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Antimicrobials Flashcards

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1
Q

Which 3 antimalarial agents can be administered to a patient with a life-threatening malaria infection?

A

Quinidine in the United States, quinine outside of the United States, or artesunate

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2
Q

Why are fluoroquinolones contraindicated for women who are pregnant or breastfeeding and for children younger than 18 years of age?

A

Possibility of cartilage damage (fluoroquinolones hurt attachments to your bones)

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3
Q

Which protein synthesis–inhibiting antibiotics are bacteriostatic?

A

Tetracyclines, chloramphenicol, clindamycin, erythromycin (linezolid is variable: bacteriostatic and bactericidal)

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4
Q

Which of the 2 aminopenicillins (amoxicillin and ampicillin) has a greater oral bioavailability?

A

Amoxicillin (AmOxicillin has better Oral bioavailability)

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5
Q

What is the mechanism of action of daptomycin?

A

Lipopeptide disrupts gram-positive cocci cell membranes by creating transmembrane channels

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6
Q

A patient requests prophylaxis against Mycobacterium tuberculosis before travel. What is the one drug that can be used as solo prophylaxis?

A

Isoniazid

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7
Q

What is the mechanism of action of the antipseudomonal penicillins (piperacillin and ticarcillin)?

A

Same as that of penicillin (they inhibit peptidoglycan cross-linking in bacterial cell walls)

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8
Q

What are the common CNS adverse effects of fluoroquinolones?

A

Headaches, dizziness

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9
Q

Name the 3 respiratory fluoroquinolones.

A

Levofloxacin, moxifloxacin, and gemifloxacin

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10
Q

Name a skin condition that can be treated with tetracycline antibiotics.

A

Acne

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11
Q

Anion gap metabolic acidosis develops in a patient being treated for HIV. What is the most likely cause?

A

Nucleoside reverse transcriptase inhibitor–induced lactic acidosis (nucleoside agents only)

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12
Q

Which antifungal agent deposits into keratin-containing tissues, thus making it effective against dermatophyte infections?

A

Griseofulvin

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13
Q

List the organisms that can be treated with metronidazole.

A

Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (Bacteroides, Clostridium difficile), Helicobacter pylori (GET GAP on the Metro with metronidazole!)

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14
Q

What is the mechanism of action of nystatin?

A

It forms membrane pores on fungi, allowing electrolytes to leak

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15
Q

What 5 medications can be given to a person traveling to an area in which malaria is endemic?

A

Atovaquone-proguanil, doxycycline, mefloquine, primaquine, or chloroquine (for areas with sensitive species)

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16
Q

Why is daptomycin ineffective against pneumonia?

A

Daptomycin binds to and is inactivated by surfactant before acting on the lungs (“Dapto-myo-skin” is used for skin infections but can cause myopathy)

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17
Q

What is the consequence of treating latent tuberculosis solely with rifamycins (eg, rifampin)?

A

Development of rapid resistance

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18
Q

At what point during disease progression are carbapenem antibiotics considered?

A

Because of their significant adverse effects, they are used when other medications have failed or when an infection is life threatening

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19
Q

What are the major adverse effects of dapsone?

A

Hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, methemoglobinemia, and agranulocytosis

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20
Q

What are the adverse effects of trimethoprim?

A

Hyperkalemia (high doses), leukopenia, granulocytopenia, megaloblastic anemia (TMP Treats Marrow Poorly)

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21
Q

Describe the mechanism of action for sulfonamide antibiotics.

A

They prevent folate synthesis by inhibiting dihydropteroate synthase, which prevents bacterial replication (bacteriostatic)

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22
Q

What is the mechanism of action of amphotericin B?

A

Amphotericin B binds ergosterol (unique to fungi) and forms membrane pores (“tears” holes), allowing leakage of electrolytes

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23
Q

A patient presents with peripheral neuropathy and sideroblastic anemia after being treated for tuberculosis. What medication is the most likely cause?

A

Isoniazid

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24
Q

List the antibiotics that inhibit the 30S subunit of the bacterial ribosome.

A

Aminoglycosides, Tetracyclines (30S); “Buy AT 30, CCEL (sell) at 50”

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25
Q

Which drug is effective in treatment of both disseminated Lyme disease and gonorrhea?

A

Ceftriaxone

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26
Q

What is the mechanism of action of isoniazid?

A

Decreases the synthesis of mycolic acids

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27
Q

Why should griseofulvin be avoided in the treatment of pregnant patients with fungal infections ?

A

It is teratogenic

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28
Q

By what 3 mechanisms can bacteria develop resistance to a flouroquinolone antibiotic?

A

Chromosome-encoded mutation in the bacterial DNA gyrase, efflux pumps, or resistance mediated by plasmids

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29
Q

Why do patients require different dosages of isoniazid?

A

People are either fast or slow acetylators, and the half-life of isoniazid differs depending on the individual rate of acetylation

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30
Q

At what pH does pyrazinamide work best?

A

Acidic pH (eg, phagolysosomes)

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31
Q

A patient receiving antiretroviral therapy for HIV has nausea, diarrhea, lipodystrophy, and episodes of hyperglycemia. Which class of drug is the patient likely taking?

A

An HIV protease inhibitor

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32
Q

What are some adverse effects of penicillinase-resistant penicillins?

A

Interstitial nephritis and hypersensitivity reactions

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33
Q

Which 2 antimicrobials act by disrupting membrane integrity?

A

Daptomycin, polymyxins

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34
Q

Which 50S-inhibiting antibiotic inhibits peptidyl transferase activity?

A

Chloramphenicol

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35
Q

Cefepime (fourth-generation cephalosporin) has increased activity against which organisms?

A

Pseudomonas and gram-positive organisms

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36
Q

What is the major adverse effect of cidofovir and how can it be minimized?

A

Nephrotoxicity; coadministration with probenecid and intravenous saline solution

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37
Q

What are the 2 major indications for use of cidofovir?

A

Cytomegalovirus retinitis in immunocompromised patients and acyclovir-resistant herpes simplex virus infections

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38
Q

How does the microbial coverage of amoxicillin and ampicillin compare with that of penicillin?

A

Ampicillin and amoxicillin have a broader spectrum of coverage (AMinoPenicillins are AMPed-up penicillin)

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39
Q

Which bacterial enzyme is needed to activate isoniazid?

A

Catalase-peroxidase (encoded by KatG)

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40
Q

Which types of organisms are treated with vancomycin?

A

Gram ⊕ only: MRSA, Staphylococcus epidermidis, Enterococcus spp, Clostridium difficile (oral dosing for pseudomembranous colitis)

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41
Q

What is the 4-drug regimen commonly used to treat tuberculosis?

A

Rifampin, Isoniazid, Pyrazinamide, and Ethambutol (RIPE for treatment)

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42
Q

What generation of cephalosporins is used for severe gram-negative infections resistant to previously prescribed β-lactams (eg, amoxicillin)?

A

Third-generation cephalosporins (eg, ceftriaxone, cefotaxime, cefpodoxime, or ceftazidime)

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43
Q

What 2 common adverse effects of metronidazole are NOT associated with alcohol use?

A

Headache and metallic taste

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44
Q

Polymyxins are used to treat which types of infections?

A

Last resort treatment for multidrug-resistant gram ⊖ bacterial infections and topical treatment for superficial skin infections

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45
Q

In patients with HIV, what is the indication for use of fluconazole?

A

Long-term suppression of cryptococcal meningitis

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46
Q

What is the mechanism of action of dicloxacillin, nafcillin, and oxacillin?

A

Inhibition of peptidoglycan cross-linking in bacteria cell walls (same as penicillin)

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47
Q

Addition of a certain bactericidal antibiotic leads to misreading of the mRNA by inhibition of which ribosomal subunit?

A

30S ribosomal unit (blocked by aminoglycosides and can cause misreading of mRNA)

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48
Q

Which types of influenza are oseltamivir and zanamivir effective against?

A

Influenza A and B (for treatment and prevention)

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49
Q

What is the mechanism of action of elvitegravir?

A

As an integrase inhibitor, elvitegravir stops HIV genome integration into host cell DNA

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50
Q

Which class of HIV medication binds to the gp41 protein?

A

Entry inhibitors; this is enfuvirtide, which inhibits fusion

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51
Q

Against which organisms are dicloxacillin, nafcillin, and oxacillin useful?

