educational workshops 2009 keynote presentation management of the diabetic foot author: paul...

EDUCATIONAL WORKSHOPS 2009

KEYNOTE PRESENTATIONKEYNOTE 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 HistoryA 76 year old man was admitted as an emergency with a

red and swollen right footApyrexial and haemodynamically stableDiagnosed with type 2 diabetes two years earlierOral hypoglycaemic therapy: blood sugar control

moderate


InvestigationsX-ray of the foot showed changes consistent with both

osteomyelitis and soft tissue infectionC-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).


Illustration reproduced with permission from Clinical Publishing Ltd, Oxford

Diagnosis & Initial managementModerate diabetic foot infection

limb-threateningcritical ischaemia not present

Treated empirically with IV vancomycin and piperacillin/tazobactam


Microbiological investigationPolymicrobial 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.


Surgical InterventionOn 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.


Further managementOn day 7 piperacillin-tazobactam was changed to oral

amoxicillin plus ciprofloxacin. 4 weeks of antimicrobial therapy were given in totalOngoing wound and foot care was provided by the

Podiatry team


Diabetic foot infectionMost common reason for diabetes-related admission to

hospital

High morbidity – may result in amputations


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


Prevention of DFIAppropriate foot care/pressure relief

Podiatry services

Good glycaemic controlSpecialist diabetes services


CID 2004; 39:885-910

Multidisciplinary Foot-care TeamPhysicianPodiatristMedical Microbiologist/ID PhysicianVascular surgeonFoot surgeonRadiologist


Microbiological SamplesSamples should be collected following cleansing and

debridementTissue samples should be obtained from the base of an

ulcer by curettage, or at surgeryBone biopsy (including histopathological examination) is

important in establishing a diagnosis of osteomyelitisSamples should be transported without delay to the

laboratory and cultured under both aerobic and anaerobic conditions.


Microbiological pathogensInfection is typically polymicrobial where ulceration is

presentAerobic Gram positive cocci

Staphylococcus aureusΒ-haemolytic streptococci

EnterococciEnterobacteriaceaeObligate anaerobes(Nonfermentative Gram negative rods)(Candida spp.)


Diagnosis and AssessmentDFI is diagnosed clinically by signs and symptoms of

inflammationInfections are categorized as mild, moderate or severe,

on the basis of clinical and laboratory featuresCategorization helps to guide appropriate clinical

managementAssessment made as to whether an episode is life or limb

threatening


Mild infectionPurulent or inflamed wound presentLimited to skin and superficial soft tissuesInflammation extends <2cm from woundNot systemically unwell

Treatment usually by oral routee.g. flucloxacillin, doxycycline, clindamycin

Microbiological sampling not routinely required for mildinfection unless recent antimicrobial therapy or previousantibiotic-resistant organisms


Moderate infectionPurulent or inflamed wound present in a patient who issystemically well and/or one of the followinginflammation extends >2cm from woundlymphangitisspread beneath superficial fasciaabscess formationnecrosis or gangreneinvolvement of muscle, tendon, joint or boneTreatment by oral or parenteral routes according to clinicalassessment and choice of agent


Moderate infectionTreatment options includeamoxicillin/clavulanateclindamycin + ciprofloxacinrifampicin + levofloxacinpiperacillin/tazobactamertapenemNB. Choices influenced by local policy with consideration oflocal issues such as C. difficile and MRSA incidence

Add glycopeptide, linezolid or daptomycin if MRSA infectionis suspected or infection is life/limb-threateningAuthor: Paul Chadwick, Salford Royal Hospitals Trust

Severe infectionInfection in a patient with evidence of systemicinflammatory response syndrome

IV treatment, at least initially, as an inpatient, e.g.clindamycin + ciprofloxacinpiperacillin/tazobactammeropenem or imipenem/cilastatin

Add glycopeptide, linezolid or daptomycin if MRSA infectionis suspected or infection is life/limb-threatening


Diagnostic ImagingImaging should always be considered to identify soft

tissue abscesses or osteomyelitisOsteomyelitis is present in 30% DFIIt 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.


Clinical signs of osteomyelitisThe following are associated with osteomyelitis

Inflamed, swollen (‘sausage’) toePresence of exposed bonePositive ‘probe-to-bone’ test


‘Sausage toe’

Osteomyelitis of halluxProbe to bone?

X-rays and DFIPlain X-rays can be negative during the first 2-3 weeks of

osteomyelitisCharcot neuroarthropathy & gout may produce similar

appearancesPragmatic approach where osteomyelitis is suspected

but X-rays are negativetreat for osteomyelitis for two weeks then re-Xrayextend the course of therapy if new changes become

apparent.


Osteomyelitis distal phalanx

MR imaging and DFIMarrow oedemaCortical discontinuityperiosteal reactiondebrissequestrasoft tissue oedema/indurationjoint involvementulcerationsinus formationabscess collection


Osteomyelitis of calcaneum, T1 image

Image courtesy of Dr J Harris, Radiology Department, Salford Royal Hospital

Sinus

Marrow oedema

Marrow oedema

Soft tissue oedema

Osteomyelitis of 1st metatarsal head, STIR image

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.

? Excision & drainage? Debridement? Resection +/- reconstruction? Revascularisation? Amputation


Wound Care IssuesOngoing debridement of non-viable tissue as requiredDressings to allow daily inspection of wound and to

encourage a moist wound-healing environmentRemove pressure from the wound (off-loading)


Larval (Maggot) TherapyUseful for some sloughy woundsFeed by extra-corporeal digestion, secreting collagenasesEnzymes break down necrotic tissue into a semi-liquid

form that the maggots can ingest


Contra-indications to larvaeMetronidazole Do not use in abdominal cavityDo not use in fistulaeNot recommended near major blood vesselsAnti-coagulant therapy in the community settingDry necrotic wounds (need to be softened)


Sloughy wound beforeMaggot therapy

Maggot Therapy

Glucose ControlGood blood glucose control should be achieved

To manage the acute infection

To reduce the risk of future foot problems


Duration of Antimicrobial TherapyContinued until the signs and symptoms of infection have

resolved (ulcer may persist)May be longer than for skin and soft tissue infections in non-

diabetic patientsMild soft tissue infections 1-2 weeksModerate-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. calcaneumNB. Courses may need to be longer than for non-diabetic patients with cellulitis


Antibiotics in DFIAntimicrobial 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


OHPAT and DFIOutpatient or home parenteral antimicrobial therapy maybe appropriate as prolonged IV therapy often needed forSevere infectionOsteomyelitisMRSA infectionIntolerance of oral agentsNo response to oral agents


educational workshops 2009 keynote presentation management of the diabetic foot author: paul...

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