diabetic foot infections and the hospitalist
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Diabetic Foot Infections and the Diabetic Foot Infections and the HospitalistHospitalist
Jim Pile, MD, FACPJim Pile, MD, FACP
Divisions of Hospital Medicine and Divisions of Hospital Medicine and Infectious DiseasesInfectious Diseases
CWRU/MetroHealth Medical CenterCWRU/MetroHealth Medical Center
The ProblemThe Problem
Diabetic foot infections are common, expensive Diabetic foot infections are common, expensive and probably increasing in frequencyand probably increasing in frequency
The most frequent reason for hospitalization in The most frequent reason for hospitalization in diabetic patientsdiabetic patients
The most common reason for amputationsThe most common reason for amputations
Current treatment often fails to conform to Current treatment often fails to conform to available evidence/guidelinesavailable evidence/guidelines
Scope of Diabetic Foot InfectionsScope of Diabetic Foot Infections
CellulitisCellulitis
ParonychiaParonychia
AbscessAbscess
MyositisMyositis
Infectious tendonitisInfectious tendonitis
Septic arthritisSeptic arthritis
Necrotizing fasciitisNecrotizing fasciitis
OsteomyelitisOsteomyelitis
ULCERSULCERS
Risk Factors for Diabetic Foot Risk Factors for Diabetic Foot Ulceration and InfectionUlceration and Infection
Sensory neuropathySensory neuropathy
Motor neuropathyMotor neuropathy
Autonomic neuropathyAutonomic neuropathy
Neuro-osteoarthropathic Neuro-osteoarthropathic deformities (eg Charcot)deformities (eg Charcot)
Peripheral vascular Peripheral vascular diseasedisease
HyperglycemiaHyperglycemia
Host factorsHost factors
Patient non-adherencePatient non-adherence
Sub-optimal care by Sub-optimal care by health care systemhealth care system
Audience Response QuestionAudience Response Question
Treatment of cellulitis in the patient with Treatment of cellulitis in the patient with longstanding diabetes should include coverage longstanding diabetes should include coverage of:of:
A. Gram positive organismsA. Gram positive organisms
B. Gram positive and negative organismsB. Gram positive and negative organisms
C. Gram positives and anaerobesC. Gram positives and anaerobes
D. All of the above D. All of the above
Microbiology of Diabetic Foot InfectionsMicrobiology of Diabetic Foot Infections
Gram positive organisms predominate, Gram positive organisms predominate, especially in acute woundsespecially in acute wounds
--Staph aureus--Staph aureus
--B-hemolytic strep (especially groups A and B)--B-hemolytic strep (especially groups A and B)
Chronic wounds and/or recent antibiotics:Chronic wounds and/or recent antibiotics:
--Enterobacteriaceae (and gram positives)--Enterobacteriaceae (and gram positives)
Chronic, heavily treated infections:Chronic, heavily treated infections:--Coag neg Staph, Pseudomonas, anaerobes (+ above)--Coag neg Staph, Pseudomonas, anaerobes (+ above)
Microbiology of DFIsMicrobiology of DFIs
Polymicrobial wounds typically demonstrate 3-5 Polymicrobial wounds typically demonstrate 3-5 pathogens on culturepathogens on culture
Significance of all of these often unclear, Significance of all of these often unclear, howeverhowever
Limb (and life) threatening infections should be Limb (and life) threatening infections should be assumed to be polymicrobial until proven assumed to be polymicrobial until proven otherwiseotherwise
Wound CultureWound Culture
Neglected or done incorrectly much of timeNeglected or done incorrectly much of time
Don’t Don’t culture uninfected ulcers!culture uninfected ulcers!
