Skin and Soft Tissue Infection/Diabetic Foot Infections Flashcards
What are the risk factors of SSTI?
hx of SSTI (most common), PAD, CKD, DM, IV drug use
What are the complications of SSTI?
increase risk of ulcers, bacteremia, endocarditis, osteomyelitis, sepsis
What are the types of SSTIs?
non-purulent, purulent, and necrotizing fasciitis
staph and strep are most common pathogens found on human skin
What are the types of non-purulent SSTIs?
cellulitis and erysipelas
What are the characteristics of non-purulent SSTIs?
NO pus
really only impacts epidermis, superficial infection
What is the patient presentation of non-purulent SSTIs?
only localized signs of infection; tender, erythema, swelling, warm to touch, orange peel-like skin
What cultures should you get done in non-purulent SSTIs?
skin/blood cultures not routinely used (b/c culture would be contaminated with normal skin flora)
blood cultures recommended IF: immunocompromised, severe infection, animal bites
What imaging should be done in non-purulent SSTIs?
CT/MRI to rule out necrotizing fasciitis or presence of abscess
reserved for pts not improving on therapy
What is the classification of non-purulent SSTIs?
mild - NO systemic signs of infection
moderate - systemic signs of infection
severe - meets SIRS criteria (need to have 2 out of the 4): temp >38C or <36C, HR >90 bpm, RR >24 bpm, WBC >12K or <4K
What are the causative pathogens of non-purulent SSTIs?
streptococcus spp. - specifically S. pyogenes
MRSA if: penetrating trauma, evidence of MRSA elsewhere, nasal colonization with MRSA, IVDU, SIRS/severe infection, failed non-MRSA antibiotic regimen
What is the treatment for mild non-purulent SSTIs?
oral antibiotics: penicillin VK or cephalosporin or dicloxacillin (no longer used) or clindamycin
What is the treatment for moderate non-purulent SSTIs?
IV antibiotics: penicillin or ceftriaxone or cefazolin or clindamycin
What is the treatment for severe non-purulent SSTIs?
emergent surgical inspection/debridement
empiric antibiotics: vancomycin PLUS piperacillin/tazobactam –>
C&S –> narrow based on culture and sensitivity
What is the duration of treatment for non-purulent SSTIs?
5 days
What are the types of purulent SSTIs?
abscesses, furuncles, and carbuncles
What are the characteristics of purulent SSTIs?
Pus
What are abscesses?
collection of pus within the dermis and deeper skin tissues
What are furuncles?
small abscess formation of the hair follicle
What are carbuncles?
infection involving several adjacent follicles
What is the patient presentation of purulent SSTIs?
tender, red nodules, erythema, warm to touch
systemic signs of infections (systemic signs way less common in pts with furuncles)
What cultures should you get to diagnose purulent SSTIs?
wound cultures are recommended for all abscesses, carbuncles, and patients with systemic signs of infection, regardless of severity
What imaging should you get done in purulent SSTIs?
CT/MRI to confirm presence of abscess
What is the classification of purulent SSTIs?
mild - NO systemic signs of infection
moderate - systemic signs of infection
severe - meets SIRS criteria (need to have 2 out of the 4): temp >38C or <36C, HR >90 bpm, RR >24 bpm, WBC >12K or <4K
What are the causative pathogens of purulent SSTIs?
MRSA!, MSSA, and streptococcus spp.
What is the treatment for mild purulent SSTIs?
I&D (incision and drainage, NO antibiotics)
What is the treatment for moderate purulent SSTIs?
I&D and C&S –>
empiric antibiotics: TMP/SMX or doxycycline –>
targeted antibiotics:
for MRSA - TMP/SMX or doxycycline
for MSSA: dicloxacillin or cephalexin
What is the treatment for severe purulent SSTIs?
I&D and C&S –>
empiric antibiotics: vancomycin or daptomycin or linezolid –>
targeted antibiotics:
for MRSA - same as empiric
for MSSA: nafcillin or cefazolin or clindamycin
What is the duration of treatment for purulent SSTIs?
5 days
What are the characteristics of necrotizing fasciitis?
medical emergency! - associated with high morbidity and mortality
severe, non-purulent skin and soft tissue infection
What is the patient presentation of necrotizing fasciitis?
profound systemic toxicity
change in color of skin to maroon/purple/black, crepitus (cracking of skin from gas buildup), edema, severe pain
What cultures should you get to diasnose necrotizing fasciitis?
blood cultures are recommended given severe infection
wound cultures likely obtained from surgery
What imaging should you get done in diagnosing necrotizing fasciitis?
