ID-SSTI Flashcards
Two most common microbes causing SSTI
S. aureus and group A beta hemolytic strep
Erisypelis–describe it
Occurs on face and legs
It is superficial and involves the dermis
Caused by group A strep
More indurated then cellulitis
Skin layers involved in cellulitis
Diffuse and involves the dermis and subcutaneous tissues
Match the organism causing cellulitis and the how it is contracted:
-Aeromonas hydrophila
- Aeromonas hydrophila: fresh water lakes, streams, or rivers; medicinal leeches
- nonspecific cellulitis
SSTI: Vibrio sp.
Organism, clinical features
- Vibrio sp.: salt water, brackish water; or contact with drippings from raw seafood
- Direct inoculation, or ingested leading to bacteremia and secondary skin infection; hemorrhagic bull in area of cellulitis; LIVER FAILURE is a risk factor for V. vulnificus
SSTI: Erysipelothrix rhusiopathiae
Organism, clinical features
-Erysipelothrix rhusiopathiae: contact with saltwater marine life (also associated with freshwater fish); contact with infected animals such as swine and poultry
cellulitis involves hand an fingers in those handling fish, shellfish, or occasionally poultry, meat contaminated with bacterium
SSTI: Pasteurella multocida
organism, clinical features
-Pasteurella multocida: cats
cellulitis at cat bite or scratch mark
SSTI: Capnocytophaga canimorsus
organism, clinical features
-Capnocytophaga canimorsus: dogs
Cellulitis and sepsis particularly in patients with functional or anatomic asplenia
SSTI: Bacillus anthracis
organism, clinical features
- Mycobacterium marinum
- Mycobacterium foruitum
Edematous pruritic lesion with central eschar; spore-forming organism
-Bacillus anthracis: infected animals or animal products’ bioterrorism
SSTI-Francisella tularensis
organism, clinical features
-Francisella tularensis: contact with or bite from infected animal (cats) or ticks
Ulceroglandular syndrome characterized by ulcerative lesion with central eschar and localized tender LAD; constitutional symptoms are often present
SSTI:
-Mycobacterium marinum
organism, clinical features
-Mycobacterium marinum: fresh water or salt water, fish tanks, swimming pools
Clinical: often trauma associated; papular lesions become ulcerative at site of inoculation, ascending lymphatic spread and can be seen “sporotrichoid”; absence of systemic toxicity
SSTI:
-Mycobacterium fortuitum
organism, clinical features
Mycobacterium foruitum: exposure to freshwater footpaths/pedicures at nail salons; infection following breast augmentation and open heart surgery, shaving with razors; Clinical: multiple boils, razor shaving strongly associated with it
Primary way to treat CA-MRSA abscess
I&D
When is antibiotic therapy recommended for CA-MRSA
- If I&D does not make it go away
- disease is extensive or has rapid progression
- immunodeficiency and multiple comorbidities
- very young or very old
- signs of systemic illness
- septic phlebitis is known
what is Type I Nec fasciitis
polymicrobial with aerobic and anaerobic gram positive and gram negative organisms
What is Type II Nec fasciitis
monomicrobial
most commonly strep pyogenes
also can be caused by S. aureus, vibrio vulnificus, streptococcus agalactiae
What is Type III Nec Fasciitis
gas gangrene, clostridial myonecrosis; most commonly caused by Clostridium perfringens
Diagnosis and Txt of Nec Fasciitis
X ray can show subQ gas
MRI very useful
Gold standard for treatment and diagnosis is surgery
Abx: vancomycin plus zosyn/imipenem/meropenem
-Add clindamycin if evidence of group A strep
Antibiotic for vibrio vulnificus necrotizing fasciitis
doxycycline plus ceftazidime
Antibiotic for Aeromonas hydrophila-associated NF
doxycycline plus cipro
Diagnostic Criteria for Staphylococcal Toxic Shock Syndrome
Fever >38.9
Systolic BP <90
Diffuse macular rash with subsequent desquamation, especially on palms and soles
Involvement of 3 organ systems
Negative results on serologic testing for RMSF, leptospirosis, measles, negative CSF
pg12
Common causes of staphylococcal toxic shock
tampon use, wounds, history of injection drug use, burns, nasal packings, catheters
Abx therapy for:
MSSA toxic shock syndrome
MRSA TSS
S. pyogenes TSS
MSSA: oxacillin or nafcillin +clindamycin
MRSA: oxacillin or nafcillin+clindamycin
Strep: penicillin +clindamycin
Contact precautions for suspected group A strep in necrotizing fasciitis or TSS. What about for household contacts?
Droplet precautions and contact precautions
household contacts with comorbidities, immunocompromised, or elderly: benzathine penicillin G plus rifampin, clindamycin, or azithromycin
How to manage an animal bite?
Prompt wound irrigation with normal saline, removal of any foreign bodies and debridement of ketotic tissue
Give rabies and tetanus shots
Augmentin prophylaxis ONLY in those who are immunosuppressed, have moderate to severe wounds, wound on face or hands, wounds near a joint or bone, wound with significant crush injury
how to manage a human bite?
always give prophylactic augmentin
Antibiotic coverage for diabetic foot ulcer
MRSA coverage, Pseudomonas, and anaerobes
