microbio

Question 1

what are the most common pathogens seen in MSK?

Answer 1

gram positive cocci

Question 2

give some examples of gram positive cocci

Answer 2

• staphylococcus aureus
• staphylococcus epidermis
• streptococcus pyogenes

Question 3

how to differentiate staph aureus from other gram positive bacteria?

Answer 3

catalase test (it is the only one that is catalase positive)

Question 4

is staphylococcus gram positive or gram negative?

Answer 4

positive

Question 5

what does staphylococcus look like?

Answer 5

cocci in clusters

Question 6

is staphylococcus aerobic or anaerobic?

Answer 6

it is aerobic and facultatively anaerobic (grows best aerobically but also grows anaerobically)

Question 7

give an example of a coagulase positive staphylococcus

Answer 7

only staph aureus is coagulase positive

Question 8

give an example of a coagulase negative staphylococcys

Answer 8

• staph epidermis

- staph saprophyticus

Question 9

what will be seen in a coagulase positive result and why?

Answer 9

if a test is coagulase positive there will be clots in the test tube as coagulase converts fibrinogen to fibrin resulting in clotting

in an agar it looks golden

Question 10

what antibiotics are usually used to treat staph aureus infection?

Answer 10

vancomycin
daptomycin
teicoplanin

Question 11

whats the difference between planktonic and sessile bacteria?

Answer 11

planktonic- are responsible for most symptoms, these rapidly colonise on new surfaces

sessile bacteria- dorment bacteria on biofilm

Question 12

what is a biofilm?

Answer 12

an accumulation of microorganisms causing a thin mucilage layer adhering to a solid surface