Failure to debride wound before culture a Failure to debride wound before culture a common mistakecommon mistake
Tissue from debrided ulcer base provides Tissue from debrided ulcer base provides optimal material for cultureoptimal material for culture
But swab from But swab from debrideddebrided ulcer also acceptable ulcer also acceptable
Staging Severity of InfectionStaging Severity of Infection
Staging classification adopted by International Consensus Staging classification adopted by International Consensus on Diabetic Foot and IDSA utilizes PEDIS acronym:on Diabetic Foot and IDSA utilizes PEDIS acronym:
--PP: perfusion: perfusion
--EE: extent/size: extent/size
--DD: depth/tissue loss: depth/tissue loss
--II: infection: infection
--SS: sensation: sensation
--Lipsky B, Clin Infect Dis 2004;39:885Lipsky B, Clin Infect Dis 2004;39:885
DFI StagingDFI Staging
Uninfected (PEDIS 1)Uninfected (PEDIS 1)
Mild infection (PEDIS 2)Mild infection (PEDIS 2)
--Superficial, cellulitis < 2 cmSuperficial, cellulitis < 2 cm
Moderate infection (PEDIS 3)Moderate infection (PEDIS 3)
--Cellulitis > 2 cm, lymphangitis, abscess, gangreneCellulitis > 2 cm, lymphangitis, abscess, gangrene
Severe infection (PEDIS 4)Severe infection (PEDIS 4)
--Systemic involvement (fever, hypotension, leukocytosis, Systemic involvement (fever, hypotension, leukocytosis,
severe hypoglycemia, renal failure, etc.)severe hypoglycemia, renal failure, etc.)
Admission CriteriaAdmission Criteria
Essentially all patients Essentially all patients with severe infection, and with severe infection, and some with moderate, some with moderate, require hospitalizationrequire hospitalization
Most patients with mild Most patients with mild infection may be treated infection may be treated as outpatientsas outpatients
Reasons for admissionReasons for admission::
-Systemic toxicity-Systemic toxicity
-Severe metabolic -Severe metabolic disturbancesdisturbances
-Rapid progression-Rapid progression
-Critical ischemia-Critical ischemia
-Unable to care for self-Unable to care for self
-Need for urgent diagnostic or -Need for urgent diagnostic or therapeutic interventionstherapeutic interventions
Audience Response QuestionAudience Response Question
A 44 year old woman with A 44 year old woman with poorly controlled T2DM poorly controlled T2DM and a plantar ulcer to the R and a plantar ulcer to the R great toe of > 1 month great toe of > 1 month duration presents with duration presents with several days of several days of progressive pain, erythema progressive pain, erythema and swelling of the foot. and swelling of the foot. Tc is 38.4Tc is 38.4° C, her WBC is ° C, her WBC is 14K and her BS is > 400.14K and her BS is > 400.
Audience Response QuestionAudience Response Question
Which of the following antibiotic regimens is Which of the following antibiotic regimens is MOST appropriate?MOST appropriate?
A. MeropenemA. Meropenem
B. Ciprofloxacin + metronidazoleB. Ciprofloxacin + metronidazole
C. Piperacillin-tazobactam + vancomycinC. Piperacillin-tazobactam + vancomycin
D. Clindamycin + levofloxacinD. Clindamycin + levofloxacin
Antibiotic TherapyAntibiotic Therapy
Does the patient need antibiotics?Does the patient need antibiotics?
Choice of agent will be dictated by severity of Choice of agent will be dictated by severity of infection as well as chronicityinfection as well as chronicity
Difficult to make definitive recommendations Difficult to make definitive recommendations based on available databased on available data
Mild Diabetic Foot InfectionsMild Diabetic Foot Infections
DicloxacillinDicloxacillin
ClindamycinClindamycin
CephalexinCephalexin
Trimethoprim-Trimethoprim-SulfamethoxazoleSulfamethoxazole
LevofloxacinLevofloxacin
How does progressive How does progressive emergence of CA-MRSA emergence of CA-MRSA affect these affect these recommendations?recommendations?
