Antibiotics

Question 1

Class of amoxicillin?

Answer 1

Penicillin - beta lactam, broad spectrum

Question 2

Action of amoxicillin?

Answer 2

Bactericidal - interfere with cell wall synthesis

Question 3

Indications for amoxicillin?

Answer 3

Gram +ve bacterial infections (strep, staph), gram -ve infections (haem influenzae).

UTIs, otitis media, sinusitis, bronchitis, CAP, invasive salmonellosis, listerial meningitis.

Question 4

Contra-indications of amoxicillin?

Answer 4

Penicillin hypersensitivity

Suspected glandular fever or acute/chronic lymphocytic lukaemia - risk of erythematous rash developing.

Question 5

Possible interactions?

Answer 5

OCP - decreased effectiveness
Digoxin - toxicity
Methotrexate - toxicity
Anticoagulants - prolonged bleeding

Question 6

Cephradine class?

Answer 6

Cephalosporins

Question 7

Cephradine action?

Answer 7

Broad spectrum of activity against gram +ve and gram -ve bacteria. Also highly active against most strains of penicillinase-producing staphylococci.

Question 8

Indications for cephalosporins?

Answer 8

Bacterial infections of respiratory and urinary tracts and skin and soft tissues

URTIs - sinusitis, pharyngitis, tonsilitis, otitis media
LRTIs - acute/chronic bronchitis, lobar and bronchopneumonia
UTIs - cystitis, urethritis, pyelonephritis
Skin/soft tissues - impetigo, abscess, cellulitis

Question 9

Interactions of cephradine?

Answer 9

Loop diuretics may increase nephrotoxicity

Question 10

What is trimethroprim?

Answer 10

Antifolate abx

Question 11

How does trimethoprim work?

Answer 11

Oral bacteriostatic dihydrofolate reductase inhibitor. (Folate = essential cofactor in DNA synthesis)

Question 12

Indications for trimethoprim?

Answer 12

Mainly UTIs (E.coli, proteus mirabilis)

Question 13

Contra-indications of trimethoprim?

Answer 13

Pregnancy
Severe renal impairment
Blood disorders (anaemia, thrombocytopenia)

Question 14

Interactions of trimethoprim?

Answer 14

Cyclosporins - increased risk nephrotoxicity

Pyrimethamine - increased antifolate effects

Question 15

Class doxycycline?

Answer 15

Tetracyclines

Question 16

Action of doxycycline?

Answer 16

Bacteriostatic - inhibit protein synthesis.

Question 17

Indications of doxyccycline?

Answer 17

RTIs - strep pneumoniae, haemophilus influenzae, klebsiella pneumoniae
UTIs - klebsiella, enterobacter, E.coli, strep faecalis
STIs - chlamydia trachomatis
Acne vulgaris
Chronic prostatitis, syphilis, chronic bronchitis exacerbation

Question 18

Contraindications of tetracycline?

Answer 18

Children

Question 19

Possible interactions of doxycycline?

Answer 19

Carbamezapine/phenytoin - increased doxycycline metabolism
Methotrexate - increased risk of toxicity
Milk reduces absorption

Question 20

What is gentamicin?

Answer 20

aminoglycoside - bactericidal abx - inhibits bacterial protein synthesis by binding irreversibly to 30s subunit of bacterial ribosomes.

Question 21

What is gentamicin active against?

Answer 21

Escherichia, enterobacter, klebsiella, salmonella, serratia, staph aureus, some proteus, pseudomonas
Effective against penicillin-resistant staphylococci, rarely against streptococci.

Question 22

Gentamicin side effects?

Answer 22

Nephrotoxicity, ototoxicity

Question 23

Gentamicin interactions?

Answer 23

Cyclosporin - potentiates nephrotoxic effects

Loop diuretcis - potentiate nephrotoxic/ototoxic effects

Question 24

Gentamicin contraindications?

Answer 24

Pregnancy, myasthenia gravis

Question 25

What is erythromycin?

Answer 25

macrolide

Question 26

Action of erythromycin?

Answer 26

Broad spec bacteriostatic abx - inhibits bacterial protein synthesis by binding irreversibly to 5s subunit of bacterial ribosomes

Question 27

Indications for erythromycin?

Answer 27

URTI - tonsilitis, peritonsilar abscess, pharyngitis, laryngitis, sinusitis, LRTIs - tracheitis, acute/chronic bronchitis, pneumonia, bronchiectasis, legionnaire's disease Ear infection - otitis media/externa, mastoiditis Eye - blepharitis Skin/soft tissue - boils, paronychia, abscesses, pustular acne, impetigo, cellulites GI - cholecystitis, staphylococcal entercolitis

Question 28

Erythromycin interactions?

Answer 28

Inhibitor of CYP450 so increases conc of drugs

Question 29

What is ciprofloxacin?

Answer 29

Quinolone

Question 30

How does ciprofloxacin work?

Answer 30

Broad spectrum bactericidal abx. Inhibits DNA gyrase

Question 31

Indications for ciprofloxacin?

Answer 31

Staph aureus, haem influenzae, e coli, klebsiella, pseudomonas, moraxella, mycoplasma pneumoniae, chlamydia, salmonella, shigella, campylobacter LRTIs due to gram -ve bacteria. Chronic suppurative otitis media, acute exacerbation of chronic sinusitis, UTIs, genital tract infections, infections of GI tract, intraabdominal infections, infections of skin and soft tissue, malignant external otitis, infections of bone and joints

Question 32

Contraindications of ciprofloxacin?

Answer 32

Prego, kids, epilepsy, can cause tendon rupture, can precipitate attack in G6PD deficiency

Question 33

Interactions of ciprofloxacin?

Answer 33

Is a P450 inhibitor

Question 34

What is metronidazole?

Answer 34

Anaerobic antibiotic | Bacteriacidal - toxin compounds kill microbes by interfering with nucleic acid function and synthesis

Question 35

Spectrum of metronidazole?

Answer 35

Anaerobes (clostridia, bacteriodes), protozoa, trichomonas, entamoeba histolytica, giardia lamblia, balantidium coli

Question 36

Indications of metronidazole?

Answer 36

Stuff infected with anaerobes

Question 37

Metronidazole interactions?

Answer 37

P450 inhibitor