microbiological investigations of pus

Question 1

staphylococcus and streptococcus

Answer 1

round shaped in clusters-staphy

round shaped in chains-strep

Question 2

What is fastidious organism

Answer 2

fastidious organism is any organism that has complex or particular nutritional requirements. …

Question 3

what is a facultative anaerobe and give examples

Answer 3

one that can do both but prefers anaerobic conditions but if oxygen is present it can still be alive e.g staphylococci and strepto

Question 4

staphylococcus aureus

Answer 4

bio colonies on blood agar with golden pigments - b hemolysis

Question 5

B hemolysis

Answer 5

complete hemolysis of RBC in media. the area appears lightened (yellow) and transparent. streptolysin ( exotoxin) produced by the bacteria is the enzyme that causes this lysis.

Question 6

Gram + produce

Answer 6

exotoxins

Question 7

catalase test

Answer 7

is positive for staphylococci, which converts hydrogen peroxide into water and oxygen and is negative for streptococci

Question 8

which bacteria are fastidious

Answer 8

streptococci- they require the addition of blood or serum to culture media

Question 9

coagulase tests and what its used for

Answer 9

Coagulase is a protein enzyme produced by several microorganisms that enables the conversion of fibrinogen to fibrin. In the laboratory, it is used to distinguish between different types of Staphylococcus NB!

positive - Staphylococcus aureus
negative - staphylococcus epidermidis + staphylococcus. saprophyticus

Question 10

classification of staphylococci

Answer 10

coagulase tests

positive - Staphylococcus aureus
negative - staphylococcus epidermidis + staphylococcus. saprophyticus

Question 11

classification of streptococci

Answer 11

3 types of hemolysis of blood agar
alpha- complete -S.pneumoniae
beta- partial- complete -S.pyogenes convert to biliverdin
gama- nothing -S.bovis

Question 12

Lancefield classsification

Answer 12

applies only to streptococci specifically for the B -hemolytic classification. the other 2 alpha and gama classified by biochemical testing.

lancefield realised that all species in each group generally shared properties such as type of hemolysis , normal host, body system

GROUP A - S..pyogenes
GROUP B S-agalactiae

Question 13

protein A

Answer 13

seems to be only in relation to staphylococcus auerues. this protein has a unique affinity to binding the FC receptor IG G

Question 14

Protein M

Answer 14

major virulence factor associated with certain streptococci species found on the cell wall

Question 15

what are the 3 main toxins that staphylococci produce

Answer 15

• enterotoxin -
• exfoliatin- rovokes detachment of epithelial cells
• pyrogenic - Toxic shock syndrome