Bacterial Classification

Question 1

How are streptococci categorised?

Give examples of each

Answer 1

Haemolysis
Gamma haemolysis (no haemolysis) - enterococcus (gut commensal, UTI)
Alpha haemolysis (partial haemolysis) - strep viridans (endocarditis), strep pneumoniae (pneumonia, meningitis)
Beta haemolysis (complete haemolysis) - Group A Strep - Strep Pyogenes (throat, skin infection)

Question 2

How are staphylococcus categorised?

Answer 2

Coagulase
Coag +ve - staph aureus (wound/skin infections, nose commensal)
Coag -ve - staph epidermidis (skin commensal, IV line infection)

Question 3

Describe streptococci

Answer 3

Aerobic gram positive cocci in chains

Question 4

Describe staphylococci

Answer 4

Aerobic gram positive cocci in clusters

Question 5

Name some gram positive small aerobic bacilli and what they cause

Answer 5

Corynebacterium species
Corynebacterium diptheriae - diptheria
Diptheriods - skin commensal

Question 6

Name some gram positive large aerobic bacilli and what they cause

Answer 6

Bacillus cerus - food poisoning (rice)

Bacillus anthrax - anthrax

Question 7

Name some gram positive anaerobic bacilli and what they cause

Answer 7

Clostridium sp,
C tetani - tetanus
C perfringens - gas gangree
C difficile - antibiotic-associated colitis

Question 8

Name some gram negative strict aerobic bacilli and what they cause

Answer 8

Legionella - pneumonia (air conditioning)

Pseudomonas aeruginosa - pneumonia

Question 9

Describe Neisseria. Give types and what they cause

Answer 9

Gram negative aerobic cocci
N gonorrhoea - gonorrhoea
N meningitides - meningitis

Question 10

Describe coliforms. Give examples

Answer 10

Large gram negative aerobic bacilli
E coli
Klebsiella
Proteus
Can cause UTI, wound infection

Question 11

Describe haemophilus influenza. What does it cause?

Answer 11

Small anaerobic gram negative bacillus

Acute exacerbation COPD

Question 12

Describe bordetella pertusis. What does it cause?

Answer 12

Small gram negative aerobic bacillus

Whooping cough

Question 13

Describe campylobacter

Answer 13

Gram negative small curved microaerophilic bacilli

Most common cause of gastroenteritis in the UK

Question 14

Describe helicobacter

Answer 14

Gram negative microaerophilic spiral bacili

Question 15

Describe bacteriodes. What does it cause?

Answer 15

Gram negative anaerobic bacilli

Wound infection