EXAM #2: SKIN & SOFT TISSUE/ BONE & JOINT INFECTIONS

Question 1

What two common pathogens cause impetigo?

Answer 1

1) S. pyogenes

2) S. aureus

Question 2

What is the most common pathogen to cause erysipelas?

Answer 2

S. pyogenes

Question 3

What is the most common pathogen to cause folliculitis and furuncles?

Answer 3

S. aureus

Question 4

What are the most common pathogens to cause cellulitis?

Answer 4

1) S. pyognes

2) S. aureus

Question 5

What causes hot-tub folliculitis?

Answer 5

Pseudomonas aeruginosa

Question 6

What is the gram-stain of pseudomonas?

Answer 6

Gram-negative

Question 7

Is pseudomonas a cocci or baccilus?

Answer 7

Bacillus (rod)

Question 8

You are seeing an elderly patient s/p CABG 1-year prior. Today he has cellulitis in the area of the great saphenous vein graft. What are you concerned about?

Answer 8

This is a ssociation with lymphedema, which is a nidus for infection

Question 9

In a wrestler with a large abscess and surrounding cellulitis, what organism are you concerned about?

Answer 9

MRSA

Question 10

What is the indication for anti-microbials after I/D of an abscess?

Answer 10

Surrounding cellulitis

Question 11

What is the treatment for uncomplicated non-purulent cellulitis?

Answer 11

First ask yourself if there is a risk for MRSA?

• No= Cefazolin* i.e. cephalosporin
• Yes= Vancomycin

Question 12

What is the treatment for uncomplicated purulent cellulitis?

Answer 12

1) I/D

2) Vancomycin

Question 13

What is the treatment for hot tub folliculitis?

Answer 13

None

Question 14

What are the organisms that cause Necrotizing Fasciitis? What notable organism rarely cause Nec. Fas?

Answer 14

1) Clostridium perfringens
2) Group A strep
3) Polymicrobial

*Note that MRSA is rare

Question 15

What are the clinical features of Necrotizing Fasciitis?

Answer 15

1) Severe constant pain out of proportion to PE
2) Bullous lesion
3) Systemic toxicity
4) Gas in soft tissue
5) Rapid spread

Question 16

What historical features are associated with Clostridium perfringes causing nec. fas?

Answer 16

• Tissue tramua

- Surgery

Question 17

What gram stain is C. perfringes?

Answer 17

Gram negative

Question 18

What is sporotrichosis associated with?

Answer 18

Rose-gardening

*“Marching along the lymphatics”

Question 19

What is the most common etiology of septic arthritis?

Answer 19

Hematogenous spread* most common

Question 20

What are the risk factors for septic arthritis?

Answer 20

1) RA
2) Steroid use
3) DM

Question 21

What organism most commonly causes septic arthritis?

Answer 21

S. aureus

*Followed by Steptococci and gram negative bacteria

Question 22

What organisms most commonly cause septic arthritis if there is a prosthetic joint?

Answer 22

Coagulase negative Staph (S. epidermidis)

Question 23

What is the most common viral cause of septic arthritis?

Answer 23

Parvovirus B19

Question 24

What are the clinical manifestations of septic arthritis?

Answer 24

• One joint (knee is most common)
• Pain, swelling, redness, warmth
• Fever
• Limited use/ ROM

Question 25

How is aseptic vs. septic arthritis distinguished?

Answer 25

1) Septic is more commonly associated with WBC greater than 60,000 2) Septic will have positive cultures

Question 26

How is septic arthritis treated?

Answer 26

1) Systemic antibiotics | 2) Drain infected joint

Question 27

In sexually active young adults/adults, what is the most likely cause of septic arthritis?

Answer 27

Neisseria gonorrhea

Question 28

How is N. gonorrhea septic arthritis treated?

Answer 28

Ceftriaxone (3rd generation cephalosporin)

Question 29

How is S. aureus septic arthritis treated?

Answer 29

Nafcillin or Vancomycin

Question 30

How is GAS septic arthritis treated?

Answer 30

PCN

Question 31

How is gram negative septic arthritis treated?

Answer 31

Cephalosporin

Question 32

How long are patients with septic arthritis placed on abx?

Answer 32

2-4 weeks - 2 weeks for N. gonorrhea - 4 weeks for S. aureus

Question 33

What are the possible etiologies of osteomyelitis?

Answer 33

1) Hematogenous= distant focus 2) Contiguous= adjacent spread from soft tissue 3) Direct= surgery/trauma

Question 34

What time frame distinguishes between acute and chronic osteomyelitis?

Answer 34

1 month

Question 35

What is the most common bacteria to cause osteomyelitis?

Answer 35

S. aureus

Question 36

How is osteomyelitis diagnosed?

Answer 36

1) Probe the bone 2) MRI* 3) Bone biopsy *Preferred*

Question 37

What is the standard of care for imaging possible osteomyelitis?

Answer 37

MRI

Question 38

What is the most common etiology of puncture wound osteomyelitis?

Answer 38

Pseudomonas aeruginosa

Question 39

How do the main treatment modalities change in acute and chronic osteomyelitis?

Answer 39

Acute= Abx then surgery Chronic= Surgery then abx