Antibiotics

Question 1

What are the 2 main mechanisms of antimicrobial action

Answer 1

1. Time dependent killing
2. Concentration dependent killing

Question 2

Where do beta lactams act

Answer 2

They act on the cell wall of the bacteria

Question 3

What is the mechanism of killing in a betalactam

Answer 3

They use time dependent killing

Question 4

What is the mechansim of elimination

Answer 4

Renal elimination

Question 5

What is the main adverse effects of beta- lactams

Answer 5

Hypersensitivity

Question 6

What is the most common resistance method in bacteria against beta lactams

Answer 6

Beta- lactamases: These are enzymes that are able to degrade β-lactam antibiotics and it can not be overcome by increasing the conc.

Question 7

What is the method of resistance in betalactams that can be overcome by increasing the dose

Answer 7

Mutations in penicillin binding protein, reducing the ability of β-lactam antibiotics to bind and inhibit their activity

Question 8

How do beta lactams work

Answer 8

They work by binding to Penicillin-Binding Proteins, these Penicillin-Binding Proteins catalyze the final step in peptidoglycan synthesis and so it weaken or increased the cell wall permeability leading to death of the cell

Question 9

What are the microbe classes that are susceptible to beta lactams

Answer 9

Gram positive and spirochetes

Question 10

What types of bacteria are susceptible to penicillin 5

Answer 10

Streptococci
Syphilis
Enterococci
Listeria
Actinomyces

Question 11

What are aminopenicillins and what are the 2 main types

Answer 11

They are subclass of penicillins within the β-lactam class of antibiotics. They are distinguished by an added amino group (-NH2) on the penicillin structure, which enhances their spectrum of activity against certain Gram-negative bacteria while retaining activity against Gram-positive bacteria. They 2 main types are Ampicillin and Amoxicillin

Question 12

What is the main benefit of Cloxacillin and what bacteria is it used on

Answer 12

It is good at working in beta lactamase enviroments

Question 13

Which bactria can cloxacillin and flucloxacillin be used in and what is the difference

Answer 13

They are both only able to be used in gram positive patients, the are very simiar flucloxacillin is just better absorbed orally

Question 14

What are the 2 main beta-lactamase inhibitors

Answer 14

Clavulanate and Tazobactam

Question 15

What is the benefit to beta-lactamase inhibitors

Answer 15

If used in combination with penicillin they can reverse resistance

Question 16

What is the drug of choice for Resp tract infections

Answer 16

Amoxicillin

Question 17

What is the drug of choice for Staph infections

Answer 17

Cloxacillin/flucloxacillin

Question 18

What are the 2 types of 1st generation cephalosporins and what are they used for

Answer 18

Cefazolin and Cephalexin mainly used for Strep and Staph.

Question 20

What is the second generation of cephalosporin

Answer 20

Cefuroxime it can be used against Strep, Staph, Haemophilus, community acquired gram negative infections

Question 21

What are the 2 main 3rd generation cephalosporins and what are they effective against

Answer 21

Ceftriaxone and Ceftazidime effective against Strep, Staph, CAP gram negatives and Haemophilus as well as spirochetes and typhoid

Question 22

What drug is given as surgical prophylaxis

Answer 22

Cefazolin 1g to prevent Staphylococcal infection

Question 23

What is the main excretion method used by ceftriaxone

Answer 23

Bile

Question 24

What is the drug of choice in empirical treatment of bacterial meningitis

Answer 24

Ceftriaxone because of its good CSF penetration

Question 25

What is the function of a carbapenems

Answer 25

These are very broad spectrum antibiotics that cover most types of infection

Question 26

Which antibiotic classes fall into the beta lactam family 4

Answer 26

Penicillins, cephalosporins, carbapenems, and monobactams

Question 27

What are the 3 main manifestations of penicillin allergies

Answer 27

1. Maculopapular Rash 2. Anaphylaxis 3.Angioedema, Urticaria(hives), and Bronchospasm

Question 28

What is the mechanism of killing used by Glycopeptides

Answer 28

Time dependent killing

Question 29

What are the microbes that are killed by glycopeptides

Answer 29

Gram positive bacteria

Question 30

What is the MOA of glycopeptides

Answer 30

They interfere with the synthesis of the cell wall by binding to specific components of the bacteria peptidoglycan