A

Staphylococcus aureus (except MRSA); “Use naf (nafcillin) for staph”

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52
Q

What is the activity of acyclovir, famciclovir, or valacyclovir against latent varicella-zoster virus (VZV) and herpes simplex virus (HSV)?

A

None; there is no effect on the latent forms of VZV and HSV

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53
Q

Name 3 examples of macrolide antibiotics.

A

Erythromycin, azithromycin, and clarithromycin

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54
Q

What are the clinical uses of fluoroquinolones?

A

Treat gram ⊖ rods causing urinary and gastrointestinal tract infections (including Pseudomonas), some gram ⊕ organisms, and otitis externa

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55
Q

What is the mechanism of resistance of the rifamycins (eg, rifampin), particularly with monotherapy?

A

Mutations decrease the drug’s ability to bind to the RNA polymerase

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56
Q

What is the mechanism of resistance for valacyclovir?

A

Mutation in viral thymidine kinase

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57
Q

What is the mechanism of action of aminoglycosides?

A

They are bactericidal antibiotics that irreversibly inhibit the initiation complex by binding 30S, blocking translocation, and causing misreading of mRNA

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58
Q

What is the mechanism of action of echinocandins (eg, anidulafungin, caspofungin, and micafungin)?

A

Inhibition of cell wall synthesis

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59
Q

What is the mechanism of action of sofosbuvir and dasabuvir?

A

Inhibition of NS5B, an RNA-dependent RNA polymerase that serves as a chain terminator, which prevents viral replication

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60
Q

Which macrolide antibiotics inhibit cytochrome P-450 enzymes?

A

Erythromycin, clarithromycin

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61
Q

What is the effect of ciprofloxacin on cytochrome P-450?

A

Inhibits cytochrome P-450

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62
Q

What is the mechanism of resistance of foscarnet?

A

DNA polymerase mutation

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63
Q

What is the mechanism by which bacteria develop resistance to macrolide antibiotics

A

By methylation of the 23S ribosomal RNA–binding site, which prevents the drug from binding to it

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64
Q

What are the 2 most common adverse effects of echinocandins?

A

Gastrointestinal upset and flushing (due to release of histamine)

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65
Q

What is the shared mechanism of action of oseltamivir and zanamivir?

A

Inhibition of viral neuraminidase, which blocks the release of viral progeny

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66
Q

What drug should not be taken with fluoroquinolones?

A

Antacids

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67
Q

What is the difference between disinfection and sterilization?

A

Disinfection reduces the number of pathogenic organisms to a safe level; sterilization inactivates all microbes (including spores)

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68
Q

Trimethoprim and sulfamethoxazole are used in combination to treat which types of infections?

A

Urinary tract infections, Shigella, Salmonella, and Pneumocystis jirovecii pneumonia

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69
Q

Which organisms would you consider using linezolid against?

A

Gram-positive organisms, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE)

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70
Q

What are 2 potential adverse effects of daptomycin?

A

Rhabdomyolysis, myopathy

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71
Q

Which 6 disinfection and sterilization techniques are sporicidal?

A

Autoclaving, chlorine, ethylene oxide, hydrogen peroxide, iodine and iodophors (may be sporicidal)

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72
Q

Why are tetracyclines contraindicated in pregnancy?

A

Because they inhibit bone growth in children

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73
Q

An HIV ⊕ patient has a CD4+ count of <100 cells/mm3 and must receive prophylactic therapy for Pneumocystis pneumonia and toxoplasmosis. Which medication is indicated?

A

Trimethoprim-sulfamethoxazole (TMP-SMX)

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74
Q

What is the mechanism of action of hydrogen peroxide in infection control?

A

Induction of free radical oxidation

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75
Q

A patient is found to have drug-induced systemic lupus erythematosus after completing prophylaxis for tuberculosis. Which drug is the most likely cause?

A

Isoniazid

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76
Q

Name 4 drugs that can be given with penicillin antibiotics to prevent degradation by β-lactamase (penicillinase).

A

Clavulanic acid, Avibactam, Sulbactam, Tazobactam (CAST); these are β-lactamase inhibitors

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77
Q

A patient develops orange urine after initiation of treatment for tuberculosis. What medication is the most likely cause?

A

A rifamycin (eg, rifampin)

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78
Q

An immunocompromised patient has cytomegalovirus retinitis that does not respond to ganciclovir. Which antiviral agent should be considered?

A

Foscarnet

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79
Q

What is the mechanism of resistance of isoniazid?

A

Mutations resulting in the underexpression of KatG, which encodes bacterial catalase-peroxidase

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80
Q

What is the mechanism of action of the echinocandins (eg, caspofungin)?

A

Inhibition of β-glucan synthesis, which disrupts cell wall synthesis

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81
Q

What drug is used for Mycobacterium tuberculosis prophylaxis?

A

Isoniazid

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82
Q

What are the musculoskeletal adverse effects of fluoroquinolones?

A

Leg cramps, myalgias, damage to cartilage in children, tendonitis and tendon rupture in patients older than 60 years or patients treated with prednisone

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83
Q

What organisms does tigecycline cover?

A

Anaerobic, gram-positive, gram-negative, and multidrug-resistant organisms (eg, VRE, MRSA)

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84
Q

What adverse effects are associated with cephalosporin use?

A

Disulfiram-like reaction, autoimmune hemolytic anemia, hypersensitivity reaction, vitamin K deficiency

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85
Q

Describe the mechanism of action of the bacteriostatic macrolide antibiotics.

A

They inhibit protein synthesis by binding to the 23S rRNA of the 50S subunit and preventing translocation (“macroslides”)

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86
Q

Which 2 combinations of medications are indicated for a patient with malaria caused by Plasmodium falciparum?

A

Artemether/lumefantrine or atovaquone/proguanil

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87
Q

What is the mechanism of action of nucleoside reverse transcriptase inhibitors (NRTIs) (abacavir, emtricitabine, lamivudine, tenofovir, zidovudine)?

A

Inhibition of nucleotide binding to reverse transcriptase due to lack of 3′ OH group, thus stopping DNA synthesis (NRTIs must be phosphorylated to be activated)

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88
Q

What are the adverse effects of penicillin?

A

Hypersensitivity reactions, drug-induced interstitial nephritis, and direct Coombs ⊕ hemolytic anemia

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89
Q

When selecting appropriate treatment of hepatitis C infection in pregnant women, which medication should be avoided and why?

A

Ribavirin because of severe teratogenicity

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90
Q

What is the clinical use of baloxavir?

A

Decreases the duration of illness due to influenza virus if taken within 48 hours of symptom onset

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91
Q

What is the mechanism of action of ampicillin and amoxicillin?

A

They bind penicillin-binding proteins (transpeptidases) and block cross-linking of peptidoglycan in bacterial cell walls (same as penicillin)

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92
Q

Enfuvirtide blocks which genetic processes immediately downstream of penetration?

A

Uncoating and reverse transcription

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93
Q

Which 2 antibiotics would you prescribe as prophylaxis against Mycobacterium avium-intracellulare infection?

A

Azithromycin or rifabutin

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94
Q

Which antibiotic is administered prophylactically for women with recurrent urinary tract infections?

A

Trimethoprim-sulfamethoxazole (TMP-SMX)

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95
Q

To overcome bacterial resistance, what drug must be administered with extended-spectrum β-lactams (eg, piperacillin) for pseudomonal infection?

A

β-Lactamase inhibitor because of sensitivity of Pseudomonas spp to penicillinase

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96
Q

Name the 3 drugs that belong to the sulfonamide class.

A

Sulfamethoxazole (SMX), sulfadiazine, sulfisoxazole

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97
Q

Name the 2 antibiotics that belong to the polymyxin class.

A

Colistin (polymyxin E) and polymyxin B

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98
Q

Name 5 third-generation cephalosporins.

A

Ceftriaxone, cefotaxime, ceftazidime, cefpodoxime, cefixime

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99
Q

Name the antibiotics that inhibit peptidoglycan cross-linking and are penicillinase sensitive.

A

Penicillin G and V, ampicillin, amoxicillin

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100
Q

Lack of which enzyme is to blame for premature infants developing gray baby syndrome after receiving chloramphenicol?

A

Liver UDP-glucuronosyltransferase

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101
Q

Acyclovir and valacyclovir are not useful against which 2 viruses?

A

Epstein-Barr virus (weak activity), cytomegalovirus (no activity)

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102
Q

What are the 2 most common adverse effects of pyrazinamide?

