Flashcards by gina_evans0312, updated more than 1 year ago
Created by gina_evans0312 about 7 years ago


Medical Microbiology (Skin Infections) Flashcards on S.Aureus, created by gina_evans0312 on 02/06/2014.

Resource summary

Question Answer
Culture Media Can grow on nutrient but blood is better
S.Aureus on blood agar Pinhole colones coloured yellow (S.Aureus is haemolytic)
Selecting S.Aureus (Agar) MSA- Mannitol Salt Agar (S.Aureus is salt tolerant)
Method of MSA Mannitol is fermented, which is shown by the indicator turning yellow
Blood-Coagulase Test S.Aureus can convert Fibrinogen -> Fibrin in of plasma, causing clumping
Agar-DNAse Test S.Aureus can clear a DNA-impregnated agar plate (this can be made clearer using Mannitol/Indicator)
Mild S.Aureus Infections Skin, soft tissue, food poisoning
Sever S.Aureus infections Bone/blood/organ infections, toxic shock
S.Aureus Environment Usually endogeous, can be exogenous
S.Aureus Mode of Transmission Injestion, Aeresol, contact
S.Aureus- Host Factors Age, Suppressed immune system
S.Aureus- MSCRAMMS Microbial Surface Components Recognizing Adhesive Matrix Molecule
S.Aureus- Role of MSCRAMMS Recognise and bind to a specific host molecule
S.Aureus- Uniqueness of MSCRAMM's S.Aureus can bind to multiple host molecules
S.Aureus- Metastasis Refers to its ability to travel in blood and infect other tissues
S.Aureus- Enzmyes Produces a wide variety
S.Aureus Enzmyes- Coagulase Forms a fibrin barrier around the bacteria
S.Aureus Enzmyes- Lipases Bind to/destroy host tissues
S.Aureus Enzmyes- Protein A Binds to blood Ib's and masks bacterium
S.Aureus Toxins- PVL Panton Valentine Leucocidin
S.Aureus Toxins- Role of PVL Forms pores in leukocytes to release inflammatory mediators, killing them and damaging tissues
S.Aureus Toxins- Enterotoxin Works in intestine (action unknown) causing vomiting
S.Aureus Toxins- Enterotoxin Strains A-E & G-J (A most common) Works as a super-antigen
S.Aureus Toxins- TSST1 Toxic Shock Syndrome Toxin 1
S.Aureus Toxins- Role of TSST1 Fever, rash, loss of skin & shock like symptoms
S.Aureus Toxins- Release of TSST1 Inserted into blood by bacteria (bacteria themselves not present)
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