Bacterial Competition Flashcards
what is the difference between how we study bacteria and how it is found in the natural world / what does this lead to for bacteria
we study it as an isolated strain but it rarely ever found in pure culture in the environment / bacterial competition so their species can survive
what do bacterial cells produce to intoxicate neighboring bacteria / what do humans use this for
antagonistic molecules that are used to kill neighboring bacteria which raises their fitness / antibiotics
what is considered the golden era of antibiotic discovery / why did it stop
from 1920-1960 / antibiotic resistance
why is selective toxicity important in antibiotics
they will inibit a fundamental process in bacteria but not in host cells - things lie peptidoglycan inhibitors, bacterial metabolic inhibitors, bacterial specific RNA/DNA polymerase, and protein synthesis because our ribosomes look very different
how does crosslinking in peptidoglycan occur / what catalyzes the crosslinking
the amino acid on the donor chain displaces the D-alanine on the acceptor chain - a covlalent linkage occurs / penicillin binding proteins (PBPs)
how does beta lactam antibiotics attack the petidoglycan / how does this kill a cell
the beta-lactams structurally mimic the D-ala-D-ala compenent of the peptide bridge so PBPs get covalently attached to beta-lactam instead of D-ala-D-ala / weakens the cell wall and they eventually pop
why does penicillin only affect gram-positive / what is the difference between narrow spectrum and broad spectrum antibiotics
it cannot get through the outer membrane of gram negative cells (narrow spectrum) / broad spectrum will kill any bacteria it is exposed to
how do we determine drug susceptibility of bacteria / how do we do this
Minimum inhibitory concentration (MIC) / either do a series of dilutions to see where the lowest concentration of antibiotic is that shows growth OR use E-test strips with this dilution impregnated in it
what does the Kirby-Bauer Assay do
shows which antibiotic is the most effective on a bacteria - allows us to compare a spectrum of antibiotics
how do scientist make a narrow spectrum antibiotic more broad
they chemically alter them - such as ampicillin which is penicillin with an extra methylated group (allows it to get through the membrane of a gram negative)
what are some antibiotic side effects
allergies such as penicillin allergy - we develop an immune response to the foreign protein and target the specific conjugate AND the antibiotics target conserved components of all bacteria not just the pathogens (kills off good bacteria in gut and can cause serious infection)
what do aminoglycosides cause, why / what can be activated upon microbial stress
irreversible hearing loss because they bind to 16s rRNA / gene transfer because dormant viruses activate and lysogenize
what are the basic mechanisms of antibiotic resistance
bacteria prevent entry of antibiotics by exporting the drug and breaking the drug down - they prevent binding by modifying the antibiotic and altering its target - they reverse binding by dislodging antibiotics that are bound to target
why are big pharma companies not pursuing antibiotic production anymore
they are a huge investment and not a great money generator especially if the bacteria develops resistance quickly
why is resistance so widespread
people not completing their antibiotic course or incorrectly taking the antibiotics - need to keep the level of antibiotic in the body higher than the MIC so the bacteria cannot replicate in the presence of the drug
