1. Diabetic foot infection
Meeting of the Lebanese Society of Rheumatology
6th of November 2009, Beyruth
Diabetic foot infection
Dr Aurélien DINH, MD
Pr Louis BERNARD, MD, PhD
Infectious Diseases, University Hospital Tours, France
Corresponding author:

2. 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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Colonization is physiological
Bacteria are from commensal flora

3. No infection ! Infection !
Foot ulcer and gangrene

4. 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)
The diagnosis of DFI could not be bacteriological because of continuous colonization
Infection should be clinically diagnosed
Systemic signs
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5. Gangrene and gangrene and cellulitis
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6. Are all diabetics equal for foot infection ?
NO !!
Diabetic foot infection is mostly due to peripheral neuropathy
Mainly because of
deformation (neuroarhropathy)
insensitiveness

7. Deformation
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8. Sensitive neuropathy
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9. 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)

10. 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

11. 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

12. 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
The goal is to ease clinical research to know what we are talking about
Goal is publication, communication and research
No one is perfect

13. UT Classification Wound prevalence by grade and stage
Prevalence of amputation within each wound category

14. IDSA-IWGDF classification
Lavery, CID 2007

15. How to collect specimens for microbiological diagnosis ?
Bacteriological samples :
should be performed
Only in case of clinical infection
Before antibiotic therapy
Several methods exists

16. 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

17. General principles
Wound should be cleanse and debride before obtaining specimens for culture
Samples should
be clearly identified
and promtly send to laboratory

18. 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)

19. Superficial swab
Needle aspiration

20. Soft tissue biopsy
Bone biopsy

21. Microbiological correlation between superficial sample and deep tissue biopsy (from E. Senneville)62 65 30 69 68
??? 24
Sapico 1984, Lavery 1995, Slater 2004, Kessler 2006, Senneville 2006 21

22. Microbiological correlation (between kind of wound and germs involved)
Lipsky CID 2004

23. 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

24. Concordance between superficial swabs and bone biopsy
Concordance from bone biopsy and suprficial swab vary depending on germs but is rather low
Senneville CID 2006

25. Recommanded wash out period before bone biopsy : +15 days
Witso et al. Acta Orthop Scand, 1999

26. Bone biopsy

27. 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

28. Assess risk factors Mechanical factors Vascular factors Clinical data
Systolic index pressure
Doppler
Transcutaneous oxygen pressure
others
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29. DFI management Multidiscplinary team Management
Strict glycemic control
Strict off-loading
Medical debridment
Wound care plan
Edema controll
Tetanos vacinal status

30. Glycemia/off loading Glycemia Off loading :
should be strictly controlled:
close monitoring,
insulinotherapy
Off loading :
The major factor !!
It should be total and continuous
Lot of device exists

31. 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

32. Local therapy Local antiseptic : Local antibiotherapy :
No Proof of effectiveness !!
Local antibiotherapy :

33. Wound care Wound dressing But there is: should be performed daily,
no adhesive or occlusive devices
But there is:
No good trials
No consensus
No study cost/effectiveness

34. Others Tetanos vaccine status : YES
Hyperbaric oxygenia : no proof of effectiveness
Growth factors: no proof of effectiveness

35. 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

36. 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

37. Treatment duration
Lipsky, CID 2004

38. Surgical strategies Vascular surgery Orthopedic surgery by pass
Percutaneous transluminal angioplasty
Orthopedic surgery
To control infection
To attempt to salvage limb

39. Vascular surgery (1)
Vascular disease exacerbate infection>> revascularization
Revascularisation can be realise
to save the limb
or to help healing

40. 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

41. Before

42. After

43. Benefit of revascularization (1)
Percutaneous transluminal angioplasty : first line procedure for 32 diabetic patients with foot ulcers and severe limb ischemia
High rate of healing
Jacqueminet Diabetes care 2005

44. Benefit of revascularization (2)
High rate of limb salvage
Jacqueminet Diabetes care 2005

45. 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

46. 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

48. Osteitis in DFI When think about it ? Which imagery ?
Surgery management
Which antibiotic therapy ?

49. Physical examination No healing despite appropriate care
Positive probe to bone test
(PPV:50-89% ; NPV>95%)
Sausage deformity

50. Accuracy of probe to bone test
Really good negative predictive value
Lavery Diabete care 2007

51. Ulcers not healing
An ulcers that is not healing despite appropriate care and pressure off loading suggest underlying osteomyelitis

52. CRP and osteitis Enderle et al. Diabetes Care 1999
C reactive protein is may be a diagnosis tool
Enderle et al. Diabetes Care 1999

53. Radiological diagnosis of osteitis (1)
MRI is the most accurate imaging test for diagnosis of osteo myelitis
Dinh MT CID 2008

54. Radiological diagnosis of osteitis (2)
Kapoor et al. Arch Int Med 2007

55. Radiological diagnosis of osteitis (3)
Termaat JBJS 2008

56. Surgery for osteitis Conservative surgery
Limited resection
No osteo synthesis
Antibiotherapy from 4 to 6 weeks (parenteral then oral)
Different from acute Charcot foot

58. Hartemann-heurtier,
Senneville,
Diabetes metabolism 2008

59. Microbiology in osteitis of DFI
Hartemann-heurtier, Senneville, Diabetes metabolism 2008

60. Antibiotic treatment for osteitis in DFI
Hartemann-heurtier, Senneville, Diabetes metabolism 2008

61. Preventive actions Education: Pedicure: Shoes: Preventive surgery:
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

62. 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

63. 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)