Microbiology - Shillitoe - Bacterial Infections of the Skin Flashcards Preview

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Flashcards in Microbiology - Shillitoe - Bacterial Infections of the Skin Deck (40):
1

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)

2

gram + cocci
coagulase +
beta-hemoytic
DNAase +
salt resistant

Staph aureus

3

gram +
coagulase -
beta hemolytic,
bacitracin sensitive
reactive with Strep Group A antiserum

Strep pyogenes

4

Bullous pemphigoid is associated with what bacteria due to the exfoliatoxin?

Staph aureus

5

Dissemination of impetigo

Fomites, contact

6

What are the virulence factors for Staph aureus?

SO MANY
Structural
--Protein A
--Capsule
--Coagulase
Toxins
--TSS toxin
--exfoliatoxin
--enterotoxin
--leukocidin
--DNAase

7

Biofilm protects organisms from the immune system;
piercings, medical devices

Staph epidermidis

8

gram +
cocci
growing in clumps
catalase +
coagulase -
non-hemolytic

Staph epidermidis

loves plastic and nylon

9

Severe itching due to cell-mediated hypersensitivity;
linear lesions;
wrists or genitals common

Scabies
Sarcoptes scabei
burrowing mite

10

Treatment for scabies

Permethrin to kill mite;
topical steroids for itching

11

What is furunculitis?

Superficial sweat gland or follicle infections, looks like acne
usually due to Staph aurues

12

What is a carbuncle?

Multiple skin abscesses fused sub-cutaneously

13

What anaerobic bacterium is commonly present along with Staph aureus in acne?

Propionobacterium acnes

14

How to treat abscesses

drain;
mupirocin ointment for mild cases;
Nafcillin or oxacillin for severe/systemic cases

15

What is scalded skin syndrome?

Widespread exfoliation due to a localized infection by S. Aureus;
often seen in newborns;
exfoliatoxin separates epidermal cells;
subcutaneous

16

TSS can be from which agents?

super-antigen toxic shock syndrome toxin (Staph aureus);
Streptococcal TSS toxin;
systemic immune reaction

17

deep infection of skin;
associated with fever, lymphadenopathy and bacteremia

cellulitis

erysipelas is more superficial;

S. pyogenes usually responsible, as with NF

18

What makes Strep pyogenes the prime candidate for causing NF?

Potent protease enzyme

19

NF can be caused by Step pyogenes or...

C. perfringens --> gas gangrene

20

What is the treatment for cellulitis or erysipelas?

Pencillin or cephalosporin

21

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

22

Enteric fever
Meningitis

S. typhimurium - Rose spots
N. meningitides - Petechial lesions

23

Syphilis

T. pallidum Secondary stage rashes

24

Typhus

Rickettsia - Hemorrhagic rash

25

Measles

Measles virus - Macules

26

Toxic shock syndrome

S. aureus - Desquamation

27

Blastomycosis

B. dermatidis -Papules

28

Bacterial endocarditis

Viridans Streptococci - Splinter hemorrhages

29

Impetigo

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
(Bullous impetigo).

S. aureus and S. pyogenes

30

Leprosy

M. leprae - surface infection

31

Infected piercings / catheters

S. epidermidis - surface infection

32

Scabies

Mites - surface infection

33

Follicles/ sweat glands Abscess

S. aureus

34

Erysipelas

S. pyogenes - subcutaneous infection

35

Cellulitis

S. pyogenes

36

Necrotizing fasciitis

S. pyogenes / others

37

Surgical site / wound
infections

S. aureus / others

38

coagulase-negative, beta hemolytic,
bacitracin-sensitive, reactive with Strep Group A antiserum

S. pyogenes

39

Gram + cocci which are either coagulase-positive, beta hemolytic,
DNAse-positive, salt resistant

S aureus

40

What toxin is associated with bollous impedigo?

Bullous impetigo is associated with S. aureus due to exfoliatin.