gram positive bacteria week 5

Question 1

what colour does gram stain show up for gram positive bacteria

Answer 1

purple

Question 2

what type of gram positive bacteria is anaerobic bacilli

Answer 2

clostridium spp.

• cl. tetani (tetanus)
• cl. perfiringens (gas gangrene, gastroenteritis)
• cl. difficile

Question 3

what type of bacteria is gram positive anaerobic cocci

Answer 3

anaerobic streptococci

Question 4

what are gram positive aerobic cocci clusters called

Answer 4

staphylococci

Question 5

what is gram positive aerobic staphylococci which is coagulase positive

Answer 5

staphylococcus aureus

Question 6

what is gram positive aerobic staphylococci which is coagulase negative

Answer 6

staphylococcus epidermidis

Question 7

what are gram positive aerobic cocci chains called

Answer 7

streptococci

Question 8

what are gram positive aerobic streptococci which are alpha haemolytic called

Answer 8

• streptococcus pneumoniae (pneumonia, meningitis)

- streptococcus ‘viridans’ (endocarditis)

Question 9

what is alpha haemolytic

Answer 9

partial haemolysis

- turn blood agar green

Question 10

what are gram positive aerobic streptococci which are beta haemolytic

Answer 10

• streptococcus pyogenes (group A strep.) e.g. pharyngitis, skin/soft tissue infections
• streptococcus agalactiae (group B strep.) e.g. neonatal infections

Question 11

what is beta haemolytic

Answer 11

complete haemolysis

- turn blood agar clear

Question 12

what is gram positive aerobic streptococci that is non-haemolytic

Answer 12

enterococcus spp. (UTI, endocarditis)

Question 13

what is gram positive aerobic small bacilli

Answer 13

• corynebacterium spp.

- listeria spp.

Question 14

what is gram positive aerobic small bacilli that is corynebacterium spp.

Answer 14

• corynebacterium diptheriae (diphtheria)

- diptheroids (skin colonisers)

Question 15

what is gram positive aerobic small bacilli that is listeria spp.

Answer 15

listeria monocytogenes (gastroenteritis, sepsis)

Question 16

what are gram positive aerobic large bacilli

Answer 16

bacillus spp.

Question 17

what are gram positive aerobic large bacilli that are bacillus spp.

Answer 17

• bacillus cereus (gastroenteritis)

- bacillus anthracis (anthrax)

Question 18

what is MRSA

Answer 18

methicillin resistant staphylococcus aureus

• poses major problems for infection prevention and control in hospitals
• commonly penicillin resistant due to production of penicillinase

Question 19

what is a gram positive coagulase negative staphylococcus you should beware of

Answer 19

staphylococcus lugdunensis

• mainly skin commensals
• form biofilms and may be significant pathogens in the presence of foreign bodies/prostheses e.g. pacemaker wires

Question 20

what groups are b haemolytic streptococci split into

Answer 20

groups A-G

• A, B, D, F clinically most important
• b haemolytic are further identified by carbohydrate surface antigens

Question 21

what is group A streptococci

Answer 21

streptococcus pyogenes

- pharyngitis, cellulitis, necrotising fasciitis (‘flesh eating’)

Question 22

what is group B streptococci

Answer 22

streptococcus agalactiae

- neonatal sepsis (meningitis, bacteraemia)

Question 23

what is group D streptococci

Answer 23

now re-classified as enterococcus spp.

• often non haemolytic
• found in gut as normal commensal
• cause of UTI and infective endocarditis

Question 24

staphylococcus aureus

Answer 24

• gram positive
• aerobic
• clusters
• coagulase positive

Question 25

streptococcus pyogenes

Answer 25

• gram positive
• aerobic
• chains
• b haemolytic

Question 26

streptococcus pneumoniae

Answer 26

• gram positive
• aerobic
• chains
• a haemolytic

Question 27

clostridium difficile

Answer 27

• gram positive
• anaerobic
• bacilli