Cellulitis and Infectious Myositis

Question 1

Cellulitis: What and Bacterial Causes

Answer 1

What: Spreading infection of the skin
Perioribital cellulitis: children, unilateral swelling + redness of eyelid

Bacterial Causes: Staph aureus, Group A Beta strep, H. influenzae less common but in children <3 years old, Pasteurella in animal bite

Question 2

Cellulitis: Findings & Physical Exam

Answer 2

predisposing risk, inflammation, red tender area, mild systemic symptoms

• Local symptoms – red, tender, swollen
  o Necrotizing fasciitis – group A beta hemolytic strep
  o Contact dermatitis – reaction to allergy
  o Cellulitis – redness blends to normal skin
  o Erysipelas – group A beta hemolytic strep
  o Erythema multiforme
  o Ecthyma – deeper in gluteal or perineum area
  o DVT – discoloration from abnormal blood supply
  o Folliculitis – resolve with soap
  o Impetigo – superficial, not systemic

Question 3

Cellulitis: Indicators/Diagnostics

Answer 3

• Systemic indications – increased temp/pulse, tender lymph nodes, associated lymphangitis
• Diagnostic test – swab for culture
• Treat aggressively and monitor, resolve infection, apply warm saline, mark border to assure not spreading, elevate to prevent edema, oral antibiotics or cephalexin
• Pregnant or breastfeeding need specific meds (TMP-SZS - Contraindicator)

Question 4

Infectious Myositis

Answer 4

move from skin to muscle, uncommon, young adults, most common is Staph aureus, viral is more generalized than localized

Question 5

Bacterial Pyomyositis

Answer 5

prevalent in tropical countries, muscle abscess, pain and fever, Staph A, immunocompromised,

Physical Exam: Muscle Aches, Intramuscular neoplasm

Question 6

Streptococcus Myonecrosis

Answer 6

rare, group A beta hemolytic strep, muscle necrosis without abscesses, can lead to septic shock

Question 7

Clostridium Myonecrosis

Answer 7

gas in tissue, gangrene with necrotic tissues, alpha toxin that requires zinc

exotoxin: C perfringes type A strain (alpha)

Production of thromboxane A2, IL-8, Platelet Factor

Question 8

• Tetanus (Lockjaw)

Answer 8

prolonged contraction of skeletal muscle fibers, tetanospasmin, wound contamination from cut or deep puncture, mortality rate high, toxin causes uncontrolled stimulation, localized or generalized, penicillin may be helpful but can be antagonistic, vaccination needed

Clostridium Tetani