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Microbiology > Anti-fungal & Anti-parasitic Drugs; Algae > Flashcards

Anti-fungal & Anti-parasitic Drugs; Algae Flashcards

1
Q

Anti-fungal Targets:

A
  1. Ergosterol synthesis
  2. Cell wall synthesis
  3. Cell division
  4. Nucleic acid synthesis
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2
Q

3 Classes of Drugs Targeting Ergosterol:

A
  1. Polyenes
  2. Azoles
  3. Allylamines
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3
Q

Polyenes

A
  1. Amphotericin B
  2. Nystatin
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4
Q

Amphotericin B

A

Produced by Streptomyces nodosus

Binds ergosterol
- Increases cell membrane permeability
- Causes cell lysis

Systemic fungal infections
- IV over long periods

Adverse side effects (very toxic):
1. Renal toxicity (monitor kidney function)
2. Chills/fever
3. Inflammation of vein (phlebitis)

Less toxic lipid formulations also given

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5
Q

Nystatin

A

Binds ergosterol
- Increases cell membrane permeability
- Causes cell lysis

Used to treat:
1. Oral & esophageal infections
(oral, esophageal, gastric candidiasis)
2. Vaginal candidiasis (topical)

NOT used systemically

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6
Q

Azoles

A

Chemically synthesized drugs

Inhibit cytochrome P450 14a-demethylase (P45014DM)
- Enzyme in sterol biosynthesis pathway (lanosterol –> ergosterol)
- Depletion of ergosterol
- Increased membrane permeability

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7
Q

Azole Drugs

A

Imidazoles:
1. Ketoconazole
2. Mixonazole & Clotrimazole

Triazoles (less toxic):
1. Fluconazole
2. Itraconazole
3. Posaconzale

OTC:
1. Ketoconazole
2. Clotrimazole
3. Miconazole

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8
Q

Ketoconazole
(Imidazole)

A

Chronic mucocutaneous candidiasis

Adverse side effects:
1. Nausea
2. Vomiting
3. Hepatotoxicity
4. Inhibition of testosterone

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9
Q

Miconazole & Clotrimazole
(Imidazole)

A

Topical fungal infections

  1. Cutaneous candidiasis
  2. Tinea versicolor
  3. Dermatophytosis
    (tinea pedis, tinea corporis, etc.)
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10
Q

Fluconazole
(Triazole)

A

Cutaneous & vaginal candidiasis (Diflucan - pink pill)

Systemic candidiasis & cryptomeningitis

Most commonly used

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11
Q

Itraconazole
(Triazole)

A

Broad-spectrum anti-fungal

Spectrum of activity includes:
1. Chromoblastomycosis
2. Histoplasmosis
3. Coccidioidomycosis
4. Blastomycosis

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12
Q

Posaconzale
(Triazole)

A

Excellent activity against:
Candida & Aspergillus

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13
Q

OTC Azoles

A

Superficial skin infections or vaginal candidiasis

  1. Ketoconazole
  2. Clotrimazole
  3. Miconazole
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14
Q

Allylamines

A

Inhibition of squalene epoxidase
- Essential step in ergosterol synthesis
(squalene –> lanosterol –> ergosterol)

Dermatophyte infections
(superficial skin infections)
- Chronic tinea pedis
- Tinea corporis

  1. Naftitine (topical)
  2. Terbinafine (topical & oral)
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15
Q

Echinocandins

A

Capsofungin

Target cell wall synthesis
- Inhibits beta-1,3 glucan synthesis
(inhibits secretion of subunits)
- Depletion of cell wall component
(falls apart)

Candida & Aspergillus infections

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16
Q

Griseofulvin

A

Produced by Penicillium species

Targets cell division
- Disrupts spindle formation
- Prevents mitosis

Taken orally for months
- Becomes concentrated in dead keratinized layers of skin
- Inhibits growth (fungus takes up)

Ringworm of skin, nails, hair
- Trichophyton spp.
- Epiderophyton spp.
- Microsporum spp.

NOT effective against:
- Superficial candidiasis
- Tinea versicolor

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17
Q

Flucytosine

A

Targets nucleic acid synthesis
- Replaces uracil with 5-fluorouracil in fungal RNA (chain inhibitor)
- Inhibits protein synthesis (transcription)

Candidiasis & cryptococcosis
- Used synergistically with Amphotericin B

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18
Q

Anti-protozoan Drugs

A
  1. Intestinal/urogenital protozoa
  2. Anti-malarial drugs
  3. Trypanosomiasis & Leishmaniasis
    - African Sleeping Sickness
    - Chaga’s Disease
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19
Q

Metronidazole

A

Flagyl (trade name)

Activated by anaerobic metabolism

Interferes with electron transport & alters DNA (either paralyses or kills)

Used against intestinal/urogenital protozoa:
1. Entamoeba histolytica
2. Giardia lamblia
3. Trichomonas vaginalis

20
Q

4 Types of Malaria

A
  1. P. vivax
  2. P. ovale
  3. P. malariae
  4. P. falciparum
21
Q

Anti-Malarial Drugs

A

Persistent malaria:
1. Primaquine-Sulfadoxine
2. Quinocide

Acute malaria:
1. Chloroquine
2. Amodiaquine
3. Mefloquine

Artemisin
(traditional Chinese medine)

22
Q

Persistent Malaria

A

Exo-erythrocyte cycle

Infection of liver cells
- Enter hepatocytes via blood
- Undergo at least 1 liver stage
- Release merozoites into blood

23
Q

Primaquine-Sulfadoxine

A

Targets liver stage

Kills liver holdouts
- Prevents recurrences of P. vivax & P. ovale

Destroys gametes
- Prevents reinfections of Anopheles mosquitoes

Treats chloroquine-resistant P. falciparum

24
Q

Quinocide

A

Same drug family as Primaquine

Targets liver stage

25
Q

Acute Malaria

A

Erythrocytic cycle

Merozoites infect RBCs (& lyse)

