Flashcards in Microbiology - Shillitoe - Bacterial Infections of the Skin Deck (40):
Smears from pus may show gram + cocci in clumps or chains;
usually a combination of S. aureus and S. pyogenes;
surface only (epidermis)
gram + cocci
reactive with Strep Group A antiserum
Bullous pemphigoid is associated with what bacteria due to the exfoliatoxin?
Dissemination of impetigo
What are the virulence factors for Staph aureus?
Biofilm protects organisms from the immune system;
piercings, medical devices
growing in clumps
loves plastic and nylon
Severe itching due to cell-mediated hypersensitivity;
wrists or genitals common
Treatment for scabies
Permethrin to kill mite;
topical steroids for itching
What is furunculitis?
Superficial sweat gland or follicle infections, looks like acne
usually due to Staph aurues
What is a carbuncle?
Multiple skin abscesses fused sub-cutaneously
What anaerobic bacterium is commonly present along with Staph aureus in acne?
How to treat abscesses
mupirocin ointment for mild cases;
Nafcillin or oxacillin for severe/systemic cases
What is scalded skin syndrome?
Widespread exfoliation due to a localized infection by S. Aureus;
often seen in newborns;
exfoliatoxin separates epidermal cells;
TSS can be from which agents?
super-antigen toxic shock syndrome toxin (Staph aureus);
Streptococcal TSS toxin;
systemic immune reaction
deep infection of skin;
associated with fever, lymphadenopathy and bacteremia
erysipelas is more superficial;
S. pyogenes usually responsible, as with NF
What makes Strep pyogenes the prime candidate for causing NF?
Potent protease enzyme
NF can be caused by Step pyogenes or...
C. perfringens --> gas gangrene
What is the treatment for cellulitis or erysipelas?
Pencillin or cephalosporin
What complication is similar to rheumatic fever but tends to follow skin infections rather than Strep pharyngitis?
Associated with M protein strep types;
3-4 weeks later;
no treatment, recurrences can lead to kidney failure
S. typhimurium - Rose spots
N. meningitides - Petechial lesions
T. pallidum Secondary stage rashes
Rickettsia - Hemorrhagic rash
Measles virus - Macules
Toxic shock syndrome
S. aureus - Desquamation
B. dermatidis -Papules
Viridans Streptococci - Splinter hemorrhages
Yellow crusted skin lesions – near nostrils typically - can spread across face and appear on trunk and limbs. More common in children. Very contagious. Some cases show severe bullae
S. aureus and S. pyogenes
M. leprae - surface infection
Infected piercings / catheters
S. epidermidis - surface infection
Mites - surface infection
Follicles/ sweat glands Abscess
S. pyogenes - subcutaneous infection
S. pyogenes / others
Surgical site / wound
S. aureus / others
coagulase-negative, beta hemolytic,
bacitracin-sensitive, reactive with Strep Group A antiserum
Gram + cocci which are either coagulase-positive, beta hemolytic,
DNAse-positive, salt resistant