Microbiology and Immunology

Question 1

What are the common gram positive bacteria
-Types (4)
-Common property (2)

Answer 1

1. Types:
   -Staphylococcus - coccus
   -Streptococcus - coccus
   -Clostridium - baccili
   -Listeria - bacilli
2. Common properties
   -Thick polysaccharide - absorbs crystal violet
   -More likely to have exotoxins - toxic shock

Question 2

What are the common gram negative bacteria
-Types (5)
-Common properties (2)

Answer 2

1. Types:
   -Neisseria gonorrhoea /meningitidis (cocci)
   -E. coli
   -Haemophillis influenza
   -Klebsiella pneumonia
   -Spirochaetes
2. Common properties
   -Thin polysaccharide wall- can’t hold crystal blue, stains red
   -More likely to have endotoxins

Question 3

Discuss bactericidal antibiotics
-Mode of action
-Mechanism (2)
-Types of antibiotics (3)

Answer 3

1. MOA - kills bacteria
2. Mechanisms
   -Inhibits cell wall synthesis
   -Inhibits cell membrane synthesis
3. Types of antibiotics
   -Penecillins, cephalosporins, glycopeptides

Question 4

Discus bacteriostatic antibiotics
-Mode of action
-Mechanisms
-Types of antibiotics (5)

Answer 4

1. Mode of action - inhibits bacterial growth
2. Mechanisms
   -Inhibits cell DNA synthesis
   -Inhibits RNA synthesis
   -Inhibits protein synthesis
3. Types
   -Ciprofloxacin
   -Metronidazole
   -Rifampicin
   -Erythromycin / Azthromycin
   -Doxycycline

Question 5

What antibiotics have the following coverage
-Only gram positive (1)
-Gram negative only (2)
-Anaerobes cover only (1)
-Broad cover of Gram positive/negative and anaerobes (6)

Answer 5

1. Only gram positive
   -Flucloxacillin
2. Only gram negative cover
   -Azythromycin
   -Erythromycin
3. Anaerobes only cover
   -Metronidazole
4. Broad spec cover
   -Augmentin
   -Co-trimoxazole
   -Moxifloxacin
   -Cefuroxime
   -Ceftriaxone
   -The penems

Question 6

Discuss immunity in the pregnant mother
-Changes to acquired immunity (3)
-Changes to complement and acute phase proteins
-Changes to antibodies

Answer 6

1. Changes to acquired immunity
   -Activity of acquired immunity remain the same
   -Humoural tends to dominate
   -Cellular tends to be suppressed by progresterone
2. Changes to complement and acute phase proteins
   -Completement levels increase
   -APP levels increase
3. Changes to antibodies
   -Decreased levels of IgG, IgA, IgM, NK cell activity

Question 7

Discuss fetal immunity (3 points)

Answer 7

1. Fetus produces IgM from 11/40
2. Only IgG can cross the placenta by passive transport
3. Syncytiotrophoblasts don’t express MCH antigens