Exam 3: Skin and Soft Tissue Infections/ Diabetic Foot Infections Flashcards
What are the risk factors for developing skin and soft tissue infections?
*History of SSTI
Peripheral Artery Disease
Chronic Kidney Disease
Diabetes Mellitus
IV Drug Use
What are the 3 types of skin and soft tissue infections?
Non-purulent
Purulent
Necrotizing fasciitis
What are the 2 types of non-purulent skin and soft tissue infections?
Cellulitis
Erysipelas
What is the defining characteristic of non-purulent skin and soft tissue infections?
NO PUS
Why do we not obtain skin cultures with non-purulent infections?
The culture would be contaminated with skin bacteria
What are the symptoms of non-purulent SSTIs?
Tender, Erythema, Swelling, Warm to touch
Orange peel-like skin
What testing should we do for non-purulent SSTI’s?
*Skin and blood cultures are not routinely recommended
Blood cultures recommended if: immunocompromised, animal bites, severe infection
CT/MRI imaging to rule out necrotizing fasciitis or abscess
In what 3 circumstances would we take blood cultures for a patient with a non-purulent SSTI?
Immunocompromised
Severe infection
Animal bites
What are the 3 classifications used for both non-purulent and purulent SSTIs?
Mild
Moderate
Severe
What is a mild non-purulent or purulent SSTI?
No systemic signs of infection
What is a moderate non-purulent or purulent SSTI?
Systemic signs of infection
What is a severe non-purulent or purulent SSTI?
Meets at least 2 SIRS criteria
What are the 4 SIRS criteria?
Temp <36C or >38C
HR > 90bpm
RR> 24bpm
WBC <4k or >12k
What is the SIRS criteria regarding temperature?
<36C or >38C
What is the SIRS criteria regarding HR?
> 90bpm
What is the SIRS criteria regarding respiratory rate?
> 24bpm
What is the SIRS criteria regarding WBCs?
<4k or >12k
What is the most common pathogenic organism in non-purulent SSTIs?
Streptococcus species
-S. pyogenes
-S. agalactiae
-S. equismilis
-S. anginosus
Under what circumstances would we want to add MRSA coverage in a non-purulent SSTI?
Always add MRSA coverage if patient meets SIRS criteria
Otherwise:
-Penetrating trauma
-Evidence of MRSA elsewhere
-Nasal colonization with MRSA
-IV drug user
-SIRS/Severe infection
-Failed a non-MRSA antibiotic regimen
How long is the typical non-purulent SSTI therapy duration?
5 days
What is the treatment for a non-purulent MILD SSTI?
Oral Antibiotics (pick 1)
-Penicillin VK
-Dicloxacillin
-Cephalosporin
-Clindamycin
What is the treatment for a non-purulent moderate SSTI?
IV antibiotics (systemic, pick 1)
-Penicillin
-Ceftriaxone
-Cefazolin
-Clindamycin
What is the treatment for a non-purulent severe SSTI?
Emergency Surgical Inspection/Debridement
Empiric Antibiotics:
-Vancomycin + Piperacillin/Tazobactam
Then send to lab and narrow based on culture
What are the 3 types of purulent SSTIs?
Abscesses
Furuncles
Carbuncles
What is the defining characteristic of a purulent SSTI?
Pus is present
What is an abscess?
A collection of pus in the dermis and deeper skin tissues
What is a furuncle?
(boil)
Small abscess that forms at a hair follicle
What is a carbuncle?
Infection involving several adjacent hair follicles
What is the presentation of a purulent SSTI?
Tender, Red nodules, Erythema, Warm to touch
**Systemic signs of infection (less common with furuncles)
What testing should be done to diagnose purulent SSTIs?
Cultures
*recommended for ALL abscesses, carbuncles, and patients with systemic infection regardless of severity
CT/MRI imaging to confirm presence of abscess
What is the most common causative pathogen of Purulent SSTIs?
MRSA
-also MSSA and streptococcus species
How long is the typical duration of Purulent SSTI treatment?
5 days
What is the one treatment that all purulent SSTI patients should receive?
Incision and Drainage!
What is the treatment for mild purulent SSTIs?
Incision and drainage
-no abx therapy needed
What is the treatment for moderate purulent SSTIs?
Incision and Drainage
Culture + Stain
Empiric (pick 1):
-TMP/SMX
-Doxycycline
Targeted:
MRSA (both):
-TMP/SMX
-Doxycycline
MSSA (pick 1):
-Dicloxacillin
-Cephalexin
What is the treatment for severe purulent SSTIs?
Incision and Drainage
Culture and Stain
Empiric (pick 1):
-Vancomycin
-Daptomycin
-Linezolid
Targeted:
MRSA:
*same as empiric
MSSA (pick 1):
-Nafcillin
-Cefazolin
-Clindamycin
What are the characteristics of necrotizing fasciitis?
