Microbiology - Shillitoe - Bacterial Infections of the Skin Flashcards
(40 cards)
Smears from pus may show gram + cocci in clumps or chains;
very contagious;
children common
Impetigo
usually a combination of S. aureus and S. pyogenes;
surface only (epidermis)
gram + cocci coagulase + beta-hemoytic DNAase + salt resistant
Staph aureus
gram + coagulase - beta hemolytic, bacitracin sensitive reactive with Strep Group A antiserum
Strep pyogenes
Bullous pemphigoid is associated with what bacteria due to the exfoliatoxin?
Staph aureus
Dissemination of impetigo
Fomites, contact
What are the virulence factors for Staph aureus?
SO MANY Structural --Protein A --Capsule --Coagulase Toxins --TSS toxin --exfoliatoxin --enterotoxin --leukocidin --DNAase
Biofilm protects organisms from the immune system;
piercings, medical devices
Staph epidermidis
gram + cocci growing in clumps catalase + coagulase - non-hemolytic
Staph epidermidis
loves plastic and nylon
Severe itching due to cell-mediated hypersensitivity;
linear lesions;
wrists or genitals common
Scabies
Sarcoptes scabei
burrowing mite
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?
Propionobacterium acnes
How to treat abscesses
drain;
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;
subcutaneous
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
cellulitis
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?
Post-streptococcal glomerulonephritis;
Associated with M protein strep types;
3-4 weeks later;
no treatment, recurrences can lead to kidney failure
Enteric fever
Meningitis
S. typhimurium - Rose spots
N. meningitides - Petechial lesions
Syphilis
T. pallidum Secondary stage rashes
Typhus
Rickettsia - Hemorrhagic rash
