Skin and soft tissue Infections Flashcards
What is the 1st dx approach to a poorly differentiated infection?
Its hot, its red, its tender…
The first thing you should always do is look for pus. Look for a pus pocket- by palpation or by US.
The presence of a pus pocket means there is an abscess, and it generally excludes a nonpurulent cellulitis. And it generally excludes the need for antibiotics.
If you convince yourself there is no pus…
4 points: 1) There usually is pus. If you are doing things right you should usually be going over here. 2)utility of US - we have been impressed with how useful US is for the occasional deep abscess or one where fluctuance is not apparent on palpation, 3) Once you are comfortable that there is no abscess, don’t forget to consider 4) Of the 3 main dx here, abscess, celluliti, nec fasc, 3 are surgical. In fact, the majority of SSTI that we see are a surgical problem, not an antibiotic problem.
what would you use to treat uncomplicated abscesses?
not antibiotics.
Antibiotics reserved for purulent cellulitis & complicated abscesses
Purulent cellulitis defined
Associated with abscess (incl. just a pustule), ulcer, purulent wound
Purulant focus can, and should, be opened and cultured
does strep/staph aureua cause pus?
no
Strep. species almost never produce purulence, so Strep. coverage is not needed
Purulent cellulitis drugs to treat
Drugs TMP/SMX PO Vancomycin IV Doxycycline is a PO option Clindamycin is second line so, again, you DO NOT need to add keflex to you Septra to cover Strep
would you use ULS for purulent cellulitis?
can be misleading
Nonpurulent cellulitis bugs?
Bugs
β-hemolytic strep.
S. pyogenes (Group A Strep)
Group B, G, C Strep
Staph. aureus is uncommon (up to 11-25%)
MRSA ~ 1%So you need to cover strep, and you ought to cover MSSA, but you don’t need to cover MRSA.
Nonpurulent cellulitis drugs?
Drugs 1st generation cephalosporins Cefazolin (Ancef) IV Cephalexin (Keflex) PO Anti-Staph penicillins Nafcillin IV Dicloxacillin PO No need for MRSA coverage
Erysipelas: def
a superficial, nonpurlent cellulitis, typically toxic
Erysipelas is simply a special form of nonpurulent cellulitis that occurs in the superficial dermis. Classically described on the face. More common actually on the lower extremity in association with preexisting pedal edema. This pt on the right was a recent case. Fever 102, WBC 20
NSTI diagnosis
High clinical suspicion
Pattern recognition
CT
OR
NSTI imaging
CT, if there is time, is a good way to go. It may reveal gas not apparent on plain film, or tissue inflammation spreading beyond what you would expect from the outside.Definitive diagnosis & definitive treatment are the same
NSTI bugs
Bugs Monomicrobial Strep. pyogenes (Group A Strep.) Clostridium – perfringens…novyi, sordelli Vibrio vulnificus CA-MRSA (USA 300) Polymicrobial / synergistic Staph. of all kinds Strep. of all kinds Anaerobes of all kinds Gram negatives
Nonpurulent cellulitis bugs?
Bugs
β-hemolytic strep.
S. pyogenes (Group A Strep)
Group B, G, C Strep
Staph. aureus is uncommon (up to 11-25%)
MRSA ~ 1%So you need to cover strep, and you ought to cover MSSA, but you don’t need to cover MRSA.
Nonpurulent cellulitis drugs?
Drugs 1st generation cephalosporins Cefazolin (Ancef) IV Cephalexin (Keflex) PO Anti-Staph penicillins Nafcillin IV Dicloxacillin PO No need for MRSA coverage
Erysipelas: def
a superficial, nonpurlent cellulitis, typically toxic
Erysipelas is simply a special form of nonpurulent cellulitis that occurs in the superficial dermis. Classically described on the face. More common actually on the lower extremity in association with preexisting pedal edema. This pt on the right was a recent case. Fever 102, WBC 20
