SSTI-Table 1

Question 1

What are the most common etiologies of skin and soft tissue infections?

Answer 1

S aueus and B hemolytic streptococci

Question 2

What is staphylococcus aureus?

Answer 2

Gram + cocci, catalase + and coagulase +

Normal in nasal passage, skin and mucous membranes

Question 3

How can you tell if it is MSSA?

Answer 3

If it is oxacillin sensitive

Question 4

What are the DOC for MSSA?

Answer 4

Penicillinase resistant penicillins and cephalosporins
o Nafcillin, oxacillin, dicloxacillin
o Cefazolin, cephalexin

Question 5

What are alternative therapies for MSSA?

Answer 5

Clindamycin
–Inducible resistance may be of concern ( D – test )
–about 20% are resistant, high risk C diff
Trimethoprim/sulfamethoxazole
Vancomycin
– don’t use if you can help it, esp in bacteremia
Tetracyclines- doxy used often

Question 6

What is MRSA resistant to almost all of? What is the exception?

Answer 6

Beta-lactam antibiotics

Ceftaroline

Question 7

What is the DOC for MRSA?

Answer 7

Vancomycin if AUC/MIC ≥ 400

Question 8

When should you not use vanco?

Answer 8

if MIC to vanco is >/=2 even though the list will say it is susceptible

Question 9

What are other options for MRSA? When should/shouldn’t they be used?

Answer 9

1) Daptomycin:Not in pneumonia
2) Linezolid (static- good lung penetration but myelosupressive and can cause pancytopenia)/tedizolid
3) Tigecycline- don’t use this if the infection is in the blood stream!
4) Dalbavancin- ordavancin half life of 250 hours, one dose only for skin anf soft tissue, 16-30x more potent then vanco to staph- new drugs though
5) Ceftaroline- only use if MRSA with bacteremia or endocarditis bc need IV and expensive

Question 10

What are the oral agents for MRSA skin infections?

Answer 10

Tetracyclines, trimethoprim/sulfamethoxazole

Clindamycin

Question 11

What is streptococcus pyogenes?

Answer 11

• Aerobic, gram positive cocci in chains or pairs
• Catalase negative
• Beta hemolytic

Question 12

What does strep pyog have that makes it so dangerous?

Answer 12

Virulence factors- this can lead to streptococcal toxic shock syndrome

Question 13

Strep pyogenes is involved in what mind-mod infections?

Answer 13

Pharyngitis
•Impetigo
•Scarlet fever (rash)
•Cellulitis

Question 14

What severe and rapidly progressive infections is strep pyogenes involved in?

Answer 14

• Necrotizing fasciitis-emergency
• Myositis- into muscle
• Streptococcal toxic shock syndrome

Question 15

What is the DOC for strep pyogenes infections?

Answer 15

PCN- all strains are uniformly susceptible to penicillin

Question 16

What are agents for strep pyogenes infections?

Answer 16

Cefazolin, vancomycin( only if MRSA or its 3-4th line)

Question 17

Strep pyogenes is not an organism of resistance, but an organism of what?

Answer 17

Virulence

Question 18

What is cellulitis?

Answer 18

skin infections that develop as a result of bacterial entry via breaches in the skin barrier

Question 19

What are s/s of cellulitis?

Answer 19

Erythema, edema, local tenderness and pain, Fever, chills, malaise, warm to the touch, and poorly demarcated

Question 20

What is the most common etiology of cellulitis? When might it be gram negative? What is it most often in IV drug users?

Answer 20

Strep pyogenes
Immunocompromised or previous failed therapy
Staph Aureus

Question 21

How long does it take for cellulitis to improve after tx is initiated?

Answer 21

•Will need min of 24 – 48 hours to see an improvement… he says 3 days!
If no improvement in 3-4 days, look for abscess as cause – a US/CT will suffice

Question 22

Why doesn’t PNC work in the stationary phase of disease progression?

Answer 22

Eagle effect- Cell walls are not being replicated, which is why clindamycin is sometimes added on to prevent toxin production here (nec fasc)

Question 23

What is the DOC for necrotizing fasciitis?

Answer 23

PCN with clindamycin for the first few days- this is for the exotoxins

Question 24

What are s/s of MRSA?

Answer 24

• Pimples, boils, or rashes
• Often contains pus
• May feel itchy or warm
• May be swollen or red
• swollen “spider bite”.

Question 25

Does DM with cellulitis = a DM foot ulcer?

Answer 25

NO- these are different organisms and processes – it is often still just strep!

Question 26

What is the difference in tx obese pt with cellulitis?

Answer 26

Difficult to tx not bc resistance but bc abx take longer to kick in and they often have other issues like venous stasis and insuff that slow down the healing process- imp to elevate legs!!!