Anti Biotics

Question 1

Group represents of beta lactams

Answer 1

Penicillins, cephalosporins, carbapenems

Question 2

Group representatives of quinolones

Answer 2

Ciprofloxacin

Question 3

Group representatives of macroslides

Answer 3

Erythromycin

Question 4

Group representatives of aminoglycosides

Answer 4

Gentamicin

Question 5

Group representatives of glycopeptides

Answer 5

Vancomycin

Question 6

Group representatives of tetracycline

Answer 6

Oxytetracyclines

Question 7

Group representatives of folate antagonists

Answer 7

Trimethoprim/sulphonamide

Question 8

Group representatives of imidazoles

Answer 8

Metronidazole

Question 9

What are beta lactams selective for

Answer 9

Peptidoglycan cell wall

Question 10

Penicillin hypersensitivity

Answer 10

Rare and dramatic - angiogenic oedema
Cross reaction in 10% with cephalosporins
Can use carbapenems and aztreonam
Skin testing does NOT work
Patients on amoxicillin/ampicillin can get a maculopapular rash
So its usage is dependent on the severity of the infection and if there are alternative treatments

Question 11

Carbapenems

Answer 11

E.g.
Imipenem
Meropenen
Ertapenem
Fantastically stable to all GNB beta lactaminases
Only rare acinetobacter/pseudomonas resistant and New Delhi metallobetalactamase NDM
No activity against MRSA/VRE but covers lots of other common pathogens

Question 12

Glycopepetides

Answer 12

E.g.
Vancomycin
Teicoplanin
Important for MRSA and resistant enterococci
Clostridium difficile - taken orally not absorbed
Potentially nephrotoxic - i.v. Only
Can be given by bolus - no red man syndrome - used for prophylaxis
Best treatment for c diff. - fecal transplant

Question 13

Quinolones

Answer 13

Nalidixic acid
Ciprofloxacin
Levofloxacin
Moxifloxacin
Expensive - better gram +ve activity and -ve but not MRSA
Particularly valuable for uni resistant bacteria
Resistance rising 15-20%
Pseudomonas - resistance can emerge by mutation - targets DNA gyrase
Safe but c diff issues

Question 14

Macrolides

Answer 14

Erythromycin

Clarityromycin

Question 15

Aminoglycosides

Answer 15

Gentamicin
Tobramycin
Amikacin

Question 16

Tetracycline

Answer 16

Oxytetracyclines
Minocycline (better absorbed, expensive)
Tigecycline ( new compound active against MRSA and acinebacter)

Question 17

Antibacterial orphans

Answer 17

Chloramphenicol
Fusidic acid 
Linezolid
Mupirocin
Nitrofurantoin
Daptomycin
Fidaxomicin
Metronidazole

Question 18

Folate antagonists

Answer 18

Sulphonamide
Trimethoprim
Co-trimoxazole
Metronidazole

Question 19

What do beta lactams do?

Answer 19

Bind to and inhibit enzymes which catalyse the link between subunits that from the peotidoglycan cell wall

Question 20

What do glycopeptodes do

Answer 20

Bind to terminal D-ala-D-ala, prevent incorporation of subunit into growing peptidoglycan

Question 21

Carbapenems facts

Answer 21

Stable to all Gram negative bacteria beta lactamases
Only rare acinetobacter/pseudomonas resistant and New Delhi metallobetalactamase NDM
No activity against MRSA or VRE (vancomycin resistant enterococcus)

Action against
S. Pneumoniae, group A strep

Question 22

Glycopeptides facts

Answer 22

Important for MRSA and resistant enterococci
C diff diarrhoea - used for severe disease oral not absorbed
Potentially nephrotoxic (I.v. Only)

Question 23

Quinolones facts

Answer 23

Active against Gram+ve and -ve but NOT MRSA streptococci
Particularly valuable for UTI (resistant bacteria)
Resistance rising (15-20%)
Pseudomonas: resistance can emerge by mutation (target DNA gyrase), safe but c diff issues

Expensive but better Gram +ve activity

Question 24

Macrolides facts

Answer 24

Active:
S pneumonia (+ resistance) 
Beta-haemolytic strepts 
S aureus (+resistance) 
H influenzae 
Legionella, mycoplasma 
NOT active: 
Enterobacteriaceae 
Enterococci 
Pseudomonas

Safe particularly penicillin allergy

Adverse effects:
Vomiting
Hunger pains

Question 25

Aminoglycosides facts

Answer 25

Relatively nephrotoxic toxic so: given only I.v./i.m. Active: pseudomonas, GNBs including some nosocomial staph aureus NOT active: streptococci, anaerobes

Question 26

Tetracycline facts

Answer 26

Do not give in pregnancy - children TEETH Uses: chlamydiae infections, COPD, acne Poorly absorbed with antacids

Question 27

Orphans - chloramphenicol

Answer 27

Rarely used in U.K. Broad spectrum particularly against +ve

Question 28

Orphans - fusidic acid

Answer 28

Related to steroid hormones | Specific activity against staphylococci

Question 29

Orphan - linezolid

Answer 29

Valuable anti- staphylococcal agent (good for MRSA and VRE) oral and I.V. Can be toxic over 2 weeks, monitor WBC

Question 30

Orphans- mupirocin -

Answer 30

For topical nasal decolonisation of MRSA carriage

Question 31

Orphans - daptomycin

Answer 31

Potent I.v. Anti-MRSA (also VRE) agent v cidal good in endocarditis and foreign body infections inc CPK sometimes

Question 32

Orphans - nitrofurantoin

Answer 32

Lower UTI (no tissue levels) Adverse effects GI common

Question 33

Orphans - fidaxomicin

Answer 33

A macrocyclic alternative to metronidazole /vancomycin for c diff - £1300 course

Question 34

Folate antagonists - sulphonamide

Answer 34

Widespread resistance only used against strenotrophomonas and as co-trimoxazole for pneumocystis jirovecii

Question 35

Folate antagonists - trimethoprim

Answer 35

Cheap, oral heavily used for UTI | Resistance 20-30%

Question 36

Folate antagonists co-trimoxazole

Answer 36

Trimethoprim and sulphamethoxazole combined | No advantage in UTI

Question 37

Folate antagonists - metronidazole

Answer 37

Active agent almost all anaerobes Long term use --> peripheral neuropathy Antabuse effect with alcohol

Question 38

How does trimethoprim work

Answer 38

Bacteria have to make there own folic acid where as humans can use folic acid Trimethoprim has a greater affinity for bacterial DHFR (dihydrofolate reductase) so acts on it preventing its use

Question 39

3 main mechanisms by which resistance is mediated

Answer 39

1) inactivation of antibiotic such that it becomes unable to bind to target molecule e.g. Production of beta-lactamases as with penicillins 2) mutation in target molecule: antibiotic cannot bind e.g. Streptomycin 3) altered permeability of cell membrane prevents entry of antibiotic e.g. Tetracyclines