Biol Chap 14.2 & 3 - Mechanisms of Antibacterial Drugs

What is Dosage?

concentration is given in a certain time period

• Based on mass for children; standard for 12+

What is Narrow spectrum?

targets specific group of microbes

• best choice

What is Broad spectrum?

targets wide variety

• Downside: superinfection

What are Superinfections?

new infection develops during the course of treatment with broad-spectrum antibiotics

What is Synergetic?

adding two drugs together; increasing the action of drugs

What is Antagonistic?

adding two drugs together; decreasing the action of drugs

What is Selective toxicity?

inhibiting/killing microbe but not harm to host

What drugs are Inhibitors of Cell Wall Synthesis?

• β-lactams

• Vancomycin

• Bacitracin

What is the MOA of β-lactams?

blocks cross-linking of peptide chains in new peptidoglycan

What drugs fall under β-lactams?

• Penicillins

• Cephalosporins

• Carbapenems

• Monobactams

What are Penicillins?

derivatives from fungi; Most G+ some G-

What are Cephalosporins?

similar to penicillins; resistance to β-lactamases

What are Carbapenems?

broad spectrum against G+/G-

What are Monobactams?

narrow spectrum, G- only

What is the MOA of Vancomycin?

binds to end of peptide chain to block subunits from adding to peptidoglycan backbone; G+ only

What is the MOA of Bacitracin?

derived from B. subtilis; blocks transport of peptidoglycan precursors

What drugs are inhibitors of Protein synthesis?

• Aminoglycosides

• Tetracyclines

• Macrolides

• Lincosamides

• Chloramphenicol

• Oxazolidinones
  

What is the MOA of Aminoglycosides?

bind to 30S subunit of ribosome and impair “proofreading” ability

What are examples of Aminoglycosides?

streptomycin, gentamicin, neomycin

What is the MOA of Tetracyclines?

bind to 30S; blocks association of tRNA with ribosome

What is the MOA of Macrolides, Lincosamides, and Chloramphenicol?

bind to 50S subunit & inhibit peptide bond
formation in specific combos of amino acids

What are Macrolides?

broad spectrum; -static

What are examples of Macrolides?

erythromycin, azithromycin

What are Lincosamides?

narrow spectrum; -static; particularly active against streptococcal and staphylococcal infections

What are Chloramphenicol?

broad spectrum; -static; rarely used now because of serious side effects

Which drugs are Inhibitors of Membrane function?

• Polymyxins

• Daptomycin

What is the MOA of Polymyxins?

lipophilic & interact w/ LPS to disrupt
outer & inner membrane of Gram (-)

• not selectively toxic

What is the MOA of Daptomycin?

cyclic lipopeptide that inserts and disrupts Gram (+) membrane

Which drugs are Inhibitors of Nucleic-acid synthesis?

• Metronidazole

• Rifampin

• Fluoroquinolones

What is the MOA for Metronidazole?

interferes w/ DNA replication; not very selective in toxicity(targets anaerobic bacteria AND protozoa)

• Broad spectrum; -cidal

What is the MOA for Rifampin?

blocks RNA polymerase activity; can treat semi-
dormant M. tuberculosis; BUT can be antagonistic & hepatotoxic

• Narrow spectrum (mainly G+, some G-); -cidal

What is the MOA for Fluoroquinolones?

inhibit DNA gyrase enzyme; selective toxicity but many side effects

• Broad spectrum; -cidal

Which drugs are Inhibitors of Metabolic pathways?

• Sulfonamides

• Trimethoprim

• Isoniazid

What are Antimetabolites?

competitive inhibitors of enzymes to stop certain pathways

What is the MOA of Sulfonamides?

(sulfa drugs) – halts folic acid synthesis and production of pyrimidines & purines;

• Often used in combo with Trimethoprim

• Broad spectrum; -static without Trimethoprim

What is the MOA of Trimethoprim?

inhibits later stage of folic acid synthesis

• Sulfamethoxazale & Trimethoprim are commonly used in combination to boost effect (-cidal)

What is the MOA of Isoniazid?

specific toxicity; block synthesis of mycolic acid

Which drug is an Inhibitor of ATP synthase?

Diarylquinolines

What is the MOA of Diarylquinolines?

inhibits mycobacterial growth; exact mechanisms is unknown but evidence shows interference with ATP synthase and reducing available ATP

What are the drugs in Triple antibiotic ointment?

• Neomycin

• Polymyxin

• Bacitracin