A

Hepatotoxicity and hyperuricemia

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103
Q

How does isoniazid affect cytochrome P450?

A

It is an inhibitor of cytochrome P-450

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104
Q

Which 6 antibiotics can be used to treat methicillin-resistant Staphylococcus aureus (MRSA)?

A

Ceftaroline, daptomycin, doxycycline, linezolid, tigecycline, and vancomycin

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105
Q

Can aminoglycosides kill anaerobic bacteria?

A

No, because they require oxygen for uptake

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106
Q

Which process does rifampin block to exert antimicrobial effects?

A

The synthesis of bacterial messenger RNA via inhibiting RNA polymerase

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107
Q

What is the mechanism of resistance of Plasmodium falciparum to chloroquine?

A

Membrane pumps decrease intracellular concentrations of the drug

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108
Q

Is ritonavir a cytochrome P-450 inhibitor or inducer?

A

Inhibitor

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109
Q

What are the 4 most common adverse effects of terbinafine therapy?

A

Gastrointestinal upset, headache, taste disturbances, hepatotoxicity

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110
Q

What is the mechanism of action of ethambutol?

A

Blocks arabinosyltransferase, thus decreases carbohydrate polymerization in the mycobacterial cell wall

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111
Q

What is unique regarding seizures induced by isoniazid toxicity?

A

Seizures caused by isoniazid toxicity are refractory to benzodiazepines

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112
Q

What are the 3 different mechanisms by which bacteria develop resistance against sulfonamides?

A

Alteration in bacterial dihydropteroate synthase, decreased uptake, or increased synthesis of para-aminobenzoic acid

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113
Q

What are the 3 first-line antiviral agents used to treat herpes simplex virus and varicella-zoster virus infections?

A

Valacyclovir, famciclovir, and acyclovir

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114
Q

Which antiviral medication prevents HIV virions from attaching to host cells?

A

Maraviroc

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115
Q

Why are trimethoprim and sulfamethoxazole used in combination?

A

To synergistically inhibit folate metabolism and thus DNA synthesis (becoming bactericidal instead of bacteriostatic)

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116
Q

What antiprotozoal agent is used to treat Trypanosoma cruzi infection?

A

Nifurtimox

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117
Q

How would an organism become resistant to linezolid?

A

From a point mutation in the ribosomal RNA

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118
Q

What are 2 major adverse effects of acyclovir, famciclovir, and valacyclovir?

A

Acute kidney injury and obstructive crystalline nephropathy in association with inadequate hydration

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119
Q

In a pregnant patient taking an aminoglycoside, what adverse effect would be expected in the fetus?

A

Ototoxicity

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120
Q

Name the narrow-spectrum, penicillinase-resistant antibiotics.

A

Nafcillin, oxacillin, dicloxacillin

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121
Q

Name the drug that is a monobactam.

A

Aztreonam

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122
Q

What is the mechanism of action of terbinafine?

A

It inhibits squalene epoxidase (converts squalene into squalene epoxide), which inhibits synthesis of the cell membrane

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123
Q

Which antibiotics belong to the carbapenem group?

A

Doripenem, ertapenem, imipenem, meropenem

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124
Q

What are the 5 major adverse effects caused by macrolides?

A

MACRO: GI Motility issues, Arrhythmia (prolonged QT interval), acute Cholestatic hepatitis, Rash, eOsinophilia

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125
Q

Which antibiotics inhibit bacterial translocation?

A

Antibiotics that act on translocation such as the macrolides and clindamycin, which inhibit the 50S subunit

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126
Q

What are 2 common adverse effects of efavirenz?

A

CNS symptoms and vivid dreams

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127
Q

Compared with other β-lactams, cephalosporins are more resistant to what bacterial enzyme?

A

Penicillinase

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128
Q

Which 2 infections are the echinocandins used to treat?

A

Invasive aspergillosis, Candida infections

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129
Q

What are 2 clinical uses of griseofulvin?

A

Superficial infections (oral therapy) and dermatophytoses, such as tinea and ringworm.

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130
Q

Why should chlarithromycin not be prescribed for pregnant patients?

A

It is known to cause embryotoxicity

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131
Q

What types of infections is daptomycin used to treat?

A

Vancomycin-resistant enterococcus, bacteremia, endocarditis, and skin infections with Staphylococcus aureus (especially methicillin-resistant strains)

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132
Q

Which antimicrobials are used to treat anaerobic infections below and above the diaphragm?

A

Metronidazole treats anaerobic infections below the diaphragm; clindamycin treats anaerobic infections above the diaphragm

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133
Q

Which 2 classes of HIV antiviral drugs act by inhibiting reverse transcriptase?

A

Nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs)

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134
Q

Sulfonamides are active against which organisms?

A

Gram ⊕ and gram ⊖ organisms and Nocardia

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135
Q

What is the mechanism of action of chlorine in infection control?

A

Oxidizes and denatures proteins

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136
Q

Which 2 infection control techniques disrupt cell membranes?

A

Alcohols and chlorhexidine

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137
Q

What is the advantage of using valacyclovir over acyclovir?

A

Valacyclovir is a prodrug of acyclovir with better oral bioavailability

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138
Q

What is the mechanism of action of ethambutol?

A

Inhibition of arabinosyltransferase, which prevents carbohydrate polymerization of mycobacterial cell walls

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139
Q

Which antifungal agent is primarily used to treat dermatophytoses, especially onychomycosis?

A

Terbinafine

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140
Q

You want to prescribe a triple therapy regimen for a patient with Helicobacter pylori, but she has a penicillin allergy. How do you alter your treatment plan?

A

Replace amoxicillin with metronidazole (triple therapy also includes a proton pump inhibitor and clarithromycin)

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141
Q

Localized or less serious systemic mycoses are an indication for which class of antifungal agents?

A

Azoles

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142
Q

How can megaloblastic anemia seen with trimethoprim-sulfamethoxazole (TMP-SMX) be avoided?

A

By coadministration of leucovorin (folinic acid)

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143
Q

What viruses are targeted by the antiviral medications, acyclovir and ganciclovir?

A

Acyclovir targets herpes simplex virus and varicella zoster virus, while ganciclovir targets cytomegalovirus

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144
Q

What is a common suffix for the protease inhibitor class?

A

-navir: atazanavir, darunavir, fosamprenavir, indinavir, lopinavir, ritonavir, saquinavir

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145
Q

What is the clinical use for remdesivir?

A

Treatment of patients with COVID-19 who require hospitalization

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146
Q

What is the mechanism of action of the antibiotic linezolid?

A

Binds to the 50S subunit and blocks formation of the initiation complex, inhibiting protein synthesis

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147
Q

How do bacteria develop resistance to penicillin?

A

By producing a β-lactamase (such as penicillinase), which cleaves the β-lactam ring, or by mutations in the penicillin-binding proteins

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148
Q

Which antiviral medications are inhibitors of viral DNA polymerase?

A

Cidofovir and foscarnet

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149
Q

What is the mechanism of action of the antiviral medications acyclovir and ganciclovir?

A

They are guanosine analogs that inhibit DNA replication

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150
Q

What is the mechanism of action of metronidazole?

A

Forms free radical metabolites that damage bacterial DNA, leading to cell death (bactericidal)

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151
Q

A patient receiving single-agent therapy for latent tuberculosis has abnormal liver function test results. Which medication is the most likely cause?

A

Isoniazid

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152
Q

Name the 4 carbapenem antibiotics.

A

Doripenem, Imipenem, Meropenem, and Ertapenem (“Pens” (carbapenems) cost a DIME)

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153
Q

What is the most serious adverse effect of flucytosine?

A

Bone marrow suppression

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154
Q

A patient taking a cephalosporin develops a prolonged prothrombin time. Why?

A

Cephalosporin use can cause vitamin K deficiency, leading to ↓ clotting factors

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155
Q

Describe the mechanism of action of trimethoprim.

A

It blocks dihydrofolate reductase (like pyrimethamine), preventing bacterial replication (bacteriostatic)

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156
Q

A patient reports blurry vision after being treated for malaria. What is the most likely cause?

A

Chloroquine-induced retinopathy

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157
Q

A patient with chronic obstructive pulmonary disease being treated with inhaled steroids develops oral candidiasis. Which antifungal medication is indicated for this patient?

A

Nystatin (swish and swallow)

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158
Q

What antiprotozoal agent is used to treat toxoplasmosis?

