Antimicrobials

Question 1

what drug do you use to treat giadia infection that causes diarrhoea?

Answer 1

Tinidazole or metronidazole

Question 2

what drug do you use to treat clostridium difficile infection causing pseudomembranous colitis?

Answer 2

metronidazole

Question 3

What antibiotics and antivirals would you give post transplant

Answer 3

Bactrim (pcp) and valgancyclovir (cmv) and niostatin (anti fungals)

Question 4

What antimicrobials are nephrotoxic?

Answer 4

Gentamicin, sulfonimides, penicillins, rifampicin, acyclovir

Question 5

A 13 year-old female presented to the emergency department looking unwell and septic. She was started on ceftriaxone IV. A diagnosis of pyelonephritis was subsequently made, with no evidence of obstruction on ultrasound.

You are notified by the microbiology lab that her urine culture results are consistent with a urinary tract infection, with a pure culture of Enterobacter cloacae that is sensitive to ceftriaxone. Would you prescribe ceftrioxone?

Answer 5

No. enterobacter cloacae are part of the ESCAPPM organisms that develop resistance to ceftriaxone.
They all share a chromosomally-encoded cephalosporinase (a type of beta-lactamase) that is inducible. Thus they tend to develop cephalosporin resistance during treatment.

Question 6

What drug would you use for an Ecoli UTI?

Answer 6

Trimethoprim

Question 7

what drug do we use for PCP

Answer 7

bactrim= co trimoxole

Question 8

what would you use if a patient needed penicillin but was hypersensitive to it? (think alternatives)

Answer 8

ceftriaxone

Question 9

as you move from first gen cephalosporins to 3rd gen, what organisms do you increase cover of?

Answer 9

First gen–> mostly staph; then by the time you get to 3rd gen you get more gram negative cover

Question 10

what groups of antibiotics are bacteriocidal in general?

Answer 10

those that target the bacterial cell wall or membrane, as well as those that interfere with bacterial enzymes
e.g. penicillin, cephalosporins, polymyxins, aminoglycosides and sulfonamides

Question 11

what groups antibiotics are bacteriostatic?

Answer 11

those that target protein synthesis. For example, macrolides, and tetracyclines

Question 12

give an example of an amino glycoside, and tell me how it works.

Answer 12

Gentamycin, tobramycin, neomycin. Aminoglycosides have strong gram negative cover, and inhibit bacterial protein synthesis

Question 13

what does penicillin, carbapenams, cephalosporins and monobactams have in common?

Answer 13

beta lactam ring

Question 14

what is another name for benzylpenicillin?

Answer 14

penicillin G

Question 15

give examples of macrolides?

Answer 15

erythromycin, azithromycin. Inhibit cytochrome p450 system

Question 16

what are some SEs of tetracyclines

Answer 16

oesophagitis, enamel decay

Question 17

what are the narrow spectrum penicillins?

Answer 17

benzylpenicillin IV, benzathine penicillin IM, phenoxymethylpenicillin PO

Question 18

which cephalosporins treat enteroccocus?

Answer 18

only 5th generation cephalosporins

Question 19

what are the antimicrobials that inhibit DNA synthesis

Answer 19

trimethoprim, sulfonamides, metronidazole

Question 20

first generation of cephalosporins?

Answer 20

cephazolin –> good for MSSA

Question 21

what is an example of 3rd gen cephalosporins?

Answer 21

ceftriaxone –> not good for staph, but more for gram negatives

Question 22

what kind of drug is vancomycin

Answer 22

glycopeptide antibiotic therapy

Question 23

contraindication to bactrim?

Answer 23

G6PD deficiency and pregnancy

Question 24

SE of bactrim?

Answer 24

steven johnson syndrome

Question 25

how do fluoroquinolones work?

Answer 25

interfere with DNA gyros, prevents bacterial replication

Question 26

Se of fluoroquinolones?

Answer 26

tendonitis

Question 27

How does nitrofurantoin? what is it used for?

Answer 27

It inhibits enzymes and DNA activity. Prophylactic measures for UTIs

Question 28

what SE is due to nitrofurantoin?

Answer 28

pulmonary fibrosis

Question 29

what does hydronephritis

Answer 29

dilation of the urinrary collecting system

Question 30

what do you think if you saw a younger male with gas in the urinary system?

