antibiotics MT1 Flashcards by Jessyka Yard

what are the 5 different ways that antibiotics work (mechanisms of action)

inhibition of cell wall synthesis
inhibition of protein synthesis
inhibition of nucleic acid synthesis
alteration of cell membrane function
alteration of cell metabolism

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a microbiology lab determines the _______ by mixing a standard concentration of the organisms that the patient has grown with increasing concentrations of the antibiotic in a broth solution. the mixture with the lowest concentration of antibiotic where there is no visible growth is deemed to be the ___________

MIC - minimun inhibitory concentration

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is this susceptible, intermediate or resistant?
if the MIC < breakpoint, at typical doses the antibiotic would have a high probability of being effective

susceptible (S)

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is this susceptible, intermediate or resistant?
if the MIC is approaching or near the determined breakpoint. the antibiotic may be effective at higher doses (if safely attainable)

intermediate (I)

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is this susceptible, intermediate or resistant?
if the MIC is greater than the breakpoint the antibiotic would be unlikely to achieve therapeutic success

resistant (R)

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what three classes of antibiotics are bacteriostatic?

macrolides (azithromycin, clarithromycin, erythromycin)
tetracyclines (doxycycline)
linezolid

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what are some mechanisms of resistance that bacteria can produce

enzymatic destruction
altered binding sites
efflux pumps
modified cell wall porins

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what antibiotics are considered to be beta-lactams

penicillins (e.g. pen V/G, amoxicillin, cloxacillin)
cephalosporins (cephalexin, cefuroxime, cefixime)
carbapenems (imipenem, meropenem, ertapenem)

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what are some examples of macrolides

erythromycin, clarithromycin, azithromycin

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what are some examples of tetracyclines

tetracycline, doxycycline, minocycline

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what are some examples of fluoroquinolones

ciprofloxacin, norfloxacin, levofloxacin, moxifloxacin

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what are some examples of aminoglycosides

gentamicin and tobramycin

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what is the mechanism of action of beta-lactams

beta-lactams bind to penicillin binding proteins (PBP) which cause the peptidoglycan barrier to not form properly causing cell lysis.

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what is the most common mechanism of bacterial resistance in beta-lactams

enzymatic destruction and altered PBP sites

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are beta-lactams bactericidal or bacteriostatic

bactericidal

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are beta-lactams time dependant or concentration dependant

time dependant

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what is the most common ADR for beta-lactams

hypersensitivity reaction

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true/false: delayed rashes caused by penicillin, if after a few doses/days and NO itchiness/hives are typically indicative of a true IgE-mediated allergy

false - worried if rash happens right away with itchiness/hives

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what should be done when patients have an uncertain penicillin allergy (such as reaction took place >10 years ago, or when reaction took places after days rather than hours when taking the antibiotic

refer patients for skin testing

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if patient develops a rash with no itching/urticaria from penicillin, what other drug can be given?

a beta-lactam such as a cephalosporin can be given

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this cephalosporin has a unique side chain to all other beta-lactams

cefalozolin

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this beta-lactam is known for causing idiopathic skin rashes (maculopapular - not allergy associated)

amoxicillin

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this beta-lactam seems to cause more hematologic issues

pip-tazo

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this beta-lactam can bind to Ca (causing precipitation) and biliary slugging, mostly in paediatrics therefore should not use together with IV Ca

Ceftriaxone

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this beta-lactam can cause seizure in renal dysfunction

cefepime

what pencillins must be taken on an empty stomach

Pen V and cloxacillin

all of the oral cephalosporins have excellent oral absorption except these two

cefixime and cefuroxime

this type of bacteria produces beta-lactamases, therefore the primary pencillins (pen V and pen G) did not have coverage for them. Cloxacillin was then introduced to help cover this type of bacteria

staph aureus

true/false: cloxacillin has strep coverage

true - not DOC but cloxacillin is active against strep spp.

these bind to beta-lactamase enzymes and therefore restore any susceptibility that was lost due to bacterial development of beta-lactamases (e.g. staph aureus, h. influenza, moxarella) and bacteria that always intrinsically produced beta-lactamases (e.g. b. frag)

beta-lactamase inhibitors (e.g. clavulin, tazobactam)

this penicillin medication was introduced to help cover gram -ve bacteria. it has a longer side chain which allows it to bind to different sites (PBP) and therefore has better gram negative coverage including some Pseudomonas spp.

piperacillin/tazobactam

true/false: as you go up in generations of cephalosporins, you get more gram -ve coverage

true

what are examples of first generation cephalosporins

cefadroxil, cephalexin, cefazolin "CEFA"

what pneumonic can be used to remember the gram -ve coverage for first gen cephalosporins

PEK P-proteus spp. E- e.coli (not ESBLs) K-Klebsiella (not ESBLs)

what are some examples of second generation cephalosporins

cefuroxime, cefprozil, cefoxitin

what pneumonic can be used to remember the gram -ve coverage for second gen cephalosporins

HPEK H- H.influenzae (and M. catarrhalis) P-proteus spp. E- e.coli (not ESBLs) K-Klebsiella (not ESBLs)

what are examples of third generation cephalosporins

cefixime, cefotaxime, ceftriaxone, ceftazidime "ends in one or me"

what pneumonic can be used to remember the gram -ve coverage for third gen cephalosporins

HENPEK H - H.influenzae E- enterobacter spp. N- N. meningiditis P-proteus spp. E- e.coli (not ESBLs) K-Klebsiella (not ESBLs)

this third generation cephalosporin has very poor activity against gram positive bacteria.

cefatazidime

What are some examples of fourth generation cephalosporins

Ceftobiprole and cefepime

What are examples of fifth generation cephalosporins

Ceftolozone/tazobactam

If you over treat with this second generation cephalosporin, it will cause an influx of beta-lactamases

Cefoxitin (IV)

these are structurally more resistant to beta-lactamases. has a major toxicity of seizures.