A

Pyrimethamine

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159
Q

What is the mechanism of action of non-nucleoside reverse transcriptase inhibitors (NNRTIs)?

A

Binding of reverse transcriptase at different locations than NRTIs; NNRTIs do not require phosphorylation or completion with nucleotides to be activated (unlike NRTIs)

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160
Q

Why should ribavarin be avoided in the treatment of pregnant patients with hepatitis C?

A

It is teratogenic

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161
Q

What organisms do ampicillin and amoxicillin cover that penicillin does not?

A

Haemophilus influenzae, Helicobacter pylori, Escherichia coli, Enterococci, Listeria monocytogenes, Proteus mirabilis, Salmonella, and Shigella (HHEELPSS kill enterococci)

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162
Q

What is the most common electrical cardiac abnormality seen with erythromycin?

A

Prolonged QT interval

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163
Q

A patient with herpes simplex virus has a strain resistant to acyclovir. Which antiviral agent should be considered?

A

Foscarnet

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164
Q

Does ganciclovir or valganciclovir have better oral bioavailability?

A

Valganciclovir, because it is a prodrug of ganciclovir

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165
Q

Ganciclovir inhibits which viral enzyme?

A

Viral DNA polymerase

166
Q

What is the treatment for tuberculoid leprosy?

A

Long-term regimen of dapsone and rifampin

167
Q

Through inhibition of which enzyme do fluoroquinolones and quinolones exert their antibacterial effects?

A

DNA gyrase inhibition

168
Q

What neurologic injury can sulfonamides cause in infants?

A

Kernicterus

169
Q

Are patients with penicillin allergies likely to be allergic to cephalosporins?

A

No; cephalosporins have a low rate of cross-reactivity even in patients with penicillin allergy

170
Q

Name the bacterial infections that can be treated with tetracycline antibiotics.

A

Mycoplasma pneumoniae, Chlamydia, Borrelia burgdorferi, Rickettsia, community-acquired methicillin-resistant Staphylococcus aureus (doxyclycline)

171
Q

What is the mechanism of action of streptomycin?

A

Blocks the 30S subunit of the bacterial ribosome

172
Q

A patient is given a triple antibiotic ointment for a superficial skin infection. Which antibiotic in the topical therapy is a cationic polypeptide?

A

Polymyxin B

173
Q

What are the major adverse effects of ampicillin and amoxicillin?

A

Rash, hypersensitivity reaction, pseudomembranous colitis

174
Q

What are the 4 R’s of Rifampin?

A

RNA polymerase inhibitor Ramps up microsomal cytochrome P-450 Red/orange body fluids Rapid resistance when used alone

175
Q

Which azole antifungal medication is indicated for Aspergillus and some Candida infections?

A

Voriconazole

176
Q

Name 3 antibiotics that belong to the tetracycline class of antibiotics.

A

Doxycycline, minocycline, and tetracycline

177
Q

What are the possible adverse effects of the carbapenem class of antibiotics?

A

Skin rashes, gastrointestinal distress, and central nervous system toxicity (seizures)

178
Q

A patient being treated for HIV is receiving a nucleoside reverse transcriptase inhibitor (NRTI) that does not require intracellular phosphorylation. What drug is this?

A

Tenofovir, which is already a nucleoTide; all other NRTIs require phosphorylation

179
Q

Ribavarin is used to treat infection with which 2 viruses?

A

Respiratory syncytial virus, hepatitis C virus

180
Q

What antiprotozoal agent is used to treat leishmaniasis?

A

Sodium stibogluconate

181
Q

Why should fluoroquinolones be avoided in patients older than 60 years of age?

A

Fluoroquinolones may cause tendinitis/tendon rupture in people older than 60 years of age (fluoroquinolones hurt attachments to your bones)

182
Q

A young female presents for treatment of tinea corporis. What do you need to remember when considering the antifungal griseofulvin for her?

A

It is teratogenic and contraindicated in pregnancy; perform a pregnancy test before starting therapy

183
Q

Aminoglycosides are synergistic with which class of antibiotics?

A

β-Lactams

184
Q

Itraconazole is indicated for which 4 fungal infections?

A

Histoplasma, Blastomyces, Coccidioides, Sporothrix schenckii

185
Q

What is the mechanism of action of fluoroquinolones?

A

Bactericidal; inhibition of prokaryotic topoisomerase II (DNA gyrase) and topoisomerase IV

186
Q

A patient presents with low hemoglobin soon after initiation of treatment with sulfadiazine. Which underlying enzyme deficiency does this patient likely have?

A

Glucose-6-phosphate-dehydrogenase (G6PD) deficiency, causing hemolytic anemia

187
Q

A patient with HIV develops leukopenia, neutropenia, and thrombocytopenia after starting treatment for cytomegalovirus esophagitis. What is the most likely cause?

A

He most likely began taking ganciclovir, which has an adverse effect on bone marrow suppression

188
Q

What is the mechanism of action of an integrase inhibitor (eg, raltegravir)?

A

Reversibly blocks viral DNA integration into host cell genome for transcription

189
Q

What is a common suffix for nucleoside reverse transcriptase inhibitors (NRTIs)?

A

-ine: emtricitabine, lamivudine, zidovudine; others are abacavir and tenofovir

190
Q

What is a common dermatologic adverse effect of fluoroquinolones?

A

Rash

191
Q

What infectious processes are commonly treated using clindamycin?

A

Aspiration pneumonia, lung abscesses, and oral infections involving anaerobic organisms

192
Q

What antibiotic do you prescribe as prophylaxis against streptococcal pharyngitis for a child with a history of rheumatic fever?

A

Oral penicillin V or benzathine penicillin G

193
Q

What are the major adverse effects of amphotericin B?

A

Anemia, arrhythmias, fevers, chills, nephrotoxicity, hypotension, and intravenous phlebitis

194
Q

A patient develops an anion gap metabolic acidosis after being treated for tuberculosis. What is the most likely causal medication?

A

Isoniazid

195
Q

Acyclovir, famciclovir, and valacyclovir are guanosine analogs that inhibit which viral enzyme?

A

Viral DNA polymerase through chain termination

196
Q

Neuraminidase inhibitors are used to treat which viral infections?

A

Influenza A and B infections (the 2 neuraminidase inhibitors are oseltamivir and zanamivir)

197
Q

A patient with HIV contracts tuberculosis. Why would rifabutin be favored over rifampin for this patient?

A

Less P-450 stimulation (rifampin ramps up cytochrome P-450, but rifabutin does not)

198
Q

What is the treatment for lepromatous leprosy?

A

Long-term regimen of dapsone, rifampin, and clofazimine

199
Q

What are 2 indications for topical nystatin?

A

Vaginal candidiasis and diaper rash

200
Q

A patient being treated for HIV infection develops anemia. Which drug is responsible?

A

Zidovudine (ZDV)

201
Q

While prescribing antiretroviral therapy (ART), you discover that your patient has an HLA-B*5701 mutation. What drug is contraindicated?

A

Abacavir (nucleoside reverse transcriptase inhibitor) because of increased risk of hypersensitivity

202
Q

Vancomycin is bactericidal except against which bacteria?

A

Clostridium difficile (bacteriostatic)

203
Q

Which 5 medications can be used in the treatment of vancomycin-resistant enterococcus (VRE)?

A

Daptomycin, tigecycline, linezolid, and streptogramins (quinupristin, dalfopristin)

204
Q

A patient develops minor hepatotoxicity after starting treatment for tuberculosis. What class of medications is the most likely cause?

A

Rifamycins

205
Q

What is the mechanism by which echinocandins (eg, anidulafungin) cause flushing?

A

Release of histamine

206
Q

In a pregnant patient taking a sulfonamide, what adverse effect would be expected in the fetus?

A

Kernicterus

207
Q

What biochemical variation in methicillin-resistant Staphylococcus aureus (MRSA) makes nafcillin ineffective?

A

Alteration of the penicillin-binding protein target site

208
Q

Which 3 anti-mite/louse agents may be used to treat an infection with scabies (Sarcoptes scabiei) or lice (Pediculus and Pthirus)?

A

Permethrin, malathion, ivermectin

209
Q

What is the mechanism of action of azoles?

A

They block fungal synthesis of sterols (ergosterol) by inhibiting cytochrome P-450 enzymes from converting lanosterol to ergosterol

210
Q

Pancytopenia develops in a patient being treated for HIV. Which drugs should be considered to counteract this adverse effect?