Ideal regimen will reliably Ideal regimen will reliably cover CA-MRSA and B-cover CA-MRSA and B-hemolytic Strephemolytic Strep
Moderate DFIModerate DFI
Trimethoprim-Trimethoprim-sulfamethoxazolesulfamethoxazole
Amox/clavulanateAmox/clavulanate
LevofloxacinLevofloxacin
CefoxitinCefoxitin
CeftriaxoneCeftriaxone
Amp/sulbactamAmp/sulbactam
Linezolid (+/- aztreonam)Linezolid (+/- aztreonam)
Daptomycin (+/- Daptomycin (+/- aztreonam)aztreonam)
ErtapenemErtapenem
Cefuroxime +/- Cefuroxime +/- metronidazolemetronidazole
Piperacillin/tazobactamPiperacillin/tazobactam
FQ + clindamycinFQ + clindamycin
Severe DFIsSevere DFIs
Piperacillin-tazobactamPiperacillin-tazobactam
Levofloxacin Levofloxacin or or ciprofloxacin + clindamycinciprofloxacin + clindamycin
Imipenem-cilastatin Imipenem-cilastatin
Vancomycin + ceftazidime (+/- metronidazole)Vancomycin + ceftazidime (+/- metronidazole)
Surgical IndicationsSurgical Indications
Urgent:Urgent:
-Gas gangrene-Gas gangrene
-Necrotizing fasciitis-Necrotizing fasciitis
-Compartment syndrome-Compartment syndrome
-Critical ischemia-Critical ischemia
Other indications:Other indications:
-Abscess-Abscess
-Progressive infection -Progressive infection despite antibioticsdespite antibiotics
-Unexplained foot pain-Unexplained foot pain
-Need for ulcer -Need for ulcer debridementdebridement
Goals of SurgeryGoals of Surgery
Drainage of pusDrainage of pus
Correction of severe ischemiaCorrection of severe ischemia
Control of infectionControl of infection
Salvage of functional footSalvage of functional foot
Surgical expertise varies locallySurgical expertise varies locally
Important Adjuncts to Ulcer Important Adjuncts to Ulcer HealingHealing
Off-loadingOff-loading-Mechanical stress on ulcerated area MUST be prevented-Mechanical stress on ulcerated area MUST be prevented
-Bedrest, crutches, surgical/half shoes, removable cast walker, etc. -Bedrest, crutches, surgical/half shoes, removable cast walker, etc.
DebridementDebridement-Sharp debridement generally preferable-Sharp debridement generally preferable
Appropriate dressingAppropriate dressing-Moist wound environment promotes epithelialization-Moist wound environment promotes epithelialization
-Many commercial products available, none clearly superior-Many commercial products available, none clearly superior
Emerging TherapyEmerging Therapy
Hyperbaric oxygenHyperbaric oxygen
Negative pressure dressingsNegative pressure dressings
G-CSFG-CSF
Maggot therapyMaggot therapy
None of above should be a substitute for None of above should be a substitute for appropriate antibiotics and surgical therapyappropriate antibiotics and surgical therapy
Discharge CriteriaDischarge Criteria
No evidence-based No evidence-based criteria existcriteria exist
Extrapolating from Extrapolating from community-acquired community-acquired pneumonia literature, as pneumonia literature, as a minimum the following a minimum the following should be met:should be met:
T T ≤ 37.8 C≤ 37.8 C
Blood pressure > 90Blood pressure > 90
Pulse < 100Pulse < 100
Mental status at baselineMental status at baseline
-Mandell LA, IDSA/ATS Consensus -Mandell LA, IDSA/ATS Consensus
Guidelines on the Management of CAP Guidelines on the Management of CAP in Adults. CID 2007;44:S27-72.in Adults. CID 2007;44:S27-72.
Discharge CriteriaDischarge Criteria
Adequate glycemic control should be presentAdequate glycemic control should be present
Any immediately necessary surgery should be Any immediately necessary surgery should be accomplishedaccomplished
Clear wound care and off-loading plans should be Clear wound care and off-loading plans should be outlined and clear to patientoutlined and clear to patient
Definitive antibiotic regimen selectedDefinitive antibiotic regimen selected
Site of care, follow-up appointments and Site of care, follow-up appointments and communication with PCPcommunication with PCP
"Dealing with osteomyelitis is perhaps "Dealing with osteomyelitis is perhaps the most difficult and controversial the most difficult and controversial aspect in the management of diabetic aspect in the management of diabetic foot infections."foot infections."
-Lipsky BA. Diagnosis and Treatment of Diabetic Foot -Lipsky BA. Diagnosis and Treatment of Diabetic Foot Infections. Clin Infect Dis 2004;39:885-910Infections. Clin Infect Dis 2004;39:885-910
Suspect Osteomyelitis When . . . .Suspect Osteomyelitis When . . . .
