Lecture 7 - Antibiotics And Resistance

Question 1

What are categories of antimicrobials?

Answer 1

Anti-bacterials
Anti-fungal
Anti-viral
Anti-protozoals

Question 2

What does it mean if an Antibacterial is Bactericidal?

Answer 2

Completely kills bacteria

Question 3

What does it mean if an antibiotic is Bacteriostatic?

Answer 3

Prevents bacterial replication

Question 4

What is meant by a broad spectrum antibiotic?

Answer 4

Targets lots of different types of bacteria

Question 5

What are some examples of broad categories that a broad spectrum antibiotic might act on?

Answer 5

Gram +
Gram -
Anaerobic

Question 6

How can antibiotics sensitivity/effectiveness be measured?

Answer 6

Paper disc soaked in antibiotic
Disc placed in agar culture of bacteria
Area of clearance measured (diameter)
Larger diameter = more effective

Question 7

What is MIC (Minimum Inhibitory Concentration)?

Answer 7

The minimum concentration of antimicrobial agent which visibly inhibits growth

Question 8

What are the 4 main mechanisms of action of anti bacterial?

Answer 8

Cell wall synthesis Inhibitors
Proteins synthesis inhibitors
Nucleic acid synthesis Inhibitors
Cell membrane function Inhibitors

Question 9

What type of mechanism of antibacterial action does Penicillin have?

Answer 9

Cell wall synthesis inhibitor

Question 10

How does Penicllin actually act as a cell wall synthesis inhibitor?

Answer 10

Prevents formation of cross linkages in cell wall

It binds to the penicillin binding protein which prevents the binding protein forming cross linkages

Question 11

What are the 2 types of antibiotic resistance?

Answer 11

Intrinsic

Acquired

Question 12

What is intrinsic antibiotic resistance?

Answer 12

When a species is naturally resistant to an antibiotic

Question 13

Why do some bacteria have intrinsic antibiotic resistance?

Answer 13

The specific characteristics that the antibiotic targets not on bacteria

Doesn’t have target protein on bacteria surface

Question 14

What is acquired antibiotic resistance?

Answer 14

When new genetic material is acquired or mutation occurs

Question 15

How does a bacteria get acquired immunity from acquiring new genetic material?

Answer 15

Horizontal gene transfer (Plasmid)

Question 16

What is the process of horizontal gene transfer?

Answer 16

Pili between donor and recipient bacteria extend and conjugate with each other
Donor plasmid replicates
Single stranded DNA from plasmid enters into recipient

Question 17

What is adaptive antibiotic resistance?

Answer 17

When the bacteria responds to a stress (like low levels of antibiotic)

Question 18

What are the mechanisms for antibiotic resistance (acquired)?

Answer 18

-Enzyme modification to destroy antibiotics
-Enzyme modification to change the target for antibiotic (cant bind)
-Target for antibiotic mutates and changes (cant bind)

Question 19

What mechanism of action do Beta-lactams have?

Answer 19

Cell wall synthesis inhibition

Question 20

What antibiotics are in the Beta-lactam family?

Answer 20

-Penicillins
-Cephalosporins
-Carbapenems
-Glycopeptides

Question 21

What are the penicillins?

(Order is most narrow spectrum at the top, most broad spectrum at the bottom)

Answer 21

Benzylpenicillin
Penicillin V
Amoxicillin
Flucloxacillin

Question 22

What is an example of a Cephalosporin?

Answer 22

Ceftriaxone

Question 23

What are some Carbapenems?

Answer 23

Meropenem
Imipenem

Question 24

What IV antibiotic is commonly given as a first line defence to sepsis?

Answer 24

Ceftriaxone

Question 25

What bacteria does penicillin usually work on?

Answer 25

Streptococci (Gram +)

Question 26

What bacteria does Amoxicillin work on?

Answer 26

Gram + and some Gram -

Question 27

What does Flucloxacillin work against?

Answer 27

Staphylococci and Streptococci (Both gram +)

Question 28

Why do you typically pair cephalosporins with another antibiotic?

Answer 28

They have no anaerobe activity

Question 29

What type of infections are Carbapenems used for? What group of people to you have to be careful using carbapenems like meropenem and imipenem with?

Answer 29

Gram negative infections Normally safe with penicillin allergy but safer to avoid Very broad spectrum (inc anaerobes)

Question 30

What are 2 glycopeptides?

Answer 30

-Vancomycin -Teicoplanin

Question 31

What bacteria does Vancomycin and Teicoplanin act against?

Answer 31

Gram +

Question 32

How is vancomycin usually administered and why?

Answer 32

IV antibiotic Not absorbed into the body in the gut

Question 33

When is Vancomycin delivered orally? What infection is it used for and why?

