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WorksheetsProtozoan Infections and Nitroimidazoles
Total questions: 47
Worksheet time: 24mins
Which statement best defines a parasite in a host relationship?
Organism producing nutrients for the host
Organism protecting the host from infection
Organism living on or in another organism
Organism living independently without a host
Amebiasis primarily affects which anatomical site and is caused by which protozoan?
Lungs by Pneumocystis jirovecii
Large intestine by Entamoeba histolytica
Vagina by Trichomonas vaginalis
Kidneys by Giardia lamblia
Which symptom profile most aligns with giardiasis?
Jaundice and dark urine
Painful urination and vulvar itching
Watery diarrhea and abdominal cramps
Bloody sputum and chest pain
Pneumocystis pneumonia typically occurs in which patient population?
Healthy adolescents without comorbidities
Individuals with severely impaired immune systems
Pregnant women in second trimester
Older adults with controlled diabetes
Which clinical feature best characterizes severe Pneumocystis pneumonia?
Cutaneous ulcers with black eschar
Formation of cysts in liver parenchyma
Rapid multiplication primarily in lung tissue
Chronic vaginitis with foul discharge
Trichomoniasis in females most commonly presents with which findings?
Dry cough and night sweats
Bloody stools and tenesmus
Profuse foul-smelling discharge and vaginitis
Asymptomatic without discharge
Which causative agent is correctly paired with its disease?
Giardia lamblia with PCP
Leishmania donovani with African sleeping sickness
Entamoeba histolytica with cutaneous leishmaniasis
Trypanosoma cruzi with Chagas disease
Which subspecies cause African sleeping sickness in different regions?
T. brucei rhodesiense East, T. brucei gambiense West
T. cruzi East, T. donovani West
T. vaginalis East, T. lamblia West
T. histolytica East, T. jirovecii West
Which stage description matches Stage II of African sleeping sickness?
Watery diarrhea and distention
Acute dysentery and liver tenderness
Daytime somnolence and extrapyramidal signs
Fever with hematologic changes
Visceral leishmaniasis, also called kala-azar, is caused by which organism?
Trichomonas vaginalis
Pneumocystis jirovecii
Trypanosoma cruzi
Leishmania donovani
Which drug set is appropriate for amebiasis, giardiasis, or trichomoniasis?
Diloxanide and atovaquone
Eflornithine and pentamidine
Metronidazole and tinidazole
Atovaquone and pentamidine
Which agents are listed under nitroimidazoles?
Chloroquine, quinine, primaquine
Atovaquone, eflornithine, amphotericin
Iodoquinol, diloxanide, pentamidine
Metronidazole, tinidazole, ornidazole
Which initial step occurs in the mechanism of action of nitroimidazoles?
Hydrolysis to form aldehyde groups
Acetylation of nitro moiety
Reduction to nitro radical anion
Oxidation to nitro radical cation
Which sequence correctly links ROS formation during nitroimidazole action?
Hydroxyl radical then superoxide formation
Superoxide formation then hydrogen peroxide
Hydrogen peroxide then nitro group regeneration
Nitro group regeneration then acetyl radicals
What is the ultimate effect of reactive oxygen species generated by nitroimidazoles on parasites?
Enhance parasite nutrient uptake
Neutralize host gastric acidity
Cause damage to critical cellular components
Increase host immune cell proliferation
Which statement best describes atovaquone’s mechanism of action in protozoa?
Blocks folate synthesis at DHFR enzyme
Alkylates microtubules causing depolymerization
Inhibits ubiquinone reductase at cytochrome bc1
Chelates iron from heme detoxification
Pentamidine isethionate most directly causes which molecular consequence in mitochondrial DNA?
Single-strand nicks and base excision
Crosslinking between adjacent bases
Double-strand breaks and linearization
Point mutations in coding regions
Which target is primarily inhibited by pentamidine isethionate?
Thymidylate synthase in cytosol
UDP-glucose transferase in ER
Type II topoisomerase of mitochondrial DNA
DNA-dependent RNA polymerase of nucleus
Eflornithine treats protozoal infections by which enzyme action?
Irreversible inhibition of dihydrofolate reductase
Suicide inhibition of ornithine decarboxylase
Allosteric activation of S-adenosylmethionine
Competitive inhibition of ODC active site
Blocking ornithine decarboxylase primarily reduces synthesis of which metabolite?
Putrescine, the rate-limiting polyamine
Homocysteine, a sulfur amino acid
Cysteamine, a redox regulator
Spermidine, a mitochondrial cofactor
Which property differentiates nonpolar esters of diloxanide furoate from polar esters?
Nonpolar esters are less potent clinically
Nonpolar esters are more potent activity
Nonpolar esters are always water soluble
Nonpolar esters are selective for tissue cysts
Iodoquinol is recommended for which clinical indication?
Extratestinal amebiasis management
Prophylaxis against blood flukes
Routine traveler’s diarrhea therapy
Acute and chronic intestinal amebiasis
Which limitation restricts routine use of iodoquinol for traveler’s diarrhea?
