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Pharm MSU NUR909 final > anti-infectives > Flashcards

anti-infectives Flashcards

1
Q

What factors contribute to antibiotic resistance?

A

1.) Increasing populations of immunocompromised pts
2.) increase in number and complexity of invasive medical procedures
3.) increase survival of pts with chronic diseases
4.) excessive and inappropriate use of abx
5.) prophylactic ordering of abx

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2
Q

List some of the leading risk factors for having a drug resistant pathogen.

A

Recent use of abx, younger than 2 yo or older than 65 yo, daycare attendance, exposure to young children, multiple medical comorbidities, recent hospitalization, immunosuppression (714)

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3
Q

True or False. Resistance has developed in every class of antibiotics.

A

True

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4
Q

List the antibiotic classes in the beta-lactams category.

A

Penicillins, cephalosporins, carbapenems & monobactams (715)

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5
Q

Describe the mechanism of action of penicillin antibiotics.

A

bacterial cell wall inhibitors

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6
Q

Penicillins have activity primarily against gram-________ organisms.

A

+ anaerobic

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7
Q

Explain how the activity of aminopenicillins are different than that of penicillins. What causes this difference?

A

-Cover gram + & - organisms; 1st group of penicillins w/activity against gram - bac (PPT)
-Aminopenicillins have greater activity against gram - bac bc of their enhanced ability to penetrate these organisms’ outer membrane (715)

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8
Q

How is the activity of an aminopenicillin enhanced by adding a beta-lactamase inhibitor?

A

BLIs protect hydrolysable penicillins from inactivation by beta-lactamases (PPT)
-BLIs prevent the destruction of beta-lactam abx by serving as a competitive inhibitor of beta-lactamase; BLIs also contain a beta-lactam ring but have poor antimicrobial activity alone (715)

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9
Q

Amoxicillin is prescribed to children with acute otitis media at a dose of 80 to 90 mg/kg/day. How does this dose compare to dosing for other indications? What is the rationale for this dosing regimen?

A

Cost - affordable, high efficacy & long hx of safe use; taste & convenience
-amoxicillin requires 2-3 doses/day, penicillin V requires 2-4 doses/day (723)
- the high dose raises the concentration in the middle ear fluid to be effective against intermediate and resistant strains of s. pneumoniae

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10
Q

What percentage of patients are truly allergic to penicillins?

A

3-10%

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11
Q

1st generation cephalosporin spectrum of coverage

A
  • staph aureus, strep pyogenes
    -some gram (-) bacilli: proteus, e. coli, klebsiella
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12
Q

2nd generation cephalosporin spectrum of coverage

A

-less active against gram + than 1st gen, but cover more gram - : H. flu, Enterobacter, some Neisseria, and Moraxella catarrhalis

-cefoxitin and cefotetan have anaerobic activity

-Cefuroxime and cefprozil cover strep pneumoniae

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13
Q

3rd generation cephalosporin spectrum of coverage

A
  • improved gram (-): Enterobacteriaceae, E. coli, less gram (+) coverage

-Ceftazidime: Psudomonas aeruginosa

-Ceftriaxone and cefotaxime: good CNS penetration, excellent coverage against S. pneumonia (menengitis)

  • beta-lactamase stable
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14
Q

4th generation cephalosporin spectrum of coverage

A
  • Gram (-) and gram (+)
  • Pseudomonas aeruginosa
  • Covers S. pneumoniae similar to ceftriaxone
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15
Q

5th generation cephalosporin spectrum of coverage

A
  • Enhanced gram (+); covers MRSA, S. pneumoniae, and E. faecalis
  • Similar gram (-) coverage to 3rd and 4th gen
  • NO pseudomonas coverage
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16
Q

Patients with what type of penicillin allergy should probably not be prescribed a cephalosporin?

A

IgE-mediated rxns to penicillin (Type I rxns)

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17
Q

How is the spectrum of coverage different from ampicillin/sulbactam to piperacillin/tazobactam?

