Gram Positive Cocci Flashcards
Enumerate the clinically significant genera of Gram positive cocci.
STAPHYLOCOCCI
MICROCOCCI
STREPTOCOCCI
3 most common species of Staphylococci
S. aureus
S. epidermidis
S. saprophyticus
Describe the staphylococcus based on its arrangement
grape-like cluster
Staphylococcus can grow on what environment? Tell the percentage.
7.5% - 10% Sodium Chloride
they are halophiles - loves saline environment
Staphylococcus are resistant to what? How many units?
0.02 - 0.04 units of bacitracin (Taxo A)
What is a catalase Test?
a presumptive test to differentiate staphylococci and micrococci from streptococci.
What is the result of Staphylococcus and Micrococcus in Catalase Test?
POSTIVE
Catalase test uses what reagent?
Hydrogen Peroxide
How many Percent of hydrogen peroxide is used?
3%
What is the principle of Catalase test?
The enzyme, catalase, will breakdown hydrogen peroxide into water and oxygen, forming bubbles/effervescent
What indicates a positive result in catalase test?
Bubble formation/Effervescent
What are the two methods used in catalase test?
tube and slide method
When performing catalase test, colonies from what media should not be used? Why should it not be used?
BAP; it can lead to false positive result
Despite considered as a normal flora, S. aureus can also cause what?
Toxin mediated diseases and Non-toxin mediated diseases
Enumerate examples of Toxin mediated diseases
Food poisoning
Toxic Shock Syndrome
Scalded skin syndrome/Ritter’s Disease in newborn
Food poisoning is caused by what virulence factor?
Enterotoxin A and B
Toxic Shock Syndrome is caused by what virulence factor?
Pyrogenic Exotoxin C
Pyrogenic Exotoxin C is also known as
Toxic Shock Syndrome Toxin - 1
Exfoliatin can cause what disease?
Scalded skin syndrome/Ritter’s Disease in newborn
Major Virulence Factor of Staphylococcus aureus?
COAGULASE
Considered as the marker of virulence for S. aureus?
Coagulase
Responsible for the resistance of S. aureus penicillin and other beta lactam antibiotic?
Beta-lactamase
what is the action of beta lactams?
cell-wall inhibitors
Purpose of Cephalosporinase test?
detect beta-lactamase production
What substrate is used in cephalosporinase test?
Nitrocefin
Positive result in cephalosporinase test?
pink to red
Other name for hyaluronidase?
Duran Raynal Factor
What is the action of hyaluronidase?
to enhance the ability of the microorganism to invade the tissue
What virulence factor is responsible for the degradation of DNA?
DNAse/ Thermonuclease
It decreases the viscosity of exudates in order to allow more mobility of the organism
DNAse/ Thermonuclease
Other terms of Beta hemolysin
Sphingomyelinase C ; Hot-cold lysin
Responsible for the beta hemolytic property of the S. aureus
Beta-hemolysin
