Staph Aureus Flashcards
(18 cards)
1
Q
Where does it Colonize
A
Nasopharynx
(also skin)
2
Q
Asymptomatic Carriage?
A
20 - 30% among general population but Obligate Pathogen
3
Q
Gram
A
Gram Positive
4
Q
Morphology
A
- Golden colonies
- Grape-like clusters
- Ferments Mannitol
- Resistant to environmental conditions
5
Q
Hemolysis?
A
B-Hemolytic
6
Q
Non-Toxic Virulence Factors
A
- End/Exocoagulase (+)
- Capsule
- Protein A
- Teichoic Acid
- Biofilm formation
- Catalase +
- Hyaluronidase, Fibrinolysin, Protease, Lipase, Nuclease
7
Q
Protein A
A
Binds Fc region of antibodies to prevent them from binding and opsonization so no phagocytosis
8
Q
Toxic Virulence Factors
A
- TSST
- Exfoliative Toxin A/B
- Heat stable Enterotoxins
(Superantigens) - Leukocidins
- Hemolysins
9
Q
Diseases by Toxin
A
- TSS
- Scalded Skin S (Ritter)
- Food Poisoning
10
Q
Toxic Shock Syndrome & what can cause it
A
- From TSST superantigen
- Develops from prolonged tampon, unchanged gauze
- Initially flu-like then dermal rash & shock, MOF
11
Q
Scalded Skin Syndrome
A
- Exfoliative Toxins
- Cleave Desmogelin 1 which holds skin layers together
- No inflammation
- Positive Nikolsky sign where top layers slip off lower when rubbed
12
Q
Food Poisoning
A
- Enterotoxin B
- Heat stable so even killing bacteria still causes symptoms
- Rapid onset within hours
13
Q
Systemic Diseases
A
- Osteomyelitis
- Pneumonia (post-viral) & patchy X-ray infiltrate
14
Q
Skin & Soft tissue Infections
A
- Folliculitis
- Furuncle
- Carbuncle
- Impetigo
- Wound infections
- Cellulitis
- Bullous Impetigo
15
Q
Treatment MSSA
A
- Nafcillin (methicillin)
- Oxacillin
- Flucloxacillin
16
Q
Treatment MRSA
A
Resistant to all B-lactams by PBP modification
- IV Vancomycin
- Daptomycin
- Linezolid
- 5th Gen Cephalosporins
17
Q
Microbiological Diagnosis
A
- Catalase test (staph vs strep)
- Coagulase (aureus): Tube or Clumping test
18
Q
Special about Staph Aureus
A
Only Staph that is Coagulase Positive