A

Ampicillin/sulbactam covers gram (+) & gram - organisms;

Piperacillin/tazobactam covers:
-Gram (+) & (-) organisms
-Strep Group A, B, C
-Strep pneumoniae
-Best empiric use for pseudomonas aeruginosa
-Anaerobic activity

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18
Q

Nafcillin would be considered the most narrow coverage for which organism below?

a. MRSA
b. MSSA
c. Strep pneumoniae
d. Pseudomonas aeruginosa

A

B.) MSSA

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19
Q

MOA for fluoroquinolones.

A

Inhibit bacterial DNA function or synthesis

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20
Q

Which fluoroquinolones are considered “respiratory quinolones”?

A

Levofloxacin, moxifloxacin

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21
Q

Explain the boxed warning associated with fluoroquinolone antibiotics.

A

Risk of tendon rupture

-Pts at greatest risk are those >60 yrs old, those taking a corticosteroid, & kidney, heart, & lung transplant recipients

-Rupture may occur as soon as 1 day after beginning therapy or several months after stopping the meds

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22
Q

List three macrolide antibiotics and describe their mechanism of action.

A

-Erythromycin
-Clarithromycin
-Azithromycin

Bacterial protein synthesis inhibitors via ribosome binding

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23
Q

Describe the precautions and contraindications to the use of macrolides

A

-epigastiric distress
-cholestasis
-transient ototoxicity
-rare QT prolongation and ventricular arrythmias, including torsades de pointe

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24
Q

Clindamycin may be used in aspiration pneumonia as it has activity against what type of organism?

A

S. pneumoniae

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25
Q

Clindamycin is associated with what serious GI side effect?

A

c-diff

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26
Q

What is the spectrum of activity of linezolid? Is resistance common or uncommon?

A

-Linezolid is most effective against aerobic gram (+) organisms.
- resistance uncommon (NIH)

-Main susceptible orgs include group A & B Streptococcus, S. pneumoniae, S. aureus (both MSSA & MRSA); some activity against mycobacterium TB; activity against the most resistant forms of Enterococcus including VRE; weakly effective against H. influenzae & M. catarrhalis

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27
Q

Describe the drug interaction between linezolid and antidepressants. What is the possible outcome of this interaction?

A

Interaction with MAOI/serotonin-containing rx & tyramine-containing foods

-serotonin syndrome (PPT)

28
Q

Identify the spectrum of activity and mechanism of action for sulfonamides

A

Spectrum of Sulfonamides
-E. coli, Nocardia, pneumocystis, TMP/SMX broader spectrum: S. pneumoniae, S. aureus, H. flu & other gram- orgs (PPT)

MOA: folate antagonists

29
Q

Identify the spectrum of activity and mechanism of action for trimethoprim

A

Spectrum of activity:
-active against both gram- (Enterobacter, E. coli, H. influenzae, B. pertussis, Nocardia, Salmonella, Shigella) & gram+ orgs (S. pneumoniae, staphylococci) (756)

-Trimethoprim folate antagonist but NOT a sulfonamide

30
Q

Identify the spectrum of activity and mechanism of action for nitrofurantoin

A

-Spectrum of activity:
-used in prevention/tx of UTIs cx’d by E. coli, S. aureus, Enterococcus, Klebsiella, & Enterobacter

-MOA: Bacteria in the urine reduce the drug to its active form - inhibits several bacterial enzyme systems, interfering with metabolism & possibly cell wall synthesis

31
Q

Identify the spectrum of activity and mechanism of action for fosfomycin

A

-Spectrum of activity - primarily used for tx of uncomplicated lower UTIs in women d/t E. coli (not 1st-line)

-MOA- acts at an early stage of bacterial cell wall synthesis

32
Q

Sulfonamides, trimethoprim, and nitrofurantoin are frequently prescribed for urinary tract infections. Can these agents be used in pregnant patients? Why or why not?

