Effects of Antibiotics on Life Cycle of bacteria Flashcards
what is the difference b/w bactericidal and bacteriostatic
bactericdal kills all whereas bacteriostatic slows activity
what are the characteristics of an ideal antibiotic ?
broad spectrum of activity, no resistance, high therapeutic index, selective toxicity
what does a low therapeutic index mean for an antibiotic
it means it will take a toxic dose (to the host) in order to kill the bacteria
what 4 parts of bacteria should you attack to achieve selective toxicity
cell wall, unique replication/transcription enzymes, unique metabolites, ribosomes
what are the 5 main ways to inhibit bacteria
1-inhibit cell wall synthesis 2-disrupt cell membrane function 3-inhibit protein synthesis 4-inhibit nucleic acid synthesis 5-act as antimetabolite
how does penicillan act to inhibit bacteria
disrupts cell wall synthesis
what does polymyxin B sulfate do to inhibit bacteria, and what is its drawback as an antibiotic
disrupts cell membrane function, but also attacks eukaryotes so only used as a topical antibiotic
what is the most common strategy for an antibiotic to inhibit bacteria, Why ?
inhibit protein synthesis, because the bacterial ribosome is structurally different than the eukaryotic ribisome
what enzymes would an antibiotic attack if it were inhibiting nucleic acid synthesis
DNA gyrase (bacteria only have this), RNA polymerase
T/F an antibiotic trying to inhibit nucleic acid synthesis is good if it binds to DNA ?
F, do NOT want it to bind to DNA else would be toxic to host human
what specific antibiotic acts as an antimetabolite
sulfanilamide
macrolides, linezoid,tetracycline, and aminoglycosides all have what in common ?
antibiotics that block the ribosome cycle thus blocking protein synthesis
what is the main cause of bacteria to develop antibiotic resistance
selective pressure and overuse
what are the 3 steps in the action of an antibiotic to be effective
1 - penetrate the envelope
2-transport into the cell
3-bind to target
what are the 3 mechanisms of drug resistance
1-synthesis of enzymes that inactivate drug
2- prevention of access to target site
3-modificaton of target site
Beta lactamases is an example of what kind of enzyme
an enzyme bacteria have developed that inactivates penicillan (caused bacteria resistance)
bacteria developing efflux pumps to pump tetracycline out of the cell is a demonstration of what mechanism of drug resistance
preventing access to the target site
if bacteria can modify an enzymes affinity for a particular drug it is an exp of what mechanism of drug resistance
modification of the target site
what are the 3 ways antibiotic resistance can spread
1-chromosome associated resistance
2-plasmid mediated resistance
3-rapid spread of resistance
why it is so crucial to completely finish an antibiotic for the reccomended time period
Because an antibiotic will kill the most sensitive bacteria 1st, then the int. bacteria, and lastly the highly resistant bacteria (if dont finish wont kill this last group then your fucked )
3 ways to combat an antibiotic resistant pathogen
synergism, antagonism, indifference
what is the difference b/w synergism and antoagonism antibiotics
synergism uses 2 drugs to amplify effect, antagonism uses 2 but 1 is bacteriostatic and other is bactericidal
T/F antibiotics are effective against all microbes
F, do not affect virus
what are potential drawbacks of administering an antibiotic cocktail (2 or more drugs together)
- could become resistant to 2 drugs
- doesnt eliminate bacteria and get superinfection
- synergistic toxicity to host