Question 31

What is the main glycopeptide used and its side effects

Answer 31

Vancomycin is the main glycopeptide used and the main side effects is that it is nephro and oto toxic

Question 32

What are aminoglycosides most effective against

Answer 32

Aerobic gram negative bacilli

Question 33

What is the MOA of a aminoglycoside

Answer 33

They act as bactericidal inhibitors of protein synthesis

Question 34

What is the mechanism of killing of an aminoglycoside

Answer 34

They kill by concentration dependent killing

Question 35

What are 2 examples of aminoglycosides

Answer 35

Gentamicin and Amikacin

Question 36

What is gentamicin used to treat

Answer 36

Pyelonephritis and is often combined with beta lactams for polymicrobial infections or for its synergistic effects

Question 37

What is the mechanism of action of a quinolone

Answer 37

It targets gyrase and topoisomerase enzymes used in DNA synthesis

Question 38

What are the signs of toxicity in Quinolones

Answer 38

1. Rashes 2. CNS disturbances

Question 39

What are examples of 2nd generation quinolones and what is the uses 1

Answer 39

Ciprofloxacin, They are used in very serious infections and are the drug of choice in conditions like bacterial dysentery and pyelonephritis

Question 40

What is an example of a 3r generation Quinolone and what is it main use

Answer 40

Levofloxin, MDR TB

Question 41

What is the MOA of a macrolide

Answer 41

It inhibits the 50s ribosomal component thus inhibiting protein synthesis

Question 42

What are macrolides most effective against

Answer 42

The are active against gram positive bacteria. and are also used for S. pneumoniae resistance

Question 43

What is the most common side effect

Answer 43

GIT disturbance

Question 44

What are 2 examples of macrolides and what is the benefit of the one over the other

Answer 44

Erythromycin and Azithromycin Macrolides inhibit CYP450 metabolism but azithromycin does not

Question 45

What is the main therapeutic use of macrolides

Answer 45

They are used in atypical pneumonias like Legionella, Mycoplasma and Chlamydophila

Question 46

What is the MOA of tetracyclines

Answer 46

They function by inhibiting the synthesis of proteins by inhibiting 30s ribosomes

Question 47

What are the 2 main mechanisms of resistance in tetracycline

Answer 47

1. Efflux 2. Enzymatic breakdown

Question 47

What are the forms of toxicity that occur in doxycycline 3

Answer 47

1. Nausea 2. Photosensitivity 3. Teeth discolouration

Question 48

Why should tetracyclines be avoided in children

Answer 48

It causes permanent discolouration of the teeth

Question 49

Which infections are treated with tetracyclines

Answer 49

Rickettsia Brucellosis Acne in low doses

Question 50

What infection can tetracycline be given as prophylaxis

Answer 50

Falciparum malaria

Question 51

What are the 2 active components in Cotrimoxazole

Answer 51

Sulfamethoxazole and trimethoprim

Question 52

What is the function of Trimethoprim

Answer 52

Enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, which is needed for the synthesis of nucleotides and ultimately DNA.

Question 52

What is the function of Sulfamethoxazole

Answer 52

It interferes with the folic acid pathway to thus inflencing the DNA synthesis in bacteria

Question 53

What is the main side effect of sulphonamide hypersensitivity

Answer 53

Stevens-Johnson Syndrom

Question 54

What is the main use of cotrimoxazole in HIV patients 3

Answer 54

1. Pneumocystis jirovecii pneumonia 2. Toxoplasmosis 3. Cystoisospora belli diarrhoea

Question 55

What is the MOA of metronidazole

Answer 55

It is toxic to DNA and forms free radicals in anaerobic metablism

Question 56

What is the main side effects of long term metronidazole use

Answer 56

Neurotoxic and neutropenia

Question 57

Which protozoans are affected by metronidazole

Answer 57

1. Entamoeba histolytica 2. Trichomonas vaginalis 3. Giardia lamblia