Antimicrobial Drugs & Drug Resistance Flashcards
What are antimicrobial drugs?
Compounds that kill or control the growth of microorganisms in the host
What kind of toxicity do antimicrobial drugs have?
Selective
What are the 2 broad categories of antimicrobial drugs?
Synthetic & natural
What is meant when drugs are described as “synergistic”?
One drug is good, but two drugs are better
What type of drugs disrupt eukaryotic cells more and why?
Drugs that disrupt plasma membranes because eukaryotic cells do not have a cell wall
Which type of antimicrobial drugs are for external use only?
Ones that target cytoplasmic membrane structure and function
What do antimicrobial drugs that target RNA elongation do?
Interfere with translation
What is the difference between growth factors & growth factor analogs?
- Structurally similar
- Growth factors function in the cell, while growth factor analogs do not
What do sulfa drugs do?
Inhibit growth of bacteria by inhibiting folic acid synthesis, thus inhibiting nucleic acid synthesis
What do quinolones do?
Inhibit DNA gyrase, which prevents DNA supercoiling
What type(s) of bacteria are quinolones active against?
Gram negatives & Gram positives
What organisms produce antibiotics naturally?
Bacteria & fungi
Less than 1% of known antibiotics are _______
Clinically useful
What are semi-synthetic antibiotics?
Artificially modified natural antibiotics
With respect to antibiotics, how do microbes differ?
The susceptibility of microbes to different antibiotics varies greatly
What are the 2 types of antibiotics?
Broad-spectrum & narrow-spectrum
What do broad-spectrum antibiotics do?
Target most of bacteria that it sees (no preference)
When are broad-spectrum antibiotics given?
When a patient has an infection but the cause is unknown
What is the disadvantage to broad-spectrum antibiotics?
Kill normal flora
When are narrow-spectrum drugs given?
When the cause of the infection is known
What is the advantage to narrow-spectrum drugs?
Preserve normal flora
Define bacteriostatic
Interfere with growth of bacteria which keeps the number constant so immune system can kill the bacteria
Define bacteriocidal
Destroys bacteria and eliminates threat entirely
What are beta-lactam antibiotics?
Cell wall synthesis inhibitors
What are 2 examples of beta-lactam antibiotics and what are their similarities & differences?
- Penicillins & cephalosporins
- Similar mode of action (target cell wall)
- Cephalosporins have a more broad spectrum than penicillins
What is penicillin effective against?
Gram positive bacteria
Who discovered penicillin?
Alexander Fleming
What are cephalosporins resistant to?
Beta-lactamases
What are cephalosporins commonly used to treat?
Gonorrhea
What are aminoglycosides?
Amino sugars bonded by glycosidic linkages
What do aminoglycosides target?
30S subunit of a ribosome
What are examples of aminoglycosides?
Streptomycin, kanamycin, neomycin, & gentamicin
What type of bacteria do aminoglycosides target?
Gram negatives
Which antibiotics are considered “last resort antibiotics”?
Aminoglycosides
What are macrolides & are they broad- or narrow-spectrum?
- Lactone rings bonded to sugars
- Broad-spectrum
What do macrolides target and what does this lead to?
- 50S subunit of a ribosome
- Leads to partial inhibition of protein synthesis
How are tetracyclines produced?
- Naturally by several species of Streptomyces
- Semi-synthetically
Are tetracyclines broad- or narrow-spectrum?
Broad
What do tetracyclines inhibit?
30S subunit of ribosome
What are the 2 most widely used antibiotics?
Penicillins & tetracyclines
What are 2 examples of novel antibiotics?
Daptomycin & platensimycin
What is daptomycin?
Cyclic lipopeptide active against Gram positives
What does daptomycin do?
Forms pore in cell membrane, which causes depolarization
How is daptomycin produced?
By Streptomyces
What is platensimycin?
Fatty acid biosynthesis inhibitor
Is platensimycin broad- or narrow-spectrum?
Broad
What is antimicrobial drug resistance?
Ability of a microorganism to resist the effects of an antimicrobial agent to which it is normally sensitive
What are the 2 types of antimicrobial drug resistance?
Chromosomal & plasmid-encoded
What are 5 mechanisms of antimicrobial drug resistance?
1) Reduced permeability
2) Inactivation of antibiotic
3) Alternation of target
4) Development of resistant biochemical pathway
5) Efflux
How is reduced permeability used for antimicrobial drug resistance and what is an example of a drug that uses this?
- Keeps drug to exterior of bacterial cell
- Penicillin
How is inactivation of the antibiotic used for antimicrobial drug resistance and what are examples of drugs that uses this?
- Enzyme cuts at vital area to reduce antimicrobial properties
- Penicillins, chloramphenicol, aminoglycosides
What are examples of drugs that uses alternation of target for antimicrobial drug resistance?
Erthromycin, streptomycin, norfloxacin
What is an example of a drug that uses development of resistant biochemical pathways for antimicrobial drug resistance?
Sulfonamides
How is efflux used for antimicrobial drug resistance and what is an example of a drug that uses this?
- Bacteria let drug inside, but pumps it to the exterior once it realizes that it is causing harm
- Tetracyclines, chloramphenicol, fluoroquinolones
What are 80% of antibiotics produced for?
Use in agricultural practices
What does MRSA stand for?
Methicillin-resistant Staphylococcus aureus
What does VRE stand for?
Vancomycin-resistant enterococci
What are 4 methods for preventing antimicrobial resistance?
1) Prevention of infections
2) Rapid, conclusive diagnosis
3) Prudent use of antimicrobials
4) Prevention of transmission
