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

Anti-fungal & Anti-parasitic Drugs; Algae Flashcards

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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

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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

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

Anti-Malarial Drugs

Study These Flashcards
A

Persistent malaria:
1. Primaquine-Sulfadoxine
2. Quinocide

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

Artemisin
(traditional Chinese medine)

22
Q

Persistent Malaria

Study These Flashcards
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

Study These Flashcards
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

Study These Flashcards
A

Same drug family as Primaquine

Targets liver stage

25
Acute Malaria
Erythrocytic cycle Merozoites infect RBCs (& lyse)
26
Chloroquine (& derivatives)
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
Amodiaquine
Mainly active against merozoites (of all 4 species) EXCEPT: chloroquine-resistant P. falciparum
28
Mefloquine
Most effective - Prophylaxis & treatment of acute malaria
29
Artemisin
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
Other ways to control malaria:
1. Insecticides & repellents (with DEET) 2. Mosquito nets 3. Proper clothing
31
African Sleeping Sickness Drugs (Trypanosomiasis & Leishmaniasis)
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
Chaga's Disease Drugs (Trypanosomiasis & Leishmaniasis)
Acute stage: 1. Nifrutimox 2. Benzonidaxole NO treatment against chronic stage (most people don't get this stage)
33
Anti-Helminth Drugs
1. Intestinal nematodes - Mebendazole, thiabendazole, albendazole - Pyrantel pamoate - Piperanzine 2. Filariasis - Ivermectin
34
Intestinal Nematodes
1. Ascaris lumbricoides 2. Necator americanus 3. Enterobius vermicularis 4. Trichuris trichiura 5. Stronglyoides stercoralis
35
Intestinal Nematode Drugs
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
Ivermectin
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
Algae differ from other photosynthetic organisms:
1. Lack organized vascular system 2. Simple reproductive system
38
Methods of Algae Classification:
1. Principal photosynthetic pigment 2. Cell wall structure 3. Type of storage products 4. Mechanisms of motility 5. Mode of reproduction
39
Color Classification of Algae:
1. Chlorophytes - green algae 2. Rhodophyta - red algae 3. Chrysophyta - golden brown algae & diatoms 4. Phaeophyta - brown algae
40
Unicellular Algae (Microscopic Algae)
1. Diatoms 2. Some green algae 3. Dinoflagellates 4. Euglenids 5. Few red algae
41
Specialized Structures of Macroscopic Algae
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
Algae Cell Wall Components:
1. Cellulose (often associated with pectin) 2. Carragreen 3. Agar 4. Silicon dioxide
43
Algae Cell Structures:
1. Nucleus 2. Chloroplasts (photosynthesis) 3. Mitochondria (respiration & oxidative phosphorylation)
44
Algae Reproduction
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
Algae Toxin Production "Red Tides"
Algal blooms - Overgrowth of specific types of algae Caused by several dinoflagellates in Group Pyyrophyta: 1. Karenia brevis 2. Gonyaulax species (Alexandrium fundyense)
46
Karenia brevis (formerly Gymnodinium breve)
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
Gonyaulax species
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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