Microbiology Review

A set of flashcards covering key concepts in microbiology related to staphylococci and streptococci identification tests.

What is the Gram stain result for Staphylococcus aureus?

Gram positive cocci in clusters.

What type of hemolysis does Staphylococcus aureus exhibit on blood agar?

Beta hemolysis.

What agar shows yellow coloration due to mannitol fermentation by Staphylococcus aureus?

Mannitol Salt Agar.

What is the catalase test result for Streptococcus pyogenes?

Negative.

Which streptococcus species is susceptible to Taxo A (Bacitracin)?

Streptococcus pyogenes.

What hemolytic pattern does Streptococcus agalactiae exhibit?

Beta hemolysis.

What is the Lancefield Group for Streptococcus agalactiae?

Group B.

What are the characteristics of Escherichia coli on MacConkey Agar?

Dark pink/red colonies (Lactose fermenter).

What type of hemolysis does Enterococcus faecalis exhibit?

Gamma (non) hemolysis.

Which organism is known for producing H2S among Gram negative rods?

Proteus mirabilis.

What organisms are gram negative rods?

E. coli, P. mirabilis, P. aeruginosa

What organisms are gram positive cocci

S. aureus, S. epidermidis, S. pneumoniae, Enterococcus spp.

Stains as gram positive cocci in clusters. It grows on Mannitol Salt Agar and turns that agar yellow. It is catalase positive and coagulase positive

Staphylococcus aureus

Stains as gram positive cocci in chains. It does not grow on Mannitol Salt Agar. It is catalase negative. It is resistant to bacitracin. It is bile esculin negative. It is beta hemolytic on blood agar

Streptococcus agalactiae

Stains as gram positive cocci in chains. It does not grow on MSA Agar. It is catalase negative. It grows in the presence of 6.5% sodium chloride. It is bile esculin positive

Enterococcus faecalis

Stains as a gram positive cocci in chains. it is beta hemolytic on blood agar. It is catalase negative, and susceptible to bacitracin

Streptococcus pyogenes

Stains as gram positive diplococci, alpha hemolytic on blood agar, with wet and mucoid looking colonies. It is susceptible to optochin. It is catalase negative

Streptococcus pneumoniae

Grows on MAC agar as clear football shaped colonies. Oxidase positive and is often found in burn wounds

Pseudomonas aeruginosa

If you perform a beta-lactamase test on an organism, and the result is positive, which is true based on the results

organism is RESISTANT to antibiotics that have a beta—lactam ring

Grows on MAC agar as a non lactose fermenter. It is oxidase negative. It will produce blackening of the agar in a SIM tube

Proteus mirabilis