3 - antibiotics Flashcards
what are antibiotics
soluble compounds that are produced and released by microorganisms that inhibit the growth or kill other microorganisms
what are the 3 different kinds of ways you can classify bacteria
aerobic vs. anaerobic
shapes
gram
which gram stain has thicker peptidoglycan layer
gram positive
which gram stain has thinner peptidoglycan layer
gram negative
which gram stain has the second layer of lipopolysaccharides and lipoproteins
gram negative
which kind of gram stain is most bacteria
gram negative
what consists of the peptidoglycan structure
alternating glycan strands of NAG and NAM
what does glycosyltransferase do
polymerizes individual strands (connects nag and nam) into peptidoglycan chain
what does transpeptidase do
cross link the strands to contribute the overall structure of the shape
which protein is targeted by many antibiotics (penicillin binding protein)
transpeptidases
why do pathogens require an immunocompromised or injured host
they dont
they have big mechanisms to attack healthy people
what is the spectrum of activity
narrow or broad spectrum depending on the number different bacterial species against which they exhibit useful activity
what is bacterial sensitivity
assessing the ability of bacterial strain to replicate following antibiotic exposure
what is a bactericidal antibiotic
death, permanent loss of replicative ability
what is a bacteriostatic antibiotic
leads to temporary loss of growth and replicative ability
what is therapeutic index
ratio of the minimum concentration likely to produce an adverse effect to the minimum concentration needed to produce a desired effect
what is ability to penetrate
delivery of antibiotic to the site of inection is the most difficult challenge of antibiotic delivery
what are the 4 ways to describe efficacy and potency
spectrum of activity
bacterial sensitivity
therapeutic index
ability to penetrate
what are the 4 classes of antibiotics we need to know
cell wall inhibitors
folic acid inhibitors
DNA synthesis inhibitors
protein synthesis inhibitors
what are the two beta lactams
penicillin and cephalosporin
what kind of antibiotics are beta lactams
cell wall inhibitors
why are they called beta lactams
they have an unusual 4 membered ring
how do beta lactams work
inhibit cell wall synthesis by inhibiting transpeptidase that cross links the components of the cell wall
are beta lactams bacteriostatic or cidal
cidal
what are beta-lactamases
bacterial enzymes made by bacteria that hydrolyze the beta lactam ring
what does vancomycin
inhibits peptidoglycan cross linking
but not a beta-lactam
is vancomycin a beta lactam
no
what does calvulanic acid do
inhibits beta lactamases
what is PABA
a nutrient obtained from the environment that is the precursor for folate in bacteria
what is the use of folic acid in bacteria
they use it to synthesized nucleic acids
what do sulfonamides do
competes with PABA
what do trimethoprim do
compete with dihydrofolic acid
what are the folic acid inhibitors
sulfonamides and trimethoprim
why are sulfonamides and trimethoprim usually taken together
to block the sequential steps in synthesis of folic acid
which are the three protein synthesis inhibitors that we need to know
chloramphenicol
tetracyclines
macrolines
what are the broad spectrum protein synthesis inhibitors
chrloramphenicol and tetracyclines
what are the moderate spectrum protein synthesis inhibitors
macrolides
what are the narrow spectrum protein synthesis inhibitors
we dont need to know
how do bacteria make protein
from mRNA template within the 70s ribosomal complex (50s + 30s)
tRNA (t6) transfers amino acids (transpeptidation)
what is transpeptidation
when tRNA (t6) transfers an amino acid to the growing amino acid chain
how does chloramphenicol work
bind to the 50s subunit and block transpeptidation
how do macrolides work
bind to the 50s subunit and block transpeptidation
how do tetracyclines work
bind to the 30s subunit and prevent binding of incoming DNA
where do aminoglycosides bind
30s ribosomal subunit
what do aminoglycosides do
block initiation of 30s complex
cause misreading of mRNA template
inhibit translocation
why doesnt chloramphenical hurt human cells
it does not bind to the 80s subunit, only the 70s
why doesnt PABA inhibitors affect humans
humans cannot synthesis folic acid from paba
what are 4 ways bacteria create resistance
drug inactivation (b-lactamases)
alteration of binding site
alteration of metabolic pathway (use folic acid from enviro instead of PABA)
reduced drug accumulation (efflux)
what is stevens-johnson syndrome and toxic epidermal necrolysis
rare condition where the skin becomes detached from the underlying tissue and sloughs off the body due to antibiotics