A
  • Sulfonamides considered Category D at or near term, D = DANGEROUS (PPT); jaundice, hemolytic anemia & kernicterus have occurred (757)
  • Trimethoprim is Pregnancy Category C, C = CAUTION, may interfere w/folic acid metabolism, only use if benefits outweigh risk; TMP-SMZ combo product Category D in all trimesters (757)
  • Nitrofurantoin is Pregnancy Category B, use for women of childbearing age only when it is clearly needed; do NOT give to pregnant pts at term or during labor/delivery d/t potential risk of cx’ing hemolytic anemia in newborn bc of immature enzyme systems (contraindicated in infants < 1 mos) (758)
  • Fosfomycin is Pregnancy Category B, info is limited but it crosses the placenta (758)
33
Q

Describe patients who could not be prescribed nitrofurantoin.

A

Renal impairment (CrCl < 30 mL/min); accumulation l/t peripheral neuropathy may occur in pts w/CrCl < 60 mL/min; possible pulmonary toxicity w/prolonged therapy (PPT)

34
Q

Many patients report having a “sulfa” allergy. What drugs may cross-react in a patient with a sulfa allergy?

A

Sulfasalazine and dapsone

35
Q

List the side effects from tetracyclines that make them contraindicated in children younger than eight.

A

These drugs form a stable Ca complex in any bone-forming tissue, decreasing bone growth; they also may cx permanent yellow/gray/brown discoloration of deciduous & permanent teeth, enamel hypoplasia also reported; less likely to occur w/doxy but risk outweighs potential benefit (763)

36
Q

What dietary counseling should be provided to patients who are prescribed a tetracycline antibiotic?

A

-Food & polyvalent cations (Ca 2+, Zn 2+, Mg 2+, Fe 3+ & Al 3+) decrease absorption of tetracyclines (762) -Ex’s: antacids, multivitamins, sucralfate can chelate w/certain abx, greatly reducing PO absorption (PPT)

37
Q

What is the spectrum of activity of vancomycin?

A

MRSA, C. diff (PO form only), enterococcus faecalis

38
Q

Oral vancomycin is used most commonly for the treatment of what condition?

A

c-diff

39
Q

What is AUC/MIC monitoring? When should it be considered for a patient being treated with vancomycin? What are the benefits of AUC/MIC monitoring as compared to peak/trough monitoring?

A

-AUC = area under the curve, MIC = minimum inhibitory concentration- AUC/MIC should be considered for serious MRSA infxs (PL) -Trough goals of 15-20 mg/L are no longer recommended d/t lack of safety & efficacy data; AUC-guided monitoring is assoc w/significant decrease in AKI than trough-based dosing (PL)

40
Q

List some of the reasons why mycobacterial infections are so difficult to treat.

A

(1) Mycobacteria grow slowly & are relatively resistant to drugs that are largely dependent on how rapidly cells are dividing
(2) Have a lipid-rich cell wall relatively impermeable to many drugs
(3) Usually intracellular & inaccessible to drugs that do not have good intracellular penetration
(4) Have the ability to go into a dormant state
(5) easily develop resistance to any single drugs -Also, adherence is often poor d/t regimens that include multiple drugs & last for months (769)

41
Q

Describe common side effects for isoniazid and rifampin.

A

-Isoniazid - peripheral neuropathy (most common), pyridoxine (B6) prevents this; elevated AST/ALTs (hepatoxicity) (773)

-Rifampin - hepatotoxicity but less likely than w/isoniazid, harmless orange-red discoloration of body fluids (tears, saliva, urine, CSF, feces) (773)

42
Q

What vitamin should you consider co-prescribing with isoniazid? What is the reason for this?

A

Pyridoxine (B6) to prevent peripheral neuropathy (773)

43
Q

How does rifampin affect the metabolism of other medications?

A

Rifamycins are potent inducers of liver metabolism, may l/t subtherapeutic concentrations of other rx metabolized by CYP enzymes & tx failures may occur (771)

44
Q

List the 3 antivirals in the nucleoside analogues class. What are similarities and differences between them?

A

Acyclovir, famciclovir, valacyclovir (783);

Similarities - renal failure has been reported w/all rx in this group, all Pregnancy Category B (acyclovir/valacyclovir preferred d/t limited data w/famciclovir), vala/acyclovir have the same ADRs but valacyclovir has a higher incidence of ADRs (783)

Differences - acyclovir least expensive, only 1 available IV (PPT)

45
Q

What is the name of the topical OTC antiviral that can be used for herpes simplex 1 (i.e. cold sores)?

