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EXAM 6 > Antibiotics > Flashcards

Antibiotics Flashcards

1
Q

selective toxicity

A

want a very high therapeutic index

LD50/ED50

hurt bacteria not host

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2
Q

DNA replication abx

A

quinolones

binds to DNA gyrase (which helps unwind DNA while it’s replicating) - allows it to make breaks but not close them- kills

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3
Q

RNA synthesis abx

A

Rifampin

binds to RNA polymerase and revents from transcription

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4
Q

Protein synthesis

A

tetracyclines, macrolides, aninoclygosides

binds to subunit of ribosome (large or small) ad inhibits binding of tRNA

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5
Q

metabolism

A

sulfonamides

inhibit tetrahydropfolate synthesis - bacteria has to make FH4

binds way more tightly to bac enzyme then human enzyme

structural mimicry or so can’t recycle into FH4

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6
Q

cell wall synthesis

A

beta lactams, vancomycin

inhibit transpeptidase (second step in linking of polypeptides)

beta lactam ring = mimicry - binds to beta lactam - formed irreversibly and stuck so crosslinking of cell wall can’t happen

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7
Q

Vancomycin

A

cell wall synthesis blocker but blocks transglycolase and transpeptidase

only kills cells that are growing

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8
Q

bacteriostatic v bacteriocidal

A

bacteriostatic - arrest cell growth so immune system can kick in and control

bacteriocidal - don’t want to wait for immune - kill!

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9
Q

efflux pump

A

tetracycline

pumps drug out of cell so it can’t have an effect

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10
Q

beta-lactamase

A

made by bacteria - breaks important bond in beta-lactam so it is ineffective

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11
Q

vancomycin-resistant bacteria

A

sub D-lactate for terminal D-ala

vancomycin can’t bind!! ineffective

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12
Q

clavulanate

A

inactivates beta lactamase - looks like beta lactam and inactivates the enzyme so beta-lactam can work

synergistic activity

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13
Q

concentration dependent killing

A

higher dosee kill better!

high dose extended intervals - high peak concentration

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14
Q

time dependent killing

A

no persistent effects

dose frequently (or continuously)

beta lactams!

try to exceed MIC for 50% of interval

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15
Q

when bacteriocidal

A

in immune compromised - can’t take over to kill!

immune priveleged sites (meningitis)

non-removable sources - device relate infection (endocarditis)

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16
Q

Combination therapy

A

synergy - enterococcus! PCN (upsets cell membrane) and aniglycoside (only works if gets in)

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17
Q

General Beta-Lactams

A

i.e. PCN

any gram

time dependent

bind PBP, prevent crosslinking of peptidoglycans, lead to lysis

majorty eliminated by kidney

allergy (PCN - hypersensitivity - cross to other beta lactams, use something else unless syphillus then desensitize)

gallstones with cetriaxone!

pregnant woman with syphillus and pcn allergy

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18
Q

Penicillin G

A

Natural Penicillin

gram positive, narrowest

strep A!

normal beta-lactam action

seizures at high dose

narrow spectrum - strep (a and b) enterococcus, psirochetes, s. pneumonae (community)

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19
Q

aminopenicillin

A

ampicillin, amoxicillin

covers same as natural PCN + gram negatives/enterococci- slightly broader! (adds e. coli, H. influenze, enterococcus)

normal beta lactam activity

20
Q

Aminopenicillin adverse rxn

A

rash especially with EBV! not IgE mediated

21
Q

Penicillinase-Resistant Penicilllins

A

Oxacillin, Nafcillin

same as PCN G but adds MSSA (s. aureus)

normal beta lactam but resistant to beta-lactamase (beta lactam ring can’t be opened)

22
Q

Penicillinase-Resistant Penicillin adverse rxn

A

interstitial nephritis

(nafcillin, nephritis)

23
Q

Extended spectrum penicillins

A

piperacillin

broadest and best gram negative coverage, includes psuedamonas aeruginosa

hospital acquired pneumonia!

NOT s. aureus when used alone, needs beta-lactamase inhibitor for full spectrum not MSSA!

