Antibiotic Therapy

Question 1

What is an antibiotic?

Answer 1

A drug used to treat or prevent infection caused by microorganisms

Question 2

What is a bacteriostatic antibiotic?

Answer 2

One that inhibits the growth of bacteria

Question 3

What is a bacteriocidal antibiotic?

Answer 3

One that kills bacteria

Question 4

What does it mean for an antibiotic to have a narrow or broad spectrum?

Answer 4

It’s the range of microorganisms antibiotics affect

Question 5

What is selective toxicity?

Answer 5

Where an antibiotic doesn’t kill human cells, just bacteria

Question 6

What is the ideal antibiotic?

Answer 6

Selectively toxic
Bacteriocidal
Long half life
Appropriate tissue distribution
No adverse drug interactions or side effects 
Oral and parental preparations

Question 7

What does the half-life of an antibiotic affect?

Answer 7

How often dosages are taken

Question 8

Where are antibiotics that are absorbed excreted?

Answer 8

In the urine

Via the liver, biliary tract, and into the faeces

Question 9

What are the three methods of administering antibiotics?

Answer 9

Orally
Intravenously
Intramuscularly

Question 10

What is the disadvantage of taking antibiotics orally?

Answer 10

Much of the antibiotic is not absorbed and is excreted unchanged in the faeces

Question 11

What are common examples of antibiotic targets?

Answer 11

Cell wall
Ribosomes
DNA replication 
DNA gyrases
Metabolic pathways

Question 12

What are three types of commonly prescribed cell wall antimicrobials?

Answer 12

Penicilins
Cephalosporins
Glycopeptides

Question 13

What are examples of penicillins?

Answer 13

Penicillin
Amoxicillin
Flucloxacillin
Temocillin
Co-amoxiclav

Question 14

What is an example of a cephalosporin?

Answer 14

Ceftriaxone

Question 15

Are penillilins, cephalosporins and glycopeptides beta-lactam antibiotics?

Answer 15

Penicillins and cephalosporins are beta-lactam antibiotics

Glycopeptides are not beta-lactam antibiotics

Question 16

What are the targets of beta-lactams?

Answer 16

Penicillin Binding Proteins (PBPs)

Question 17

What is a beta-lactam antibiotic?

Answer 17

One with a beta-lactam ring in its molecular structure

Question 18

How do beta-lactams compromise the cell wall?

Answer 18

Act as a suicide substrate and halt cell wall synthesis

Question 19

What are the advantages of the penicillins?

Answer 19

Safe with few side effects
They have variety due to being very flexible with side groups and chains able to alter multiple features
Range from narrow to broad spectrum
Excreted via kidneys
Safe in pregnancy

Question 20

What are the limitations of the penicillins?

Answer 20

Patients can be allergic
Rapid excretion via kidneys requires frequent dosage
Resistance common

Question 21

What are examples of beta-lactams?

Answer 21

Penicillins
Cephalosporins
Carbapenems

Question 22

What is a gram positive penicillin?

Answer 22

Flucloxacillin

Question 23

What are gram positive and negative penicillins?

Answer 23

Amoxicillin

Co-amoxiclav

Question 24

What is a gram negative penicillin?

Answer 24

Temocillin

Question 25

What are the three principle compounds of penicillin?

Answer 25

Benzylpenicillin Phenoxymethyl penicillin Benzathine penicillin

Question 26

What are the advantages of amoxicillin?

Answer 26

Safe and well tolerated Well-absorbed when taken orally Low binding to plasma proteins and good tissue distribution

Question 27

What are the disadvantages of amoxicillin?

Answer 27

Effectiveness challenged by the spread of beta-lactamases

Question 28

What are beta-lactamases?

Answer 28

Enzymes that destroy the beta-lactam ring

Question 29

What is co-amoxiclav a combination of?

Answer 29

Amoxicillin and clavulanic acid

Question 30

What is clavulanic acid?

