Antibiotics Flashcards
What are the bacteria that are commonly used to determine the activity spectrum of an antibiotic?
Gram (+), Gram (-), mycobacteria, pseudomonas
Difference between bacteriostatic, bactericidal, and a bacteriolytic antibiotic.
‘static = prevents growth
‘cidal = kills bacteria
‘lytic = causes lysis
What is a therapeutic index
range of doses that are effective without causing unacceptable adverse events (or harm)
What are four common unwanted side effects of antibiotic use
- Allergies develop
- Toxicity (end up affecting human cells)
- Suppression of normal flora
- Selection for antibiotic resistant “superbugs”
Why are several successive generations of antibiotics produced?
To improve the antibiotic by changing its properties or administration route
What are five major antibiotic targets in bacteria
- Lipid membrane
- Cell wall (peptidoglycan)
- Nucleic acid synthesis
- Protein synthesis
- Folate biosynthesis
Mode of action: beta-lactams
cell wall
prevent PG crosslink
can be inactivated by beta-lactamase enzymes (resistance)
Mode of action: vancomycin
cell wall
prevent PG transglycosylation and transpeptidation
Mode of action: bacitracin
cell wall
prevent monomer transport across membrane
Mode of action: fluoroquinolones
Nucleic acid synthesis
inhibit gyrase
Mode of action: rifamycin
Nucleic acid synthesis
inhibit RNA polymerase
Mode of action: polymyxin
cell membrane
peptide antibiotic
Mode of action: cubucin
cell membrane
dissipates PMF
Mode of action: sulfa drugs
folic acid synthesis
competitive inhibitor for PABA
Mode of action: trimethoprim
inhibits intermediate in folic acid synthesis
What five antibiotic are protein synthesis inhibitors
Synercid
Macrolide
Aminoglycoside
Lincosamide
Linezolid
What are four major targets of antiviral drugs
Uncoating (nucleic acid liberation)
Synthesis
Assembly
Release
Mode of action of amantadine and oseltamivir on influenza virus
amantadine: targets uncoating in flu virus
oseltamivir: inhibits neuraminidase (release) in flu
What are the three main classes of nucleic acid synthesis inhibitors
- nucleoside analogs
- polymerase inbibitors
- RTase inhibitors
How do protease inhibitor drugs prevent the assembly of some viruses
inhibits protease
What are the main targets of antifungal drugs + examples
- Plasma membrane (azoles)
- Cell wall (echinocandins)
- Cell division (griseofulvin)
What are five antiprotozoal drugs + uses
Intestinal infections
a. Metronidazole
Helminths
b. Ivermectin
c. Piperazine
Malaria
d. Artemisinin
e. Chloroquine
What are three ways to determine the effectiveness of an antibiotic against a particular bacterium
- Minimum Inhibitory Concentration (serial dilution)
- Kirby Baur Susceptibility testing (disc)
- E test (strip)
What are four mechanisms where bacteria develop resistance
- Destroy antibiotic
- Chemically modify antibiotic
- Alter target of antibiotic
- Decrease uptake
What are R-plasmids?
R plasmids are a type of F plasmid that have multiple genes for resistance, it can be transmitted by transformation, conjugation, or transduction
How can bacteria can become resistant to several antibiotics if they were only exposed to one?
multiple drugs may target the same mechanism
