CELLULITIS

Question 1

(1) An acute bacterial infection of the dermis and subcutaneous (SC) tissue.
(2) Typically caused by bacterial penetration through a break in the skin.
(3) Microbiology: - B-Hemolytic streptococci, Staphylococcus aureus, including MRSA, and gram-negative aerobic bacilli are most common.

Answer 1

Cellulitis

Question 2

classic signs of inflammation:

Answer 2

(a) Erythema
(b) Edema
(c) Tenderness to palpation
(d) Elevated skin temperature surrounding area of infection

Question 3

Location

Answer 3

Unilateral lower-extremity involvement is typical and systemic symptoms are usually absent

Question 4

Most common portal of entry for lower leg cellulitis

Answer 4

toe web intertrigo with fissuring, 2/2 interdigital tinea pedis

Question 5

History

Answer 5

(1) Previous trauma, surgery, animal/human bites, dermatitis, and fungal infection are portals of entry for bacterial pathogens.
(2) Pain, itching, and/or burning
(3) Fever, chills, and malaise

Question 6

Physical Exam

Answer 6

(1) Localized pain and tenderness with erythema, induration, swelling, and warmth
(2) Regional lymphadenopathy
(3) Purulent drainage (from abscesses)

Question 7

Diagnostic Tests and Interpretation

Answer 7

(1) With good history & physical exam, primarily a clinical diagnosis.
(2) Consider labs if signs of systemic disease (fever, heart rate >100 bpm, or systolic blood pressure <90 mm Hg)
(3) Swab open cellulitis wounds for culture, however, blood cultures rarely positive (normal flora)
(4) Plain radiographs, CT, or MRI are useful if osteomyelitis, fracture, necrotizing fasciitis, retained foreign body, or underlying abscess is suspected.
(5) US to r/o Deep Vein Thrombosis (DVT)

Question 8

Cellulitis Treatment

Answer 8

(1) Demarcate area w/a sharpie to measure progress once you start treatment.
(2) Immobilize and elevate involved limb to reduce swelling.
(3) Sterile saline dressings or cool aluminum acetate compresses for pain relief.
(4) Compression stocking for edema.
(5) Acetaminophen +/- NSAIDs for pain relief.
(6) Tetanus immunization if needed, particularly if there is an open (traumatic) wound.
(7) Antimicrobial treatment:
(a) Non-purulent cellulitis (target treatment toward B-hemolytic streptococci and MSSA)
1) Cephalexin 500 mg PO q6h
2) Dicloxacillin 500 mg PO q6h
(b) Purulent cellulitis (probable CA-MRSA)
1) Clindamycin 450mg PO
2) Trimethoprim-sulfamethoxazole (TMP-SMX) 1 DS tab PO BID
3) Doxycycline 100 mg PO BID
(c) Human/animal Bites
1) Amoxicillin + clavulanic acid (Augmentin)

Question 9

Disposition

Answer 9

(1) Based on location, severity and control of the infection.
(2) Most cases resolve properly with antibiotic therapy.
(3) Consider Med advice:
(a) Elevated white blood cell count with marked left shift.
(b) Failure to respond to oral antibiotics.
(c) Severe infection, suspicion of deeper or rapidly spreading infection, tissue necrosis, or severe pain.
(d) Worsening symptoms that do not resolve/improve after 24 to 48 hours of therapy.
(e) Cellulitis of the hand and face may require hospitalization.

Question 10

Differential Diagnosis

Answer 10

(1) Other pyodermas
(2) Contact dermatitis
(3) Necrotizing fasciitis

Question 11

Complications

Answer 11

(1) Local abscess or bacteremia, sepsis
(2) Superinfection with gram-negative organisms
(3) Lymphangitis, especially if recurrent
(4) Gangrene (bad)