SSTIs

Question 1

current SSTI categorization

Answer 1

Question 2

utility of ED ultrasound

Answer 2

•Diagnosis:
unsuspected pus

•Procedural assistance:
localize pus for I&D

Question 3

Abscess and purulent cellulitis - bugs

Answer 3

• Staphylococcus aureus
• 59%-79% MRSA
• Caveats:
• Abscesses due to IDU can be polymicrobial
• Perirectal/perianal abscess contain gut flora

Question 4

abscell and purulent cellulitis - drugs

Answer 4

• •Antibiotics not necessary in uncomplicated abscesses
• •Antibiotics reserved for complicated abscesses & significant cellulitis
  
  • •PO: TMP/SMX #1 (or clindamycin, doxycycline)
  • IV: Vancomycin, clindamycin, others

Question 5

abscess - when are abx indicated

Answer 5

• •“Large” abscess (> 5cm)
• •“Significant” surrounding cellulitis
• •Infants and elderly
• •Immunocompromised patient
• •Treatment failure (on f/u after I&D alone)

Question 6

CA-MRSA infxn

Answer 6

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.

Question 7

local ring block

Answer 7

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.

Question 8

deep procedural sedation

Answer 8

propofol, ketamine

Question 9

loop drainage vs packing

Answer 9

Question 10

abscess - discharge instruction

Answer 10

• •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

Question 11

nonpurulent cellulitis

Answer 11

• Diffuse
• Circumferential (versus circular)
• Non-culturable (except occasional bullae with clear fluid)

Question 12

nonpurulent cellulitis - bugs

Answer 12

• •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

Question 13

nonpurulent cellulitis - drugs

Answer 13

• •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

Question 14

erysipelas

Answer 14

• 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.

Question 15

NSTI - bugs

Answer 15

• •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)

Question 16

NSTI - drugs

Answer 16

Pipercillin/tazobactam (Zosyn)
+

Vancomycin
+

Clindamycin

Question 17

NSTI diagnosis

Answer 17

• •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….

Question 18

diabetic foot ulcer

Answer 18

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.

Question 19

SSTIs in IDU

Answer 19

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.

Question 20

black tar heroin

Answer 20

• 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…

Question 21

NSTI imaging

Answer 21

• 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.

Question 22

Definitive diagnosis and tx

Answer 22

• 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.