Carbapenems (e.g. imipenem, meropenem, ertapenem)

true/false: all carbapenems are DOC for e.coli, klebsiella (non-ESBLs) and B.frag

false - covers ESBLS!!

what is the MOA for macrolides

bind to the 50S subunit and inhibits protein synthesis

what is the MOR for macrolides

europe - alteration of ribosomal binding site North America - reduced permeability of cell membrane/reflux

true or false: macrolides have a prolonged antibiotic effect (PAE)

true

are macrolides time or concentration dependant

time (azithromycin is conc. dependant DAAMQ)

are macrolides bacteriostatic or cidal

bacteriostatic

this macrolide should be taken on an empty stomach

erythromycin

what are some ADRs of macrolides

- taste disturbances - Qt prolongation

this tetracycline is similar to erythromycin and Pen G/V in that it is the first tetracycline and therefore has the least antimicrobial spectra of the tetracyclines.

tetracycline

what is the MOA of tetracyclines

binds to 30S ribosomal subunit therefore inhibits protein synthesis

what is the MOR for tetracyclines

decreased intracellular accumulation due to efflux by bacteria protein pump

are tetracyclines bacteriostatic or cidal

static (in MTL)

are tetracyclines time dependant or concentration dependant

time dependant

true or false: tetracyclines have prolonged antibiotic effects

true

which tetracycline should be taken on an empty stomach

tetracycline

what are the most common ADRs for tetracyclines

- photosensitivity - avoid with divalent cations - esophageal ulceration - baby teeth may turn gray

__________ is LEAST likely to cause C. diff infection

tetracyclines

this class of antibiotics are the opposite of the beta-lactams in that they started out with great gram -ve coverage but not great gram +ve.

fluorquinolones

what is the MOA of fluoroquinolones

DNA! blocks bacterial DNA synthesis by inhibiting bacterial topoisomerase II (DNA gyrase and IV

what is the MOR of fluoroquinolones

alterations in DNA gyrase making it difficult for a fluoroquinolone to bind

are fluoroquinolones bacteriostatic or cidal

cidal

are fluoroquinolones concentration or time dependant

concentration

what fluoroquinolones need to be really adjusted

levo and cipro NOT MOXI

what are ADRs in fluoroquinolones

- can affect sugars - QT prolongation - photosensitivity - drowsiness - confusion - tendinopathy

what are examples of ahminoglycosides

gentamicin and tobramycin

what is the MOA of ahminoglycosides

binds to 30S ribosomal subunit and results in a defective cell membrane

true or false: ahminoglycosides have a significant post-antibiotic effect (PAE)

true

what are some ADRs of aminoglycosides

- nephrotoxicity - ototoxicity - neuromuscular blockade

true or false: aminoglycosides only cover gram +ve bacteria

false - only gram negative

what is the MOA of vancomycin?

inhibits cell wall synthesis and the cell membrane is also damaged

true or false: vancomycin is used IV to treat C. diff

false - used po to treat C diff as it stays in the GI tract and stays in contact with the C.diff

what is the MOR for vancomycin

it binds to the extra peptidoglycan layers which are dead binding sites and therefore cannot reach the site of action

true or false: vancomycin essentially only covers gram +ve

true

true or false: vancomycin should only be used when a bacteria is resistant to other antibiotics or other antibiotics cannot be used due to ADRs or allergies

true

what are some ADRs of vancomycin

- infusion reactions - otoxicity - nephrotoxicity

what is the MOA of clindamycin

binds to the 50S ribosomal subunit, inhibiting protein synthesis

what is the MOR of clindamycin

- mutation of the ribosomal receptor site - modification of the receptor - enzymatic inactivation of clindamycin

is clindamycin bacteriostatic or cidal

static

what is one main ADR of clindamycin

diarrhea!! probably the worst for causing C. diff

this inhibits bacteria synthesis of dihrdyofolic acid by competition with para-amino benzoic acid

sulfamethoxazole

this blocks the production of THF acid from dihyrofolic acid by reversibility inhibiting the requires enzyme dihydrofolate reductase

trimethoprim

is TMP-SMX bacteriostatic or cidal

each are static on their own but cidal together

is TMP-SMX concentration or time dependant

time

what are some ADRs of TMP-SMX

- SJS/TEN -avoid in pregnancy N/V/D

this medication has an MOA of altering bacterial ribosomal proteins which inhibits synthesis of DNA, RNA and proteins

nitrofurantoin

this medication is exclusively used for UTIs and should not be used if a CrCl of < 30 ml/min

nitrofurantoin

what are some ADRs of nitrofurantoin

darken urine GI upset (take with food) `

this medication has an MOA of inhibiting cell wall synthesis. it also decreases the adherence of bacteria to the epithelial cells of the urinary tract

fosfomycin

what are some ADRs of fosfomycin

- headache - diarrhea - GI upset - hypokalemia

this medication works by passive diffusion into the cytoplasm of anaerobic bacteria. results inhibition of DNA synthesis and degradation and ultimately bacterial death; it is used for anaerobic and parasitic infections

metronidazole

antibiotics MT1 Flashcards

(94 cards)