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FA - Microbiology > Micro - Antimicrobials (Antifungals & Parasite Treatment) > Flashcards

Micro - Antimicrobials (Antifungals & Parasite Treatment) Flashcards

Pg. 189-191 in First Aid 2014 Sections include: -Antifungal therapy -Amphotericin B -Nystatin -Azoles -Flucytosine -Echinocandins -Terbinafine -Griseofulvin -Antiprotozoan therapy -Chloroquine -Antihelminthic therapy

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1
Q

Which antifungal drug inhibits lanosterol synthesis?

A

Terbinafine

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2
Q

Which type of antifungal drug inhibits ergosterol synthesis? Give 6 examples of this type of drug.

A

Azoles; (1) Fluconazole (2) Ketoconazole (3) Clotrimazole (4) Miconazole (5) Itraconazole (6) Voriconazole

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3
Q

Which type of antifungal drug inhibits cell wall synthesis? Give 3 examples of this type of drug.

A

Echinocandins; (1) Caspofungin (2) Micafungin (3) Anidulafungin

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4
Q

Which type of antifungal drug forms membrane pores? Give 2 examples of this type of drug.

A

Polyenes; (1) Amphotericin B (2) Nystatin

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5
Q

Which antifungal drug inhibits nucleic acid synthesis?

A

5-Flucytosine

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6
Q

Draw a visual depicting the methods of antifungal therapy, which include: (1) Lanosterol synthesis (2) Ergosterol synthesis (3) Cell wall synthesis (4) Forms membrane pores (5) Nucleic acid synthesis. Match of these methods to their specific drugs.

A

See p. 189 in First Aid 2014 for visual

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7
Q

What is the mechanism of Amphotericin B?

A

Binds ergosterol (unique to fungi); Forms membrane pores that allow leakage of electrolytes; Think: “ amphoTERicin “TEARs” holes in the fungal membrane by forming pores”

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8
Q

In general, what is the clinical use of Amphotericin B? What are specific examples of conditions in which Amphotericin B is used? Include details of use, where applicable/necessary.

A

Serious, systemic mycoses. Crypotococcus (amphotericin B with/without flucytosine for cryptococcal meningitis), Blastomyces, Coccidioides, Histoplasma, Candida, Mucor. Intrathecally for fungal meningitis.

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9
Q

What is used in supplement to Amphotericin B, and why?

A

Supplement K+ and Mg2+ because of altered renal tubule permeability

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10
Q

What are 6 toxicities associated with Amphotericin B?

A

(1) Fever/chills (“shake and bake”) (2) Hypotension (3) Nephrotoxicity (4) Arrhythmias (5) Anemia (6) IV phlebitis (“AMPHOTERRIble”).

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11
Q

What can decrease the nephrotoxicity associated with Amphotericin B?

A

Hydration lowers nephrotoxicity.

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12
Q

What kind of preparation of Amphotericin B lowers its toxicity?

A

Liposomal amphotericin B lowers toxicity.

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13
Q

With which other antifungal does Nystatin share its mechanism? What is that mechanism?

A

Same as amphotericin B; Binds ergosterol (unique to fungi) & Forms membrane pores that allow leakage of electrolytes;

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14
Q

What is the form of nystatin, and why?

A

Topical form because too toxic for systemic use.

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15
Q

What are 2 clinical uses of nystatin?

A

“Swish and swallow” for oral candidiasis (thrus); Topical for diaper rash or vaginal candiasis

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16
Q

What are 6 examples of Azoles?

A

(1) Fluconazole (2) Ketoconazole (3) Clotrimazole (4) Miconazole (5) Itraconazole (6) Voriconazole

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17
Q

What is the mechanism of Azoles?

A

Inhibit fungal steroid (ergosterol) synthesis, by inhibiting the cytochrome P-450 enzyme that converts lanosterol to ergosterol

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18
Q

In general, what is the clinical use of Azoles?

A

Local and less serious systemic mycoses

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19
Q

What are 2 clinical uses of Fluconazole?

A

Fluconazole for chronic suppression of cryptococcal meningitis in AIDS patients and candidal infection of all types

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20
Q

What are 3 clinical uses of Itraconazole?

A

Itraconazole for Blastomyces, Coccidioides, Histoplasma

21
Q

What is the clinical use of Clotrimazole? Which other Azole shares this clinical use?

A

Clotrimazole and Miconazole for topical fungal infections

22
Q

What are 2 toxicities associated with Azoles?

