Staphylococci

Question 1

Cocci bacteria

Answer 1

staph, strep, enterococcus

Question 2

bacilli: Spore forming

Answer 2

• Bacillus (facultative anaerobe)

- Clostridium (obligate anaerobe)

Question 3

Bacilli: Non-spore forming

Answer 3

• Listeria

- Corynebacteria

Question 4

Strep

Answer 4

catalase negative

Question 5

Staph

Answer 5

catalase positive

Question 6

What kind of infection are Staph and Strep common in?

Answer 6

• skin infections/eruptions
• wound infections
• upper respiratory infections (sinusitis/pharyngitis)
• Pneumonia
• food poisoning/TSS
• septicemia/disseminated infections

Question 7

staph/strep accounts from the majority for what kind if infections?

Answer 7

suppurative infections

• also abscess formation-> can only spread along tissue planes
• role of phagocytosis/opsonization very important

Question 8

diseases that interfere with ________ function result in pyogenic infections?

Answer 8

neutrophils

• diabetes
• chronic granulomatous disease

Question 9

is staph a native flora?

Answer 9

Yes

-ubiquitous (common cause of skin abscesses)

Question 10

Coagulase positive staph?

Answer 10

Staph. aureus

Question 11

coagulase negative staph?

Answer 11

Staph. epidermidis

• infects damaged tissue
• contamination of devices, implants-> lead to infection

Question 12

what are general forms of disease from staph?

Answer 12

• local infections/abscess formation
• bacteremia (sepsis)-> can be to heart valves, kidneys, bones, joints
• toxin-mediated diseases: food poisoning, TSS

Question 13

what are the virulence factors of Staph?

Answer 13

• coagulase +/-
• cytolytic toxins
• lipases
• penicillinase, plasmid mediated antibiotic resistance
• fibronectin and vitronectin-> bind to host cells
• protein A: binds Fc portion of immunoglobulins

Question 14

what are toxins from staph?

Answer 14

• enterotoxins
• cytolytic toxins
• exfoliative toxins
• toxic shock syndrome toxin (TSST-1)

Question 15

Pathogenic factors in S. aureus

Answer 15

• Suppurative disease: impetigo, folliculitis
• Enteritis
• TSS
• Postoperative pneumonia
• staphylococcal scalded skin syndrome
• food poisoning

Question 16

For staph infections: over growth of NF/UPT leads to?

Answer 16

sinusitis

otitis media

Question 17

For staph infections: access to sterile areas leads to?

Answer 17

• skin, wound infection
• hematogenous spread from punctures
• bacteremia spread to joints, bone, heart valves. etc

Question 18

For staph infections: deep infections in immunosuppressed/debilitated leads to?

Answer 18

necrotizing pneumonia, septicemia

Question 19

types of skin/wound infections?

Answer 19

furuncle, carbuncle, sutures/foreign bodies, impetigo

Question 20

staph infections are a common cause of ________ infections?

Answer 20

burns, surgical, nosocomial infections

Question 21

staph infections of UPT are usually caused from?

Answer 21

obstruction with overgrowth of colonizing bacteria

-sinusitis, otitis media, pharyngitis

Question 22

what are UPT is usually associated with?

Answer 22

• secondary to viral infection
• diabetes
• trauma or irritation
• foreign bodies
• duct obstruction

Question 23

what are the two toxic mediated diseases with staph?

Answer 23

food poisoning

TSS

Question 24

what toxin causes food poisoning with staph?

Answer 24

enterotoxin

• short incubation (1-6 hours)
• custards, milk, meats, potato salad

Question 25

what is TSS from staph?

Answer 25

overgrowth of bacteria with absorption of toxin - T cell super antigen (non-specific activation) - fever, diffuse macular rash, shock - confused with gram negative sepsis

Question 26

characteristics of bacteremia from staph?

Answer 26

relatively non-threatening - seeding of damaged tissue from circulation - acute endocarditis, septic arthritis, osteomyelitis, meningitis

Question 27

characteristics of bronchopneumonia from staph?

Answer 27

debilitated patients - nosocomial - secondary to viral infection, or obstructive illness - very destructive purulent lesions

Question 28

characteristics of staph saprophyticus

Answer 28

NF, periurethral and urethral flora | -UTI in young women

Question 29

characteristics of staph epidermidis

Answer 29

coagulase negative | -only infects inert objects (catheters, artificial tissues)

Question 30

MRSA

Answer 30

has hospital and community forms

Question 31

what is MRSA first detected as?

Answer 31

cluster of abscesses or spider bites

Question 32

community acquired MRSA

Answer 32

mostly skin and soft tissue infections - 5% invasive (sepsis, bone/joints) - NOT lethal organism

Question 33

how do most MRSA infections occur?

Answer 33

cuts, wounds, or abrasions that allow bacteria to enter the skin or mucous membranes -can cause local necrosis (like a spider bite), and look like a small collection of boils