Micro Staphylococci

Front 1

Staphylococci are catalase negative or positive?

Back 1

Catalase positive

Front 2

Why is it important to differentiate between staphylococci from streptococci?

Back 2

Most staphylococci are penicillin G resistant.

Front 3

Of the three staphyloccal species, which one is coagulase positive?

Back 3

Staphyloccus aureus.

Front 4

What does the coagulase enzyme perform?

Back 4

Activates prothrombin to form thrombin, which converts fibrinogen to fibrin, causing blood to clot. There will be a gold pigment around S. aureus when cultured on sheep blood agar.

Note: This protects the bacteria from phagocytosis as fibrin collects around it.

Front 5

What does catalase enzyme perform?

Back 5

Breaks down hydrogen peroxide into oxygen and water.

Front 6

What proteins does S. aureus have?

Back 6

Protein A, coagulase, hemolysins, leukocidins, penicillinase, and novel penicillin binding protein (aka transpeptidase), hyaluronidase, staphylokinase, lipase, and protease.

Front 7

What does protein A preform on S. aureus?

Back 7

Binds to the Fc portion of IgG, protecting against opsonization and phagocytosis.

Front 8

What exotoxins does S. aureus have?

Back 8

Exfoliatin, enterotoxins, and toxic shock syndrome toxin (similar to pyrogenic toxin from group A beta-hemolytic streptococci, but far more deadly).

Front 9

Exotoxins of Staph. aureus: Exfoliative toxin, enterotoxin (heat stable), and TSST (toxic shock syndrome toxin)?

Back 9

Scalded Skin Syndrome.

Enterotoxin: Exotoxins cause food poisoning, with vomiting and diarrhea

TSST: analogous to group A beta-hemolytic streptococci pyrogenic toxin, but far more deadly. It is also a superantigens that bind to MHC II, causing a massive T cell response and outpouring of cytokines.

Front 10

The toxins from S. aureus can produce?

Back 10

Toxic shock syndrome, scalded skin syndrome (Ritter's disease in newborn), and food poisoning.

Note: scalded skin syndrome (Ritters in newborn), epidermis separates and skin sloughs off with fluid loss and potential secondary infection that may lead to death. Ritter's syndrome occurs when S. aureus colonizes the cut umbilicus and release exfoliative toxin.

Front 11

S. aureus infection can cause?

Back 11

impetigo, cellulitis, folliculitis, furuncles, carbuncles, pneumonia with cavitations, acute endocarditis, meningitis, osteomyelitis, septic arthritis, UTI

Front 12

Most S. aureus are resistant to penicillin because they secrete penicillinase. What is special about MRSA?

Back 12

Penicillinase do not break down methicillin, nafcillin. However, MRSA is resistant against methicillin and nafcillin.

Front 13

What can be affective against MRSA?

Back 13

vancomycin.

Front 14

Are antibiotics effective against TSS, scalded skin syndrome, or food poisoning?

Back 14

No, they do not act on already-released exotoxin.

Front 15

S. aureus is the leading cause of?

Back 15

osteomyelitis in children and adults

Front 16

IV drug user?

Back 16

S. aureus infection causing tricuspid valve endocarditis

Front 17

Staphylococcus epidermidis is normally found where?

Back 17

Found widely on the body. Present in the nasopharynx and on the surface of the skin.

Front 18

Clinical complications of S. epidermidis?

Back 18

indwelling on medical devices (prostetic valve, prostetic joint, foley catheter, IV lines) and skin contaminant of blood cultures. It also forms a biofilm on intravascular catheter causing bacteremia and related sepsis.

Front 19

Staphylococcus saprophyticus, is the leading cause of?

Back 19

UTI (second only to E. coli) in sexually active young women. Can also cause cystitis.

Front 20

What is the treatment of S. saprophyticus?

Back 20

TMP-SMX

Front 21

How can Staphylococcus aureus cause pneumonia? How does it adhere to the cell wall?

Back 21

It causes secondary pneumonia after influenza causes destruction of ciliary defenses allowing colonization of the the bacteria.

S. aureus adheres to host cells via teichoic acid.

Front 22

What is the hallmark characteristic of S. aureus infection?

Back 22

Abscess. It consist of fibrin wall surrounded by inflamed tissues enclosing a central core of pus--consistent with the opacity of the chest x-ray.

Front 23

How do you obtain hematogenous transmission of S. aureus?

Back 23

IV drug usage.

Front 24

How do you obtain mucopurulent conjunctivitis from S. aureus?

Back 24

When having influenza, S. aureus can spread from the normal flora of the nares by a runny nose during rubbing and wiping.

Front 25

How do you treat infection from S. aureus?

Back 25

Penicillinase-resistant penicillins (nafcillin) or those who are resistant with vancomycin.

Front 26

Most strains of Staphylococcus aureus are?

Back 26

Beta-hemolytic and pigmented, ranging in color from cream-yellow to orange.

Front 27

What is generally an accepted criterion for the identification of S. aureus?

Back 27

Ability to clot plasma (coagulase).

Note: prothrombin to thrombin, which converts fibrinogen to fibrin.

Front 28

S. aureus is found where?

Back 28

On the skin, skin glands, and mucous mm of humans.

Associated with surgical wound infections.

Note: the hands are the most important instruments for transmitting infection.

Front 29

PTs with Chediak-Higashi disease usually infected with recurrent pyogenic infections due to S. aureus, whY?

Back 29

Defect in lysosomal enzyme release.

Front 30

How does osteomyelitis infection occur from S. aureus?

Back 30

Hematogenous dissemination or local extension from a skin infection and subsequent seeding of the bacteria within the bone.

Front 31

What is responsible for colonization of S. aureus in skin breaks?

Back 31

Fibronectin-binding protein.

Front 32

Where is the site of pathology in osteomyelitis in growing bones of children?

Back 32

Metaphysis.

Front 33

What is the DOC for S. aureus? For MRSA?

Back 33

Penicillinase-resistant penicillin (e.g., nafcillin).

Vancomycin.

Note: linezolid also has activity against MRSA>

Front 34

What is an antistaphylococcal soap?

What may be used by carriers or PTs with non-complicated infections to eliminate the nasal carrier state and reduce transmission?

Back 34

Chlorhexidine, especially before surgeries.

Mupirocin is used as a cream in the nares and oral rifampin.

Front 35

What is are carbuncles, chronic furunculosis, impetigo, cellulitis?

Back 35

Carbuncles: multiple interconnected abscesses or furuncles that develop into a large lesion.

Chronic furunculosis: results when immune response to pyogenic organisms is impaired.

Impetigo: caused by exfoliatin. Is limited to the epidermis and manifests as bullous, crusted, or pustular eruption of the skin.

Cellulitis: inflammation of CT with erythematous area with ill-defined margins. In the leg, develops as a large bullae and scabs.