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Pharmacology > Beta-Lactam Ab + > Flashcards

Beta-Lactam Ab + Flashcards

1
Q

what are the two major Ab that inhibit bacterial cell wall synthesis?

A

penicillins and cephalosporins

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2
Q

true or false: vancomycin, fosfomycin and bacitracin are all examples of beta-lactam drugs

A

false; they also inhibit cell wall synthesis but are NOT beta-lactam drugs

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3
Q

true or false: oral bioavailability of penicillins remains constant throughout the class

A

false: penicillins vary in their resistance to gastric acid and therefore vary in their bioavailability

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4
Q

tubular secretion of penicillins is inhibited by which drug?

A

probenecid - therefore increasing its concentration and prolonging its activity

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5
Q

true or false: most penicillins cross the BBB very easily.

A

false; most only cross when the meninges are inflamed

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6
Q

beta lactams work to inhibit cell wall synthesis by binding to specific enzymes called what? located where?

A

PBPs penicillin binding proteins; cytoplasmic membrane

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7
Q

penicillins also work to inhibit ____ which cross-link the linear peptidoglycan chains of the cell wall

A

transpeptidation reaction

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8
Q

why is it that drugs such as clavulanic acid, sulbactam, and tazobactam are often used in combination with penicillins ?

A

b/c they work as beta-lactamases inhibitors which can then prevent the inactivation of penicillin by penicillinases

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9
Q

what mechanism of resistance is responsible for MRSA and PRSP?

A

structural changes in PBPs; FYI: PRSP = penicillin resistant streptococcus pneumoniae

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10
Q

what is the mode of some gram-negative rods in terms of developing resistance to penicillins?

A

changes in porin structures in outer cell wall membrane may contribute to resistance by impeding access of penicillins to PBPs

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11
Q

what is the prototype of a subclass of penicillins that have a limited spectrum of antibacterial activity? (susceptible to beta-lactamases)

A

penicillin G

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12
Q

what is the DOC to treat syphilis?

A

penicillin G

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13
Q

which penicillin is an oral drug mainly used in oropharyngeal infections?

A

penicillin V

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14
Q

why is it that methicillin is so rarely used?

A

nephrotoxic potential

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15
Q

true or false: nafcillin and oxacillin are both penicillinase susceptible agents

A

false - penicillinase resistant, but NARROW spectrum

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16
Q

which two drugs are known to have a wider spectrum of antibacterial activity, but remains susceptible to penicillinase?

A

amoxicillin and ampicillin

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17
Q

true or false: piperacillin and ticarcillin are bother penicillinase resistant

A

false; susceptible and often used in combination with penicillinase inhibitors to enhance their activity

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18
Q

which penicillin is often associated with interstitial nephritis?

A

methicillin

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19
Q

which penicillin is associated with neutropenia?

A

nafcillin

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20
Q

what are the two most common results of penicillin toxicity?

A

allergy and GI disturbances (for the latter, especially with ampicillin)

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21
Q

true or false: most cephalosporins are administered orally

A

false; most are available for oral use, but most are administered parenterally

22
Q

what is the major method of elimination for cephalosporins?

A

renal excretion via active tubular secretion

23
Q

how is ceftriaxone mainly excreted?

A

in the bile

24
Q

true or false: most 1st and 2nd generation cephalosporins enter the CSF

A

false; most do NOT enter the CSF even when the meninges is inflamed

25
Q

true or false: cephalosporins are more susceptible to penicillinases produced by staph

A

false; structural changes make cephalosporins LESS susceptible

26
Q

cefazolin and cephalexin are members of which class of antibiotics? (be specific)

A

first generation cephalosporins

27
Q

which two drugs are currently the most active cephalosporins against penicillin-resistant pneumococci?

A

ceftriaxone and cefotaxime

28
Q

what are the two cephalosporins that are currently the DOC for treatment of gonorrhrea?

