L15 Antiprotozoals Flashcards
What protozoa can exist as a trophozoite or dormant cyst, is transmitted by ingestion of cysts in water, food, feces, primarily infects intestinal mucosa causing bloody diarrhea, but can also spread to liver?
Entamoeba histolytica
Features of Giardia
Protozoan active as a trophozoites or a dormant cyst
Infection route same as E. histolytica, i.e. ingestion of cysts from water, food, feces
Causes gastroenteritis, diarrhea major Sx c loss appetite, hematuria, loose stools, stomach cramps, bloating, gas
Sx appear 1-2 weeks after infection and can cycle
Binds small intestine and blocks nutrient absorbtion
Animals major reservoirs
What parasite exists in males and females, causes cervicitis, urethritis, vaginitis, yellow-green frothy itchy foul-smelling vaginal discharge, is sexually transmitted and is often asymptomatic in men?
Trichomonas vaginalis
Why are pregnant women and HIV patients not supposed to clean the litter box?
Domestic animals like cats carry Toxoplasmosis gondii
Mild with flu-like Sx in immune competent
AIDS or pregnant can cause disseminated life-threatening infection
What is one of the leading causes of death in HIV patients that involves a life-threatening pneumonia?
Pneumocystis jiroveci
Not sure if fungus or protozoan
What is the DOC for E. histolytica, G. lamblia, T. vaginalis?
Metronidazole (Flagyl)
What are the uses of Metronidazole (Flagyl)
DOC for E. histolytica, G. lamblia, T. vaginalis
Also used for some anaerobicbacterial infections like that from Bacteroides fragilis and C. difficile
Also used for non-specific bacterial vaginosis or Gardnerella vaginitis
Which anti-protozoal drug can cause a metallic taste, reddish urine, and disulfiram-like reaction, and must be used c caution in liver disease?
Metronidazole (Flagyl)
What are the pharmacokinetics of Metronidazole? Admin route Metabolism Where effective Drug interactions
Oral, but can be IV or topical
Metabolized in liver–can affect drugs like cimetidine, hydantoins, oral anticoagulants, others
Caution in liver disease
Effective in intestines and extra-intestinal
What drug is similar to Metronidazole, has a long half-life, is better tolerated, and has same coverage? What is the coverage?
Tinidazole (Tindimax)
E. histolytica, G. lamblia, T. vaginalis
When must you combine a drug with Metronidazole or Tinidazole for effectiveness?
For luminal amoebiasis
Must use a luminal amoebicide like Iodoquinol
What is Iodoquinol (Yodoxin)?
Luminal amoebicide effective against trophozoites and cysts of E. histolytica
Often combine with Metronidazole
Which drug is assoc. c high iodine content leading to thyroid enlargement and also can cause serious adverse effects to the eye like optic neuritis and optic atrophy leading to blindness?
Iodoquinol (Yodoxin)
Paromomycin (Humatin)
Aminoglycoside antibiotic
Oral and cream
Effective for amoebiasis, giardiasis, T. vaginalis (cream)
Effective against luminal trophozoites b/c not well absorbed
What aminoglycoside antibiotic is useful for amoebiasis, giardiasis, T. vaginalis?
Paromomycin (Humatin)
Diloxanide Furoate (Furamide)
Luminal trophozoites but not tissue trophozoites like E. histolytica
Combined with metronidazole to treat amoebiasis and asymptomatic carriers
Only available from the CDC
What drugs can be used to treat asymptomatic amoebiasis?
Iodoquinol (Yodoxin) Paromomycin (Humatin) Diloxanide Furoate (Furamide)
What drugs are combined with metronidazole to treat amoebiasis?
Iodoquinol (Yodoxin) Paromomycin (Humatin) Diloxanide Furoate (Furamide)
What drugs can be given to treat severe intestinal or systemic E. histolytica when metronidazole is not an option? What are the SE?
Emetine and Dehydroemetine (Mebadin)
Parental only
Serious cardiotoxicity, teratogenicity, and GI effects
Tetracycline use for parasites
Tetracyclines are used to kill the bacteria that E. histolytica and G. lamblia require for life
What is the treatment of choice for toxoplasmosis?
Pyrimethamine + Sulfadiazine + Folinic acid
What is the drug of choice for pneumocystosis? What are the other uses of this drug?
TMP-SMX (Bactrim)
Alternate Tx fro toxoplasmosis
Prophylaxis for P. carinii in AIDS
Preferred Tx for P. carinii in kids
What drugs can be used if TMP-SMX is not an option for pneumocystosis?
Pentamidine (Pentam; Nebupent)
Treats an active infection and nebulizer can be used for prophylaxis
SE: hypotension, arrhythmias, hypoglycemia
Atovaquone (Mepron)
What kind of organism is cryptosporidium?
Protozoan parasite
Can infect the GI or the lungs
No real treatment
What is a helminth?