24
Q

beta-lactamase inhibitor combinations

A

Augmentin (amox-clav)

beta-lactamases = PBPs but smaller

extend coverage to beta-lactamase bacteria, very broad

NEED to restore activity for MSSA, psudomonas aeruginosa

bind irreversibly to beta lactamases - restore activity of abx to some organisms

if symptoms don’t go away completely with abx

25
Q

First generation cephalosporin

A

cephazolin

beta lactam

time dependent

surgical prophylaxis (strep and staph)

they earlier the generation, the greater the gram positive activity!! bset gram positive

26
Q

second generation cephalosporin

A

beta lactam

respiratory tract infections

better gram negative, less gram positive

27
Q

third generation cephalosporin

A

ceftriaxone (TRI - 3rd!)

best for gram negative, worst for gram positive

CA-pneumonia, Lyme, meningitis

time dep

beta lactam

28
Q

fourth generation cephalosporin

A

Cefepime

very broad - good for all bac including gram neg and pseudomonas (HA-gram neg)

resistance in hospital acquired bugs

resistance to beta-lactamases!

increasing generation - more resistance to beta lactamase

29
Q

Carbapenems

A

broadest spectrum antibiotic!!

beta lactam

serious noscomial infections and broad resistance!

most stable to beta-lactamases

toxic: CNS toxicity

30
Q

Monobactam

A

Aztreonam

No = monobacrim, No allergic rxn, Negative (gram neg)

no anaplylaxis in PCN allergic patients (no ring - only side chains)

treatment of gram negative infections in PCN allergic patients

31
Q

PCN allergy

A

hypersensitivity - IgE to metabolites after beta-lactam ring opens - cross reactivity

desensitization - if allergy and can’t uses second line, administer gradually increasing doses in ICU

i.e. syphillis during pregnancy, syphilitic meningitis in HIV-infected patients

32
Q

Vancomycin

A

very braod spectrum

go to for MRSA and coagulase negative staph, enterococci

binds D-ala and prevents crosslinking (if D-lactate - resistance)

33
Q

Vancomycin adverse rxns

A

red person syndrome

non-immune release of hsitamine

treat w antihistamine and infuse more slowly

34
Q

Aminoglycosides

A

serious gram negative, pseudomonas

post antibiotic effect and concentration dependent killing - give less (less toxic)

binds ribo sunbunit (synergy with beta-lactams)

major toxiciity: nephrotoxicity - acute!

NEs: NEphrotoxicity (severe) so you NEver wanna use it, and it’s used for gram NEgative, in syNErgy (with beta-lactam antibiotics)

35
Q

Macrolides

A

erythromycin, asithrymycin

CA-pneumonia, non-gonococcal urethritis (chlamydia)

binds ribo subunit

toxicity: QT prolongation

36
Q

Clindamycin

A

Anaerobic infections (lung, dental, intraabdominal)

Antitoxin effect - used to make sure bacteria that produce toxins such as anthrax have protein synthesis inhibited before lysis

adverse: diarrhea, c. diff

excellent bioavailablitiy

37
Q

Tetracyclines

A

spirochetes (lyme, syphillis), atypical pneumonia

bind ribosome

bind divalent cations - don’t take with dairy

bacteriostatic!!

efflux pump

38
Q

Tigecycline

A

multiply drug resistant gram negative (no psuedomonas)

added activity against MRSA!

“super tetracycline”! same but no efflux pump activity

39
Q

Daptomycin

A

serious s. aureus (do NOT use for pneumonia! inactivated by surfactant)

MRSA, VISA (i.e. resistant bacteria)

gram positive

rapidly bacteriocidal, depolarizes membrane

toxic: myopathy (muscle pain)

Daptomycin starts with D, so mechanism is disrupts/depolarizes membrane. Also it’s rapidly bacteriocidal and toxic, so it’s the DAP ZAP

40
Q

Oxazolidinones

A

Linezolid

bacteriostatic

infections due to resistant gram pos! MRSA and VRE

adverse: decreased plately touts, serotonin syndrome

41
Q

Fluoroquinolones

A

complicated UTIs and prostatitis, respiratory tract, bone and joint

inhibits DNA rep (ds break)

Arthritis/Tendonitis, Can delay detection of TB, should not be used in children or during pregnancy,

Only antibiotic class with a U in the name, so Urogenital (UG)

42
Q

Quinolones adverse events

A

prolonged QT interval, arthritis/tendonitis, GI - c. diff

43
Q

Metronidazole

A

anaerobic, c.diff

concentration dependent - 100% bioavailability

inhibits DNA replication

Disulfira - NO ALCOHOL

44
Q

Trimethoprim-Sulfamethoxazole

A

UTIs, prostatitis, Pneumocystic jiroveci pneumonia and prophylaxis, CA-MRSA

prophylaxis is AIDS pts, immunocompromised

toxicities: skin rash

45
Q

Polymyxin

A

“last resort) for mult resistant gram neg - esp psuedomonas

detergent - dirupts bac cell membrane phospholipids

Toxicities: kidneys and nervous system

POLYmyxin = for gram negative, when POLY resistance to all other antibiotics

EXAM 6 (4 decks)

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