An ulcer is chronic or An ulcer is chronic or overlies boneoverlies bone
An ulcer fails to heal after An ulcer fails to heal after ≥ 6 weeks of appropriate ≥ 6 weeks of appropriate treatmenttreatment
A "sausage toe" is presentA "sausage toe" is present
A swollen foot is present A swollen foot is present with a history of foot with a history of foot ulcerationulceration
An ulcer is accompanied by An ulcer is accompanied by otherwise unexplained otherwise unexplained elevated ESR/CRPelevated ESR/CRP
Bone is visible or can be Bone is visible or can be probed in an ulcer baseprobed in an ulcer base
Any ulcer that is deep or Any ulcer that is deep or extensiveextensive
Ulcer area is > 2 cmUlcer area is > 2 cm²²
-Lipsky B, CID 2004;39:885; Butalia S, -Lipsky B, CID 2004;39:885; Butalia S, JAMA 2008;299:806JAMA 2008;299:806
Audience Response QuestionAudience Response Question
The single BEST test for the diagnosis of The single BEST test for the diagnosis of osteomyelitis in the diabetic foot is:osteomyelitis in the diabetic foot is:
A. WBC-tagged nuclear scanA. WBC-tagged nuclear scan
B. Positive probe-to-bone testB. Positive probe-to-bone test
C. MRIC. MRI
D. FDG-PETD. FDG-PET
Osteomyelitis of the Foot: Diagnostic Osteomyelitis of the Foot: Diagnostic ChallengesChallenges
Distinction between soft tissue and OM (or Distinction between soft tissue and OM (or uninfected ulcer and OM) frequently unclearuninfected ulcer and OM) frequently unclear
Changes on plain XR delayed and inconsistentChanges on plain XR delayed and inconsistent
Lab values don't provide resolution between OM Lab values don't provide resolution between OM and STIand STI
Neuro-osteoarthropathy (Charcot) may mimic OMNeuro-osteoarthropathy (Charcot) may mimic OM
Advanced imaging is expensiveAdvanced imaging is expensive
Plain FilmsPlain Films
Simple and cheapSimple and cheap
Radiographic changes lag Radiographic changes lag clinical pathologyclinical pathology
Recent review found Recent review found sensitivity/specificity sensitivity/specificity 61%/72%61%/72%
Probably underutilizedProbably underutilized
--Learch T, Advanced Imaging of the Learch T, Advanced Imaging of the
Diabetic Foot and its Complications. Diabetic Foot and its Complications. www.gentili.net/diabeticfoot.www.gentili.net/diabeticfoot.
Nuclear Medicine ImagingNuclear Medicine Imaging
Sensitivity is highSensitivity is high
Relatively expensiveRelatively expensive
Time consumingTime consuming
Specificity is problematicSpecificity is problematic
WBC-tagged scans may WBC-tagged scans may be helpful in be helpful in distinguishing Charcot distinguishing Charcot arthropathy from OMarthropathy from OM
--Lipman B, Clin Nucl Med 1998,23:77Lipman B, Clin Nucl Med 1998,23:77
MRIMRI
Focal decrease in marrow signal on T1-weighted Focal decrease in marrow signal on T1-weighted and increase on fat-suppressed T2-weighted and increase on fat-suppressed T2-weighted images suggests diagnosis of osteomyelitisimages suggests diagnosis of osteomyelitis
Sensitivity highSensitivity high
Much more specific than nuclear studiesMuch more specific than nuclear studies
Expense suggests MRI may be over-utilized in Expense suggests MRI may be over-utilized in this settingthis setting
MRI vs. Other Imaging ModalitiesMRI vs. Other Imaging Modalities
Recent meta-analysis found that at sensitivity of Recent meta-analysis found that at sensitivity of 90%, specificity of MRI for foot osteomyelitis was 90%, specificity of MRI for foot osteomyelitis was 83%83%
MRI markedly better than nuclear studies or plain MRI markedly better than nuclear studies or plain filmsfilms
DOR 150 vs. 3.6 for MRI vs. bone scanDOR 150 vs. 3.6 for MRI vs. bone scan
DOR 82 vs. 3.3 for MRI vs. plain filmsDOR 82 vs. 3.3 for MRI vs. plain films
- - Kapoor, A. et al. Arch Intern Med 2007;167:125-132.
Kapoor, A. et al. Arch Intern Med 2007;167:125-132.
