SSTIs Flashcards
current SSTI categorization
utility of ED ultrasound
•Diagnosis:
unsuspected pus
•Procedural assistance:
localize pus for I&D
Abscess and purulent cellulitis - bugs
- Staphylococcus aureus
- 59%-79% MRSA
- Caveats:
- Abscesses due to IDU can be polymicrobial
- Perirectal/perianal abscess contain gut flora
abscell and purulent cellulitis - drugs
- •Antibiotics not necessary in uncomplicated abscesses
- •Antibiotics reserved for complicated abscesses & significant cellulitis
- •PO: TMP/SMX #1 (or clindamycin, doxycycline)
- IV: Vancomycin, clindamycin, others
abscess - when are abx indicated
- •“Large” abscess (> 5cm)
- •“Significant” surrounding cellulitis
- •Infants and elderly
- •Immunocompromised patient
- •Treatment failure (on f/u after I&D alone)
CA-MRSA infxn
a few days into its natural history. The furuncle busts open and you get this necrotic lesion. First of all the old spider bite. You can certainly see why the pt assumes this is a spider bite.
local ring block
Bury the needle going under and parallel to the skin surface. As I withdraw I deposit a column of anaesthetic. March my way around the abscess in this way, forming a ring. Get all the cutaneous fibers coming into the area….save a cc or 2 for the tip of the volcano. Then walk away for 10 min.
deep procedural sedation
propofol, ketamine
loop drainage vs packing
abscess - discharge instruction
- •Keep draining wounds covered with a clean bandage
- •Wash hands frequently (soap and water or alcohol-based hand gel), esp. after touching infected wounds or soiled bandages
- •Launder clothing that is contaminated by drainage
- •Do not share contaminated items like towels, bedding, clothing or razors
- •While there is drainage, avoid activities involving skin-to-skin contact or contact sports
- •Clean contaminated environmental surfaces with bleach, detergent or disinfectant that specifies S aureus on the label
nonpurulent cellulitis
- Diffuse
- Circumferential (versus circular)
- Non-culturable (except occasional bullae with clear fluid)
nonpurulent cellulitis - bugs
- •Organism recovered in only ~30% (bl cx, punch bx)
- •β-hemolytic strep.
- •Serologic evidence in ~70%
- •S. pyogenes (Group A Strep)
- •Group B, G, C Strep
- •S. aureus less common (8-11%)
- •Unclear % MRSA
nonpurulent cellulitis - drugs
- •1st generation cephalosporins
- •Cefazolin (Ancef) IV
- •Cephalexin (Keflex) PO
- •Anti-staph. penicillins
- •Nafcillin IV
- •Dicloxacillin PO
- •Clindamycin
- •No need for MRSA coverage initially
- •Treat underlying tinea
erysipelas
- 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 - 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 (less common)
NSTI - drugs
Pipercillin/tazobactam (Zosyn)
+
Vancomycin
+
Clindamycin
NSTI diagnosis
- •High clinical suspicion
- •Pattern recognition
- •CT
- •–> OR
- 4 big points to keep in mind. –> …What I call pattern recognition. What I really mean is there are 4 infection patterns that when you see them should always make you think of an NSTI. We’ll go over them….
diabetic foot ulcer
Pattern number one that always gets us concerned is the diabetic foot ulcer. We are swimming in these. Many turn out to be quite trivial. But It can be very challenging to determine whether there is the beginning of a necrotizing infection.
SSTIs in IDU
Pattern #3 is virtually any SSTI in an IDU. Here’s an IDU muscles black tar heroin into the left shoulder and now that extremity hurts. He doesn’t look too sick. There is a lot of swelling compared to other side though. The track marks, usually depressed, are sort of ballooning up. The deltopectoral groove is filled in. Hmmm. This guy was taken to the OR, had a bad necrotizing cellulitis and died a few hours post op of refractory shock.
black tar heroin
- Whats the connection with black tar heroin? This stuff is cut with organic material like wood pulp, shoe polish and dirt. Contaminated with the ever ubiquitous clostridium spore.
- This guy is looking for a tiny hand vein, all he has left. But when he gives up he is going to skin pop or muscle it.
- Leads to these deposits under the not so healthy skin. Messed up vessels, low oxygen tension, low pH. The clostridium can germinate…produce toxins, grow quickly…
NSTI imaging
- We do an ultrasound, because that’s what we do where I work. In most cases, just tons of subcutaneous swelling and tissue edema. Here is a case where we do see a thick fluid layer along the fascia and gas.
- 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 and tx
- THEY ARE THE SAME
- The good news is the definitive diagnostic test and treatment are the same. You are going to want make these cases the surgeons problem as soon as it is suspected.
