Gram positive- Adam

Question 1

List clinically significant Gram positive bacteria

Answer 1

Staphylococcus aureus
Streptococcus pyogenes
Streptococcus pneumoniae
Clostridium difficile

Question 2

Difference between staphylococci and streptococci/enterococci

Answer 2

Staphylococci = clusters
Streptococci & enterococci = chains

Question 3

What is Staphylococcus aureus

Answer 3

• gram positive
• Coagulase positive
• commensal carried in nose, axial, perineum
• Causes septicaemia and osteomyelitis
• Commonly penicillin resistant due to production of penicillinase
• By different mechanism some strains methicillin resistant staph aureus (MRSA)
  o Major problem for infection prevention and control in hospital

Question 4

What is streptococcus pyogenes

Answer 4

Gram positive
- Beta-haemolytic streptococci
- Pharyngitis
- Cellulitis
- Necrotising fasciitis

Question 5

what is streptococcus pneumoniae

Answer 5

Gram positive
- Alpha-haemolytic streptococci
- Pneumonia, meningitis, septicaemia

Question 6

What is clostridium dificile

Answer 6

Gram positive
Anaerobic bacilli
- Important cause of diarrhoea, associated with toxin production and potentially fatal
- Increased risk with antibiotic use and anything else that disrupts normal gut flora
- Transmitted via spores
- Detect antigen and toxin in stool sample

Question 7

How are streptococci chains identified

Answer 7

Haemolytic tests
Can be:
a-haemolytic- green agar
b-haemolytic- clear agar
Non-haemolytic- no difference

Question 8

How are staphylococci identified

Answer 8

Coagulase test
Can be positive / negative

Question 9

What are the different bacilli

Answer 9

Small and large