(Exam 4) Ch 13: Sterilization

synergistic drug

greater effectiveness when used together with another drug

antagonistic drug

interfere with each other and decrease effectiveness

penicillin, cephalosporin, vancomycin

cell wall inhibitor antibiotics

quinolones (ciprofloxacin)

dna replication inhibitor antibiotic

they target specific bacteria who have the ability to go from inactive form to active form of metronidazole (we do not have an activation system like this)

how are antibiotics that target DNA synthesis selectively toxic?

dna gyrase

what is the target of dna replication inhibitor antibiotics?

polymycin and gramicidin

usually used as a topical (not orally)

cell membrane inhibitor antibiotic

topically for gram negative, in worst cases as an iv

how/when is polymycin used?

forms an ion channel which interferes with membrane potential

how/when is gramicidin used?

poke a hole in the membrane

how do antibiotics that target the cell membrane do so?

sulfonamide

metabolic inhibitor antibiotic

metabolic

what type of antibiotic target is ideal?

it blocks folic acid formation which is key to making DNA and RNA

how does sulfonoamides target metabolic activity?

chloramphenicol

large subunit (50S) inhibitor antibiotic

macrolides (erythromycin and azithromycin)

antibiotics that target the 50S subunit

tetracycline (doxycycline and minocycline)

antibiotics that target the 30S subunit

true

true or false: antibiotics work best in the log phase because that’s when bacteria are most actively growing and most antibiotics target those active processes

PBP is originally just a linkage between peptidoglycan but when penicillin or cephalosporin shows up, it gets confused and binds with it (essentially weakening the cell wall)

what is important about PBP and antibiotics that target the cell wall?

penicillin binding protein

enzymes that produce peptide cross links in peptidoglycan

penicillin and cephalosporin

what cell wall inhibiting antibiotics have a beta lactam ring?

vancomycin

what cell wall inhibiting antibiotic directly binds to d-alanine d-alanine and does not bind to PBP?

getting a gene for beta lactamase which breaks the beta lactam ring of the antibiotic

one way that bacteria has developed antibiotic resistance

random mutation in a gene for a penicillin binding protein

PBP can no longer bind to the beta lactam ring

another way that bacteria has developed antibiotic resistance

group A Streptococci pyogenes

another name for GAS is

bacterial membrane

what type of antibiotic is the least ideal target?

what antibiotics target protein synthesis?

prevent entry

prevent binding

dislodge the antibiotic

what are the three strategies that bacteria use for antibiotic resistance?

destroys antibiotic

pumps the antibiotic out

decreases membrane permeability

how do bacteria prevent entry of the antibiotic?

alters the target

modifies the antibiotic with a modification enzyme

how do bacteria prevent antibiotics from binding?

protects their ribosome using a ribosome protection protein

how do bacteria dislodge the antibiotic?

spontaneous mutant survives and reproduces

how does antibiotic resistance arise?

it is unique to fungal cells

why do antifungal agents target ergosterol?