Gram + algorithm

Question 1

Staph aureus

Answer 1

Catalase +
Coagulase +
clusters

Question 2

Staph epidermidis

Answer 2

Catalase +
Coagulase -
Novobiocin sensitive
Endocarditis and bacteremia on prothetic valves and indwelling catheters

Question 3

Staph saprophyticus

Answer 3

Catalase +
Coagulase -
Novobiocin resistant
2nd most common cause of uncomplicated UTI in young women

Question 4

Strep pneumoniae

Answer 4

Catalase -
Partial (alpha) hemolysis 
Encapsulated
Optochin sensitive
Bile-soluble
"gram + encapsulated diplococci with partial hemolysis"

Question 5

Strep viridans

Answer 5

Catalase -
Partial (alpha) hemolysis
Optochin resistant
Bile-insoluble

Question 6

Strep pyogenes (GAS)

Answer 6

Catalase -
Complete (beta) hemolysis
Bacitracin sensitive

Question 7

Strep agalactiae (GBS)

Answer 7

Catalase -
Complete (beta) hemolysis
Bacitracin resistant

Question 8

Enterococcus

Answer 8

Catalase -

No (gamma) hemolysis

Question 9

Gram + rods

Answer 9

Bacillus cereus - fried rice food poisoning
Listeria monocytogenes
Corynebacterium diphtheriae
Clostridium perfringens and botulinum

Question 10

Actinomyces

Answer 10

branching filaments
anaerobic
not acid-fast

Question 11

Norcardia

Answer 11

branching filaments
aerobic
acid-fast