Antibiotics

Question 1

What does Borelia spp cause

Answer 1

Lyme disease

Question 2

What causes typhoid

Answer 2

Salmonella typhi

Question 3

What causes syphillis

Answer 3

Treponema pallidum

Question 4

What is bronchiectasis

Answer 4

permanent enlargement of parts of the airways of the lung),

Question 5

What is minimum inhib concentration

Answer 5

the lowest conc of the antibiotic being tested that inhibits growth of the organism in a broth

Question 6

What is min bactericidal conc

Answer 6

conc: lowest concentration that kills the organism

Question 7

What drugs are beta lactams

Answer 7

Penicillin, cephalosporin and carbapenem

Question 8

What is the mechanism of action of beta lactams

Answer 8

Beta lactams act on the cell wall of the bacteria by binding to penicillin binding proteins in the cell membrane. These proteins help synthesise peptidoglycan in the cell wall. In gram negative, the beta lactam must also penetrate outer layer

Question 9

What is used for chest infection and cellulitis

Answer 9

Penicillin G (pneumococcus)

Question 10

What is used for s. aureus infection

Answer 10

Flucloaxicllin

Question 11

When are carbapenems used

Answer 11

Not used unless extremely resistant. Ertrapenem and meropenem.

Question 12

What are examples of macrolides

Answer 12

erythromycin, clarithromycin, azithromycin (go to for staphylococci and streptococci if patient allergic to penicillin and atypical pneumonia)

Question 13

What is erthyromycin

Answer 13

Erythromycin (IV and PO): Bacteriostatic macrolide antibiotic interferes with protein synthesis by ribosomal binding

Question 14

What are azithromycin and clarithromycin

Answer 14

Azithromycin (PO) and clarithromycin (IV, PO) are new macrolides with longer half live and fewer side effects

Question 15

What are examples of tetracyclines

Answer 15

Oxytetracycline, doxycline, tigecycline

Question 16

What are oxytetracycline and doxycline

Answer 16

are bacteriostatic and inhibit binding of tRNA to the ribosome. Broad spectrum but resistance frequent. Use for respiratory tract and soft tissue infection. Useful in penicillin-allergic patients who suffer side effects with macrolides.

Question 17

What is tigecyclin

Answer 17

a recent and potent broad spectrum agent with activity against Gram positive, gram negatives and anaerobes

Question 18

What are examples of glycopeptides

Answer 18

Vancomycin and teicomycin

Question 19

What is the mechanism of action of glycopeptides

Answer 19

act on bacterial cell wall, only against gram positive bacteria and mainly used for treatment of MRSA and coagulase negative staphylococcus infection.

Question 20

What are quinolones

Answer 20

Ciprofloxacin inhibit DNA gyrase, the enzyme that supercoils DNA within bacteria. The organism is disrupted by the unwound DNA. Generally used for gram negative bacteria; activity against gram positive bacteria is weaker

Question 21

What is the mechanism for trimeoprim and co-trimoxazole

Answer 21

agents block the synthesis of bacterial nucleotides in the pathway of folic acid/nucleotide synthesis. Active against gram negative and gram positive bacteria.

Question 22

What is trimethoprim used for

Answer 22

UTI

Question 23

What is co-trimoxazole used for

Answer 23

used for treatment and prophylaxis of Pneumocystis jirovecii pneumonia, Stenotrophomonas maltophilia infection and nocardiosis

Question 24

What is metronidazole

Answer 24

affects nucleic acid function by breaking DNA strands. Active
against virtually all anaerobes, amoebae and Trichomonas vaginalis.

Question 25

What is linezolid

Answer 25

an oxazolidinone. Active only against Gram-positive bacteria including
MRSA and glycopeptide-resistant enterococci.

Question 26

What is chloramphenicol

Answer 26

Owing to bone marrow toxicity reserved for occasional

therapy of meningitis and topical treatment of eye infections.

Question 27

What is rifampicin

Answer 27

Highly active against Gram-positives. Prosthetic valve endocarditis and
other prosthesis infections; part of 1st line TB regimen.

Question 28

What is fosfomycin

Answer 28

increasingly used for multi-resistant Gram-negative bacterial infections.

Question 29

What is fidaxomicin

Answer 29

only for selected cases of severe or recurrent Clostridium difficile diarrhoea
Cases. No other indication.

Question 30

What is colistin

Answer 30

dispupts bacterial membrane. Reserved for multipl- or pan-resistant GramNegative
infections. No other frequent indication.

Question 31

What is daptomycin

Answer 31

a lipopeptide. Similar activities to glycopeptides: active only against
Gram-positive bacteria.

Question 32

What is fusidic acid

Answer 32

staphylococcal infections only. Topical. If systemic: always use with
a second anti-staph agent.

Question 33

Why is penicillin not active against pseudomonas aeruginosa or escherichia coli?

Answer 33

Pseudomonas can mutate porins to prevent some anti-pseudomonal abx from penetrating the bacterial cell.

Question 34

Why is penicillin not active against strep pneumoniae

Answer 34

penicillin resistance due to altered PBPs. MRSA produces a new PBP that is not inhbitied by methicillin (flucloaxacillin).

Question 35

What’s the treatment for TB

Answer 35

Rifampicin 6-12 months
Isoniazid 6-12 months
Pyrazinamide 2 months (increases killing of macrophage, can’t always predict mono-resistance)
Ethambutol 1-2 months