Answer 30

An inhibitor of beta-lactamase

Question 31

What spectrum does flucloxacillin have?

Answer 31

Narrow

Question 32

What is the advantage of temocillin?

Answer 32

It is beta-lactamase resistant | It is active against ESBL-producing organisms

Question 33

What is an ESBL-producing organism?

Answer 33

Extended spectrum beta-lactamase producing organism

Question 34

What are the advantages of cephalosporins?

Answer 34

``` Longer half life in plasma Excreted via kidneys and urine Few side effects, reduced allergy Safe in pregnancy More resistant to beta-lactamases ```

Question 35

What are the disadvantages of cephalosporins?

Answer 35

Broad spectrum so significantly affect normal bowel flora This allows the overgrowth of C. difficile Rarely used because of this

Question 36

What are the advantages of glycopeptides?

Answer 36

Bactericidal

Question 37

What are the disadvantages of glycopeptides?

Answer 37

Excreted via kidneys and urine | Only active against bacteria with gram positive cell wall, no activity against any gram negative organisms

Question 38

How do antibiotics that inhibit protein synthesis do so?

Answer 38

Attaching to bacterial ribosomes

Question 39

Are most antibiotics that inhibit protein synthesis bactericidal or bacteriostatic and why?

Answer 39

Bacteriostatic | usually protein synthesis can resume once antibiotic removed

Question 40

What is different about ahminoglycosides?

Answer 40

The binding of these to ribosomes in order to affect protein synthesis is lethal - bactericidal - instead of bacteriostatic

Question 41

What are examples of antibiotics targeting protein synthesis?

Answer 41

Aminoglycosides Tetracyclines Macrolides

Question 42

What is an example of an aminoclycoside?

Answer 42

Gentamicin

Question 43

What is an example of a tetracycline?

Answer 43

Doxycycline/minocycline

Question 44

What is an example of a macrolide?

Answer 44

Erythromycin

Question 45

How must gentamicin be given?

Answer 45

Intravenously

Question 46

What are the advantages of gentamicin?

Answer 46

Bactericidal Active against gram negative aerobic organisms Excreted in urine

Question 47

What is the disadvantage of gentamicin?

Answer 47

causes damage to kidneys and 8th cranial nerve

Question 48

What is the mode of action of tetracyclines?

Answer 48

Actively transported into cell and binds to 30S subunit

Question 49

What are the advantages of tetracyclines?

Answer 49

Broad spectrum so useful against intracellular bacteria and atypical bacteria

Question 50

What are the disadvantages of tetracyclines?

Answer 50

Resistance is increasing | Destruction of normal flora due to bored spectrum results in increased secondary infections

Question 51

What are examples of the macrolides?

Answer 51

Erythromycin Clarythromycin Azithromycin

Question 52

What antibiotics affect nucleic acids?

Answer 52

Metronidazole Trimethoprim Fluoroquinolones

Question 53

What is the primary use of trimethoprim?

Answer 53

UTIs

Question 54

What is metronidazole active against?

Answer 54

Anaerobes

Question 55

What is the mode of action of quinolones?

Answer 55

Bind to the A subunit of DNA gyrase and prevent supercoiling of DNA to indirectly inhibit DNA synthesis

Question 56

What are inhibitors of folic acid synthesis?

Answer 56

Thymidine Purines Methionine

Question 57

What are common side effects of antibiotics?

Answer 57

Nausea Vomiting Diarrhoea

Question 58

Why are antibiotics sometimes given in combinations?

Answer 58

To cover a broad range of possible infecting organisms To prevent the development of resistance For the synergistic effect of combination

Question 59

What should you never combine?

Answer 59

Bacteriostatic and bactericidal

Question 60

What antibiotics should be avoided and why?

Answer 60

``` Cephalosporins Co-amoxiclav Ciprofloxacin Clindamycin Particularly associated with an increased risk of c. diff ```