Probe-to-Bone TestProbe-to-Bone Test
Bedside test touted as low-Bedside test touted as low-tech means of diagnosistech means of diagnosis
Positive predictive value Positive predictive value reported as 89%reported as 89%
Recent studies suggest Recent studies suggest caution with generalizing caution with generalizing these resultsthese results-Grayson M, JAMA 1995;273:721; Shone -Grayson M, JAMA 1995;273:721; Shone A, Diab Care 2006;29:945; Lavery L, Diab A, Diab Care 2006;29:945; Lavery L, Diab Care 2007;30:270Care 2007;30:270
Probe-to-Bone Characteristics Depend Probe-to-Bone Characteristics Depend on Prevalence of Osteomyelitison Prevalence of Osteomyelitis
SensSens SpecSpec PPVPPV NPVNPV PrevPrev
GraysonGrayson 66%66% 85%85% 89%89% 56%56% 66%66%
ShoneShone 38%38% 91%91% 53%53% 85%85% 20%20%
LaveryLavery 87%87% 91%91% 57%57% 98%98% 12%12%
Bone BiopsyBone Biopsy
76 patients with 81 episodes of DFO confirmed by 76 patients with 81 episodes of DFO confirmed by bone biopsybone biopsy
69 cases had ulcer swab cultures as well69 cases had ulcer swab cultures as well
Bone biopsy isolates: 77% gram +, 18% gram Bone biopsy isolates: 77% gram +, 18% gram negative, 5% anaerobesnegative, 5% anaerobes
Bone/ulcer cxs concordant in 17%Bone/ulcer cxs concordant in 17%
70% of ulcer cxs did not grow bone pathogen(s)70% of ulcer cxs did not grow bone pathogen(s)
--Senneville E, Clin Infect Dis 2006;42:57Senneville E, Clin Infect Dis 2006;42:57
IDSA Guidelines Approach to IDSA Guidelines Approach to Suspected Diabetic Foot OMSuspected Diabetic Foot OM
1. Begin with plain films of foot1. Begin with plain films of foot
-If c/w osteomyelitis, treat as such-If c/w osteomyelitis, treat as such
2. If plain films 2. If plain films not not suggestive of osteomyelitissuggestive of osteomyelitis
A. "Conservative approach":A. "Conservative approach":
--Treat soft tissue infx for 2-4 weeks, then --Treat soft tissue infx for 2-4 weeks, then repeat XRrepeat XR
B. "Aggressive approach":B. "Aggressive approach":
--Obtain MRI (or nuclear scan)--Obtain MRI (or nuclear scan)
Osteomyelitis: Medical vs. Surgical Osteomyelitis: Medical vs. Surgical TreatmentTreatment
Traditional thinking mandates resection of infected Traditional thinking mandates resection of infected bonebone
Even limited amputations may adversely affect foot Even limited amputations may adversely affect foot mechanics, setting up vicious cyclemechanics, setting up vicious cycle
Slowly mounting evidence that many cases of diabetic Slowly mounting evidence that many cases of diabetic foot OM respond to antibiotics alonefoot OM respond to antibiotics alone
Recent study of 147 pts found 77% treated medically, Recent study of 147 pts found 77% treated medically, with good result in 82% of thesewith good result in 82% of these
-Game FL, Diabetologia DOI 10.1007/s00125-008-0976-1-Game FL, Diabetologia DOI 10.1007/s00125-008-0976-1
Audience Response QuestionAudience Response Question
A 53 y.o. diabetic patient is admitted to your A 53 y.o. diabetic patient is admitted to your service with an erythematous, swollen right 3service with an erythematous, swollen right 3rdrd toe and forefoot cellulitis. The toe infection toe and forefoot cellulitis. The toe infection appears to have been prompted by a plantar ulcer appears to have been prompted by a plantar ulcer of several weeks duration. An MRI strongly of several weeks duration. An MRI strongly suggests osteomyelitis of the proximal and distal suggests osteomyelitis of the proximal and distal phalanges of the 3phalanges of the 3rdrd toe, and she undergoes ray toe, and she undergoes ray resection. How long should she be treated with resection. How long should she be treated with antibiotics post-operatively?antibiotics post-operatively?
ARS (continued)ARS (continued)
A. She doesn't require additional antibiotics, the A. She doesn't require additional antibiotics, the non-viable bone has been removednon-viable bone has been removed
B. 7-10 daysB. 7-10 days
C. 2-4 weeksC. 2-4 weeks
D. 4-6 weeksD. 4-6 weeks
Duration of Treatment for Diabetic Duration of Treatment for Diabetic Foot InfectionsFoot Infections
SummarySummary
The microbiology of DFIs is at least somewhat The microbiology of DFIs is at least somewhat predictable, based on chronicity and antibiotic predictable, based on chronicity and antibiotic exposureexposure
Cultures should be obtained from the base of a Cultures should be obtained from the base of a debrideddebrided ulcer ulcer
Many cases of diabetic foot osteomyelitis can be Many cases of diabetic foot osteomyelitis can be treated based on plain films alonetreated based on plain films alone
All tests are fallible, but MRI offers the best All tests are fallible, but MRI offers the best combination of sensitivity and specificitycombination of sensitivity and specificity