Chapter 10 - Biological Method Flashcards
Antimicrobial agents
-drugs that treat infections
Chemotherapeutic agents
drugs that act against disease
Paul Erlich
“magic bullet”
-arsenic compounds that killed microbes
Alexander Fleming
penicillin released from Penicillium
Mechanism of actions of microbial drugs
- inhibition of pathogen’s attachment to/recognition of host
- inhibition of cell wall synthesis
- disruption of cytoplasmic membrane
- inhibition of protein synth
- inhibit general metab pathway
- inhibit DNA/RNA synth
-inhibition of cell wall synthesis
- cidal
- only effective for growing cells
- prevents bacteria fr increasing amt of peptidoglycan; NO effect on existing peptidoglycan layer
- prevents cross-linkage of NAM subunit
- beta-lactam rings bind to enzymes
-inhibition of protein synth
- static
- macrolides (erythromycin)
-disruption of cytoplasmic membrane
-cidal
-inhibit general metab pathway
- static
- sulfonamides
-inhibit DNA/RNA synth
-cidal
Vancomycin
inhibits cell wall synthesis (cidal)
-interferes w bridges that link NAM subunits in many GramPos
Erythromycin
inhibits protein synth (static)
-gram pos, gram neg, chlamydias, rickettsias
Macrolides
inhibits protein synth (static)
-gram pos, gram neg, chlamydias, rickettsias
aka erythromycin
Polymyxins
disruption of cytoplasmic membrane (cidal)
- gram neg only
- toxic to human kidneys
Sulfonamides
inhibits general metab pathway (static)
-gram pos, gram neg, chlamydias, rickettsias, protozoas
3 static mechanism of action of microbial drugs
1 inhibit protein synth
2 inhibit metab pathway
3 inhibit attachment/recognition of host
3 cidal mechanism of action of microbial drugs
1 inhibit cell wall synth
2 disrupt cytoplasmic membrane
3 inhibit DNA/RNA synth
Penicillin
- inhibits synth of cell wall (peptidoglycan)
- beta-lactams bind to enzymes that cross-link NAM subunits of peptidoglycan
- only effective during log phase
advantage of semisynthetic derivatives of beta-lactams
- more stable in acidic environments
- more readily absorbed
- less susceptible to deactivation
- more active against more types of resistant bacteria
Bacitracin
inhibits cell wall synthesis (cidal)
-blocks secretion of NAG + NAM fr cytoplams
Isoniazid
inhibits cell wall synthesis (cidal)
-disrupts mycolic acid formation in mycobacterial species + used exclusively for treatment of infections w MYCObacteria (TB)
Azoles
disrupt cytoplasmic membrane (cidal)
- inhibit ergosterol synth
- broad spectrum drug
- can be used for protozoan, fungi, + worm infections
Minimum Inhibitory Concentration Test
minimum concentration of a drug required to completely inhibit growth.
Kirby Bauer test
diffusion susceptibility test looks at zone of inhibitions
Toxicity
- cause of many adverse rxn
- drugs may be toxic to kidneys, liver, nerves
- consideration needed when prescribing drugs to pregnant women
Tetracyclines
- inhibits protein synth
- block tRNA for docking site
- becomes incorporated into bones + teeth of a fetus
- consideration needed when prescribing drugs to pregnant women
Allergies
- allergic rxn are rare but life threatening
- anaphylactic shock
Retarding resistance
- maintain high concentration of drug in patient for sufficient time
- use antimicrobial agents in combination
- use antimicrobial only when necessary
synergism vs. antagonism
synergism - works better together. ex) amoxicillin-clavulanic acid + semisynthetic aztreonam
antagonism - works against each other
ex) penicillin (only works when actively dividing) + erythromycin (stops protein synth which stops growth)
penicillin + erthromycin
antagonistic combo
Quinolones
- inhibits DNA/RNA synth (cidal)
- acts against prokaryotic DNA gyrase
- aka ciprofloxacin
Ciprofloxacin
- inhibits DNA/RNA synth (cidal)
- acts against prokaryotic DNA gyrase
- aka quinolones/fluoroquinolones
antibiotics that inhibit cell WALL synth
penicillin
vancomycin
bacitracin
isoniazid
antibiotics that inhibit protein synth
macrolides/erythromycin
tetracyclines
simplest beta-lactams
-only effective against aerobic gram neg
antibiotics that disrupt cytoplasmic MEMBRANE
azoles
polymyxin
amphoterecin B
narrow spectrum meds
penicillin, isoniazid
broad spectrum meds
erythromycin, sulfonamides, azoles, tetracycline
Amphoterecin B
Attached to ergosterol in fungal membranes
-disrupts cytoplasmic membrane
antibiotics that inhibit DNA/RNA synth
quinolones
reverse transcriptase inhibitors (only against retrovirus)
nucleotide analogs