Answer 30

emphysematous pyelonephritis

Question 31

what are the classical features of acute pyelonephritis?

Answer 31

temp, fever, loin pain +/- dysuria frequency and urgency

Question 32

what are some SE of ethambutol?

Answer 32

Optic neuritis | And changes to colour vision

Question 33

side effects of pyrazinamide?

Answer 33

``` Gout Hepatic toxicity GIT upset Fever Malaise ```

Question 34

how does isoniazid work

Answer 34

Inhibits synthesis of mycolic acid in cell wall of mycobacterium

Question 35

what kind of drug is metronidazole?

Answer 35

nitroimidazole. Used to be an antiprotozoal drug but now used for anaerobic bacteria

Question 36

what would you want to advise a patient who is about to commence metronidazole

Answer 36

abstain from alcohol

Question 37

how do quinolones work

Answer 37

inhibit topoisomerase II (a bacterial DNA gyrase)

Question 38

what are some adverse effects of chloramphenicol?

Answer 38

pancytopenia and grey baby syndrome and HS reaction

Question 39

what is the difference between gentamicin and chloramphenicol in terms of how they inhibit ribosomal protein synthesis?

Answer 39

chloramphenicol (and macrolides) inhibits 50s subunit, gentamicin inhibit 30s subunit

Question 40

are tetracyclines bacteriostatic or bactericidal?

Answer 40

bacteriostatic

Question 41

how do sulphonamides work?

Answer 41

they have a structural analogue to PABA. PABA is needed for folate synthesis. So they inhibit folate synthesis (by competing for the same Dihydropterate synthetase enzyme as PABA) and thus interfere with DNA synthesis and replication

Question 42

how do trimethoprim work?

Answer 42

inhibits enzyme dihydrofolate reductase in folate synthesis pathway

Question 43

SE of vancomycin?

Answer 43

* Ototoxicity * Nephrotoxicity * Red man syndrome- dosing consideration

Question 44

How does vancomycin work? how does resistance to Vancomycin develop?

Answer 44

* Acts on GRAM POSITIVE BACTERIA ONLY- MRSA usually * BINDS TO D-ALA, D-ALA preventing crosslinking of NAM/NAG polymers that make up the backbone of peptidoglycan cell wall RESISTANCE TO VANCOMYCIN: D-ALA gets converted to D-LAC so vancomycin cannot bind.

Question 45

name the beta lactams

Answer 45

``` • Penicillins • Cephalosporin's • Antipseudomonals • Carbapenams Monobactams ```

Question 46

how do beta lactams work?

Answer 46

Inhibit the synthesis of bacterial cell walls by inhibiting penicillin binding proteins, i.e. enzymes transpeptidase and carboxypeptidase.

Question 47

how does resistance to beta lactams occur?

Answer 47

1. beta lactamase enzyme encoded in plasmid | 2. change in penicillin binding proteins

Question 48

what is a haematological consideration you would have before prescribing antimalarials?

Answer 48

A patient with G6PD deficiency--> as it can cause oxidative haemolysis

Question 49

what drug protocol do we use for Multi drug resistant TB?

Answer 49

``` • Pyrazinamide, Ethambutol • 5 active agents • Injectable AMIKACIN • Moxifloxacin --> treat for 2 years ```

Question 50

What empirical therapy do we give for severe CAP?

Answer 50

Severe CAP- ceftriaxone (cephalosporin) IV daily + AZITHROMYCIN (macrolide)

Question 51

What antibiotic do you prescribe for an infective exacerbation of COPD without consolidation on CXR?

Answer 51

doxycycline

Question 52

What empirical antibiotics for a man who presents with LIF abdo pain and fever? (worried about perforated diverticulitis)

Answer 52

Tazocin OR Ampicillin, metronidazole, gentamicin

Question 53

When would tazosin be contraindicated

Answer 53

Contraindicated when there is a hx of jaundice or liver problems

Question 54

Adverse effects of clindamycin?

Answer 54

TEN, taste disturbance, C. difficile colitis

Question 55

what constitutes tazocin?

Answer 55

Piperacillin + tazobactam

Question 56

why might you prescribe flucloxacillin and rifampicin?

Answer 56

for staphyloccocal dermatitis infections and osteomyelitis. Rifampicin reduces the amount of flucloxacillin required