Antibiotics

Question 1

Name a few Bactericidal Abx.

Answer 1

Penicillins & Cephalosporins
Quinolones
Nitrofurantoin
Metronidazole
Rifampicin & Isoniazid

Question 2

Hallmark features of Cephalosporins ??

Answer 2

Beta-lactam Abx. & are Bactericidal
- Less susceptible to Penicillinase than Penicillins
- Disrupts the Cell wall synthesis by (-) Peptidoglycan Crosslinking
Mechanism of Resistance
- Changes to Penicillin-Binding-Proteins, a type of Transpeptidases (produced by bacteria that cross-links Peptidoglycan chains => forms Rigid cell wall

Question 2

Name a few Bacteriostatic Abx.

Answer 2

Aminoglycosides & Macrolides
Trimethoprim & Sulphonamides
Chloramphenicol
Tetracyclines

Question 3

S/E of Linezolid ??

Answer 3

Thrombocytopaenia (Reversible)
MAOi: Avoid Tyramine containing foods

Question 3

Hallmarks of Linezolid ??

Answer 3

Oxazolidinone Abx. which has been introduced in recent years.
MoA: (-) bacterial protein synthesis by stopping 50s initiation complex formation
Highly active against Gram(+)ve including
- MRSA
- VRE (Vancomycin R Enterococcus)
- GISA (Glycopeptide Intermediate Staph. Aureus)

Question 4

Hallmarks of Tetracyclines ??

Answer 4

Doxycycline & Tetracycline
Derived from Streptomyces bateria
- 4 rings bound together
- Binds to A-site on 30S =(-)=> Binding of t-RNA to mRNA => Protein synthesis is stopped
Mechanism of Resistance
- Increased efflux of bacteria by Plasmid-encoded transport pumps, Ribosomal protection
Used in
- Acne vulgaris, Lyme’s,
- Chlamydia, Mycoplasma Pneumonia

Question 5

S/E of Tetracyclines ??

Answer 5

Teeth discolouration
- NOT used in < 12 yrs children
Photosensitivity
Angioedema
Black HAIRY Tongue
CI in Pregnancy & Breastfeeding => due to Discolouration of teeth