Penicillin antibiotics

Question 1

Natural Penicillins

Answer 1

Penicillin G - the prototype, requires injection
Penicillin V - the most acid-stable, taken orally

Question 2

Narrow spectrum Penicillin

Answer 2

Beta-lactamases break the beat-lactam ring
good against Gram + organisms such as Staphylococcus, streptococcus, and some Spirochetes

Question 3

Semi-synthetic Penicillin

Answer 3

Oxacillin - narrow-spectrum, Gram+ but resistant to penicillinase
Ampicillin - Extended-spectrum, many gram-

more resistant to stomach acid

Question 4

Semi-synthetic with Potassium clavulanate
Penicillin

Answer 4

Product of Streptomyces (non-competitive inhibitor of penicillinase)
Augmentin when combined with amoxicillin

Question 5

Semi-synthetic with a C in place of the S
Penicillin

Answer 5

Carbapenems
inhibits cell wall synthesis
good against 98% of the hospital isolates nosocomial
infections
Good broad-spectrum activity

Primaxin- Combination of imipenem and cilastin (Protects from degradation in the kidneys)

Question 6

Semi-synthetic - with only one ring
Penicillin

Answer 6

Monobactams
Newer synthetic antibiotic - Aztreonam
no beta-lactam ring
not affected by penicillinases
low toxicity to host
good for Pseudomonas and Escherichia

Question 7

Cephalosporins (over 70 versions) Synthetic

Answer 7

Inhibits cell wall synthesis
more resistant to penicillinases than natural penicillins
“Cephalo-wonderful”
more expensive than penicillin
broader spectrum & originally injected now some oral
Ex. Keflex

Question 8

Polypeptides (from the genus Bacillus)

Answer 8

Bacitracin -
inhibits cell wall synthesis
restricted to topical use only
Vancomycin (VRSA & VRE) -
inhibits cell wall synthesis
Narrow spectrum: good against penicillinase-
producing Staphylococci
Can be toxic to the host - careful administration

Question 9

Antimycobacterial Antibiotics

Answer 9

rifamycin -
inhibits the synthesis of mRNA
good for mycobacterium
concentrates in the CSF and abscesses
Isoniazid (INH) -
Inhibits synthesis of mycolic acid in acid-fast
organisms
good synthetic against mycobacterium
Ethambutol -
synthetic against mycobacterium
Inhibits synthesis of mycolic acid incorporation into
cell wall; therefore used as a secondary drug
because it is a weaker drug