23 Skin and Soft Tissue Infections Minejima Flashcards
What is Impetigo?
Highly contagious infection of epidermis. Typically transmitted through direct contact. Occurs in children ages 2-5 years old. Spontaneous resolution without scarring usually occurs within several weeks if left untreated
What are the two types of Impetigo?
Nonbullous (~70% of cases). Bullous
What is Nonbullous Impetigo?
Single red macule/papule that rapidly develops into a vesicle that ruptures easily to form an erosion and contents dry to form characteristic gold-colored crusts that may be pruritic
What is Bullous Impetigo?
Superficial vesicles develop to form rapidly enlarging, flaccid bullae with sharp margins and no surrounding erythema. Usually affects neonates
What often causes Bullous Impetigo?
Caused by toxin-producing S. aureus. Localized form of staphylococcal scalded skin syndrome
What are the predisposing factors of Impetigo?
Group A Strep skin colonization (10 days before appearance of impetigo) or S. aureus nasal colonization. Hot, humid summer weather. Areas with poor hygiene and in crowded living conditions. Minor trauma (insect bite, abrasion)
What are the causative organisms of Impetigo?
Staphylococcus aureus. Group A Strep/Streptococcus pyogenes
What does the treatment of Impetigo depend on?
Number of lesions, their location (face, eyelid, mouth) and the need to limit spread of infection to others
What are the treatment options for Impetigo?
Topical therapy (Mupirocin apply to lesions TID). If numerous lesions or not responding to Mupirocin: PO antibiotics active against both S. pyogenes and Staph aureus
What are the PO antibiotics active against both S. pyogenes and Staph aureus often used for Impetigo?
Dicloxacillin 250mg po QID. Cephalexin 250mg po QID, Augmentin 875/125mg po BID. B-lactam allergy: Erythromycin 250mg po QID, Clindamycin 300-400mg po TID
What is Folliculitis?
Pyoderma located within hair follicles and apocrine regions. Small (2-5mm), erythematous (sometimes pruritic papules) usually covered by central pustule
What are the causative organisms of Folliculitis?
S. aureus (most common), P. aeruginosa (swimming pools, hot tubs, whirlpools), Candida spp (prolonged antibiotics or corticosteroids)
What is the treatment for Folliculitis?
Saline compresses (promotes drainage), topical therapy with antibacterials or antifungals sufficient
What are Furuncles (Boils)?
Deep inflammatory nodule that typically develops from preceding folliculitis. Occurs in skin areas subject to friction, perspiration, and contain hair follicles (neck, face, axillae, buttocks)
What is the treatment for Furuncles?
Application of moist heat to promote drainage
What are Carbuncles?
When infection extends to involve several adjacent follicles producing a coalescing inflammatory mass with pus draining from multiple follicular orifices. Typically found at nape of neck, back, or on thighs. Fever and malaise usually present
What are the predisposing factors for Furuncles and Carbuncles?
Diabetes, obesity. Inadequate personal hygiene. Close contact with others with furuncles. Anterior nares colonization with S. aureus (recurrent cases)
What is the causative organism of Furuncles and Carbuncles?
S. aureus
What is the treatment for Furuncles and Carbuncles?
Incision and drainage (I&D). Systemic antibiotics rarely required unless extensive surrounding cellulitis or fever occurs
What is Cellulitis?
Acute, spreading infection of skin that involves subcutaneous tissues. Edema, redness, heat +/- lymphagitis and inflammation of regional lymph nodes. Vesicles, bullae, and cutaneous hemorrhage in form of petechiae or ecchymoses may develop on inflamed skin
What are the systemic manifestations of Cellulitis?
Fever, tachycardia, confusion, hypotension, leukocytosis
What are the predisposing factors for Cellulitis?
Previous trauma (laceration, puncture wound). Conditions that cause skin to be more fragile or local host defenses less effective (obesity, previous cutaneous damage, edema (from venous insufficiency or lymphatic obstruction), surgical procedures (saphenous venectomy, axillary node dissection for breast cancer, gynecologic malignancy operations))
What is the location of Cellulitis?
Commonly on lower legs
What is Cellulitis diagnosis like?
No routine diagnostic test. Given the low yield, tests are not useful unless patients with diabetes, malignancy, unusual predisposing factors such as immersion injury, animal bites, neutropenia, immunodeficiency
What is a common cause of Perifolliculitis capitis?
S. aureus
What is a common cause of Facial (cheek) Cellulitis?
Buccal cellulitis: H. influenzae
What is a common cause of Cellulitis of the hands?