A

Granulocyte colony-stimulating factor (G-CSF) and erythropoietin (EPO) to combat bone marrow suppression

211
Q

What is the mechanism of action of ledipasvir, ombitasvir, and velpatasvir?

A

NS5A inhibition, preventing RNA replication (the exact mechanism by which they inhibit NS5A is unknown)

212
Q

What drug regimen can you use to treat a Mycobacterium avium-intracellulare infection?

A

Azithromycin or clarithromycin plus ethambutol; rifabutin or ciprofloxacin can be added

213
Q

What is the effect of griseofulvin on warfarin metabolism?

A

It increases warfarin metabolism because it is a cytochrome P-450 inducer

214
Q

What are the 2 most common adverse effects of grazoprevir (NS3/4A inhibitor)?

A

Headache and fatigue

215
Q

Which bacterial species are targeted by ticarcillin and piperacillin?

A

Pseudomonas spp and gram-negative rods

216
Q

Does cidofovir have a long or short half-life?

A

A long half-life

217
Q

Name the penicillin-type antibiotics that are sensitive to penicillinase.

A

Amoxicillin and ampicillin (aminopenicillins)

218
Q

The use of azoles in treatment of fungal infections targets which fungal cell structure?

A

The cell membrane (due to inhibition of intracellular 14-α-demethylase, which reduces ergosterol synthesis)

219
Q

Name the carbapenem that is resistant to β-lactamase and is prescribed with cilastatin to prevent inactivation by the kidneys.

A

Imipenem, a broad-spectrum antibiotic (“the kill is lastin’ with cilastatin”)

220
Q

Name 4 combinations of penicillin antibiotics with β-lactamase inhibitors commonly used to treat bacterial infections.

A

Amoxicillin-clavulanate, ampicillin-sulbactam, ceftazidime-avibactam, piperacillin-tazobactam

221
Q

Which antibiotic ointment is applied to prevent gonococcal conjunctivitis in newborns?

A

Ophthalmic erythromycin

222
Q

Aztreonam is synergistic with which class of antibiotics?

A

Aminoglycosides

223
Q

A patient with renal failure needs a tetracycline for treatment of a Mycoplasma pneumoniae infection. What do you prescribe and why?

A

Doxycycline; it is fecally eliminated and can be administered to patients with renal failure

224
Q

What is the mechanism of action of metronidazole for its antimicrobial effect?

A

Free radical–induced damage to DNA integrity

225
Q

How does adjusting the dose of the antibiotic chloramphenicol influence its risk of causing anemia?

A

Lowering the dose will lower the risk of anemia because chloramphenicol-induced anemia is a dose-dependent adverse effect of the drug

226
Q

Why do antibiotics that inhibit protein synthesis generally not affect human cells?

A

They target bacterial ribosome 70S, which is smaller than the 80S of humans; thus, human ribosomes are left unaffected

227
Q

Why are tetracycline antibiotics not a good choice for infections of the central nervous system (CNS)?

A

They have limited CNS penetration

228
Q

How does adjusting the dose of the antibiotic chloramphenicol influence its risk of causing pancytopenia?

A

It has no effect because aplastic anemia is a dose-independent adverse effect of chloramphenicol

229
Q

What are the 2 most common adverse effects of the NS5B inhibitors, sofosbuvir and dasabuvir?

A

Headache and fatigue

230
Q

Against which classes of bacteria do penicillins exhibit bactericidal activity?

A

Gram ⊕ cocci, gram ⊖ cocci, gram ⊕ rods, spirochetes

231
Q

Which antibiotic targeting bacterial protein synthesis can be given prophylactically before bowel surgery?

A

Neomycin (an aminoglycoside)

232
Q

A pregnant woman is found to be HIV positive. Which nucleoside reverse transcriptase inhibitor (NRTI) is indicated?

A

Zidovudine (ZDV) can reduce the risk of vertical transmission and is also used for general prophylaxis

233
Q

Which processes do sulfonamides and trimethoprim (TMP) affect to exert their antibacterial effects?

A

Folic acid synthesis and reduction (DNA methylation); sulfonamides inhibit conversion of PABA to dihydrofolate; TMP inhibits conversion of DHF to tetrahydrofolate

234
Q

Name 5 antibiotics that belong to the aminoglycoside class of antibiotics.

A

Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin; “Mean” (aminoglycosides) GNATS caNNOT kill anaerobes”

235
Q

Which organisms are covered by the first-generation cephalosporins?

A

Gram ⊕ cocci (such as Staphylococcus auerus), Proteus mirabilis, Eschericia coli, Klebsiella pneumoniae (⊕ PEcK)

236
Q

What is the mechanism by which bacteria develop resistance to aminoglycosides?

A

Transferase enzymes in bacteria cause inactivation of the drug via acetylation, phosphorylation, or adenylation

237
Q

Name 2 examples of first-generation cephalosporins

A

Cefazolin and cephalexin

238
Q

What 2 antiprotozoal agents are used to treat Trypanosoma brucei infection?

A

Suramin, melarsoprol

239
Q

What is the mechanism of resistance against tetracyclines?

A

Decreased uptake into bacterial cells or increased efflux out of cells by plasmid-encoded transport pumps

240
Q

What are the current guidelines for initiation of antiretroviral therapy (ART)?

A

ART is commonly started at diagnosis of HIV; high viral load, CD4 count <500, or presence of AIDS-defining illness are strong indications for starting treatment

241
Q

Use of aminoglycoside antibiotics is absolutely contraindicated for patients with what neuromuscular disorder?

A

Myasthenia gravis

242
Q

Compare the modes of administration for penicillin G and penicillin V.

A

Penicillin G: intravenous or intramuscular; penicillin V: oral

243
Q

Name 3 classes of antibiotics that work by binding to the bacterial 30S ribosomal subunit.

A

Aminoglycosides (eg, gentamicin), glycylcycline (eg, tigecycline), tetracyclines (eg, doxycycline)

244
Q

Which antibiotic is most commonly used preoperatively to protect against Staphylococcus aureus wound infections?

A

Cefazolin

245
Q

Which 2 systemic reactions accompanied by diffuse rash can be seen with vancomycin toxicity?

A

Red man syndrome (diffuse flushing) and DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome

246
Q

Which drug class (1) stops viral particle budding and release in HIV-infected cells and (2) allows HIV proteins to remain within cells?

A

Protease inhibitors (eg, atazanavir), which block proteolytic processing

247
Q

Isavuconazole is indicated for which 2 fungal infections?

A

Serious Mucor or Aspergillus infections

248
Q

What is the mechanism of action of remdesivir?

A

It decreases production of viral RNA by inhibiting viral RNA-dependent RNA polymerase and evading proofreading by viral exoribonuclease

249
Q

What is the mechanism of action of the anti-hepatitis C virus drugs simeprevir and grazoprevir?

A

Inhibition of HCV protease (NS3/4A), thereby preventing viral replication

250
Q

Carbapenems are used to treat infections with which 3 types of organisms?

A

Anaerobes, gram-positive cocci, and gram-negative rods (wide spectrum)

251
Q

What abnormality might be seen on an ECG in a patient being treated with a fluoroquinolone?

A

Prolonged QT interval

252
Q

Which adverse effects are associated with aminoglycosides?

A

Nephrotoxicity, Neuromuscular blockade, Ototoxicity, Teratogenicity; “mean” (aminoglycoside) GNATS caNNOT kill anaerobes

253
Q

Which 2 azoles are commonly used to treat topical fungal infections?

A

Miconazole and clotrimazole

254
Q

Which medication is indicated in the treatment of plasmodia malaria (not including Plasmodium falciparum)?

A

Cholorquine

255
Q

Most antiretroviral drugs are effective against both HIV-1 and HIV-2. Which of these medications are not?

A

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) and enfuviritide are only effective against HIV-1

256
Q

Sulfonamides are bacteriostatic when used alone, but addition of which antibiotic can cause sulfonamides to be bactericidal?

A

Trimethoprim, a dihydrofolate reductase inhibitor

257
Q

What is the mechanism of action of praziquantel?

A

It increases Ca2+ permeability and vacuolization

258
Q

Nearly all carbapenem antibiotics are inactivated in the renal tubules by renal dehydropeptidase I. Which of the carbapenem antibiotics is not affected by this enzyme?

A

Meropenem

259
Q

In combination with amphotericin B, flucytosine is indicated in the treatment of what condition?

