Investigations of Skin & Soft Tissue infections

Question 1

What are the criteria for diagnosing Pyrexia of Unknown Origin (PUO)?

Answer 1

1) Illness lasting at least 3 weeks, 2) Fever >38.3°C on several occasions, 3) No diagnosis after one week of routine hospital workup.

Question 2

What are the main causes of PUO?

Answer 2

) Infection, 2) Neoplasm, 3) Autoimmune disease, 4) Miscellaneous causes (e.g., drug fever, factitious fever).

Question 3

Name some infectious causes of PUO.

Answer 3

Abscess, endocarditis, osteomyelitis, biliary infection, TB, malaria, viral infections, etc.

Question 4

What types of neoplasms can cause PUO?

Answer 4

Lymphoma (especially Hodgkin’s), leukemia, primary hepatoma, renal cell carcinoma, atrial myxoma.

Question 5

Which autoimmune diseases are associated with PUO?

Answer 5

Systemic lupus erythematous, Still’s disease, polymyalgia rheumatica, polyarteritis nodosa, subacute thyroiditis, Kikuchi’s disease.

Question 6

What is the key principle in managing PUO?

Answer 6

Avoid empirical antibiotics unless necessary, rely on focused investigations, and patient care should be led by an experienced clinician.

Question 7

What is the prognosis for PUO patients?

Answer 7

15-51% of PUO cases resolve spontaneously over 3-6 months; however, delay in diagnosing certain conditions (e.g., miliary TB) can lead to poor outcomes.

Question 8

What are the classical features of cellulitis?

Answer 8

Red, hot, tender skin with diffuse margins involving subcutaneous tissues.

Question 9

What differentiates erysipelas from cellulitis?

Answer 9

Erysipelas has well-defined margins and affects the outer layer of the epidermis.

Question 10

What are the characteristic features of impetigo?

Answer 10

Honey-colored, crusted lesions around the peri-oral region, common in children.

Question 11

What are the signs of lymphangitis?

Answer 11

Red tracking linear streaks toward regional lymph nodes, with swollen and tender lymph nodes.

Question 12

What are the distinguishing features of necrotizing fasciitis (NF)?

Answer 12

Rapid progression, severe pain disproportionate to skin appearance, high mortality rate (~30%).

Question 13

What causes gas gangrene, and what are its symptoms?

Answer 13

Clostridial infection after trauma, characterized by necrotic tissue and crepitus on palpation.

Question 14

What is the recommended approach for investigating diabetic foot ulcers?

Answer 14

Deep tissue culture for chronic wounds, avoid routine swabs unless clinically indicated.

Question 15

What are the typical pathogens and diagnostic methods for osteomyelitis?

Answer 15

Pathogens: Staph aureus, Gram negatives, anaerobes. Diagnosis: MRI, tissue culture, bone biopsy.

Question 16

What is the standard approach to diagnosing and treating septic arthritis?

Answer 16

Diagnosis: Joint aspirate with high WCC and Gram stain. Treatment: Joint washout and 2-6 weeks of antibiotics.

Question 17

What skin and soft tissue infections are commonly caused by Staphylococcus aureus?

Answer 17

Staphylococcus aureus is commonly responsible for cellulitis, impetigo, folliculitis, furuncles, and carbuncles.

Question 18

Which organism is the main suspect in erysipelas?

Answer 18

Group A Streptococcus is the main suspect in erysipelas.

Question 19

What are the common organisms causing lymphangitis?

Answer 19

Common organisms causing lymphangitis include Group A Streptococcus and Staphylococcus aureus.

Question 20

Which organisms are associated with Type 2 Necrotizing Fasciitis?

Answer 20

Group A Streptococcus and Staphylococcus aureus are associated with Type 2 Necrotizing Fasciitis.

Question 21

What is the role of Staphylococcus aureus in gas gangrene?

Answer 21

While Clostridium species are the primary cause of gas gangrene, Staphylococcus aureus can cause pyomyositis, which can mimic gas gangrene.

Question 22

What is the most common pathogen in haematogenous osteomyelitis in both children and adults?

Answer 22

Staphylococcus aureus is the most common pathogen in haematogenous osteomyelitis in both children and adults.

Question 23

What is the classical organism responsible for Type 2 Necrotizing Fasciitis?

Answer 23

Group A Streptococcus is the classical organism responsible for Type 2 Necrotizing Fasciitis.

Question 24

What is the typical pathogen causing septic arthritis?

Answer 24

Staphylococcus aureus is the typical pathogen causing septic arthritis.

Question 25

Which skin and soft tissue infections are commonly caused by Streptococcus pyogenes?

Answer 25

Streptococcus pyogenes (Group A Streptococcus) commonly causes erysipelas and lymphangitis.