Infection

Question 1

B lactam classes

Answer 1

Penicillins, Cephalosporins, Carbapenems, Monobactams

Question 2

Bactericidal vs bacteriostatic

Answer 2

Bactericidal: kills (usually by inhibiting cell wall synthesis), bacteriostatic: inhibits reproduction/growth (inhibits protein synthesis)

Question 3

Penicillin MOA

Answer 3

Bind to Penicillin binding protein (PBP), reduces peptidoglycan layer, bactericidal

Question 4

Penicillin resistance causes

Answer 4

B-lactamases and PBP mutations

Question 5

Cephalosporin MOA

Answer 5

Bind to Penicillin binding protein (PBP), reduces peptidoglycan layer, bactericidal

Question 6

Cephalosporin resistance causes

Answer 6

B-lactamases and PBP mutations

Question 7

Carbapenems MOA

Answer 7

Bind to Penicillin binding protein (PBP), reduces peptidoglycan layer, bactericidal

Question 8

Carbapenem resistance causes

Answer 8

B lactamases only

Question 9

Monobactams MOA

Answer 9

Bind to Penicillin binding protein (PBP), reduces peptidoglycan layer, bactericidal

Question 10

Monobactam resistance causes

Answer 10

B lactamases, less susceptible than other B lactams

Question 11

Aminoglycoside drugs

Answer 11

Gentamicin, amikacin, neomycin

Question 12

Aminoglycoside spectrum of activity

Answer 12

gram negative aerobes (and some activity against staph and mycobacteria) No activity against anaerobes of streptococci as aminoglycosides require oxygen dependant transport into cell

Question 13

Aminoglycoside MOA

Answer 13

Bind irreversibly to bacterial ribosomes (30s), inhibiting protein sysnthesis.

Question 14

Aminoglycoside resistance causes

Answer 14

Reduced cell wall permeability, enzymatic alteration of aminoglycoside

Question 15

Aminoglycoside ADRs

Answer 15

Nephrotoxicity and Ototoxicity (accumulate in renal tubular epithelial cells and cochlear/vestibular hair cells, causing cell death.

Question 16

Aminoglycoside warnings

Answer 16

neonates, elderly, renal impairment, myasthenia gravis.

Question 17

Aminoglycoside interactions

Answer 17

Loop diuretics (inc risk of ototoxicity), Nephrotoxicity risk increased with ciclosporin, platinum chemotherapy, cephalosporins or vancomycin.

Question 18

Gentamicin dosing

Answer 18

Based on IBW as only distrubutes in body water and not body fat

Question 19

Nystatin MOA

Answer 19

Bind to ergosterol in fungal cells, creates a polar pore, allows ion leakage.

Question 20

Imidazole antifungals

Answer 20

clotrimazole

Question 21

Triazole antifungals

Answer 21

fluconazole

Question 22

Imidazole and triazole MOA

Answer 22

Inhibit ergosterol synthesis, which impairs cell membrane synthesis

Question 23

Antifungal resistance

Answer 23

Rare, can occur in long term use in immunocompromised patients. Mechanisms include alteration of membrane synthesis to exclude ergosterol

Question 24

Antifungal ADRs

Answer 24

Local use - irritation
PO Fluconazole - GI upset, headache, hepatitis and hypersensitivity. Rare- severe hepatic toxicity, QT- prolongation, anaphylaxis

Question 25

Antifungal warnings

Answer 25

Topical- none

Fluconazole, liver damage, moderate renal impairment (dose reduction required).

Question 26

Antifungal Contraindications

Answer 26

Pregnancy

Question 27

Antifungal interactions

Answer 27

No significant interactions for topicals.
Fluconazole inhibits CYP450, so drugs metabolised by CYP450 including carbamazepine, phenytoin, warfarin, diazepam, simvastatin, sulphonylureas. Causes QT prolongation, so other drugs that cause QT prolongation (amiodarone, antipsychotics, quinine, quinolone, macrolides and SSRIs

Question 28

Aciclovir MOA

Answer 28

Inhibits the herpes specific DNA polymerase

Question 29

Aciclovir ADRs

Answer 29

headache, dizziness, GI disturbances, rash.

IV use: phlebitis, acute renal failure (risk reduced by slow rate and adequate hydration)

Question 30

Aciclovir warnings

Answer 30

Crosses placenta and enters breast milk, so caution in pregnancy and breastfeeding. Severe renal impairment. No CIs

Question 31

Aciclovir interactions

Answer 31

None of note

Question 32

Cephalosporins and Carbapenams spectrum of activity

Answer 32

Broad

Question 33

Antibiotics increasing C diff risk the most

Answer 33

clindamycin, cephalosporins (in particular second‑ and third‑generation cephalosporins), quinolones, co‑amoxiclav and aminopenicillins (for example, ampicillin and amoxicillin, which may be related to their volume of use rather than being ‘high risk’)

Question 34

Carbapenems warnings

Answer 34

Epilsepsy (lowers seizure threshold). CI in anaphylaxis to B lactams.

Question 35

Carbapenem and cephalosporin interactions

Answer 35

Warfarin: increases INR by killing gut bacteria that produce vitamin K.
May increase aminoglycoside nephrotoxicity

Question 36

Chloramphenicol uses

Answer 36

Bacterial conjunctivitis, otitis externa. Occasional use Po or IV, but only in very exceptional and life threatening situations.

Question 37

Chloramphenicol activity

Answer 37

Broad against gram pos and neg, aerobes and anaerobes.

Question 38

Chloraphenicol MOA

Answer 38

Binds to bacterial ribosomes, inhibits protein synthesis (bacteriostatic).

Question 39

Chloramphenicol resistance

Answer 39

acetyltransferase enzymes that directly inactivate the drug. Target modification, decreased membrane permeability and increased efflux pumps

Question 40

Chloramphenicol ADRs

Answer 40

Topical: stinging, burning, itching.
Systemic: Bone marrow toxicity - 1. dose related (more common in high doses or in accumulation due to hepatic impairment) occurs on treatment and reversed on withdrawal. 2. Aplastic anaemia - idiosynchratic, unpredictable, may occur a while after starting. Rare but life threatening.
Gray baby syndrome- circulatory collapse in exposed neonates. Optic and peripheral neuritis may occur with prolonged use

Question 41

Chloramphenicol warnings

Answer 41

CI: hypersensitivity reactions, bone marrow disorders, systemic CIs include third trimester, breastfeeding and children under 2. Topical use should also be avoided where possible.
Hepatic impairment

Question 42

OTC chlorpamphenicol red flags

Answer 42

Loss of/disturbance of vision, contact lenses use, photophobia, unresolved after using drops.