A

Systemic fungal infections, especially meningitis caused by Cryptococcus

260
Q

A patient being treated for HIV is noted to have an elevateed creatine kinase level. What is the most likely cause?

A

An integrase inhibitor (eg, elvitegravir, dolutegravir, bictegravir, raltegravir)

261
Q

How can you prevent peripheral neuropathy in a patient being treated for tuberculosis with isoniazid?

A

By coadministering pyridoxine (vitamin B6) to prevent vitamin B6 deficiency induced by isoniazid

262
Q

What aspect of nafcillin, dicloxacillin, and oxacillin makes them resistant to degradation by the bacterial enzyme β-lactamase?

A

Bulky R group in these drugs blocks access of β-lactamase to β-lactam ring

263
Q

What are 3 indications for acyclovir, famciclovir, and valacyclovir?

A

Herpes simplex virus (HSV)–induced oral and genital lesions, HSV-induced encephalitis, and prophylaxis against HSV for immunocompromised individuals

264
Q

A patient receiving a new HIV drug regimen has had several skin reactions at the site of injection. What drug was she prescribed?

A

Enfuvirtide

265
Q

Which 2 disinfection and sterilization techniques are not sporicidal?

A

Alcohols and quaternary amines

266
Q

What is the common renal manifestation of sulfonamide toxicity?

A

Tubulointerstitial nephritis

267
Q

Which 2 electrolytes must be supplemented when amphotericin B is prescribed? Why?

A

Potassium and magnesium (due to altered renal tubule permeability)

268
Q

Name the fourth-generation cephalosporin.

A

Cefepime

269
Q

What is the mechanism of action of malathion?

A

It inhibits mite/louse acetylcholinesterases

270
Q

What is the mechanism of action of griseofulvin?

A

Inhibition of microtubule function, thereby disrupting mitosis

271
Q

Intrathecal administration of amphotericin B is indicated for treatment of which fungal meningitis?

A

Meningitis caused by Coccidioides

272
Q

How are sulfonamides and dapsone similar in mechanism?

A

They both inhibit folate synthesis by blocking dihydropteroate synthase

273
Q

Why does acyclovir interfere with viral DNA synthesis and not human DNA synthesis?

A

It requires monophosphorylation by the thymidine kinase of herpes simplex virus/varicella-zoster virus and is inactive in uninfected cells.

274
Q

You prescribe metronidazole and advise the patient to avoid alcohol use. Why?

A

Metronidazole with alcohol causes a disulfiram-like reaction (severe flushing, hypotension, tachycardia)

275
Q

What is the mechanism of action of cidofovir?

A

Inhibits viral DNA polymerase

276
Q

What are 4 major adverse effects of streptomycin in the treatment of tuberculosis?

A

Ataxia, nephrotoxicity, tinnitus, and vertigo

277
Q

Which feature of tetracyclines makes them effective against Rickettsia and Chlamydia infections?

A

Their ability to accumulate intracellularly

278
Q

Amphotericin B is used to treat which serious, systemic fungal infections? (Hint: There are 6.)

A

Blastomyces, Candida, Coccidioides, Cryptococcus, Histoplasma, Mucor

279
Q

What are the 2 most common adverse effects of NS5A inhibitors (ledipasvir, ombitasvir, velpatasvir)?

A

Diarrhea, headache

280
Q

A patient receiving warfarin therapy begins taking a sulfonamide for an infection and soon notes easy bruising and dark tarry stools. What mechanism causes this adverse effect?

A

The sulfonamide increases the plasma concentration of warfarin by displacing it from albumin

281
Q

Which antiviral medication is indicated for an immunocompromised patient with a cytomegalovirus infection?

A

Ganciclovir

282
Q

An HIV ⊕ patient has a CD4+ count of <200 cells/mm3 and must be treated with prophylaxis for Pneumocystis pneumonia. Which medication is indicated?

A

Trimethoprim-sulfamethoxazole (TMP-SMX)

283
Q

What is the mechanism of action of mebendazole?

A

Inhibition of microtubules

284
Q

A patient with active tuberculosis is found to be HIV positive. How must the treatment regimen for either diagnosis be modified?

A

Rifampin causes potent CYP/UGT induction that ↓ protease inhibitor levels; it should be replaced with rifabutin

285
Q

What is autoclaving?

A

An infection control technique that involves the use of pressurized steam at temperatures >120 °C

286
Q

A patient with COPD and a recent episode of pneumonia has ↑ serum levels of theophylline. Which antibiotic is this patient likely taking?

A

A macrolide

287
Q

Which carbapenem has limited Pseudomonas coverage?

A

Ertapenem

288
Q

What organisms are targeted by clindamycin?

A

Organisms causing anaerobic lung infections (eg, Clostridium perfringens, Bacteroides spp) and group A streptococcal infections

289
Q

What are the adverse effects of foscarnet therapy?

A

Electrolyte abnormalities (hypo- or hypercalcemia, hypo- or hyperphosphatemia, hypomagnesemia, hypokalemia), seizures, nephrotoxicity

290
Q

What is the mechanism of action of the rifamycins, rifabutin and rifampin?

A

They block mRNA synthesis via inhibition of DNA-dependent RNA polymerase

291
Q

What is the mechanism of action of terbinafine?

A

Inhibits squalene epoxidase in fungal cells

292
Q

What is the benefit of utilizing rifampin in the treatment of Mycobacterium leprae?

A

It delays resistance to dapsone

293
Q

Name 5 antibiotics that work by binding to the bacterial 50S ribosomal subunits and blocking protein synthesis.

A

Chloramphenicol, clindamycin, linezolid; quinupristin, dalfopristin (streptogramins); azithromycin, clarithromycin, erythromycin (macrolides)

294
Q

Which 3 medications belong to the rifamycin class of antibiotics?

A

Rifampin, rifapentine, and rifabutin

295
Q

In a pregnant patient taking a fluoroquinolone, what adverse effect would be expected in the fetus?

A

Cartilage damage

296
Q

A patient being treated with clindamycin for pneumonia develops fever and loose stools. What is the bacterial culprit?

A

Clostridium difficile overgrowth in the colon, causing pseudomembranous colitis

297
Q

What are 2 dermatologic manifestations of sulfonamide toxicity?

A

Photosensitivity amd Stevens-Johnson syndrome

298
Q

Which 3 antibiotics can be administered prophylactically for meningococcal meningitis exposure?

A

Rifampin, ceftriaxone, ciprofloxacin

299
Q

A patient develops renal toxicity after being treated for cytomegalovirus. What is the most likely cause?

A

Ganciclovir

300
Q

What are the 3 non-nucleoside reverse transcriptase inhibitors (NNRTIs) available to treat HIV?

A

Efavirenz, delavirdine, nevirapine

301
Q

What is the mechanism of action of dapsone?

A

It inhibits dihydropteroate synthase (sulfonamides inhibit the same enzyme), impairing bacterial folate synthesis

302
Q

Which protein synthesis–inhibiting antibiotics are bactericidal?

A

Aminoglycosides (note that linezolid is variable: bacteriostatic and bactericidal)

303
Q

What is the mechanism of action of ethylene oxide in infection control?

A

Alkylation

304
Q

What are the 3 medications classified as echinocandins?

A

Anidulafungin, caspofungin, and micafungin

305
Q

List the antibiotics that inhibit the 50S subunit of the bacterial ribosome.

A

Chloramphenicol, Clindamycin, Erythromycin (macrolides), Linezold; “Buy AT 30, CCEL (sell) at 50”

306
Q

What is the mechanism of action of polymyxin antibiotics?

A

Cation polypeptides bind to phospholipids on cell membranes of gram ⊝ bacteria, which disrupts cell membrane integrity, leading to leakage of cellular components and cell death.

307
Q

A patient taking prednisone has been recently prescribed a fluoroquinolone antibiotic. What complication may arise from a drug interaction?

A

Tendon rupture; risk is increased when fluoroquinolones are combined with prednisone

308
Q

What is the mechanism of action of tigecycline?

A

It binds the 30S ribosome to inhibit bacterial protein synthesis; bacteriostatic (tetracycline derivative)

309
Q

Which organisms are typically not covered by the first 4 generations of cephalosporins?

A

LAME: Listeria, Atypicals (Chlamydia, Mycoplasma), MRSA, Enterococci

310
Q

Fluconazole is indicated for treatment of which common fungal infection?

