Bacteria

Question 1

What is toxic shock syndrome and what is it caused by?

Answer 1

Inflammatory disease characterised by high fever, headache, diarrhoea, vomiting, irritability, sore throat, and rash. Caused by an exotoxin—that is, a toxin secreted by bacteria acting as a superantigen to up regulate The cell activation, primarily Staphylococcus aureus or Streptococcus pyogenes

Question 2

What are the microbiological features of Staphylococci?

Answer 2

clustered cocci, gram +ve, non-spore-forming, non-motile, facultative anaerobes (not requiring O2) E.g. S. aureus

Question 3

What are the microbiological features of Streptococci?

Answer 3

gram +ve and non-motile eg. Strepotococcus pyrogenes

Question 4

What are the histological features of Acid-fast bacteria?

Answer 4

Thick waxy walls, cant remove stain with acid and doesn’t stain well with Gram, need specific acid stain e.g. Ziehl-Neelsen stain

Question 5

What are the O and H antigens of E.coli?

Answer 5

O antigen (polysaccharide component of LPS) H antigen (flagella)

Question 6

What are ‘sex’ pilli?

Answer 6

Hair-like appendages involved in transfer of plasmids between bacteria

Question 7

What are the functions of a capsule?

Answer 7

-protect against dehydration and phagocytosis Contribute to virulence: • Electrostatic repulsion - enhance -ve charge and make it easier to ingest • Resemble host components • Mask underlying structures - menigicoccus group B have a non-antigenic capsule

Question 8

What are endospores?

Answer 8

Specialised, resistant, dormant structure (and can survive for prolonged periods), Do not replicate, resistant to harsh conditions

Question 9

What are the differences between exotins and endotoxins?

Answer 9

Question 10

What are the targets of exotoxins?

Answer 10

• Intact host cells

via haemolysin, leucocidins

• Extracellular matrix

via hyaluronidase, collagenase

• Other host molecules

• lipid, fibrin, nucleic acids, etc.