EXAM #2: SKIN & SOFT TISSUE/ BONE & JOINT INFECTIONS Flashcards
What two common pathogens cause impetigo?
1) S. pyogenes
2) S. aureus
What is the most common pathogen to cause erysipelas?
S. pyogenes
What is the most common pathogen to cause folliculitis and furuncles?
S. aureus
What are the most common pathogens to cause cellulitis?
1) S. pyognes
2) S. aureus
What causes hot-tub folliculitis?
Pseudomonas aeruginosa
What is the gram-stain of pseudomonas?
Gram-negative
Is pseudomonas a cocci or baccilus?
Bacillus (rod)
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?
This is a ssociation with lymphedema, which is a nidus for infection
In a wrestler with a large abscess and surrounding cellulitis, what organism are you concerned about?
MRSA
What is the indication for anti-microbials after I/D of an abscess?
Surrounding cellulitis
What is the treatment for uncomplicated non-purulent cellulitis?
First ask yourself if there is a risk for MRSA?
- No= Cefazolin* i.e. cephalosporin
- Yes= Vancomycin
What is the treatment for uncomplicated purulent cellulitis?
1) I/D
2) Vancomycin
What is the treatment for hot tub folliculitis?
None
What are the organisms that cause Necrotizing Fasciitis? What notable organism rarely cause Nec. Fas?
1) Clostridium perfringens
2) Group A strep
3) Polymicrobial
*Note that MRSA is rare
What are the clinical features of Necrotizing Fasciitis?
1) Severe constant pain out of proportion to PE
2) Bullous lesion
3) Systemic toxicity
4) Gas in soft tissue
5) Rapid spread
What historical features are associated with Clostridium perfringes causing nec. fas?
- Tissue tramua
- Surgery
What gram stain is C. perfringes?
Gram negative
What is sporotrichosis associated with?
Rose-gardening
*“Marching along the lymphatics”
What is the most common etiology of septic arthritis?
Hematogenous spread* most common
What are the risk factors for septic arthritis?
1) RA
2) Steroid use
3) DM
What organism most commonly causes septic arthritis?
S. aureus
*Followed by Steptococci and gram negative bacteria
What organisms most commonly cause septic arthritis if there is a prosthetic joint?
Coagulase negative Staph (S. epidermidis)
What is the most common viral cause of septic arthritis?
Parvovirus B19
What are the clinical manifestations of septic arthritis?
- One joint (knee is most common)
- Pain, swelling, redness, warmth
- Fever
- Limited use/ ROM
How is aseptic vs. septic arthritis distinguished?
1) Septic is more commonly associated with WBC greater than 60,000
2) Septic will have positive cultures
How is septic arthritis treated?
1) Systemic antibiotics
2) Drain infected joint
In sexually active young adults/adults, what is the most likely cause of septic arthritis?
Neisseria gonorrhea
How is N. gonorrhea septic arthritis treated?
Ceftriaxone (3rd generation cephalosporin)
How is S. aureus septic arthritis treated?
Nafcillin or Vancomycin
How is GAS septic arthritis treated?
PCN
How is gram negative septic arthritis treated?
Cephalosporin
How long are patients with septic arthritis placed on abx?
2-4 weeks
- 2 weeks for N. gonorrhea
- 4 weeks for S. aureus
What are the possible etiologies of osteomyelitis?
1) Hematogenous= distant focus
2) Contiguous= adjacent spread from soft tissue
3) Direct= surgery/trauma
What time frame distinguishes between acute and chronic osteomyelitis?
1 month
What is the most common bacteria to cause osteomyelitis?
S. aureus
How is osteomyelitis diagnosed?
1) Probe the bone
2) MRI*
3) Bone biopsy
Preferred
What is the standard of care for imaging possible osteomyelitis?
MRI
What is the most common etiology of puncture wound osteomyelitis?
Pseudomonas aeruginosa
How do the main treatment modalities change in acute and chronic osteomyelitis?
Acute= Abx then surgery
Chronic= Surgery then abx