A

Candidal infections of all types (can also be used for suppression of crytococcal meningitis in patients with HIV)

311
Q

How soon after onset of influenza symptoms should treatment with oseltamivir or zanamivir be initiated?

A

Within 48 hours of symptom onset

312
Q

How does chlorhexidine affect the intracellular components of pathologic agents in infection control?

A

Coagulates intracellular components

313
Q

Which 2 antibiotics can be used against multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii?

A

Polymyxins B and E (colistin)

314
Q

Name 2 antibiotics that work by blocking peptidoglycan synthesis.

A

Bacitracin and vancomycin (glycopeptides)

315
Q

What is the mechanism of action of ribavirin?

A

Competitive inhibition of inosine monophosphate dehydrogenase, thereby inhibiting synthesis of guanine nucleotides

316
Q

Which 2 antibiotics can be administered prophylactically for pregnant women with group B streptococcal colonization?

A

Ampicillin, penicillin G

317
Q

What organisms are aminoglycosides used against?

A

Gram-negative rods, particularly in cases of severe infection

318
Q

What is the mechanism of action of isoniazid?

A

Decreases mycolic acid synthesis

319
Q

What is the mechanism of action that leads to liver dysfunction when azoles (eg, clotrimazole) are used in the treatment of fungal infections?

A

Inhibition of cytochrome P-450

320
Q

What are the 2 most common dermatologic adverse effects of the simeprevir (NS3/4A inhibitor)?

A

Photosensitivity and rash

321
Q

What is the mechanism of action of cephalosporin antibiotics?

A

They are bactericidal β-lactams that inhibit cell wall synthesis

322
Q

Name 4 examples of second-generation cephalosporins.

A

Cefaclor, cefoxitin, cefuroxime, and cefotetan (2nd graders wear fake fox fur to tea parties)

323
Q

Which third-generation cephalosporin is effective against Pseudomonas spp?

A

Ceftazidime

324
Q

What are 2 methods for reducing amphotericin B toxicity?

A

Use the liposomal formulation of the drug and hydrate the patient to prevent nephrotoxicity

325
Q

What is the mechanism of action of ganciclovir?

A

It is a guanosine analog, first phosphorylated by cytomegalovirus viral kinase and then phosphorylated by cellular kinases to produce ganciclovir triphosphate

326
Q

What is the mechanism of action of the antibiotic chloramphenicol?

A

Inhibits peptidyltransferase activity in the 50S subunit of the ribosome

327
Q

What is the mechanism of action of the antibiotic chloramphenicol?

A

Inhibits peptidyltransferase activity in the 50S subunit of the ribosome

328
Q

A patient is taking warfarin because of a recent pulmonary embolism. What complication could arise if a macrolide is prescribed for newly diagnosed pneumonia?

A

Increased risk of bleeding due to increased serum concentration of warfarin (an oral anticoagulant) as a result of interaction with a macrolide antibiotic

329
Q

What are some of the adverse reactions associated with vancomycin?

A

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome; Nephrotoxicity, Ototoxicity, Thrombophlebitis, diffuse Flushing (red man syndrome) (NOT trouble Free)

330
Q

What is the mechanism of action of the polyenes (amphotericin B and nystatin)?

A

Create membrane pores to disrupt cell membrane integrity

331
Q

Name 2 antipseudomonal antibiotics that interfere with peptidoglycan cross-linking.

A

Ticarcillin, piperacillin

332
Q

Which antibiotics should be avoided in pregnancy?

A

Sulfonamides, Aminoglycosides, Fluoroquinolones, Clarithromycin, Tetracyclines, Ribavirin, Griseofulvin, Chloramphenicol (SAFe Children Take Really Good Care)

333
Q

What are the most common uses for chloramphenicol?

A

Treatment of rickettsial diseases (eg, Rocky Mountain spotted fever) and meningitis (Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae)

334
Q

What adverse effect is more commonly seen in dark-skinned individuals taking chloroquine?

A

Pruritus

335
Q

Which component of the cell wall is targeted by antibiotics acting at the level of cell wall?

A

Peptidoglycans

336
Q

Which organisms do second-generation cephalosporins cover?

A

Gram ⊕ cocci, Haemophilus influenzae, Enterobacter aerogenes, Neisseria spp, Serratia marcescens, Proteus mirabilis, Escherichia coli, Klebsiella pneumoniae (HENS PEcK)

337
Q

Which antifungal agent inhibits nucleic acid synthesis?

A

Flucytosine

338
Q

What dermatologic adverse effect results from use of tetracyclines?

A

Photosensitivity

339
Q

What are 3 well-known adverse effects of linezolid?

A

Peripheral neuropathy, bone marrow suppression (especially thrombocytopenia), and serotonin syndrome (due to partial monoamine oxidase inhibition)

340
Q

What is the mechanism of action of quaternary amines on microbes?

A

Impairment of cell membrane permeability

341
Q

Why should chloramphenicol not be prescribed for pregnant patients?

A

It can cause gray baby syndrome

342
Q

What is the mechanism of action of baloxavir?

A

It decreases viral replication by inhibiting the “cap snatching” endonuclease activity of influenza virus RNA polymerase

343
Q

What types of infections are macrolides used to treat?

A

Sexually transmitted diseases (Chlamydia), atypical pneumonias (eg, Mycoplasma), gram ⊕ cocci (streptococcal infections in patients allergic to penicillin), Bordetella pertussis

344
Q

Which agent, when given with amoxicillin, protects against β-lactamases?

A

Clavulanic acid

345
Q

Name a fifth-generation cephalosporin.

A

Ceftaroline

346
Q

A patient being treated for HIV experiences paresthesia and decreased sensation in both legs. What is the most likely cause?

A

Nucleoside reverse transcriptase inhibitor–induced peripheral neuropathy

347
Q

What is the mechanism of action of pyrazinamide?

A

Unclear; it acts via an unknown mechanism intracellularly

348
Q

What is the recommended combination of antiretroviral therapy (ART) medication classes in HIV therapy?

A

2 nucleoside reverse transcriptase inhibitors (NRTIs) and a third agent (integrase inhibitors are preferred)

349
Q

A patient with a severe bacterial infection is allergic to penicillin. Is aztreonam a good treatment option?

A

Yes; aztreonam has no cross-sensitivity to penicillins

350
Q

What is the mechanism by which bacteria develop resistance to carbapenems?

A

Via carbapenemases, which inactivate the drug (typically produced by Eshcerichia coli, Klebsiella pneumoniae, and Enterobacter aerogenes)

351
Q

Which individuals should receive prophylactic amoxicillin?

A

Patients at high risk for endocarditis who are undergoing surgical or dental procedures

352
Q

Dapsone is used for prophylaxis against infection with which organism?

A

Pneumocystis jirovecii

353
Q

Which 2 enzymes does foscarnet inhibit?

A

Viral DNA/RNA polymerase and HIV reverse transcriptase

354
Q

A patient being treated for systemic mycoses develops gynecomastia. What is the most likely causal agent?

A

Ketoconazole (most likely azole) secondary to inhibition of testosterone synthesis

355
Q

How do penicillins, antipseudomonals, cephalosporins, carbapenems, and monobactams work?

A

They block cell wall synthesis by inhibiting cross-linking of peptidoglycans

356
Q

What 2 diseases is dapsone indicated to treat?

A

Leprosy (both lepromatous and tuberculoid forms), Pneumocystis jirovecii (if used with trimethoprim)

357
Q

What is the function of the HIV-1 protease from the pol gene?

A

Cleaves polypeptides made from HIV mRNA into functional components; therefore, protease inhibitors prevent the maturation of new viruses

358
Q

Which antiviral medication is most appropriate for treating herpes zoster?

A

Famciclovir

359
Q

What is the mechanism of action of clindamycin?

A

It is a bacteriostatic antibiotic that inhibits peptide transfer (translocation) at the 50S ribosomal subunit

360
Q

Which antifungal agent acts like amphotericin B but is only available in topical formulations because of systemic toxicity?

A

Nystatin (same mechanism as amphotericin B)

361
Q

What is the mechanism of resistance of ganciclovir?

A

Mutation of viral kinase

362
Q

Hemolysis may occur as an adverse effect in which patients taking dapsone?

A

Patients who are glucose-6-phosphate dehydrogenase (G6PD) deficient

363
Q

A patient being treated for ringworm experiences flushing, tachycardia, and hypotension after a bachelor party. What drug interaction occurred?

