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Dental Bacteriology Exam 1
Staphylococcus
41
Biology
Graduate
08/26/2009

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Term
3 species of staph are responsible for the majority of staph infections. What are they?
Definition
S. aureus, S. epidermis, and S. saprophyticus
Term
What is one way to differentiate between S. aureus, S. epidermis, and S. saprophyticus?
Definition
S. aureus is coagulase (+) and the others are coagulase (-)
Term
True or False: S. aureus causes more frequent and more varied diseases than any other human pathogen
Definition
True
Term
True or false: Serious staph infections usually occur in compromised hosts.
Definition
True
Term
Staph is Gram _____
Definition
Gram (+)
Term
Which species of Staph is a different color than others and what are the colors?
Definition
S. aureus appears golden yellow, and other species appear white.
Term
What are the metabolic conditions for S. aureus?
Definition
facultative anaerobe
Term
How is the peptidoglycan of Staph unique?
Definition
the peptidoglycan of staph is unique because it is susceptible to lysostaphin (which cleaves glycine-glycine linkages) which is useful for identification
Term
Is S. aureus catalase positive or negative?
Definition

Under aerobic conditions, S. aureus is catalase (+)

 

**Helps to distinguish between strep because strep is catalase (-)

Term
What is the optimum temperature range for growth of S. aureus?
Definition
6.5-46 degrees C
Term
Extracellular enzymes of S. aureus:
Definition

1. coagulase - clots plasma

2. hyaluronidase

Term
toxins for S. aureus:
Definition

1. alpha toxin

2. enterotoxin

3. exfoliative toxins

4. toxic shock syndrome toxin-1 (TSST-1)

Term
How does alpha toxin work?
Definition
alpha toxins are membrane active toxin that causes lysis of RBCs
Term
How do enterotoxins work?
Definition
they are super-antigens that act on neural receptors in the upper G.I. tract
Term
What illness do enterotoxins cause?
Definition
cause food poisoning--vomiting and diarrhea 2-5 hours after ingestion
Term
How have enterotoxins evolved to resisit host defense?
Definition
They are resistant to gastric enzymes and and heating at 100 degrees C for 30 minutes
Term
exfoliative toxins mechanism of action:
Definition
causes lysis of the intracellular attachment between cells of the granular layer of the epidermis
Term
What illness/syndrome is caused by exfoliative toxins?
Definition
scalded-skin syndrome - usually in young children
Term
Toxic shock syndrome toxin-1 (TSST-1) mode of action:
Definition
super-antigen: direct toxic effects on endothelial cells resulting in capillary leakage and hypotension
Term
Symptoms of TSST-1
Definition
lethal hypotension, rash with multiple organ system involvement
Term
Staph. aureus is commonly resistant to:
Definition
 penicillins and cephalosporins
Term
Resistance for all staphylococci:
Definition

**relatively more resistant to adverse environmental conditions than most nonsporulating bacteria

***survive for weeks in dried pus and sputum

****Resistant to common disinfectants; i.e. phenols and mercuric chloride

Term
What are the clinical manifestations of S. aureus?
Definition

1. skin infections

2. respiratory infections

3. metastatic infections

4. food poisoning

5. TSS

Term
What forms of skin infections do you get from staph aureus?
Definition
folliculitis, carbuncles, boils, impetigo (usually in children)
Term
True or False: Staph Pneumonia is often seen as a complication of other bacterial or viral infections:
Definition
true
Term
What is a characteristic of Staph Bacteremia?
Definition

Metastatic abscesses--most frequently on the

1. skin,

2. subcutaneous tissue,

3. and lungs.

**predisposed by trauma and debilitating disease

Term
Symptoms of food poisoning from S. aureus:
Definition

avg. 4 hours after ingestion

1. severe cramping

2. abdominal pain

3. nausea

4. vomiting

5. diarrhea

Term
Symptoms of Toxic Shock (TSS):
Definition

1. pyrogenic

2. hypotensive following vascular coagulation

3. renal failure

4. acidosis

5. rash

Term
In males, TSS from Staph is associated with what body part:
Definition

strong association with focal staph infections: skin

 

Term
In females, TSS is associated with what area of the body:
Definition
vaginal association
Term
Catheter and shunt infections occur with what form of Staph?
Definition
saprophiticus and epidermis
Term
which form of staph is estimated as the most common cause of bacteremia?
Definition
S. epidermis
Term
Which form of staph is the most common contaminant of specimens?
Definition
S. epidermis
Term
Sites of infection for S. epidermis:
Definition

1. bacteremia (IV lines and valves)

2. meningitis (shunts)

3. periotenitis (via dialysis catheter)

4. septic arthritis (prosthetic joint)

5. endocarditis (prosthetic heart valve)

6. UTI

7. Local infections from implants

Term
S. saprophiticus is most commonly involved in infections where?
Definition

UTI

* in young sexually active women

Term
Where is staph found in the body as normal flora?
Definition

1. nasopharynx

2. perineum

3. skin

4. mucous membrane

5. and gut

Term
Tests to diagnose staph:
Definition

1. Gram stain

2. streak on blood agar

3. inoculate into broth medium

4. Latex agglutination

Term
To find the epidemiology of staph, what tests do you do?
Definition

1. antibiograms/biotyping

2. bacteriophage typing

3. serotyping

Term
What percentage of staph are sensitive to penicillin?
Definition
10%
Term
What percentage of staph are resistant to Beta Lactamase resistant pennicilin?
Definition
10-25%
Term
To treat penicillinase resistant penicillin (methicillin), what antibiotic do you give?
Definition

1. a first generation cephalosporin: cephalothin

2. vancomycin for MRSA

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