Antimicrobial Medications Flashcards
Which 2 groups of microbes are sources of most clinically useful antibiotics?
- bacteria
- molds/yeasts
What is the strict definition of an antibiotic? (What is a true antibiotic)
- small molecule (smaller than a protein)
- made by a microbe
- effective at low concentrations
- kills or inhibits growth of another microbe
What is a semi-synthetic antimicrobial?
-naturally occurring antibiotics that are modified by humans
Why are semi-synthetic antibiotics created?
-they can act against bacteria that are resistant to the original compound, have a greater spectrum of activity, or cause fewer side effects
What is a synthetic antimicrobial?
-purely human-made molecules
What microbes are targeted by antimicrobial medications?
What are more specific terms for these antibiotics?
- bacteria (antibacterial)
- fungi (antifungal)
- protozoans (antiprotozoans)
- helminths (antihelminthic)
Which one group of antimicrobial medications are not called antibiotics?
-Antiviral medications (all synthetic)
What is selective toxicity?
-ability to kill or inhibit the growth of microbes without harming or damaging human (host) cells.
Why is it difficult to find selective poison the more evolutionary related a microbe is to humans?
-enzymes and cellular structures in the microbe are similar to those in human cells
What are the 8 groups of microbes under the antimicrobial spectrum?
Prokaryotes:
1) Myobacteria
2) Gram - bacteria
3) Gram + bacteria
4) Chlamydias
Eukaryotes
5)Fungi
6) protozoa
7) helminths
8) Viruses
What does it mean if an antimicrobial medication is broad spectrum or narrow spectrum?
- Narrow: affects a single group
- broad: affects at least 2 groups
What are the. 6 most common cellular targets for antibacterial medications?
1) Cell wall (peptidoglycan)
2) Ribosome (translation)
3) RNA polymerase (transcription)
4) DNA Replication (DNA gyrase)
5) Bacterial membranes
6) metabolic pathway (actions of enzyme inhibitors)
How do antibacterial medications affect cells walls?
- penicillins and cephalosporins inhibit transpeptidase enzyme
- weaken cell wall
How do antibacterial mediations affect their target ribosomes?
Examples?
- prevent peptide bond formation (blocks translation)
- aminoglycosides decrease fidelity of ribosome
- Ex. Tetracycline
How do antibacterial medications affect their target RNA polymerase?
-stops transcription
if there is no mRNA, ribosomes have no instructions
-rifampin inhibits RNA polymerase
How do antibacterial medications affect their target of DNA replication?
-fluoroquinolones inhibit DNA gyrase, an enzymes need for DNA to unwind during DNA replication
How do antibacterial medications affect bacterial membranes?
- causes damage to the membrane resulting in the lass of concentration gradients and/or lysis
- ex. Polymyxin B disrupts gram negative outer membrane
How antibacterial medications affect metabolic pathways?
- prevents folate synthesis; an essential chemical reaction that builds ATG bases and methionine amino acids
- ex. Sulfa, trimethphan
Compare and contrast tetracycline and aminoglycosides
- Tetracycline stops the translation process (bacteriostatic)
- aminoglycosides decrease the fidelity of the ribosome (bacteriocidal)
Define bacteriostatic
-capable of inhibiting the growth or reproduction of bacteria
Define bacteriocidal
-capable of killing the bacteria
List 3 emerging drug resistant bacterial infections
1) MRSA
2) Tuberculosis
3) Gonorrhea bacteria
Compare and contrast inherent resistance and specific resistance
- Inherent resistance
- the antibiotic never works against a particular group of microbes (outside the spectrum)
- specific resistance
- certain species/strain develops resistance
Define susceptible in context of antimicrobial drugs
-microbial infection is likely to be cured by the antimicrobial medication
What are four ways bacteria can attain specific resistance to antibiotics?
1) block entry of antibiotic
2) pump out antibiotic
3) degrade antibiotic
4) alter the target
Why are antibiotics given to livestock even when those animals are not suffering form infection?
- will eliminate individuals with certain traits
- the reproduction of survivors will increase frequency of traits that enhanced survival and reproductive success
Targets for antifungal medicines (3)
1) plasma membrane: ergosterol in plasma membrane instead of cholesterol
2) metabolic pathway: lipid synthesis enzymes
3) DNA/RNA synthesis
Targets for antiprotozoal medicines (2)
1) inhibit DNA synthesis
2) interfere with anaerobic metabolism
Targets for antihelminthic medicines (4)
1) block ion channels (paralysis)
2) inhibit ATP production
3) prevent nutrient absorption
4) disrupt membranes
(Severe side effects)