A

Alcohol and griseofulvin caused a disulfiram-like reaction

364
Q

What is the clinical use of streptomycin?

A

Second-line treatment for Mycobacterium tuberculosis

365
Q

What is the mechanism of action of azoles?

A

Decreased ergosterol synthesis from lanosterol via the inhibition of 14-α-demethylase

366
Q

How do bacteria develop resistance to vancomycin?

A

Conversion of D-Ala-D-Ala to D-Ala-D-Lac; (If you Lack a D-Ala [dollar], you can’t ride the van [vancomycin])

367
Q

How do iodine and iodophors work to control infection?

A

Halogenation of proteins, RNA, and DNA

368
Q

What is the mechanism by which bacteria develop resistance to chloramphenicol?

A

By acquiring a plasmid-encoded acetyltransferase that inactivates the drug

369
Q

Which of the carbapenem antibiotics has a lower risk of seizures?

A

Meropenem

370
Q

A patient taking an antidepressant is prescribed linezolid for MRSA pneumonia. Which serious adverse effect might you worry about?

A

Serotonin syndrome; more likely to occur if a patient is also taking a selective serotonin reuptake inhibitor (due to partial monoamine oxidase inhibition)

371
Q

What is the mechanism of action of tetracyclines?

A

They are bacteriostatic, binding to 30S and preventing the attachment of aminoacyl-tRNA

372
Q

Name the 4 nonrespiratory fluoroquinolones.

A

Ciprofloxacin, norfloxacin, ofloxacin, and enoxacin

373
Q

Which cephalosporins work particularly well in the treatment of meningitis and why?

A

Third-generation cephalosporins because they can cross the blood-brain barrier

374
Q

Aztreonam is active against which organisms?

A

Gram-negative rods only

375
Q

What second agent can be administered with amphotericin B to treat cryptococcal meningitis?

A

Flucytosine

376
Q

What is the mechanism of action of chloroquine?

A

Stops the detoxification of heme into hemozoin, causing an accumulation of heme, which is toxic to plasmodia

377
Q

What is the mechanism of resistance to ampicillin and amoxicillin?

A

Bacterial penicillinase (a type of β-lactamase) cleaves the β-lactam ring (avoid this by coprescribing clavulanic acid, which inhibits penicillinases)

378
Q

What is the mechanism of action of flucytosine?

A

Flucytosine is converted to 5-fluorouracil by cytosine deaminase; 5-fluorouracil inhibits DNA and RNA synthesis

379
Q

Which 2 antibiotics can be used as prophylaxis against postsurgical Staphylococcus aureus infection?

A

Cefazolin; vancomycin for methicillin-resistant Staphylococcus aureus (MRSA) infections

380
Q

What is the core structure of penicillin and penicillin derivatives?

A

β-Lactam ring

381
Q

Where does foscarnet bind on viruses (eg, cytomegalovirus)?

A

The pyrophosphate-binding site of either viral DNA/RNA polymerase or HIV reverse transcriptase (foscarnet = pyrofosphate analog)

382
Q

What is the major toxicity associated with ethambutol?

A

Optic neuropathy (think “eyethambutol”), which commonly manifests as red-green color blindness and is usually reversible

383
Q

Name the antibiotics that inhibit peptidoglycan cross-linking and are penicillinase resistant.

A

Oxacillin, nafcillin, dicloxacillin

384
Q

Ethambutol is used to treat which bacterial infection?

A

Mycobacterium tuberculosis

385
Q

What is the mechanism of action of oseltamivir and zanamivir?

A

They inhibit neuraminidase, thus blocking the release of progeny virus from the cell

386
Q

A child presents with discolored teeth, inhibited bone growth, and gastrointestinal distress secondary to antibiotic treatment. What antibiotic was used?

A

A tetracycline, which should be avoided in children because of these adverse effects

387
Q

What is a major hematologic adverse effect of ribavirin?

A

Hemolytic anemia

388
Q

What is the mechanism of action of maraviroc?

A

Inhibits viral attachment by binding to CCR-5 on T cells/monocytes; this prevents CCR-5 interaction with gp120 (maraviroc inhibits docking)

389
Q

What is the mechanism of action of vancomycin?

A

It binds the D-Ala D-Ala part of cell wall precursors, inhibiting the formation of peptidoglycan cell wall (bactericidal against most bacteria)

390
Q

How does cilastatin work to decrease inactivation of carbapenem antibiotics?

A

Inhibitor of renal dehydropeptidase I, which decreases the inactivation of carbapenem antibiotics

391
Q

You add a bacteriostatic antibiotic to bacteria and notice that the A-site tRNA binding is reduced. Which ribosomal subunit is inhibited?

A

30S (this is caused by tetracycline antibiotics)

392
Q

A patient with hepatitis C refractory to newer therapies is in need of which medication adjunct?

A

Ribavirin

393
Q

When would you consider using clindamycin over metronidazole to treat an anaerobic infection?

A

Clindamycin is useful for anaerobic infections above the diaphragm; metronidazole, for those below it

394
Q

Ceftaroline (fifth-generation cephalosporin) is active against which organisms?

A

Gram-positive and gram-negative organisms, including MRSA and Enterococcus faecalis (note: no coverage of Pseudomonas spp)

395
Q

A patient with sepsis receiving an aminoglycoside is also prescribed a cephalosporin. What adverse effect could occur?

A

When combined with aminoglycosides, cephalosporins increase the potential for nephrotoxicity

396
Q

What is the mechanism of action of protease inhibitors?

A

They stop viral maturation by preventing the formation of polypeptide products (Navir [never] tease a protease)

397
Q

What is the mechanism of action of penicillin?

A

As a D-Ala-D-Ala structural analog, it binds transpeptidases (penicillin-binding proteins) and inhibits transpeptidase cross-linking of peptidoglycan in cell walls

398
Q

β-Lactamase inhibitors are used to protect antibiotics from bacterial penicillinases. Would you use these with vancomycin?

A

No, because vancomycin is resistant to β-lactamases

399
Q

What are 2 common adverse effects of all non-nucleoside reverse transcriptase inhibitors (NNRTIs)?

A

Rash and hepatotoxicity

400
Q

What diet modifications must a patient taking a tetracycline follow?

A

Avoid milk (Ca2+), antacids (eg, Ca2+ or Mg2+), and iron-containing preparations because divalent cations inhibit tetracycline absorption in the gut

401
Q

The autoclave is not reliably successful against what pathologic agents?

A

Prions

402
Q

Besides treatment of mycobacterial infections, what are 2 other uses for rifamycins (eg, rifampin)?

A

Meningococcal prophylaxis and chemoprophylaxis for contacts of children with Haemophilus influenzae type b

403
Q

What are the 3 major adverse effects of the drugs belonging to the polymyxin class?

A

Nephrotoxicity, neurotoxicity (slurred speech, paresthesias, weakness), and respiratory failure

404
Q

What is the mechanism of resistance to cephalosporins?

A

Inactivation of the drug by cephalosporinases (a type of β-lactamase) or by structural changes in the penicillin-binding proteins (transpeptidases)

405
Q

Combinations of which 3 drug classes can be used to treat chronic hepatitis C infections?

A

NS5A inhibitors, NS5B inhibitors, NS3/4A inhibitors (alternative drugs include ribavirin)

406
Q

What is the major reason for the limited use of chloramphenicol in the United States?

A

High level of toxicity (although still widely used in some countries because of its low cost)

407
Q

In a pregnant patient taking a tetracycline, what adverse effect would be expected in the fetus?

A

Discolored teeth, inhibited bone growth

408
Q

A Cushing-like syndrome can be an adverse effect of which class of HIV medications?

A

Protease inhibitors

409
Q

Aztreonam inhibits peptidoglycan cross-linking by binding to which protein?

A

Penicillin-binding protein 3

410
Q

What is the mechanism of action of the rifamycin class?

A

Inhibition of DNA-dependent RNA polymerase

411
Q

Which 5 agents can be used to treat helminthic infections?

A

Pyrantel pamoate, Ivermectin, Mebendazole, Praziquantel, Diethylcarbamazine (helminths get PIMP’D)

412
Q

A patient treated with vancomycin develops diffuse flushing (image). How could this have been prevented?

A

Pretreatment with antihistamines and a slow infusion rate can prevent red man syndrome, which is seen in vancomycin toxicity

Microbiology (7 decks)

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