A

docosanol (Abreva)

46
Q

If a patient has HSV-1 or HSV-2, should they be prescribed a topical or oral antiviral?

A

HSV-1 (oral) topical tx, not systemic; HSV-2 (genital) PO tx, systemic (782)

47
Q

What is the typical duration of treatment for hepatitis C? Is the treatment considered a curative or suppressive?

A

Undetectable HCV RNA level in 12 wks of tx (787); curative

48
Q

Which antiviral is approved for the treatment of acute symptoms of influenza in children as young as 2 weeks old?

A

Oseltamivir (789)

49
Q

For best efficacy, how long after symptom initiation should an antiviral be initiated in a patient with influenza?

A

within 48 hours

50
Q

Which antivirals have been FDA approved for pre-exposure prophylaxis?

A

Descovy & Truvada (PL)

51
Q

What are the similarities between Descovy and Truvada?

A

-Cost $1,800 -Dosed 2x/d -SEs: diarrhea, nausea, etc. -Emphasize adherence -Educate on ways to reduce HIV risk (condoms, etc.)

52
Q

What are the differences between descovy & truvada?

A

Descovy: - emtricitabine/tenofovir ALAFENAMIDE - Better for pts w/CrCl down to 30 mL/min or bone disease

Truvada: -emtricitabine/tenofovir DISOPROXIL fumarate, caution in pts with high cholesterol, may cause wt gain

53
Q

What is the primary cellular target for systemic antifungal medications?

A

ergosterol (793)

54
Q

Which organ system is most susceptible to toxicity from antifungal medications? What labs should be monitored in patients taking these medications?

A

Hepatoxicity, transaminases (795)

55
Q

True or False. Drug interactions with antifungal medications are uncommon.

A

False

56
Q

For which indication is oral terbinafine most commonly prescribed?

A

Onychomycosis (793); also used off-label for tinea capitis, corporis or cruris, pedis (801)

57
Q

For what type of infections is metronidazole most commonly prescribed?

A

-Anaerobic bacterial infxn & CDI (808) -Has antiparasitic & antibacterial properties (807)

58
Q

List the precautions or contraindications to metronidazole therapy.

A

caution in patients with hepatic impairment. Disulfiram-like effect with alcohol- avoid for 72 hours post.

59
Q

Describe the interaction between metronidazole and alcohol. How long after the last dose of metronidazole can a patient safely consume alcohol?

A

-A disulfiram-like rxn may occur w/ETOH & pts are warned not to consume ETOH while taking this rx & for 48 hrs after completing it (807) -Disulfiram-like rxn s/s: abd cramps, N/V, HA & flushing (808)

60
Q

You prescribe trimethoprim/sulfamethoxazole as a 3-day course for treatment of an uncomplicated urinary tract infection. Which of the following is associated with the use of this medication?

a. Sun sensitivity
b. Constipation
c. Tooth discoloration
d. Sedation

A

A

61
Q

What drug interaction would be exhibited by adding fluconazole to a person’s medication regimen that includes warfarin (stabilized at an international normalized ratio [INR] of 2.5)?

a. Fluconazole and warfarin concentrations would both be reduced.
b. An increase in INR would be expected.
c. Warfarin CYP450 metabolism would be induced
d. An interaction would not be expected.

A

B

62
Q

atypical organisms

A
  1. mycoplasma pneumoniae
  2. legionella pneumoniae
  3. chlamydia pneumoniae
63
Q

Sulfonamides, trimethoprim MOA

A

folate antagonists

64
Q

beta-lactams, vanco MOA

A

bacterial cell wall inhibitors

65
Q

tetracycline, aminoglycosides, macrolides, clindamycin MOA

A

bacterial protein synthesis inhibitors via ribosome binding

66
Q

quinupristin/dalfopristin, linezolid, telithromycin MOA

A

bacterial protein synthesis inhibitors via other mechanisms

67
Q

fluoroquinolones, quinolones, metronidazole MOA

A

inhibitors of bacterial DNA function or synthesis

Pharm MSU NUR909 final (10 decks)

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