Infection

Question 0

What is virulence

Answer 0

The degree of pathogenicity within a group of parasites as indicated by fatality and ability to invade a host’s tissues

Question 1

5 stages of how microorganisms cause disease

Answer 1

Exposure Invasion Adherence Multiplication Dissemination

Question 2

Pathogenicity

Answer 2

Ability to cause disease. Determined by virulence factors

Question 3

List some virulence factors

Answer 3

Exotoxins Endotoxins

Question 4

What is a bacteriophage

Answer 4

Virus which infects and replicates within a bacterium

Question 5

What is a cluster of cocci called?

Answer 5

Staphylococci

Question 6

What is a chain of cocci called?

Answer 6

Streptococci

Question 7

What is in the infection model?

Answer 7

Patient - person, time, place Mechanism of infection - type of spread Infection - attachemnt? Toxins? Host defences? Inflammation? Damage? Management - diagnosis based in history, examination and investigations, treatment, infection prevention

Question 8

What is specific treatment?

Answer 8

A medicine that has properties especially useful for treatment of a disease eg antimicrobials, surgery

Question 9

What is supportive treatment?

Answer 9

Aimed at reinforcing patient’s own defences in overcoming a disease eg fluids

Question 10

Classification of antibiotics?

Answer 10

Antibacterials, antivirals, antifungals, antiprotozoa

Question 11

Classify further antibacterials

Answer 11

Bactericidal/bacteriostatic

Spectrum - broad, narrow

Target site/mechanism of action

Chemical structure

Question 12

Ideal features of antibiotics

Answer 12

Get to site of infection

Selective toxicity

Few adverse effects

Easy to take/administer (oral/IV)

Long half-life

No inteference with other drugs

Question 13

Give the classifications of antibiotics based on their mechansim of action

Answer 13

Protein synthesis

Cell wall synthesis

Nucleic acid synthesis

Cell membrane function

Question 14

What do beta-lactams do?

Answer 14

Inhibit petidoglycan cross-linking in cell walls. B-lactam ring binds to an enzyme which would normally do the cross-linking

Question 15

Examples of beta-lactams?

Answer 15

Penicillins

• Amoxicillin
• Penicillin
• Flucloxacillin

Question 16

What bacteria does amoxicillin target?

Answer 16

Gram positive mostly, some Gram negative

Upper respiratory tract infections

Streptococcus pneumoniae

Haemophilus influenzae

Enterococcus faecalis (endocarditis, UTIs)

Beta haemolytic streptococci

NOT ACTIVE AGAINST STAPH AUREUS

Question 17

Give some examples of antibiotics that inhibit cell wall synthesis

Answer 17

Penicillins and glycopeptides

Question 18

What do glycopeptides do?

Answer 18

Bind to amino acids in the cell wall preventing peptidoglycan cross-links

Affect Gram positive only

Question 19

Examples of glycopeptides

Answer 19

Vancomycin

Teicoplanin

Question 20

What bacteria does vancomycin affect?

Answer 20

Staph aureus (including MRSA)

Streptococci

Enterococci

C. diff

Question 21

Examples of antibiotics that affect protein synthesis?

Answer 21

Tetracyclines, aminoglycosides, macrolides

Question 22

How do tetracyclines work?

Answer 22

Lock tRNA to septal site of mRNA, blocking translation.

Question 23

Which bacteria do tetracyclines have an effect on?

Answer 23

Many Gram positives and some Gram negatives.

Question 24

How do aminoglycosides work?

Answer 24

Stop translation Potentially nephrotoxic and ototoxic

Question 25

What are aminoglycosides used to treat?

Answer 25

Endocarditis, UTIs, staph aureus, E. coli

Question 26

How do macrolides work? Which bacteria do they affect?

Answer 26

Bind to 50S ribosome, intefering with protein synthesis. Affect Gram positive cocci, chlamydia, anaerobes

Question 27

Which antibiotics affect cell membrane function and how?

Answer 27

Polymixins Interact with phospholipids so that cations and nucleic acids can leak out.

Question 28

Which bacteria do polymixins affect?

Answer 28

Gram negative

Question 29

3 methods of antibiotic resistance

Answer 29

Altered uptake Drug inactivating enzymes Altered target

Question 30

How does altered target work in drug resistance?

Answer 30

Lower affinity of target enzymes due to mutations

Question 31

How does altered uptake work in drug resistance?

Answer 31

Make themselves impermeable to drugs Eg E. coli is resistant to tetracyclines by acquisition of an efflux pump.

Question 32

How do drug-inactivating enzymes work?

Answer 32

Eg Staph aureus produce beta-lactamase breaking down beta-lactam ring in penicillin. Or add a chemical group to drugs eg aminoglycosides

Question 33

How do polyenes work?

Answer 33

Inhibit cell membrane function in fungal infections

Question 34

Give two types of polyenes and what they are used to treat

Answer 34

Nystatin - Candida Amphotericin - Sytemic fungal infections through an IV

Question 35

How do azoles work?

Answer 35

Used to treat yeasts and moulds. Inhibit cell membrane synthesis

Question 36

What does aciclovir do?

Answer 36

Inhibits viral DNA polymerase.

Question 37

What is aciclovir used against?

Answer 37

Herpes simplex Varicella zoster (chicken pox and shingles)