45: Diabetic Foot Infections - Drown

Question 1

clinical diagnosis of infection

Answer 1

• presence of purulent secretions
• presence of at least 2 cardinal signs of inflammation
  
  • erythema
  • edema
  • warmth
  • induration
  • pain or tenderness to the affected extremity

Question 2

mild v. moderate. v. severe diabetic foot infection

Answer 2

Question 3

goals of 3 level (whole, affected foot, wound) approach to pt evaluation

Answer 3

• determine extent/everity of infection
• determine microbial eitioloy of infection
• determine cause of wound/ulcer
• determine any contibuting co-morbidities

Question 4

is hospital admission required?

Answer 4

• severe infection
• critical limb ischemia
• mild or moderate infections w/ complicating factors

Question 5

labs to draw

Answer 5

CBC

BMP

ESR

CRP

Question 6

what technique for culture?

Answer 6

• deep tissue preferred over swap
  
  • more accurate
  • swab greater range but may not identigy deeper
  • swab yield fewer anaerobes
• needle aspiration useful for obtaining purulent samples

Question 7

when should cultures be obtained?

Answer 7

• —When wound is determined to be infected based on clinical assessment
• —Cultures should be obtained to identify organism causing clinical infection not to diagnose infection
• —Whenever possible, obtain cultures prior to initiation of antibiotics
  
  • —If patient is stable but not responding to current therapy, stop antibiotics for short period of time (48-72 hrs) then re-culture

Question 8

should you use antibiotics for the purposes of prophylaxis against infection or for the enhancement of wound healing?

Answer 8

not supported

• encourages resistance (choose one with lowest MIC)
• unnecessary financial burden
• drug related adverse effects

Question 9

escalation and de-escalation theory

Answer 9

MRSA coverage based on prevalance

mild - aerobic gram-positive cocci

severe - broad-spectrum

Question 10

when should you consider surgical intervention?

Answer 10

• presence of deep abscess
• extesnive bone or joint involvement
• crepitus
• necrosis or gangrene
• necrotizing fasciitis

when considering surgery –> pt should be evaluated for adequate vascular status/need for revascularization and consider vascular surgery consult when indicated

Question 11

osteomyelitis pathogens

Answer 11

—S. aureus – Most common and most virulent gram positive organism

—Pseudomonas – Most resistant gram negative organism

Fungi - rare pathogens in cases of osteomyelitis

Question 12

how do you diagnose osteomyelitis?

Answer 12

clinical

• probe to bone
• overlying ulcer greater than 2 cm²
• ulcers of long durations (greater than 4-6 wk)

lab marker

• leukocytosis
• elevated CRP
• elevated ESR

Imaging

• plain radiographs (infectioncan precede radiologic changes by up to 4 wks)
• MRI *imaging modality of choice

gold standard diagnose osteomyelitis = bone biopsy

Question 13

four scenarios for consideration of non-surgical management

Answer 13

1. No acceptable surgical target (resection would lead to unacceptable loss of function)
2. Vascular disease for which reconstruction is not an option but patient wants to refrain from amputation
3. Infection restricted to forefoot with minimal soft tissue loss
4. Risk outweighs benefit

Question 14

Determines if residual infection is present and will also help distinguish acute vs. chronic process and therefore determine length & route of antibiotic therapy ***

Answer 14

surgical margin for micro and path after resection is performed

Question 15

key treatment for infection

********

Answer 15

• —Eradicate bacterial load with incision and drainage and debridement
• —This step must be done regardless of vascular supply
• Must remove ALL Non-Viable Bone and Soft tissue. Worry about closure of wound when infection eradicated

Question 16

tx of non-limb threatening infections

Answer 16

• —Debride necrotic tissue
• —Start with broad spectrum antibiotic
• —Deep culture should be taken
• —Adjust antibiotic according to culture and patient response
• —Local wound care and plan for closure

Question 17

treatment of limb/life-threatening infections

Answer 17

• —Admission to hospital
• —Incision and drainage of abscess and debridement of all necrotic soft tissue and bone
• —May require surgical debridement every 48 hours until necrotic tissue is eradicated
• —Start with broad spectrum antibiotic
• —Deep culture should be taken
• —Adjust antibiotic according to culture and patient response
• —Assess for vascular disease
• —Optimize medical and nutritional status
• —Local wound care and plan for final closure when infection is eradicated