Infection 4 Intro To Antibiotics

Question 1

Antimicrobial classification

Answer 1

Antibacterial agents
Antifungal agents
Antiviral agents
Antiprotozoal agents

Question 2

Antibacterial agents classification

Answer 2

Bactericidal or bacteriostatic
Spectrum - broad vs narrow
Target site (mechanism of action)
Chemical structure - antibacterial class

Question 3

What needs to be considered when choosing an antibiotic?

Answer 3

Cause of infection
Is it active against target organism?
Does it reach the site of infection?
Is it available in the right formulation? IV vs oral
Half life
Interaction with other drugs
Toxicity issues?
Drug monitoring needed?

Question 4

Ways to measure antibiotic activity

Answer 4

• Disc sensitivity - paper on agar plate for zone of inhibition
• Minimal inhibitory concentration - first conc. of antibiotic that inhibits bacterial growth

Question 5

What is a minimum inhibitory concentration test and what is it done via?

Answer 5

Test to identify the first conc. of antibiotic that inhibits bacterial growth
Done via broth microdilution or E-test strip

Question 6

What is a bactericidal antibiotic?

Answer 6

Lethal to bacteria

Question 7

What is a bacteriostatic antibiotic?

Answer 7

Stops/slows growth + reproduction

Question 8

What is a broad spectrum antibiotic?

Answer 8

Attack a wide variety of bacteria

Question 9

What is a narrow spectrum antibiotic?

Answer 9

Specific to only a few types of bacteria

Question 10

What type of antibiotics inhibit cell wall synthesis?

Answer 10

Beta-lactams - penicillins, cephalosporins
Glycopeptides e.g. vancomycin

Question 11

Examples of beta-lactams

Answer 11

Penicillins
Cephalosporins
Cerbapenems

Question 12

Mechanism of action of beta-lactams

Answer 12

Inhibit cell wall synthesis

Question 13

Mechanism of action of glycopeptides

Answer 13

Inhibits cell wall synthesis

Question 14

What type of antibiotics inhibit cell membrane function?

Answer 14

Polymixins

Question 15

Example of polymixin antibiotic

Answer 15

colistin

Question 16

What type of antibiotics inhibit nucleic acid synthesis?

Answer 16

Quinolones - DNA gryase
Trimethoprim - folate synthase
Rifampicin - RNA polymerase

Question 17

What drugs are penicillins?

Answer 17

Penicillin
Amoxicillin
Flucoxacillin

Question 18

Suffix of penicillins

Answer 18

-cillin

Question 19

Prefix of cephalosporins

Answer 19

Cef-

Question 20

What drugs are cephalosporins?

Answer 20

Ceftriaxone

Question 21

Suffix of carbapenems

Answer 21

-penem

Question 22

What drugs are carbapenems?

Answer 22

Mecropenem
Imipenem

Question 23

What drugs are glycopeptides?

Answer 23

Vancomycin
Teicoplanin

Question 24

Examples of a drug which is a quinolones?

Answer 24

Ciprofloxacin

Question 25

Suffix of quinolones

Answer 25

-floxacin

Question 26

What type of antibiotics inhibit protein synthesis?

Answer 26

Tetracyclines Aminoglycosides Macrolides

Question 27

Mechanism of action of polymixins

Answer 27

Inhibit cell membrane function

Question 28

Mechanism of action of quinolones

Answer 28

Inhibit nucleic acid synthesis - DNA gyrase

Question 29

Mechanism of action f trimethoprim

Answer 29

Inhibit nucleic acid synthesis - folate synthesis

Question 30

Mechanism of action of rifampicin

Answer 30

Inhibit nucleic acid synthesis - RNA polymerase

Question 31

Mechanism of action of tetracyclines

Answer 31

- Inhibit protein synthesis - Act on 30s ribosome subunit

Question 32

Mechanism of action of aminoglycosides

Answer 32

- Inhibit protein synthesis - Act on 30s ribosome subunit

Question 33

Mechanism of action of marcolides

Answer 33

- Inhibit protein synthesis - Act on 50s ribosome subunit

Question 34

Mechanisms of antibiotic action against bacterial cells

Answer 34

Inhibition of cell wall synthesis Inhibition of cell membrane function Inhibition of protein synthesis Inhibition of nucleic acid synthesis

Question 35

What are penicillins good against?

Answer 35

Mainly streptococci

Question 36

Why is *ceftriaxone* good a treating meningitis?

Answer 36

Good level of activity in CSF as it can cross the blood brain barrier

Question 37

Examples of tetracyclines

Answer 37

*doxycycline* *tetracycline*

Question 38

What are tetracyclines good against? Example

Answer 38

Gram positive bacteria *doxycycline* *tetracycline*

Question 39

What are aminoglucosides good against? Example

Answer 39

Gram negative bacteria *gentamicin*

Question 40

Examples of macrolides

Answer 40

*Clarithromycin* *Erythromycin*

Question 41

Mechanisms of *aciclovir* Use

Answer 41

Inhibits viral DNA polymerase Herpes simplex Varicella zoster - chicken pox + shingles

Question 42

What does *metronidazole* target? Use

Answer 42

**Anaerobic bacteria** - C.difficle Protozoa

Question 43

What are the three types of antibitoics resistance?

Answer 43

- **intrinsic**: no target - permanent - **acquired**: acquires new genetic material or mutates - permanent - **adaptive**: only resistant when exposed to antibiotic - susceptible once antibiotic is removed

Question 44

What is amoxicillin good against?

Answer 44

Gram negative bacteria

Question 45

Mechanism of *oseltamivir* Use

Answer 45

Inhibits viral neuraminidase Influenza A + B

Question 46

What are two subgroups of antifungals?

Answer 46

Azoles Polyenes

Question 47

Mechanism of azoles Examples + uses

Answer 47

Inhibit cell membrane synthesis *flucanazole*- **candida**

Question 48

Mechanism of polyenes Examples and uses

Answer 48

Inhibit cell membrane function *nystatin* - **candida**

Question 49

Consequences of antibacterial resistance

Answer 49

Treatment failure Prophylaxis failure Economic costs

Question 50

Mechanism of antibiotic resistance

Answer 50

- enzymatic modification of enzyme - enzymatic alteration of antibiotic targets - mutation of bacterial target site

Question 51

Outline horizontal gene transfer

Answer 51

Plasma in donor shared through pili between DNA Can share to more DNA

Question 52

Why is *co-amoxiclav* more commonly prescribed than *amoxicillin* alone?

Answer 52

*co-amoxiclav* contains a beta lactamase inhibitor Helps combat the resistance to *amoxicllin*

Question 53

What are the classes of antibacterials?

Answer 53

Inhibition of: - Cell wall synthesis - Cell membrane function - Nucelic acid synthesis - Protein synthesis

Question 54

Generally, antibitoics that begin with C (not co-) have an association with what?

Answer 54

Clostridioides difficile infection

Question 55

Define antibiotic cross reactivity?

Answer 55

A hypersensitivity reaction to an antibiotic that is similar in structure to an antibiotic with a known allergy