“Severe non-purulent infection”
Medical emergency
High morbidity + mortality
What is the typical presentation of necrotizing fasciitis?
-Profound systemic toxicity (fever, lethargy, disorientation)
-Change in skin color to maroon/purple/black
-Crepitus (cracking/popping sound)
-Edema
-Severe pain
What tests should be run to diagnose necrotizing fasciitis?
Blood cultures recommended
Wound cultures (obtained from surgery)
CT/MRI imaging to confirm necrotizing fasciitis or presence of abscess (looking for presence of gas)
What is the #1 cause of necrotizing fasciitis?
Streptococcus species (especially pyrogenes)
-causes toxin production
What is the treatment for necrotizing fasciitis?
Emergency surgical inspection/debridement
Empiric antibiotics:
-Vancomycin + Piperacillin/Tazobactam
Targeted antibiotics:
S. Pyogenes:
Penicillin + Clindamycin
Polymicrobial:
Vancomycin + Piperacillin/Tazobactam
What is the typical duration of necrotizing fasciitis treatment?
-Until further debridement is no longer necessary
-Patient has clinically improved
-Fever has been absent 48-72 hours
Why is clindamycin used in necrotizing fasciitis treatment?
-Inhibits streptococcal toxin production
-Inoculum effect: clears a pathway for penicillins to work in the high bacterial load
What is Impetigo?
A highly contagious superficial skin infection caused by skin abrasions
Where is impetigo most common?
Children
Hot/Humid weather
What is the typical presentation of impetigo?
Small, painless, fluid filled vesicles that can lead to thick golden crusts
-Systemic signs of infection are rare
What testing can be done to diagnose impetigo?
Cultures from pus/exudates are recommended but not required
How do we treat Impetigo with few lesions?
Topical abx for 5 days
-Mupirocin
How do we treat Impetigo with many lesions/an outbreak in a household?
Oral for 7 days:
Dicloxacillin or Cephalexin
If streptococcus only:
-Penicillin
If allergies/MRSA:
-Doxycycline
-Clindamycin
-TMP/SMX
What testing should be done on animal bites?
Blood cultures are recommended
What is considered an established infection for animal bites?
x 7-14 days
What is considered a Preemptive infection for animal bites?
x 3-5 days
For animal bites, who should receive preemptive therapy?
Immunocompromised/ Asplenia
Moderate to severe bites
Bites on face/hand
Bites that penetrate joints
What is the drug of choice for animal bites?
Amoxicillin/ Clavulanate
Who should receive a Tdap vaccine with animal bites?
Anyone who is due for one
What tests should we run on diabetic foot infections?
Wound cultures are not recommended for mild infection
Bone cultures are normally obtained after debridement
Blood cultures can be considered
What are the most common pathogens in a diabetic foot infection?
S. aureus
Streptococci species
What are the risk factors for MRSA with diabetic foot infections?
Previous MRSA infection in the last year
Local MRSA prevalence >30-50%
Recent hospitalization
Failed non-MRSA antibiotics
What are the risk factors for Pseudomonas with diabetic foot infections?
History of pseudomonas infection
Soaking feet in water
Warm climate
Severe infection
Failed non-pseudomonal antibiotics
What are the 3 parts of diabetic foot infection management?
Surgical intervention
Glycemic control
Antibiotics
What are the 1st line therapy options for a Mild diabetic foot infection?
Dicloxacillin
Cephalexin
Clindamycin
If a patient with a mild diabetic foot infection has used antibiotics recently, what do we switch their treatment to?
Amoxicillin/Clavulanate
Levofloxacin
Moxifloxacin
If a patient with a mild diabetic foot infection has MRSA risk factors what do we switch their treatment to?
Sulfamethoxazole/Trimethoprim
Doxycycline
How long do we treat a mild diabetic foot infection?
1-2 weeks
What are the first-line options for a moderate diabetic foot infection?
Moxifloxacin
Amoxicillin/Clavulanate
Cipro/Levofloxacin + Clindamycin/Metronidazole
If a patient with a moderate diabetic foot infection has pseudomonal risk factors what do we do for treatment?
Switch to:
Cipro/Levofloxacin + Clindamycin/Metronidazole
If a patient with a moderate diabetic foot infection has MRSA risk factors what do we do for treatment?
Doxycycline
Linezolid
Vancomycin
Sulfamethoxazole/Trimethoprim
How long do we treat a moderate diabetic foot infection?
2-3 weeks
What are the first line agents to treat a severe diabetic foot infection?
Piperacillin/Tazobactam
Carbapenem
Cefepime + Clindamycin/Metronidazole
What treatment options do we have to treat a severe diabetic foot infection with MRSA risk factors?
Vancomycin
Linezolid
Daptomycin
How long do we treat a severe diabetic foot infection?
2-3 weeks (same as moderate)