Answer 33

With C.difficile Stays in the lumen of the gut since it can’t be absorbed

Question 34

What are the major side effects/concerns with cephalosporins?

Answer 34

C.difficile infection

Question 35

When is Teicoplanin usually given instead of Vancomycin?

Answer 35

When patient no longer in hospital (IV is more difficult)

Question 36

When is a Tetracycline e.g Doxycycline used?

Answer 36

Penicillin allergy Gram + bacteria But is Broad spectrum

Question 37

How are tetracyclines (doxycycline) always given?

Answer 37

Oral

Question 38

Who should never receive tetracyclines like doxycycline and why?

Answer 38

Children younger than 12yrs Pregnant or Breastfeeding women Causes staining of developing bones and teeth

Question 39

What mechanism of action do tetracyclines act by?

Answer 39

Protein synthesis inhibition

Question 40

What are 3 groups of antibiotics that act via the protein synthesis inhibition mechanism?

Answer 40

-Aminoglycosides -Tetracyclines -Macrolides ATM Go to the ATM because protein is expensive AF

Question 41

What is the most common Aminoglycoside? What is the mechanism of action of this antibiotic?

Answer 41

Gentamicin Protein synthesis inhibition

Question 42

When are Amino-glycosides mainly used/reserved for?

Answer 42

Severe Gram negative sepsis Good against gram negative bacteria

Question 43

Why are Aminoglycosides like gentamicin reserved for severe gram negative sepsis?

Answer 43

Potentially nephrotoxic so requires constant monitoring since its easy to reach toxic levels

Question 44

What is an example of a Macrolides? What is the mechanism of action of this antibiotic?

Answer 44

Erythromycin Protein synthesis inhibition

Question 45

What ribosome subunit do tetracyclines and Aminoglycosides target?

Answer 45

30s

Question 46

What subunit do Macrolides and Linezolids target?

Answer 46

50s

Question 47

What are 3 groups of Nucleic acid synthesis inhibitors (DNA or RNA)?

Answer 47

-Quinolones -Trimethoprim -Rifampicin

Question 48

What is the most common Quinolone? What is this antibiotics method of action?

Answer 48

Ciprofloxacin Nucleic acid synthesis inhibition

Question 49

What are the risks surrounding use of Quinolones like Ciprofloxacin?

Answer 49

Risk of Tendinitis and rupture (Achilles tendon) Aortic dissection (tearing of aorta) C.difficile

Question 50

How do Trimethoprim and sulphonamides inhibit DNA synthesis in a bacteria?

Answer 50

Inhibits folic acid synthesis

Question 51

What is Co-trimoxazole?

Answer 51

Trimethoprim + sulphamethoxazole

Question 52

What microorganism is Co-trimoxazole used to treat? What disease does this microbe usually cause? When is this infection commonly seen?

Answer 52

Pneumocystis jirovecii (PJP) A fungal pneumonia Causes Pneumocystis pneumonia Pneumocystis pneumonia commonly seen in patients with HIV infection (immunocompromised)

Question 53

What disease does the organism Pneumocystis jirovecii cause?

Answer 53

PCP (Pneumocystis pneumonia)

Question 54

What is PCP and who are more prone to developing it?

Answer 54

A fungal pneumonia caused by the fungus Pneumocytis jirovecii People with HIV/AIDS

Question 55

What are the 2 categories of Antifungals?

Answer 55

-Azoles -Polyenes

Question 56

What is the mechanism of action of Azoles? What category of anti-microbial are they?

Answer 56

Inhibit cell-membrane synthesis Anti-fungal

Question 57

What are the most common Azoles?

Answer 57

Fluconazole Itra/Vori/posaconazole

Question 58

What does Fluconazole treat?

Answer 58

Candida (thrush)

Question 59

What Itra/vori/posaconazole used to treat?

Answer 59

Aspergillus

Question 60

What are 2 polyenes? What broad category of anti-microbial are these a part of?

Answer 60

Nystatin Amphotericin Anti-fungal

Question 61

What is nystatin used for?

Answer 61

Topical treatment of Candida

Question 62

What is Amphotericin used to treat? What category of anti-microbial is it?

Answer 62

Systemic fungal infections (Aspergillus) via IV Anti-fungal

Question 63

What are 2 Antivirals?

Answer 63

Acyclovir Oseltamivir

Question 64

What does Acyclovir treat?

Answer 64

Herpes simplex (genital herpes + encephalitis) Varicella zoster - chicken pox and shingles

Question 65

What does Oseltamivir treat?

Answer 65

Influenza A and B

Question 66

What microbes does Metronidazole work against?

Answer 66

Its an: Antibacterial (anaerobic) Antiprotozoal

Question 67

What Protozoa is Metronidazole effective against?

Answer 67

Amoebae (dysentery and systemic) Giardia (diarrhoea) Trichomonas vaginalis (vaginitis)