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Patient Case: Cellulitis

Patient Case: Cellulitis

Discussion

A 48-year-old man presents to the emergency department with progressive redness, swelling, and pain in his left lower leg for the past four days. He initially noticed a small cut on his shin after bumping into a table but did not seek medical attention. Over time, the area became warm, tender, and swollen, and he developed a low-grade fever (38.2°C/100.8°F), chills, and fatigue.

His past medical history includes type 2 diabetes and obesity. On examination, his left lower leg is diffusely red, swollen, and warm, with poorly demarcated borders extending from the shin to the calf. There is no pus or abscess formation, but the skin appears tight and slightly shiny. Mild tenderness is noted with palpation, and he has difficulty bearing weight on the affected leg.

A diagnosis of cellulitis is made, likely caused by Streptococcus pyogenes or Staphylococcus aureus. Given the extent of the infection and his risk factors, he is started on oral antibiotics (cephalexin or clindamycin), advised to elevate the leg, keep it clean, and monitor for worsening symptoms. He is also educated on proper wound care and diabetes management to prevent recurrent infections.

Questions
1. What is the most likely diagnosis in this patient?

a) Cellulitis
b) Erysipelas
c) Deep vein thrombosis (DVT)
d) Contact dermatitis

2, Which of the following is the most common causative organism of cellulitis?

a) Streptococcus pyogenes
b) Pseudomonas aeruginosa
c) Candida albicans
d) Escherichia coli

3. What is the best initial treatment for this patient’s cellulitis?

a) Oral antibiotics such as cephalexin or clindamycin
b) Topical antifungal cream
c) High-dose intravenous antibiotics for all cases
d) Surgical debridement

4. Which of the following is a major risk factor for developing cellulitis?

a) Type 2 diabetes
b) Frequent handwashing
c) Low intake of spicy foods
d) Daily use of sunscreen

Reveal answers

Answers

  1. (a) Cellulitis
    • The progressive, poorly demarcated redness, swelling, warmth, and tenderness, along with systemic symptoms such as fever and chills, are characteristic of cellulitis. Erysipelas (b) has a well-defined, raised border. DVT (c) may cause swelling and pain but lacks redness and fever. Contact dermatitis (d) is an allergic reaction, typically with itching rather than pain.
  2. (a) Streptococcus pyogenes
    • Streptococcus pyogenes (Group A Strep) and Staphylococcus aureus are the most common bacteria causing cellulitis. Pseudomonas aeruginosa (b) is associated with infections in moist environments, like hot tub folliculitis. Candida albicans (c) is a fungal pathogen, not a common cause of cellulitis. Escherichia coli (d) is more commonly linked to urinary and gastrointestinal infections.
  3. (a) Oral antibiotics such as cephalexin or clindamycin
    • Mild to moderate cellulitis is typically treated with oral antibiotics like cephalexin (for Strep and MSSA) or clindamycin (for MRSA coverage if needed). Topical antifungals (b) are ineffective for bacterial infections. IV antibiotics (c) are only necessary for severe or rapidly spreading infections. Surgical debridement (d) is only indicated if there is necrotizing fasciitis or tissue necrosis.
  4. (a) Type 2 diabetes
    • Diabetes increases the risk of cellulitis due to impaired immune function, poor circulation, and delayed wound healing. Frequent handwashing (b) reduces infection risk. Spicy food intake (c) has no relevance. Sunscreen (d) is beneficial for skin protection but does not affect cellulitis risk.

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