MicroBio - CH 12

Drugs, Microbes, Host Chemotherapy

What is the primary target of Penecillins?

block synthesis of peptidogylcan, causing the cell to lyse

What is the primary target of cephalosporins?

block the synthesis of peptidogylcan, cuasing the cell wall to lyse

What drug do you usually use against streptococci, meningococci, and syphilis spirochete?

Penicillin

What are some narrow-spectrum derivatives of penicillin?

Dicloxacillin, Nafcillin

What are some broad-spectrum derivatives of penicillin?

Ampicillin, Amoxicillin (semisynthetic)

What are some semisynthetic penicillins?

Methicillin, Ampicillin, Carbenicillin, and Amoxicillin

What is the fraction of cephalosporins that account for all antibiotics administered?

1/3

What is a first generation cephalosporin?

cephalothin, cefazolin- most effective against gram + cocci and a few gram -

What is a second generation cephalosporin?

cefaclor, cefinacid- most effective against gram -

What is a third generation cephalosporin?

cephalexin, ceftriaxone- broad spectrum activity against eneteric bacteria with beta-lactamases

what is a fourth generation cephalosporin?

cefepime- widest range, both gram - and gram +

Vancomycin contains beta lactam ring.

false

Vancomycin is used as a last resort becuase of it’s high toxicity.

true

Vancomycin is narrow spectrum.

true

Bacitracin is narrow spectrum.

true

What is the mode of action in bacitracin?

blocks peptidoglycan elongation in gram +

What drugs are often combined with bacitracin.

neomycin and polymyxin

bacitracin is a peptide antibiotic.

true

Isoniazid (INH) is a broad spectrum drug.

false

What does Isoniazid inhibit?

it inhibits mycolic acid synthesis.

What disease is usually treated with isoniazid?

TB, mycobacterium tuberculosis

What drugs are usually combined with isoniazid?

rifampin and ethambutol

What is the mode of action of polymyxins

interact with phospholipids and cause leakage, particularly in gram - bacteria

what is the mode of action for Amphotericin B and nystatin?

form complexes with sterols (cholesterol-humans and ergosterol-fungus) on fungal membranes which cause leakage

What can happen if you use too much polymyxins?

kidney toxicity

Polymyxins B and E (colistin) are used clinically.

True

Tetracycline is a broad spectrum antibiotic/

True

What cellular structure does tetracycline bind to?

ribosomes

What are some derivatives of tetracycline?

doxycline, minocycline