26
Q

Chloroquine
(& derivatives)

A

Prevents crystallization of heme in RBCs
- Makes RBCs uninhabitable
- Destroys parasites

Mainly active against merozoites (of all 4 species)

Most prescribed anti-malarial drug
- Begin taking before & after travel to prevent malaria
- Only effects parasites that come out of liver

27
Q

Amodiaquine

A

Mainly active against merozoites (of all 4 species)

EXCEPT: chloroquine-resistant P. falciparum

28
Q

Mefloquine

A

Most effective
- Prophylaxis & treatment of acute malaria

29
Q

Artemisin

A

Nobel Prize Medicine 2015

Isolated from Traditional Chinese medicine
- Plant (Artemesia annua)

Generates free radicals within parasite
- Damages membrane
- Definitive target unknown

Very effective BUT resistance growing

30
Q

Other ways to control malaria:

A
  1. Insecticides & repellents (with DEET)
  2. Mosquito nets
  3. Proper clothing
31
Q

African Sleeping Sickness Drugs
(Trypanosomiasis & Leishmaniasis)

A

Treatment depends on stage

  1. Suramin
    - Does NOT cross BBB
    - Not effective once parasite crossed into CNS (begins showing symptoms)
  2. Melarsoprol
    - Arsenical compound
    - Crosses BBB
    - EXTREMELY toxic
32
Q

Chaga’s Disease Drugs
(Trypanosomiasis & Leishmaniasis)

A

Acute stage:
1. Nifrutimox
2. Benzonidaxole

NO treatment against chronic stage
(most people don’t get this stage)

33
Q

Anti-Helminth Drugs

A
  1. Intestinal nematodes
    - Mebendazole, thiabendazole, albendazole
    - Pyrantel pamoate
    - Piperanzine
  2. Filariasis
    - Ivermectin
34
Q

Intestinal Nematodes

A
  1. Ascaris lumbricoides
  2. Necator americanus
  3. Enterobius vermicularis
  4. Trichuris trichiura
  5. Stronglyoides stercoralis
35
Q

Intestinal Nematode Drugs

A
  1. Mebendazole, thiabendazole, albendazole
    - Paralyze worms (passed out in stool)
  2. Pyrantel pamoate
    - Paralyze worms
  3. Piperazine
    - Paralyze worms

Other drugs irritate worms
- Migrate out of small intestine to other organs (can be fatal)

36
Q

Ivermectin

A

Effective against filariasis
- River blindness (Onchocerca)
- Elephantiasis (Wuchereria)

Binds to glutamate-gated chloride channels
- Increases Cl- permeability
- Paralyzes worms

Nobel Prize Medicine 2015

Commonly used as anti-worm for horses

37
Q

Algae differ from other photosynthetic organisms:

A
  1. Lack organized vascular system
  2. Simple reproductive system
38
Q

Methods of Algae Classification:

A
  1. Principal photosynthetic pigment
  2. Cell wall structure
  3. Type of storage products
  4. Mechanisms of motility
  5. Mode of reproduction
39
Q

Color Classification of Algae:

A
  1. Chlorophytes - green algae
  2. Rhodophyta - red algae
  3. Chrysophyta - golden brown algae & diatoms
  4. Phaeophyta - brown algae
40
Q

Unicellular Algae
(Microscopic Algae)

A
  1. Diatoms
  2. Some green algae
  3. Dinoflagellates
  4. Euglenids
  5. Few red algae
41
Q

Specialized Structures of Macroscopic Algae

A
  1. Holdfast
    - Anchors organism to substrate
  2. Stipe
    - Stalk of algae
  3. Bladders
    - Gas-filled (helps float on surface)
    - Maximizes exposure of blades to sunlight
  4. Blades
    - Leaf-like structures attached to stipe
    - Sites of photosynthesis
42
Q

Algae Cell Wall Components:

A
  1. Cellulose
    (often associated with pectin)
  2. Carragreen
  3. Agar
  4. Silicon dioxide
43
Q

Algae Cell Structures:

A
  1. Nucleus
  2. Chloroplasts
    (photosynthesis)
  3. Mitochondria
    (respiration & oxidative phosphorylation)
44
Q

Algae Reproduction

A

Asexual
1. Binary fission
- Single-celled algae
- Mitosis
2. Fragmentation
- Multicellular filamentous species

Sexual
- Occurs regularly in most algae
- Haploid gametes fuse together & become diploid zygotes

45
Q

Algae Toxin Production
“Red Tides”

A

Algal blooms
- Overgrowth of specific types of algae

Caused by several dinoflagellates in Group Pyyrophyta:
1. Karenia brevis
2. Gonyaulax species (Alexandrium fundyense)

46
Q

Karenia brevis
(formerly Gymnodinium breve)

A

Algal blooms in Gulf of Mexico

Produces brevetoxin
- Neurotoxin
- Kills fish that feed on phytoplankton

Human ingests fish:
1. Tingling sensation in mouth/fingers
2. Reversal of hot/cold perceptions
3. Reduced pulse rate
4. Diarrhea

Rarely deadly (recovery in 2-3 days)

47
Q

Gonyaulax species

A

Alexandrium fundyense

Blooms in Atlantic ocean (east coast USA)

Produces poisonous neurotoxins:
1. Saxitoxin
2. Gonyautoxin

Toxins accumulate in shellfish that feed on dinoflagellates
- Doesn’t cause harm
- Clams, mussels, scallops

Paralytic shellfish poisoning (human):
1. General numbness
2. Dizziness
3. Muscle weakness
4. Impaired respiration (death from respiratory failure)

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