Antibiotics

Question 1

Name 3 important types of G +ve cocci

Answer 1

Staphylococci, Streptococci, Enterococci.

Question 2

Name 2 important types of G -ve cocci

Answer 2

Neisseria Meningitidis, N. Gonorrhoea.

Question 3

Name 5 important types of G +ve bacilli

Answer 3

Clostridia, Corynebacterium, Bacillus, Lactobacillus, Mycobacterium.

Question 4

Name 4 important types of G -ve bacilli

Answer 4

E coli, Pseudomonas, salmonella, Haemophilus influenzae.

Question 5

Name 2 important types of G -ve spirilla

Answer 5

Campylobacter and Helicobacter.

Question 6

Which type of bacteria is Metronidazole particularly good against and in which context might it be given?

Answer 6

Anaerobes- prophylaxis for ‘dirty’ gut surgery.

Question 7

Classify the pathogen “cryptococcus neoformans”.

Answer 7

Despite the name suggesting it’s a coccus bacteria, it’s actually a fungus. It may cause meningitis or blindness.

Question 8

Suggest ways in which antibiotics may be classified.

Answer 8

Bactericidal or Bacteriostatic, Broad spectrum or narrow spectrum, the Target site, and the Chemical structure.

Question 9

Which types of antibiotics affect cell wall synthesis?

Answer 9

Beta lactams and glycopeptides.

Question 10

Which types of antibiotics affect protein synthesis?

Answer 10

Tetracyclines, aminoglycosides, macrolides.

Question 11

Which types of antibiotics affect nucleic acid synthesis?

Answer 11

Quinolones, rifampicin.

Question 12

Give a brief description of the mechanism of action of penicillin.

Answer 12

Inhibits Penicillin Binding Protein from forming the cross links in the cell wall.

Question 13

Give a brief description of the mechanism of action of vancomycin.

Answer 13

Binds to the chains of the cell wall, preventing PBP from binding to form cross links between them.

Question 14

Outline mechanisms of antibiotic resistance.

Answer 14

Microbe produces drug inactivating enzymes (e.g. Beta lactamases), the target of the antibiotic is altered, or the permeability of the wall is reduced so the drug can’t reach it’s target.

Question 15

Outline mechanisms of resistance transfer.

Answer 15

Reproduction, or horizontal transfer via conjugation (direct), transduction (viral vector), or transformation (freely through the cell wall).

Question 16

What type of antibiotic is penicillin and what type of bacteria is it mostly effective against?

Answer 16

Beta lactams- effective against G +ve cocci.

Question 17

What type of antibiotic are cephalosporins and when might they be used?

Answer 17

Beta lactam. Ceftriaxone has good activity in the CSF- meningitis. However, there is general cause for concern about their association with C difficile.

Question 18

What type of antibiotic are carbapenems and what type of bacteria are they mostly effective against? When might they be used?

Answer 18

Beta lactam. Broad spectrum, active against most G -ve bacteria, but resistance is developing. May be used in Sepsis.

Question 19

What type of antibiotic is vancomycin and what type of bacteria is it mostly effective against?

Answer 19

Glycopeptide. G +ve, NOT absorbed by the gut, has a narrow therapeutic window so requires monitoring.

Question 20

What type of antibiotic are tetra- and doxycycline and what type of bacteria are they mostly effective against?

Answer 20

Tetracyclines. Broad spectrum, useful for penicillin allergy, usually given for G +ve.

Question 21

What type of antibiotic is gentamicin and what type of bacteria is it mostly effective against? When might they be used?

Answer 21

Aminoglycoside. Used vs G -ve, has good activity in blood and urine BUT may be nephrotoxic and damage the ears. Generally reserved for severe G-ve sepsis.

Question 22

What type of antibiotic is erythromycin and what type of bacteria is it mostly effective against?

Answer 22

Macrolide. Good alternative to penicillin for mild G +ve infections.

Question 23

What type of antibiotic is ciprofloxacin and what type of bacteria is it mostly effective against?

Answer 23

Quinolone. V active against G -ve, however there is increasing resistance from C diff.

Question 24

What type of antibiotic is trimethoprim and how does it work, and when might it be used?

Answer 24

Antifolate DHFR inhibitor. Inhibits folic acid synthesis, which ultimately inhibits bacterial DNA synthesis. Used for UTI.

Question 25

What type of medication is fluconazole and what type of pathogen is it mostly effective against?

Answer 25

Antifungal. Inhibits cell membrane synthesis, used to treat Candida.

Question 26

What type of medication is amphotericin and what type of pathogen is it mostly effective against?

Answer 26

Antifungal. Used in IV treatment of serious systemic fungal infections e.g. aspergillus.