CT/MRI to confirm necrotizing fasciitis or presence of abscess
What are the causative pathogens of necrotizing fasciitis?
monomicrobial and polymicrobial
streptococcus spp (most common!), vibrio vulnificus, peptostreptococcus spp, CA-MRSA, aeromonas hydrophila, clostridium perfringens
Treatment of necrotizing fasciitis
emergent surgical inspection/debridement
empiric antibiotics: vancomycin PLUS piperacillin/tazobactam –> C&S –> targeted antibiotics:
S. pyogenes - PCN PLUS clindamycin
polymicrobial - vancomycin plus piperacillin/tazobactam
use surgical intervention + broad spectrum antibiotics
What is the duration of treatment for necrotizing fasciitis?
further debridement is no longer necessary
patient has improved clinically
fever has been absent for 48-72 hours
Why clindamycin?
inhibits streptococcal toxin production
inoculum effect
maintains efficacy regardless of bacteria load!
What are other SSTIs?
impetigo and animal/human bites
What are the features of impetigo?
highly contagious superficial skin infection caused by skin abrasions
common in children and in hot/humid weather
patient presentation: small, painless, fluid filled vesicles that can lead to thick golden crusts; systemic signs of infection are rare
What cultures should you get to diagnose impetigo?
cultures from pus/exudates are recommended but are not required
What is the treatment of impetigo?
empiric coverage against: streptococcus spp and S. aureus
if few lesions are present - topical x 5 days - mupirocin
if many lesions are present/outbreak - oral x 7 days -
dicloxacillin or cephalexin (1st line)
streptococcus only: pencillin
allergies/MRSA: doxycycline, clindamycin, TMP/SMX
What is the patient presentation for animal/human bites?
cat bites: deep, sharp puncture wound
dog/human bites: cellulitis signs and symptoms
What cultures should you get done if you have an animal bite?
blood cultures are recommended
What are the causative pathogens of animal/human bites?
human bites - eikinella corrodens and streps
animal bites - pasturella spp (cat bites)
need to cover aerobic and anaerobic because anaerobes commonly found in the mouth
What is the treatment of animal/human bites?
established infection: x 7-14 days
preemptive: x 3-5 days - immunocompromised, asplenia, moderate-severe bites, bites on face/hand, bites that penetrate joints
DOC: amoxicillin/clavulanate
alternative: 2nd/3rd generation cephalosporin + anerobic coverage
beta-lactam allergy present: cipro/levofloxacin + anaerobic coverage OR moxifloxacin
vaccines: Tdap if due, +/- rabies
What are the risk factors for diabetic foot infections?
neuropathy, angiopathy/ischemia, immunologic defects, poor wound healing
What is the patient presentation of diabetic foot infections?
typical local signs of infection, +/- purulent secretions
more specific to DFI: discolored tissue, foul odor
What cultures should you get to diagnose diabetic foot infections?
wound cultures: not recommended for mild infection
bone cultures: typically obtained following I&D
blood cultures: may be considered (reserved for pts with severe infections)
What are the causative pathogens for diabetic foot infections?
all have S. aureus and streptococci spp.
macerated ulcer due to soaking: also has pseudomonas aerogenes, which is a water bug!
What are the risk factors for MRSA in diabetic foot infections?
previous MRSA infection within past year
local MRSA prevalence > 30-50%
recent hospitalization
failed non-MRSA antibiotics
if pt is in indy, add on MRSA coverage!!
What are the risk factors for pseudomonas in diabetic foot infections?
history of pseudomonas infection
soaking feet in water
warm climate
severe infection
failed non-pseudomonal antibiotics
What is the overall management of diabetic foot infections?
surgical intervention
glycemic control
antibiotics
What is the treatment for mild diabetic foot infections?
need to cover: MSSA, streptococci spp.
first line: dicloxacillin, cephalexin, clindamycin
duration: 1-2 weeks
recent antibiotics?: switch to - amoxicillin/clavulanate, levofloxacin, or moxifloxacin
MRSA risk factors?: switch to - sulfamethoxazole/trimethoprim, or doxycycline
What is the treatment for moderate diabetic foot infections?
need to cover: MSSA, streptococci spp, enterobacteriaceae, anaerobes
first line: moxifloxacin, amoxicillin/clavulanate, cipro/levofloxacin + clindamycin or metronidazole
duration: 2-3 weeks
pseudomonal risk factors?: switch to - cipro/levofloxacin + clindamycin or metronidazole
MRSA risk factors?: ADD - doxycyline, linezolid, vancomycin, sulfamethoxazole/trimethoprim
What is the treatment for severe diabetic foot infections?
need to cover: MSSA, streptococci spp, enterobacteriaceae, anaerobes, pseduomonas
first-line: piperacillin/tazobactam, carbapenem, cefepime + clindamycin or metronidazole
duration: 2-3 weeks
MRSA risk factors?: ADD - vancomycin, linezolid, daptomycin
