chapter 10 Flashcards
a chemical that kills or stops the growth of a microorganism
antibiotic or antimicrobial agent
the antibiotic is produced by and organism and then engineered in a lab to be more effective, longer lasting or easier to administer
semisynthetic antibiotics
antibiotics that are completely made in a lab
synthetic antibiotics
the antibiotic is more toxic to the pathogen than our cells
selective toxicity
who proposed the idea of chemotherapy, the use of chemicals that would selectively kill pathogens with little to no harm to the patient
paul ehrlich
chemicals that would bind to the receptors of bacteria while ignoring host cells that did not possess the same receptors
magic bullets
who discovered the antibacterial action of penicillin released from pencicillium mold which created a zone where bacteria could not grow
alexander fleming
discovered the first antimicrobial agent affective in treating a wide range of bacterial infections (broad spectrum antibiotic)
gerhard domagk
stops the synthesis of folic acid which is required for the synthesis of RNA in DNA in bacteria only
sulfanilamide
discovered that microbes are an invaluable source of producing antimicrobial agents
selman waksman
how does streptomyocin work
binds to small subunit of the ribosome blocking protein synthesis in bacteria
what is the antimicrobial strategy to stop cell wall synthesis
stop enzymes from making NAM-NAM cross bridges
a class of drugs that contain a beta-lactam ring that irreversibly binds to enzymes that produce NAM-NAM cross bridges
beta-lactams
EXAM QUESTION #1
Bacteria cells need to produce peptidoglycan strands and add them to their cell wall to grow and divide. They use an enzyme to make NAM-NAM tetrapeptide cross bridges to attach the new peptidoglycan strands to the cell wall. Beta-lactam drugs irreversibly bind to the enzyme that makes tetra cross bridges which weakens cells wall which will then result in death by osmotic pressure
block the formation of specific alanine crossbridges which weakens the cell wall
vancomyocin and cycloserine
blocks transport of NAG and NAM from cytoplasm; if you cannot get NAG and NAM out of the cytoplasm you cannot build the cell wall
bacitracin
the only drugs that disrupt mycolic acid formation in mycobacterium
isoniazad and ethambutol
examples of drugs that inhibit protein synthesis
tetracyclin, chloramphenicol and streptomycin
which drug binds to the ribosome and blocks the tRNA from being able to dock and deliver a new amino acid - the synthesis of the protein is prevented
tetracycline
a critical support molecule in the plasma membrane that fungi contain, lipid that maintains the structural integrity of the cell membrane of fungal cells
ergosterol
class of fungicides that bind to ergosterol
polyenes
a polyene that binds to ergosterol and drills a hole through it
amphotericin B
drugs that inhibit the cell’s ability to make ergosterol
azoles and allylamines
what happens without ergosterol
a fungal cell’s cytoplasmic membrane does not remain intact -> cell death
why are azoles and allylamines harmless to humans
they target a chemical pathway to produce ergosterol that does not exist in our bodies
binds to DNA and effectively blocks DNA replication and RNA transcription not only in bacteria but in their host cells - affected because bacteria and cancer cells divide much faster that normal cells in our body
used to treat bacterial infections and in chemotherapy
actinomycin
inhibit the activity of an enzyme called DNA gyrase stopping DNA replication
quinolones
an enzyme that exists only in prokaryotes and is necessary for the correct coiling and uncoiling of DNA that is replication
DNA gyrase
binds to RNA polymerase a lot more in prokaryotes than eukaryotes which stops transcription in bacteria - they then cannot make mRNA and bacteria cannot make proteins without mRNA
rifampin
molecules that are structurally very similar to the normal nucleotides
nucleotide analogs
the sum of all reactions that occur in an organism and provide energy for sustaining living processes
metabolism
affect metabolic process that are unique to pathogens and do not occur in humans
antimetabolic agents
prokaryotes convert PABA into
folic acid
acts as a coenzyme that is required to synthesize nucleotides
folic acid
act as structural analog of PABA and bind to an enzyme involved in its conversion to folic acid
sulfonamides or sulfa drugs
what is the strategy to inhibit virus attachment to a cell
use a protein or carbohydrate that blocks the chemical interaction between a virus and a host cell
class of drugs being researched that prevent virus from attaching to a host cell which prevents injection of viral DNA
attachment antagonists
antiviral drugs that prevent dissociation of the protein coat which is necessary for a virus to inject into a host cell
dissociation antagonists
prevent the release of newly formed viruses from host cells
transition antagonists
characteristic of ideal antibiotic
- inexpensive
- readily available
- chemically stable
- easily administered
- non-toxic
- selectively toxic against a wide range of pathogens
effective against few organisms
narrow spectrum
effective against many organisms
broad spectrum
if normal flora is killed what happens
there is additional space and resources for pathogens and bacteria to colonize which leads to secondary infections
the bacteria that are part of our normal flora occupy space and use resources preventing bacteria from gaining access to our body or colonize
microbial antagonism
number of different pathogens a drug acts against
spectrum of action
what is the diffusion of susceptibility test also known as
kirby-bauer test
clear area where the pathogen did not grow
zone of inhibition
how does the molecular wight of the antibiotic affect the size of the zone of inhibition
light weight diffuses a larger distance into agar where heavy weight diffuses a small distance from disc
the smallest amount of an antibiotic that will stop growth and reproduction of a pathogen
minimum inhibitory concentration
the mic is often determined by a
broth dilution test
drug used for external infection
topical application
requires no needles and is self-administered
oral route
administration delivers drug via needle into muscle
intramuscular
administration delivers drug directly to the bloodstream
intravenous
resistance by bacteria aquired in two ways
- new mutations of chromosomal genes
- acquisition of resistance plasmids via conjugation, transduction, and translation
resistant and persistors are in the majority or minority
minority
what is in the majority
regular bacteria
cells in a population that resist the effects of antimicrobial drugs despite being genetically identical to susceptible cells
persister cells
why are persister cells believed to be tolerant
metabolically inactive and grow slowly
