8 Staph Pathogenesis

Question 1

What are key symptoms of Schlievert’s story of Infectious Endocarditis?? (4)

Answer 1

fever
night sweats
Weight loss
fatigue

Question 2

What are key signs of Schlievert’s story of Infectious Endocarditis? (4)

Answer 2

• Elevated PMN’s
• Abnormal heart sounds
• Cultures show catalase-positive, coagulase-positive gram-positive cocci (S. Aureus)
• Not in story but often: metastatic abscesses

Question 3

What happens to the patient after hospitalization in Schlievert’s story? (4)

Answer 3

-stroke left side, takes 2 yrs to recover movement and 1 yr to recover speech-Hospitalized 6 weeks w/ “suportive care”-Lost 60 lbs-Practices medicine today.

Question 4

What are the common causes of infectious endocarditis? (3)

Answer 4

• Staph aureus [45%] highly valve-destructive
• Viridans streptococci [35%]
• Enterococcus faecalis & faecium [15%]

Question 5

What makes enterococcus faecalis & faecium so bad?

Answer 5

-highly antibiotic resistant, including to vancomycin. Can transfer this resistance to other gram-positives.

Question 6

How do we treat infectious endocarditis? (4)

Answer 6

-antibiotics-supportive care-valve replacement-manage complications (stroke)

Question 7

What does staph aureus do to skin? (7) Important!!

Answer 7

Primary inflammation: boils (furuncles), carbuncles (multiple boils), pimples (folliculitis), paronychia (nail beds), impetigo, soft tissue abscesses, atopic dermatitis

Question 8

What is staph aureus’s virulence key is skin?

Answer 8

walling off organism by cell surface virulence factors, then spreading by secreted virulence factors

Question 9

What does staph aureus do to mucous membranes thru inflammation? (6)

Answer 9

Primary inflammation (less inflammation than skin due to less alpha-toxin made by these strains):sinusitis, chronic otitis media, bronchial pneumonia, urinary tract infection vaginal infection, enterocolitis

Question 10

What does staph aureus do to mucous membranes when non-inflammatory? (3)

Answer 10

• Scalded Skin syndrome
• Toxic shock syndrome (TSS)!! (including menstrual)
• Staphylococcal food poisoning (pre-formed toxins)

Question 11

What is scalded skin syndrome?

Answer 11

-1-2 day old infant skin peeling due to exfoliative toxins (becomes very susceptible to secondary serious infections

Question 12

What are symptoms of staph food poisoning?

Answer 12

vomiting, diarrhea 2-8 hrs after eating, lasts up to 48 hrs

Question 13

What systemic infections does staph aureus cause? (5)

Answer 13

-Septicemia-TSS-Endocarditis-Osteomyelitis-Necrotizing fasciitis/myositis

Question 14

What is septicemia?

Answer 14

high fever, hypotension, DIC & metastatic abscesses

Question 15

What are necrotizing fasciitis/myositis symptoms?

Answer 15

fever, necrotizing tissue damage often with TSS

Question 16

T/F S. aureus usually remains localized?

Answer 16

T

Question 17

T/F S. aureus all give rise to systemic superantigens, and if so then which?

Answer 17

T

TSST-1, SEB, SEC

Question 18

TSS: What cytokines?

Answer 18

IL1-B (fever), TNF-alpha & beta (hypotension), IFN-gamma, IL-2 (rash 7 other symptoms)

Question 19

Menstrual TSS is most common in which type of tampon?

Answer 19

absorbent. (oxygen)

Question 20

What is TSS often a complication of?

Answer 20

influenza

Question 21

How is TSS defined? (6)

Answer 21

• Fever over 102 degrees
• hypotension
• systolic under 90-rash
• macular erythroderma
• peeling of skin if survive
• 3 mulit-organ changes

Question 22

What if some criteria for TSS are missing?

Answer 22

-1 missing: “Probable TSS”-More missing: “Toxin-mediated disease”

Question 23

Name “other” systemic signs of staph infection (see photos) (3)

Answer 23

-Kidney abscess-Splinter nails-gangrene (lack of perfusion from hypotension)

Question 24

How do we treat staph aureus skin or mucous membrane infections?

Answer 24

antibiotics, surgery to drain abscess/furuncle, remove infected hair/nails

Question 25

How do we treat more serious ones? (recall infectious carditis treatment earlier card)

Answer 25

• antibiotics (MRSA!)
• B.P. support
• Debridement in necrotizing illness
• IVIG-Activated protein C (drotrecogin-alpha if needed)
• Remove affected object (tampon etc)
• Influenze vaccine to prevent future post-influenze TSS

Question 26

how to do prevention in hospitals? (don’t memorize)

Answer 26

hand-wash, antibiotic sensitivity monitoring, dust low, monitor infected patients, monitor visitors

Question 27

Coagulase-negative staph group includes what 3 pathogens?

Answer 27

-Staph epidermidis-Staph saprophyticus-Staph lugdenensis

Question 28

staph epidermidis causes what 2 problems?

Answer 28

• Septicemia (number 1 cause) & endocarditis associated w/ catheterization biofilms. [due to PIA & cytolysins, rarely superantigen]
• UTI (urinary tract infection) associated w/ catheterization

Question 29

Staph saprophyticus causes what problem?

Answer 29

UTI

Question 30

Staph lugdenensis causes what problem?

Answer 30

endocarditis

Question 31

How are the 3 coagulase-negative infections treated?

Answer 31

Same as S. aureus, except must decide if the primary infection is staph or if it only came from catheterization thru the skin

Question 32

Do more inflammatory strains of staph live on skin or mucous membranes?

Answer 32

skin

Question 33

How does a fununcle (boil) form? (3 basic steps)

Answer 33

• staph inside skin.
• Fc of Ab’s are binding to staph, but the cell surface virulence factors are secreted & clotting cascade walls it off in a furuncle.
• Once high density of bacteria inside, cell surface virulence factors turn off. Secreted virulence factors turn on & now it spreads to other areas of skin.

Question 34

What is are the key differences in the way staph behaves when on mucosal surfaces? (2)

Answer 34

• Not walling itself off w/ coagulase

- Doesn’t make much alpha toxin

Question 35

Clotting in nailbeds is a strong sign of? (2)

Answer 35

-Endocarditis (staph or strep) -staph sepsis

Question 36

Which type of endocarditis progresses most quickly to death in a couple days?

Answer 36

staph