LG 1.9 - Intro Musculoskeletal Infections

Question 1

List the nonspecific defenses of the skin?

Answer 1

• Physical barrier to infection!
• Cool
• ~ pH 5
• Mostly dry
• Sweat glands (salty)
• Sebaceous glands (fatty acids, wax esters)
• B-defensins (cationic peptides, we make, protect us from microbes, permeabilize microbes)
• Lysozyme
• Neutraphils, langerhans cells (epidermal macrophages)
• Normal microbiota

Question 2

(4) What is cellulitis?

Answer 2

• Acute, spreading infection deeper dermis and subcutaneous fat.

Question 3

(4) What 2 specific infectious agents usually cause cellulitis, which general agents cause cellulitis in the immunocompromised?

Answer 3

• Streptococcus pyogenes
• Staphylococcus aureus
• Gr- bacilli (more common in immunocompromised)

Question 4

(4) Where does cellulitis usually originate from? Where is it most common (location on body and population)? What are some risk factors for cellulitis?

Answer 4

• Usually originates from superficial skin lesions (ex: boils, ulcers, tine pedis) or following trauma.
• More common in lower extremities.
• Usually middle aged, elderly
• Risk factors: diabetes, varicella, impaired peripheral circulation, chronic steroid use.

Question 5

What is the oxidase test, what will it tell you?

Answer 5

• A test that you can perform on microorganisms that will tell you if the organism has cytochrome C oxidase. Turns colorless substrate to purple product.