GP Organisms

Question 1

1. Large flat rough dry B haemolytic colonies
2. NLF on MAC
3. GPB, spores
4. Catalase POS

Answer 1

Bacillus cereus

Question 2

1. GPB Obligate anaerobe, can be encapsulated, non motile
2. Catalase NEG
3. Double zone of haemolysis (B inner, a outer)
4. Spores hard to demonstrate, orange on chromagar

Answer 2

Clostridium pefringens

Question 3

1. GPB non hemolytic small medium opaque white colonies
2. Catalase POS, oxidase NEG
3. Scant growth on MAC
4. Colonies on BA either biotype intermedius (grey/transluscent) or mitis (like gravis but B haem)
5. Small, pleomorphic (gram stain)

Answer 3

Corynebacterium dipthaeriae var gravis

Question 4

1. GPB, narrow zone B haemolysis (like group B strep but antigen neg) small medium grey white colonies
2. VERY small colonies on MAC and LF, small colonies on MH
3. Catalase POS, GPB small and pleomorphic
4. Hippurate test POS, tumbling motility at RT POS o/n

Answer 4

Listeria monocytogenes

Question 5

1.GPC narrow zone of B haemolysis, small medium grey white colonies
2. Small LF colonies on MAC
3. Catalase NEG, group B pos
4. Hippurate pos, non motile, red on granada media

Answer 5

Streptococcus agalactiae

Question 6

1. GPC small grey white colonies with large zone B haemolysis, can have hockey puck effect
2. NG on MAC, Catalase NEG, Bacitracin sensitive on BA for throat swabs (any zone= S)
3. Group A pos, NG on MH, PYR test pos
4. treat with penicillin or erythromycin or clindamycin if S to penicillin and R to erythro

Answer 6

Streptococcus pyogenes

Question 7

1. GPC small grey white colonies with B haemolysis/non (most common) with bright pink pinpoint LF colonies on MAC
2. Catalase NEG, PYR pos 6.5% salt tolerant, group D pos, pinpoint on non enriched media

Answer 7

Enterococcus faecalis

Question 8

1. GPC, draughtsman= small medium green grey colonies w A haemolysis and flat depressed centre. Mucoid= small medium grey colonies shiny, still A haemolytic
2. NG on MAC, Catalase NEG, bile soluble and optochin sensitive, NG on MH

Answer 8

Streptococcus pneumoniae

Question 9

1. GPC cream white, LF on MAC creamy. non/B haemolytic
2. Catalase POS, coagulase POS, DNAse POS, cream with yellow pigment
3. at 48hrs centre dot visible

Answer 9

Staphylococcus aureus

Question 10

1. GPC medium grey white cream, LF on MAC creamy on single colonies. NON haemolytic
2. Catalase POS, coagulase NEG, DNAse NEG, creamy white on MH
3. Novobiocin S in urine

Answer 10

Staphylococcus epidermidis

Question 11

1. GPC VERY white colonies, non haemolytic, LF on MAC creamy on single colonies
2. Catalase POS, coagulase NEG, DNAse NEG, cream white on MH
3. Novobiocin R found in urine

Answer 11

Staphylococcus saprophyticus

Question 12

1. GPC (larger than staph), often forms tetrads, small canary YELLOW colonies and NLF on MAC
2. NON haemolytic, modified OX POS, coagulase NEG, yellow on MH

Answer 12

Micrococcus luteus