Session 1 And 2

Question 1

Describe the basic infection model.

Answer 1

Pathogen infects patient; pathogens mechanism of infection begins; infection is identified and managed; outcome varies depending on management (get better or worse/death).

Question 2

Which fungi are unicellular and which are multicellular?

Answer 2

Yeast are uni-, mounds are multi-.

Question 3

Which parasites are unicellular and which are multicellular?

Answer 3

Protozoa are uni-, helminths are multi-.

Question 4

Classify bacteria, fungi and parasites as either prokaryotic or eukaryotic.

Answer 4

Bacteria: prokaryotes
Fungi: eukaryotes
Parasites: eukaryotes

Question 5

What is contiguous spread of infection?

Answer 5

Pathogen moves from a part of the body where it is usually found to one where it isn’t and results in infection

Question 6

What is innocuous spread of infection?

Answer 6

Infection due to inoculation, e.g. surgical site infections or infection from splinter injuries.

Question 7

WHat is infection via ingestion?

Answer 7

Infection due to eating/drinking a pathogenic microorganism.

Question 8

What does infection by ingestion usually result from?

Answer 8

Fecal-oral transmission.

Question 9

What is infection via inhalation?

Answer 9

Infection due to breathing in a pathogen as a droplet or aerosol.

Question 10

What is infection via a vector?

Answer 10

Infection caused by contact with an organism carrying a pathogen.

Question 11

What is infection via vertical transmission?

Answer 11

Infection transmitted to a baby from its mother in utero, delivery or breastfeeding.

Question 12

By what mechanisms may a pathogen cause infection?

Answer 12

By directly damaging cells, causing inflammation, via endotoxins release.
Usually damage is due to hosts inflammatory response.

Question 13

How can antimicrobials be classified?

Answer 13

By type of organism they act on; bactericides/bacteriostatic properties; broad/narrow spectrum; by target site; by chemical structure.

Question 14

What are the ideal features of an antimicrobial agent?

Answer 14

Selective toxicity; few adverse effects; able to reach site of infection; both oral and IV formation availability; long half-life; no interference with other drugs.

Question 15

How does penicillin operate?

Answer 15

Inhibits transpeptidase enzymes so crosslinking in the cell wall cant occur. An imbalance between synthesis and degredation results causing the cell wall to become more fluid so the cell dies.

Question 16

What is penicillin effective against and why?

Answer 16

Gram positive bacteria, particularly streptococci, staphylococci, clostridium and listeria.
Not effective against gram negative bacteria as they have a protein layer outside their peptidoglycan layer in the cell wall so penicillin is blocked from attaching.

Question 17

What is vancomycin’s mechanism of action?

Answer 17

It binds to amino acid residues in the cell wall which prevents penicillin-binding protein from attaching. This prevents cross-links from forming so the cell wall becomes more fluid and the cell dies.

Question 18

What is vancomycin effective against and why?q

Answer 18

Gram positive bacteria, gram negative bacteria have a different method of cell wall synthesis so vancomycin is ineffective in them.

Question 19

What infections is vancomycin typically used against?q

Answer 19

Severe sepsis, MRSA, severe skin, bone and LRT infections.

Question 20

How do fluoroquinolones work?

Answer 20

Target enzymes involved in DNA replication in bactaeria, usually DNA gyrase in gram -ve bactaeria and topoisomerase in gram +ve bactaeria.

Question 21

By what mechanisms may antibiotic resistance occur?

Answer 21

Drug may be inactivated; target enzyme may be altered; antibiotic uptake may be altered.

Question 22

How can antibiotic sensitivity be tested for?

Answer 22

Using disc sensitivity testing: if growth is inhibited then the microbe isn’t resistant.

Question 23

How can the minimum inhibitory concentration of an antibiotic be determined?

Answer 23

Use test tubes containing known concentrations of antibiotic and introduce the organism to them. If a turbid broth is formed then growth isn’t inhibited

Question 24

What is penicillin mainly effective against?

Answer 24

Streptococci.

Question 25

What is flucloxicillin effective against?

Answer 25

Staphylococci and streptococci.

Question 26

What feature of cephalosporins make them effective against meningitis?

Answer 26

Can penetrate the CSF

Question 27

What group of microbes do cephalosporins have no effect on?

Answer 27

Anaerobes.

Question 28

Tetracyclines can be given as an alternative treatment if a patient has what allergy?

Answer 28

Penicillin

Question 29

What is gentamycin effective against?

Answer 29

Gram negative bacteria.

Question 30

What type of infection is trimethoprim often used against?

Answer 30

UTIs

Question 31

Name some antiviral agents.

Answer 31

Aciclovir, tamiflu.