Skin And Soft Tissue Infections
Impetigo
Staphylococcus aureus or Streptococcus Pyogenes. Common in young children, tropical areas, crowded areas.
Presents superficially as vesicular-pustule lesions. The blister ruptures and creates a honey crust appearance.
Treatment
Topical cream.
Folliculitis
Staphylococcus Aureus or Candida.
Inflammation and infection of hair follicles. Also pseudomonas, or hot tub folliculitis. They are erythematous pustular lesions appearing in clusters or pyoderma localized to hair follicles.
Treatment
Generally benign.
Furuncles and Carbuncles
Staphylococcus Aureus or Mycobacterium fortuitum. Typically found in areas of friction and perspiration and are associated with contact sports. Can become Methicillin-resistant Staphylococcus aureus (MRSA).
Furuncles are coalescences of inflamed hair follicles, while carbuncles are collections of furuncles within subcutaneous tissue which drains the follicle.
Treatment
TMP/SMX, clindamycin, doxycycline.
For hospital acquired MRSA: Linezolid, vancomycin
Cellulitis and Erysipelas
Staphylococcus aureus or Streptococcus Pyogenes. Legs are the most common location.
Patient presents with erythema (redness), edema, warmth, severe pain. Erysipelas is a superficial form of cellulitis presenting with an advancing border with clear demarcation.
Treatment
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Toxin Mediated Syndromes
Staphylococcus Aureus
Food poisoning
Enterotoxin A-F.
Nausea, vomiting, watery diarrhea.
Scalded skin syndrome
Exfoliative toxin. Typically infants.
Peri-oral erythema (redness), exfoliative bullous dermatitis, Nikolysky’s sign.
Toxic shock syndrome
TSST-1, enterotoxin A/B (superantigens). Most common in menstruating females through tampon use and post-operation patients.
Fever, rash, desquamation, hypotension with poor peripheral perfusion, conjunctival suffusion.
Treatment: Clindamycin (decreases toxic protein production), nafcillin, vancomycin
Necrotizing Fasciitis
Related to M1 and M3 proteins of Streptococcus Pyogenes.
Type I: Polymicrobial
Type II: Monomicrobial
Causes deep tissue infection, bacteremia, and multiorgan failure with high mortality.
Treatment
Surgery, PCN with clindamycin, IV immunoglobulins.
Fournier's Gangrene
Synergistic polymicrobial infection. Anaerobes, Enterobacteriaceae, Gram Positive Cocci. Common in diabetic or obese patients.
Rapidly spreading infection of skin and soft tissues of the male GU tract.
Treatment
Surgery.
Clostridia Myonecrosis (Gas Gangrene)
Clostridia perfringens alpha toxin. Found in GI or trauma surgery because Clostridia in the gut can colonize the surgical site.
Spreads rapidly to muscle and soft tissues. Local pain, edema, pallor, bullous lesions, tachycardia, hypertension, AKI, hemolysis.
Treatment
Surgery, penicillin, clindamycin (turns off alpha toxin production).
Unusual Pathogens
Pseudomonas Aeruginosa
Ecthyma gangrenosum
See here: Hospital Acquired Infections > Pseudomonas Aeruginosa
Tattoo ink and water contaminate
Mycobacterium chelonae
Furuncles common from nail salons
Mycobacterium fortuitum
Seafood and seawater injury pathogen
Vibrio Vulnificus.
Those with any type of liver disease are more at risk. See here: Enterics > V. vulnificus