Staphylococcus aureus

Question 1

What are the two types of patients?

Answer 1

Normal Patient

Patient with compromising or predisposing factors

Question 2

Patients with compromising or predisposing factors are due to these 5 things?

Answer 2

Surgery or trauma

Immunoincompetence or immunosuppression

Diabetic

Alcoholism or drug use

Pregnancy

Question 3

What are the two modes of infection acquisition? (two ways you acquire infectious disease)

Answer 3

Community acquired

Hospital acquired

Question 4

What are the three geographic distribution and/or “work” environments?
(places to acquire infections?)

Answer 4

Insect vectors/ climate

Farm & ranch

Construction Work

Question 5

Is Staphylococcus aureus gram + or gram -?

Answer 5

Gram +

Cocci in clusters

Question 6

What causes about 90% of invasive tissue infections?

Answer 6

Staphylococcus aureus

Question 7

True/ False

Staphylococcus aureus pyogenic

Answer 7

True

Question 8

What is folliculitis?

What microbe causes this?

Answer 8

Infection of the hair follicle

Staphylococcus aureus

Question 9

What is a furnuncle? What microbe causes this?

Answer 9

Deep seated infections (subcutaneous tissue involved) in and around the hair follicle.

Staphylococcus aureus

Question 10

What is cellulitis? What microbe causes this?

Answer 10

Similar to folliculitis/boils in skin or tissues but spreads beneath the skin.
Staphylococcus aureus

Question 11

What is impetigo? What microbe causes this?

Answer 11

Superficial skin infection characterized by small “blisters”/pustules followed by a thin crust over the area

Staphylococcus aureus

Question 12

Staphylococcus aureus is the etiologic agent of?

Answer 12

Invasive tissue infections 
Food poisoning 
Toxic Shock Syndrome 
Scalded Skin Syndrome
Septicemia/bacteremia
Bone and joint infections 
Pneumonia/Lower Respiratory & Lung Abscess infections

Question 13

Staphylococcus aureus can cause this especially after surgery or trauma often due to external contamination?

Answer 13

Wound and internal tissue infections (abscess)

Question 14

Staphylococcus aureus can cause this due to numerous invasive enzymes and toxins.

Answer 14

Tissue damage. Some invasive infections can be very severe.

Question 15

Staphylococcus aureus food poisoning is due to ingestion of this?

Answer 15

pre-formed heat-stable enterotoxin. Its an enterotoxin that affects the intestinal tract (types A,B,C, etc SEB).

Question 16

What are the commonly affected foods of Staphylococcus aureus that causes food poisoning?

Answer 16

Cooked or processed meat (especially ham), salads, and cream filled desserts.

Question 17

What are the clinical symptoms of food poisoning caused by Staphylococcus aureus

Answer 17

Nausea
Vomiting
Abdominal cramps
Watery diarrhea

Question 18

Food poisoning symptoms of Staphylococcus aureus start within how many hours and last to about how many hours?

Answer 18

Starts within 1-6 hours and lasts from a few hours to about 24 hours.

Question 19

True or False

Staphylococcus aureus growth on food produces no change in flavor or odor.

Answer 19

True

Question 20

Food Poisoning:

What are the conditions Staphylococcus aureus (certain strains) will produce enterotoxin?

Answer 20

When growing at 28C or higher for 2 to 4 hours.

Question 21

Certain strains of Staphylococcus aureus produce Toxic Shock Syndrome Toxins (TSST). The TSST toxin probably causes?

Answer 21

Massive and unregulated stimulation of the immune system.

Question 22

TSST produces what symptoms?

Answer 22

Acute illness with:
High fever
Diffuse rash 
Hypotension 
Skin desquamation

Question 23

What is TSST infection normally associated with?

Answer 23

Use of highly absorbent tampons (about 75% of cases) or with focal or surgical wound infections in men or non-menstruating women.

Question 24

In TSST, how does the tampon cause infection?

Answer 24

Absorption of fluids causes change of microbial growth environment resulting in change or host-microbe dynamics.

Question 25

True or False | TSST test for toxins is usually performed in routine microbiology labs.

Answer 25

False

Question 26

What does Scalded Skin Syndrome cause in children under 5?

Answer 26

Toxic Epidermal Necrolysis (TEN)

Question 27

Strains of scalded skin syndrome produce what kind of toxins? and they are destructive to?

Answer 27

Exfoliatin Toxins Destructive to epithelial cells

Question 28

What are the symptoms of Toxic Epidermal Necrolysis in children under 5?

Answer 28

Initially a localized red rash, often following conjunctivitis or upper respiratory tract infection. Followed by large flaccid bullae.

Question 29

The bullae of scalded skin syndrome do what?

Answer 29

Rupture and sheets of epidermis peel off to reveal moist, red, "scalded" dermis.

Question 30

True or False | Bacteria are recovered from the bullae and not from the initial infection.

Answer 30

False

Question 31

Staphylococcus aureus Bloodstream infection resulting from deep, poorly draining infections which invade the bloodstream and spread to numerous body sites.

Answer 31

Septicemia/ | Bacteremia

Question 32

Is septicemia/bactermia life-threatening?

Answer 32

Yes, unless rapidly treated with effective antimicrobics.

Question 33

Staphylococcus aureus: | These infections are common following device implantation or trauma.

Answer 33

Bone and joint infections (osteomyelitis & septic arthritis)

Question 34

Staphylococcus aureus: | This can happen following viral respiratory infections or in patients with altered host defenses.

Answer 34

Pneumonia/ Lower Respiratory & Lung Abscess infections (about less than 2% of all pneumonia)

Question 35

What are the virulence factors of Staphylococcus aureus

Answer 35

Several toxins & invasive enzymes, including coagulase, fibrinolysis, lipase and a variety of proteases Adhesive Matrix Molecules Quorum-sensing regulators Super antigens (toxins)-enhance effects of toxins Pathogenicity of various strains is largely due to genes carried on plasmids and lysogenized viral genes. Resistant to multiple antimicrobics

Question 36

What antimicrobics are Staphylococcus aureus resistant to?

Answer 36

Beta-lactams (85%) Vancomycin (developing- VISA, VRSA) And probably others

Question 37

Why are most strains of Staphylococcus aureus resistant to Beta-lactams?

Answer 37

Due to beta-lactamase enzymes coded by genes carried on plasmids.

Question 38

What are Multiply Drug Resistant (MDR)?

Answer 38

Strains (of Staphylococcus aureus?) that are resistant to an exceptionally large number of antimicrobic types. - very serious infections.

Question 39

What is an example of the drug combo for MRSA?

Answer 39

Vancomycin, linezolid, & tigecycline

Question 40

What are some of the laboratory work done for a laboratory diagnosis?

Answer 40

Culture and biochemical identification- coagulase positive Antigenic identification/confirmation of the lab culture. Antimicrobic susceptibility test needed (Beta-lactamase, MRSA, MDR)