A

ceftriaxone (parenteral) and cefixime (oral)

29
Q

true or false: drugs of the 3rd generation cephalosporins class should typically be reserved to treat serious conditions

A

true

30
Q

true or false: as cephalosporins increase in generation, coverage of gram + bacteria increase

A

false; decreases

31
Q

what is the cephalosporin with activity against MRSA?

A

cefaroline

32
Q

what is the name of the cephalosporin that combines gram + activity of 1st generation agents with the wider 3rd generation agents?

A

cefepime

33
Q

true or false: cephalosporins cause more allergic reactions than does penicillins

A

false; far less

34
Q

true or false: complete cross-hypersensitivity between different cephalosporins should be assumed.

A

true

35
Q

true or false: cross-hypersensitivity between penicillins and cephalosporins is complete at approximately 65%

A

false; it is incomplete (5 to 10%) - this makes it such that penicillin-allergic pts can sometimes be treated successfully with a cephalosporin NOTE: pts with anaphylaxis to penicillin should NEVER be treated with cephalosporin

36
Q

what is the possible result of drug-drug interaction between cephalosporins and aminoglycosides?

A

nephrotoxicity

37
Q

when used in combination with cephalosporins, drugs containing a methylthiotetarzole group (ex: cefamandole) may cause what two major side effects?

A

hyPOprothrombinemia and disulfiram-like reactions with ethanol.

38
Q

which beta-lactam drug am I? a monobactam; resistant to beta-lactameses; no activity against gram + bacteria or anaerobes; inhibitor of cell wall synthesis; binds specifically to PBP3

A

aztreonam

39
Q

to which class of beta-lactam drugs do the following belong? imipenem, doripenem, meropenem, and ertapenem

A

carbapenems (chemically different from penicillins BUT have the beta lactam ring) Note: these drugs have a low susceptibility to beta-lactamases

40
Q

with the exception of which drug are the carbapenems active against p aeruginosa and acinetobacter species?

A

ertapenem

41
Q

carbapenems are often used in combination with what other drug when fighting pseudomonas infections?

A

aminoglycosides.

42
Q

why is imipenem administered in fixed combination with cilastatin?

A

b/c it is inactivated by renal dydropeptidase I and cilastatin can inhibit this enzyme therefore increasing plasma half-life of imipenem. Note: imipenem also inhibits the formation of a potentially nephrotoxic metabolite by increasing the plasma half life.

43
Q

at very high levels what is the most serious side effect of carbapenems?

A

that they cause CNS toxicity and can lead to confusion, encephalopathy and seizures

44
Q

which drug am I? binds to D-Ala-D-Ala terminal of the nascent peptidoglycan pentapeptide side chain and inhibits transglycosylation (which prevents elongation of the peptidogylcan chain and interferes with cross-linking)

A

bacterial glycoprotein, vancomycin

45
Q

what is the means of resistance for VRE and VRSA?

A

decreased affinity of vancomycin for the binding site b/c of the replacement of terminal D-Ala by D-lactate

46
Q

what is the DOC for treatment of MRSA?

A

Vancomycin

47
Q

what it the DOC for treatment of PRSP?

A

vancomycin in combination with 3rd generation cephalosporin

48
Q

rapid intravenous infusion of vancomycin may cause “red man syndrome” - why is this?

A

the diffuse flushing (“red man syndrome”) is due to an influx of histamine release

49
Q

what is a common example of an antimetabolite inhibitor of cytosolic enolpyruvate transferase ?

A

fosfomycin (its actions prevent the formation of N-acetylmuamic acid, which is an essential precursor molecule for peptidoglycan chain formation).

50
Q

which drug am I? limited to topical use due to nephrotoxicity; peptide Ab; interfere with late stage of cell wall synthesis

A

bacitracin

51
Q

which drug am I? only used to treat TB caused by organisms resistant to 1st line anti TB meds; antimetabolite that blocks the incorporation of D-Ala into the pentapeptide side chain of the peptidoglycan.

A

cycloserin

52
Q

what levels should be monitored when a patient is on daptomycin?

A

creatinine phosphokinase since it can cause myopathy

Pharmacology (15 decks)

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