Antimicrobial Drugs |
||||
24. Identify and describe the antibiotic that injures the plasma membrane. 25. List and describe the antibiotics that inhibit nucleic acid synthesis. 26. List and describe the antibiotics that inhibit the synthesis of essential metabolites. |
Polypeptides – (Polymyxin B) - Bactericidal antibiotic that damages the plasma membrane.
It is effective against gram-negative bacteria.
Mainly used in topical preparations to treat superficial infections.
Rifamycins – A group of antibiotics that inhibit RNA synthesis.
The best-known member of the family is rifampin, which is primarily an anti-mycobacterial drug used to treat tuberculosis and leprosy.
It is capable of reaching therapeutic levels in the CSF and in abscesses.
Quinolones – are a group of antibiotics that inhibits DNA synthesis by effecting DNA gyrase, which is needed for replication.
Use is limited to urinary tract infections.
Nalidixic acid is the best known.
Fluoroquinolones - have a broad spectrum of activity, penetrate tissues well, and are safe for adults.
They are not recommended for children, adolescents, and pregnant women because they may adversely affect cartilage development.
Norfloxacin, ciprofloxacin (Cipro), and levofloxacin (Levoquin) are the most commonly used.
Third and fourth generation fluoroquinolones include moxifloxacin (Avelox) and gatifloxacin (Tequin) - broader spectrum and can be taken orally, although Bristol-Myers pulled Tequin from the market in 2006 due to side effects (elevated blood sugar, kidney failure, liver damage).
Sulfonamides (sulfa drugs) – are bacteriostatic antibiotics.
The most widely used sulfa drug is trimethoprim-sulfamethoxazole (Cotrimoxazole, Septra), which interferes with folic acid metabolism.
It is very effective in penetrating brain tissue and cerebrospinal fluid.
Actions of Trimethoprim and Sulfamethoxazole