Risk of hemolysis in G6PD deficiency
High incidence of topical neuropathy
Low oral bioavailability limiting effect
Rapid resistance due to efflux pumps
Atovaquone is best characterized chemically as which type of compound?
Hydrophilic pteridine analog compound
Polar purine-like nucleoside analog
Water-soluble benzamide-like derivative
Highly lipophilic naphthoquinone analog
Which statement about atovaquone stereospecificity is accurate?
Both isomers have equal activity
Only racemic mixture is active
Trans isomer shows greater activity
Cis isomer shows greater activity
Which classification correctly pairs platyhelminth group with examples?
Cestodes include Schistosoma species
Trematodes include Hymenolepis nana
Trematodes include Taenia solium
Cestodes include Taenia saginata
Which helminth group is categorized as roundworms in this classification?
Platyhelminthes are roundworms type
Cestodes are roundworms category
Trematodes are roundworms group
Aschelminthes are roundworms class
Which clinical feature commonly characterizes helminth infections globally?
Chronic infections lasting a lifetime
Rare disease of minimal public burden
Typically acute and self-limiting course
Always restricted to temperate regions
Which pairing of tapeworm common name with species is correct?
Dwarf tapeworm is Hymenolepis nana
Fish tapeworm is Schistosoma japonicum
Pork tapeworm is Diphyllobothrium latum
Beef tapeworm is Taenia solium
Which benzimidazole mechanism directly prevents microtubule formation in helminths?
Inhibiting fumarate reductase enzyme
Binding to tubulin caps associating ends
Activating arachidonic acid metabolism
Redistributing Ca2+ within the parasite
In benzimidazoles, inhibition of fumarate reductase most directly leads to which cellular consequence?
Stabilized microtubule subunits
Enhanced ATP synthesis in worms
Uncoupled oxidative phosphorylation
Increased cyclooxygenase activity
Which drug is classified under miscellaneous anthelmintics alongside niclosamide?
Ivermectin
Oxamniquine
Praziquantel
Diethylcarbamazine
Diethylcarbamazine’s first proposed mechanism involves which host component responding to filarial antigens?
T-cell receptor signaling
Blood platelets activation
Neutrophil degranulation
Complement cascade start
Which proposed DEC mechanism targets microtubule dynamics?
Disrupts pre-formed microtubules
Blocks phosphoinositide turnover
Alkylates helminth DNA strands
Opens glutamate chloride channels
Interference with arachidonic acid metabolism by DEC likely alters which process?
Nucleic acid alkylation reactions
Calcium redistribution events
Tubulin subunit self-association
Vascular and cellular adhesiveness
Praziquantel is most noted for causing which ionic effect in parasites?
Ca2+ redistribution within tissues
Cl− efflux through gated channels
Na+ influx across tegument
K+ loss from muscle cells
In cestode infections, praziquantel’s action in the host lumen primarily causes what outcome?
Muscle contraction and paralysis
Microfilariae degeneration in utero
DNA alkylation and replication halt
Rapid scolex disintegration
Praziquantel damage to schistosome tegument most directly results in which host response?
Cyclooxygenase activation
Microtubule capping at ends
Enhanced GABAergic signaling
Antigen exposure to antibodies
Oxamniquine is activated how before exerting its antischistosomal effects?
Esterification to a biologic ester
Hydrogenation of ring aglycones
Phosphorylation of tubulin dimers
Conjugation with arachidonic acid
The electrophile formed from oxamniquine activation primarily does what to helminths?
Redistributes membrane calcium
Alkylates DNA irreversibly
Opens chloride ion channels
Blocks fumarate reductase
Niclosamide is best described as which type of anthelmintic?
Potent taeniacide for tapeworms
Broad-spectrum filaricidal agent
Antischistosomal ester prodrug
Glutamate chloride channel opener
Which structural feature is characteristic of ivermectin derivatives?
Tricyclic benzimidazole nucleus
Benzyl-linked phosphoinositide ring
Pentacyclic 16-membered aglycones
Linear polyene macrolide chain
Ivermectin’s indirect action reduces microfilarial motility by potentially acting as what?
Ca2+ pump activator in muscle
Na+ channel blocker in tegument
COX inhibitor reducing leukotrienes
GABA agonist increasing Cl− influx
Binding of ivermectin to glutamate-gated chloride channels results in which physiological effect?
Depolarization and contraction
Hyperpolarization and paralysis
ATP synthesis acceleration
DNA alkylation damage
Over time, ivermectin’s second action leads to what reproductive outcome in female worms?
Reduced microfilariae release
Enhanced egg production rate
Increased scolex regeneration
Restored nucleic acid metabolism
Which benzimidazole mechanism explains net loss of microtubule length?
Opening nematode chloride channels
Stimulating NADH oxidation to NAD
Enhancing self-association of subunits
Capping one end causing dissociation
Which drug most directly inhibits phosphoinositide metabolism leading to paralysis?
Oxamniquine
Ivermectin
Praziquantel
Diethylcarbamazine
