Chapter 150 - Superficial Cutaneous Infections and Pyodermas Flashcards
Most common cause of superficial purulent skin infections
Staphylococcus aureus
Carriage of Staphylococcus aureus is found in up to ___% of healthy people
30%
Major commensal bacterium found on the surface of human skin
Staphylococcus epidermidis
Common sites of colonization of Staphylococcus aureus in carriers (6)
Inguinal region Axilla Perirectal skin Nasal mucosa Pharynx mucosa Rectal mucosa
Formation of small crateriform pits that coalesce to form a large discrete defect with serpiginous borders on the plantar surface on the foot
Pitted keratolysis
Etiologic agents of pitted keratolysis (3)
Kytococcus sedentarius
(Micrococcus sedentarius)
Dermatophilus congolensis
Corynebacterium sp
Common complaint of pitted keratolysis
Sliminess of skin (70%)
Malodor (2/3)
Treatment for pitted keratolysis
Aluminum chloride 20% solution
BPO 5% gel
Topical clindamycin, erythromycin, miconazole, fucidic acid
Superficial bacterial infection characterized by well-defined irregular reddish brown patches in intertriginous areas or fissuring and white maceration in toe clefts between 4th-5th toes
Erythrasma
Etiologic agent of erythrasma
Corynebacterium minutissum
Wood’s lamp of erythrasma reveals ____ fluorescence due to ____
Coral red; coprophyrin III
Management of erythrasma
BPO 5% wash
Topical clindamycin, erythromycin
If widespread, oral erythromycin 250mgQID for 14 days
Or Clarithromycin 1g PO single dose
Bacterial infection of hair shaft that consist of tan, reddish, yellowish, or black concretions on surface of hair shaft
Trichobacteriosis
Wood’s lamp of trichobacteriosis reveal a
Pale yellowish fluorescence
Management of trichobacteriosis
Shaving
BPO 5% gel
Topical clindamycin/ erythromycin
Pyogenes, Latin for
Pus generating
After a group A Streptococcal infection, the ff may ensue (4)
Guttate psoriasis
Acute rheumatic fever
Rheumatic heart disease
Glomerulonephritis
Key virulence factor of GAS infection
M protein
Streptococci group which causes impetigo, cellulitis, otitis in newborns
Group B
Intense perianal erythema with pain on defecation, blood streaked stools associated with anal fissure
Perianal group A streptococcal cellulitis
Large tense blister filled with seropurulent fluid on volar skin pad of distal fingers and toes with erythematous base
Blistering distal dactylitis
Ddx of acute lymphangitis
UE: sporotrichosis
LE: superficial thrombophlebitis
Poststreptococcal pharyngitis occurs ___ weeks ff GAS impetigo; occurs ____ weeks ff GAS pharyngitis
3-6 weeks
1-3 weeks
Most common cause of acute nephritis in children
PSGN
Acute rheumatic fever occurs ___ weeks after GAS pharyngitis
2 weeks
Symptoms of choreoathetosis, OCD, or tic disorder is associated with antecedent GAS infection
PANDAS Pediatric Autoimmune Neuropsychiatric Disorders with Streptococcal Infection
Grps of streptococci implicated in impetiginous lesions, secondarily infected dermatitis, wound infections with lymphangitis
Grp C and Grp G
Grps of streptococci isolated from infections of skin lesions secondary to ischemia or venous stasis involving perineal area and operative wound sites
Grp B and Grp D
Grp of streptococci responsible for infections in meat handlers
Grp L
Pattern __ of emm gene are associated with pharyngitis; pattern ___ with skin infections; and pattern ___ with both
ABC
D
E
2 of key pore forming toxins
Streptolysin O
Streptolysin S
Produces large pores in host cell membranes leading to apoptosis of neutrophils, macrophages, and epithelial cells
Streptolysin O
Cytolytic activity against neutrophils, lymphocytes, RBCs, platelets leading to defective immune function
Streptolysin S
Key role in host defense against GAS skin infections
TLR9
Impt cell type in host defense against GAS and S aureus
Neutrophils
Titers used to detect GAS pharyngitis
Antistreptolysin O titers
Titers used to detect GAS skin infection
AntiDNAse B
Treatment for GAS skin infections
Pen V PO 25-45 mkday for 10 days Or Erythromycin 30-50mkday for 10 days Or Benazathine Pen G 1.2 M U IM Or Clindamycin 20-30mkday for 10 days
Used as secondary prophylaxis against recurrent GAS
Clindamycin 20-30mkday
Co-Amoxiclav 40mkday
Sites of colonization in neonates
Skin
Umbilicus
Circumcision
Conjunctiva
Bullous impetigo cleaves ___ in the epidermis, resulting in clusters of thin roofed bulla, vesicles, and or pustules
Desmoglein 1
Secondary infection of miliaria of neonates by S. Aureus
Periporitis staphylogenes
Small fragile dome-shaped pustules at the infundibulum (ostium or opening) of a hair follicle often on the scalp of children, beard, axilla, extremities, and buttocks of adults
Follicular or Bockhart impetigo
Deep folliculitis with perifollicular inflammation occurring in the bearded areas of face and upper lip
Sycosis barbae
Deep chronic form of sycosis barbae associated with scarring occurring as a circinate lesion
Lupoid sycosis
Differential for staphylococcus aureus folliculits
- Pseudofolliculitis barbae
- Folliculitis keloidalis
- Perifolliculitis capitis
A. Scalp
B. Nape
C. Lower beard area
C
B
A
Difference of Staphylococcal folliculitis from dermatophyte folliculitis (3)
In fungal infections,
- Hairs are broken and loosened
- Presence of suppurative or granulomatous nodules than pustules
- Painless plucking of hairs
Deep seated inflammatory nodule that develops around a hair follicle from a preceding superficial folliculitis and evolves into an abscess
Furuncle
More extensive, deeper, communicating, infiltrated, and serious inflammatory lesion
Carbuncle
CA- MRSA should be suspected in all patients with a skin abscess.
True or False
True
Purulent, chronic, subQ infection with foregn trauma playing a role
Botryomycosis
Predisposing factors of botryomycosis (4)
Trauma
Immunosuppression
Chronic alcoholism
DM
Purulent infection or abscess involving bulbous distal end of finger
Staphylococcal whitlow or felon
Systemic inflammatory response syndrome (4)
36 < T> 38
Rr> 24
HR> 90
4,000 < WBC > 12,000
Risk factors for S. Aureus SSTIs (5)
- Colonization of S. Aureus in mucosal sites (nares)
- Preexisting tissue injury or inflammation
- Immunodeficiency disorders (HIV/AIDS)
- Condition with defective neutrophil number or function (CGD)
- Patients with genetic or acquired IL17 responses
