Antimicrobials Flashcards
What are bacteriostatic drugs?
Cause bacteria to stop growing
What are bactericidal drugs?
Cause bacterial cell death
Drugs that target cell wall synthesis tend to be bactericidal
What are beta-lactam antibiotics?
Inhibit peptidoglycan synthesis (cell wall). Bacterial resistance via beta-lactamases
Penicillin, ampicillin
What are sulfonamides (aka sulfa drugs)? What are some examples?
Inhibit folate synthesis, important for bacterial cell metabolism. Often given with trimethoprim (tetrahydrofolate synthesis inhibitor).
Sulfamethoxazole, sulfacetamide
What are tetracyclines?
Inhibit bacterial protein synthesis (binds to bacterial ribosome)
Tetracycline, Doxacycline
What are Macrolides?
Inhibits bacterial protein synthesis (inhibits peptidyl transferase). Inhibit the enzyme that adds amino acids to protein chains.
Erythromycin
Clarithromycin
What are other mycins?
Antinomycin - polypeptide antibiotic, inhibits transcription
Vanomycin - glycopeptide antibiotic, inhibits Gram + cell wall synthesis
What is antibiotic resistance and how does it evolve?
Antibiotic use + selective pressure = antibiotic resistance
Mutations are random but evolve under selective pressure
Mutation rate approx 1 per 10^10 nucleotides
(S. aureus has a genome size of 2.8^6 nucleotides)
Speed of developing resistance also depends on doubling time/growth rate of microbe.
What are some examples of the mechanisms of antimicrobial resistance?
Drug deactivation Drug altering Drug degredation Drug efflux Compensatory gene expression Etc
Can bacteria develop resistance against natural compounds?
Yes - thoretically? But hasn’t been documented
What are antiviral drugs?
Are typically specialized for viral proteins and processes
What are broad spectrum antivirals and what is their mechanism of action?
Type 1 IFN (interferon) collectively inhibit viral replication by:
antiviral cytokine
Induces inflammation and recruitment of antigen presenting cells
inhibits viral replication and protein synthesis
regulates cell growth
What are oncolytic viruses?
Viruses that kill tumours
Usually modified to take advantage of the interferon pathway
Don’t cause disease because normal cells capable of combating them but the tumour cells either can’t produce interferon or respond to interferon signalling and therefore die.
What are nucleoside inhibitors?
Inhibit integration of nucleoside into DNA or RNA. Not specific for viral nucleic acid. Must be engineered to be specific for virally infected cells.
Acyclovir, gancyclovir, calacyclovir (anti-herpetics). Prodrugs activated by viral thymidine kinase enzyme
NRTIs (antiretrovials) - recognized specifically by RT enzyme
What are virus specific drugs?
Inhibit unique viral processes or proteins. Viral specificity achieved because drugs don’t interfere with normal cellular processes
Our bodies don’t have these processes or proteins so only targets virus.