A

(1) Testosterone synthesis inhibition (gynecomastia, esp. with ketoconazole) (2) Liver dysfunction (inhibits cytochrome P-450)

23
Q

Which Azole is most associated with testosterone synthesis inhibition? Which condition does this cause?

A

Testosterone synthesis inhibition (gynecomastia, esp. with ketoconazole)

24
Q

What is the mechanism of Flucytosine?

A

Inhibits DNA and RNA biosynthesis by conversion of 5-fluorouracil by cytosine deaminase

25
Q

What is the clinical use for flucytosine? For what fungal infection is it especially used? With what other antifungal drug is it used in combination?

A

Systemic fungal infections (esp. meningitis caused by Cryptococcus) in combination with amphotericin B

26
Q

What is the toxicity of Flucytosine?

A

Bone marrow suppression

27
Q

What are 3 examples of Echinocandins?

A

(1) Caspofungin (2) Micafungin (3) Anidulafungin

28
Q

What is the mechanism of Echinocandins ?

A

Inhibits cell wall synthesis by inhibiting synthesis of Beta-glucan

29
Q

What are 2 clinical uses of Echinocandins?

A

(1) Invasive aspergillosis (2) Candida

30
Q

What are 2 toxicities associated with Echinocandins?

A

(1) GI upset (2) Flushing (by histamine release)

31
Q

Which antifungal causes flushing? What is the mechanism by which this flushing occurs?

A

Echinocandins - Flushing (by histamine release)

32
Q

What is the mechanism of Terbinafine?

A

Inhibits the fungal enzyme squalene epoxidase

33
Q

What is the clinical use of Terbinafine, and especially in what contexts?

A

Dermatophytoses (especially onychomycosis - fungal infection of finger or toe nails)

34
Q

What are 4 toxicities associated with Terbinafine?

A

(1) GI upset (2) Headaches (3) Hepatotoxicity (4) Taste disturbance

35
Q

What is the mechanism of Griseofulvin? Where does it deposit?

A

Interferes with microtubule function; Disrupts mitosis. Deposits in keratin-containing tissues (e.g., nails)

36
Q

In general, what is the clinical use of Griseofulvin? What kind of fungus does it inhibit?

A

Oral treatment of superficial infections; Inhibits growth of dermatophytes (tinea, ringworm)

37
Q

What are 6 toxicities associated with Griseofulvin?

A

(1) Teratogenic (2) Carcinogenic (3) Confusion (4) Headaches (5-6) Increased P-450 and Warfarin metabolism

38
Q

Which antiprotozoal therapy is used to treat toxoplasmosis?

A

Pyrimethamine (toxoplasmosis)

39
Q

Which antiprotozoal therapy is used to treat Trypanosoma brucei?

A

Suramin and melarsoprol (Trypanosoma brucei)

40
Q

Which antiprotozoal therapy is used to treat T. cruzi?

A

Nifurtimox

41
Q

Which antiprotozoal therapy is used to treat Leishmaniasis?

A

Sodium stibogluconate (Leishmaniasis)

42
Q

What is the mechanism of chloroquine, and what effect does it have?

A

Blocks detoxification of heme into hemozoin. Heme accumulates and is toxic to plasmodia.

43
Q

What is the clinical use of Chloroquine? What (of relevance) does it not treat, and why?

A

Treatment of plasmodial species other than P. falciparum (frequency of resistance in P. falciparum is too high).

44
Q

In which kind of Plasmodium is high resistance to Chloroquine found? What causes this resistance?

A

P. falciparum; Resistance due to membrane pump that decreases intracellular concentration of drug.

45
Q

What is used to treat P. falciparum?

A

Treat P. falciparum with artemether/lumefantrine or atovaquone/proguanil

46
Q

What antiprotozoal therapy is used in the case of life-threatening malaria? Differentiate what is used in the US versus elsewhere.

A

For life-threatening malaria, use quinidine in the U.S. (quinine elsewhere) or artesunate

47
Q

What are 2 toxicities associated with Chloroquine? What population is especially affected by one of these toxicities?

A

(1) Retinopathy (2) Pruritus (especially in dark-skinned individuals)

48
Q

What are 5 examples of antihelminthic therapy? What function do they share?

A

(1) Mebendazole (2) Pyrantel pamoate (3) Ivermectin (4) Diethylcarbamazine (5) Praziquantel; Immobilize helminths

49
Q

Which antihelminthic therapy is used against flukes (trematodes)? Give an example of such flukes.

A

Use praziquantel against flukes (trematodes) such as Schistosoma.

FA - Microbiology (43 decks)

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