• When think about it ?• Which imagery ?• Surgery management• Which antibiotic therapy ?

Physical examination

• No healing despite appropriate care

• Positive probe to bone test – (PPV:50-89% ; NPV>95%)

• Sausage deformity

Accuracy of probe to bone test

Lavery Diabete care 2007

Ulcers not healing

CRP and osteitis

Enderle et al. Diabetes Care 1999

Radiological diagnosis of osteitis (1)

Dinh MT CID 2008

Kapoor et al. Arch Int Med 2007

Radiological diagnosis of osteitis (2)

Radiological diagnosis of osteitis (3)

Termaat JBJS 2008

Surgery for osteitis

• Conservative surgery– Limited resection– No osteo synthesis– Antibiotherapy from 4 to 6 weeks

(parenteral then oral)

• Different from acute Charcot foot

Hartemann-heurtier,

Senneville,

Diabetes metabolism 2008

Microbiology in osteitis of DFI

Hartemann-heurtier, Senneville, Diabetes metabolism 2008

Antibiotic treatment for osteitis in DFI

Hartemann-heurtier, Senneville, Diabetes metabolism 2008

Preventive actions

• Education: – risks of neuropathy and vascular

disease, self management and examination

• Pedicure: – nails care, managing hyperkeratosis

• Shoes: – should fit, trauma due to shoes are

the first cause of diabetic ulcers• Preventive surgery:

– if major deformation to avoid futur hyperpressure

Take home messages

• Diabetic foot ulcers are– Coming on insensitive

foot– Always colonized– Infection diagnosis is

clinical– Outcome depending

mostly on atherosclerosis and tipping off

• Management need – Precise wound care– Assess risks factors– Microbiological

specimens– Antibiotherapy– Surgery some times

Thank you for your attention !

• Thanks to – french infectious disease society, – french society of vascular surgery, – french society of microbiology

• Pr Agnès Hartmann-Heurtier (Endocrinology, Pitié Salpétrière)

• Dr Eric Senneville (Infectious disease, Lille)