Erysipeloid: Erysipelothrix rhusiopathiae
What is a common cause of Cellulitis of the extremities?
Diabetic foot. Erysipelas (cellulitis of upper dermis)
What is a common cause of Perianeum Cellulitis?
Perianal Streptococcal cellulitis: Group A Strep
What is the most common causative organism of Cellulitis?
Group A Strep
What do you need to think about when deciding to treat Cellulitis?
Diffused cellulitis not associated with a defined portal usually involves Streptococcus sp. Cellulitis associated with furuncles, carbuncles or abscesses usually involves Staph aureus
Who often gets Cellulitis caused by CA-MRSA?
Recurrent or persistent furuncles in at risk groups: jail inmates, IVDUs, contact sports teams, Native Americans, gay men, children
What is the treatment for Cellulitis caused by Strep & S. aureus (penicillinase-producing)?
B-lactam antibiotics (PO: dicloxacillin or cephalexin. IV: Oxacillin or cefazolin). If B-lactam allergic: Clindamycin, erythromycin (Strep resistance high in erythromycin)
What is the PO treatment for Cellulitis caused by CA-MRSA?
PO: TMP/SMX, doxycycline, clindamycin
What is the IV treatment for Cellulitis caused by CA-MRSA?
IV: Vancomycin, Linezolid, Daptomycin, Tigecycline, Telavancin, Ceftaroline
When is the IV route preferred for Cellulitis?
If lesion rapidly spreading. If systemic response prominent. Significant comorbidities (asplenia, neutropenia, immunocompromised, cirrhosis, cardiac or renal failure, or preexisting edema)
What is the Duration of treatment for Cellulitis?
5-14 days. Dependent on severity and response to therapy
What is the Non-Medication therapy for Cellulitis?
Elevation of affected area
What are the measures to decrease Cellulitis recurrences?
Treating interdigital maceration. Emollient use to avoid dryness/cracking. Reduce underlying edema (elevation of extremity, compressive stockings, pneumatic pressure pumps, diuretic therapy). Prophylactic antibiotic therapy if all other measures are unsuccessful
What are the prophylactic antibiotic medications for Cellulitis?
Penicillin V 1g PO BID or 1.2 MU IM Qmonth or Erythromycin 250mg PO BID
What is the definition of recurrent MRSA SSTI?
2 or more discrete SSTI episodes at different sites over 6 month period
What is the MRSA SSTI-Treatment?
Decolonization for recurrent SSTI despite optimizing wound care and hygiene measures. Mupirocin 2% nasal decolonization BID x 5-10 days. Topical body decolonization (i.e. chlorhexidine, bleach bath: 1 tsp per gallon of water) x 5-14 days. Oral abx for decolonization NOT routinely recommended
What is some general information about Bite Wounds?
Most bites are due to dogs or cats. Cat bite wounds are usually more severe and have higher proportion of osteomyelitis and septic arthritis. Human bite wounds are typically more serious than animal bites. Anaerobes present > 60% of cases
What are the predominant pathogens in bite wounds?
Normal oral flora of biting organism. Human skin organisms. Secondary invaders (ex. S. aureus and S. pyogenes)
What are the complications caused by bite wounds?
Septic arthritis, osteomyelitis, subcutaneous abscess formation, tendonitis, bacteremia (rarely)
What is the bacteriology of Dog/Cat bite wounds?
Pasteurella (50% dog bites, 75% cat bites). Staph, Strep. Capnocytophaga canimorsus (causes bacteremia and fatal sepsis especially in asplenia or underlying hepatic disease patients), etc.
What is the bacteriology of Human bite wounds?
Strep (esp. viridans). Staph. Haemophilus. Eikenella corrodens. Fusobacterium (esp: F. nucleatum), etc
What are the treatment options for Bite Wounds?
Beta-Lactamase Inhibitor agents (Augmentin (PO), Unasyn (IV), Pip/Tazo (Zosyn) (IV)). Alternatives (B-Lactam Allergic): Doxycycline, Cefuroxime + Metronidazole, FQ + Metronidazole, Bactrim + Metronidazole. Treatment duration: 5-10 days
What should be avoided in the treatment of Bite Wounds?
1st generation CEPHs and Penicillinase-Resistant PCNs, Macrolides, Clindamycin d/t poor in vitro activity against P. multocida
What are some vaccines that can be used for Bite Wounds?
Tetanus. Rabies (for all feral, wild animal bites, areas with high prevalence of rabies)