Parasitic worm
What are the 3 major groups of helminths?
Nematodes, cestodes, trematodes
What are nematodes?
Roundworms
Characteristics of Ascaris lumbricoides (roundworm)
Roundworm common in Asia, Africa, Latin America
Intestinal parasite
Infected by ingesting eggs from soil or water
Type of nematode
What helminth lays eggs in perianal area at night?
Other characteristics?
Enterobius vermicularis (pinworm) Very common in US in crowded and unsanitary places like daycare centers Intestinal parasite Fecal-oral Type of nematode
Characteristics of Necator americanus
(Hookworm) Common in tropical areas and southern US Intestinal parasite Infects through the skin, migrates to lungs, up trachea, down to GI Can cause pneumonitis in the lungs Type of nematode
(Hookworm) Common in tropical areas and southern US Intestinal parasite Infects through the skin, migrates to lungs, up trachea, down to GI Can cause pneumonitis in the lungs
Necator americanus
Type of nematode
Characteristics of Strongyloides stercoralis
Threadworm Warm climates and southern US Intestinal tract Go through the lungs and back to GI for autoinfection leading to high parasite loads Type of nematode
What dog parasite can infect humans but can’t fully develop in humans and migrates throughout many tissues causing eosinophilia and necrosis?
Toxicara canis (Visceral larva migrans)
Affects lung, brain, liver, muscles, etc
Type of nematode
What parasite infects the epidermal/dermal junction and causes inflammation and scarring of the skin? Where does this parasite usually prefer to live?
Ancylostoma braziliense (Visceral larva migrans) Adult worm lives in the intestines of dogs Type of nematode
What worm is commonly acquired through eating raw or poorly cooked pork?
Trichinella spiralis (Trichinosis)
Type of nematode
Intestinal parasite of humans, pigs, and others
Larvae migrate through intestinal wall into other tissues like skeletal muscle, heart, lungs, etc.
Wuchereria bancrofti
Roundworm–Type of nematode Major cause of lymphatic filariasis Central Africa and Nile delta, S and Central America, tropical asia Leads to elephantiasis Spread by mosquitos
Loa Loa
Round worm of the eye found in Africa and India
Causes filarial disease
What worm causes river blindness?
Onchocerca volvulus
What are cestodes?
Segmented Tapeworms
What is the beef tapeworm and where in the world is it found?
Taenia saginata
Europe, Near East, South America
From undercooked beef containing cysticerci
What worm can be picked up from eating raw fish from Japan, Europe, and parts of N and S America?
Diphyllobothrium latum (Fish tapeworm)
What intestinal tapeworm is commonly found in Mexico, Latin America, Africa, SE Asia, Philippines, and can have larvae in the brain and muscle causing cysticercosis? How is this acquired?
Taenia solium
From eating undercooked pork
What are Trematodes or flukes?
Non-segmented flatworms
What are schistosomes?
Blood flukes and hepatic flukes
Penetrate skin from contaminated water and go through lymph and blood to liver to mature. Then migrate to vessels of the intestines or bladder as adults
Unique worms in that have male and female worms
Schistosoma mansoni
Africa, Mid ast, S America
Dysentery and diarrhea
Intestinal schistosomiasis
Egg has characteristic lateral spine
Schistosoma haematobium
Africa and Mid East
Hematuria and dysuria
Urinary schistosomiasis
Schistosoma japonicum
Far East
Only blood fluke in China and Philippines
diarrhea and dysentery
Most infectious of schistosomiasis organisms
Eggs mostly in stool but can be in urine as well
Normally, laxatives are not used with antihelminthics anymore except for one exception?
Taenia solium
Want to flush out adults before segments can burst with eggs
What drugs are used for Nematodes (roundworms)?
Pyrantel Pamoate (Antiminth) Ivermectin (Mectizan)
Pyrantel Pamoate (Antiminth)
Oral drug for roundworms Broad spectrum Alternative to mebendazole Cholinesterase inhibitor for the worms Not well absorbed so few SE OTC
Ivermectin (Mectizan)
Oral Rapid absorption and wide tissue distribution Effective against many roundworms Drug of choice for filaria infection Paralyzes roundworm by intensifying GABA
What drug is useful for cestodes and trematodes?
Praziquantel (Biltricide)
Praziquantel (Biltricide)
DOC for all schistosomes
First drug for neurocysticercosis
Increases worm permeability to Ca leading to contraction and paralysis
Well-absorbed so useful for systemic infections
Drug for Trematodes only
Bithionol (Bitin)
Bithionol (Bitin)
For trematodes
Uncouples oxidative phosphorylation
Oral, well absorbed in GI for systemic infections including liver and lung flukes
Only available from the CDC
DOC for entamoeba histolytica
Metronidazole (Flagyl) + luminal amebicide
DOC for giardia lamblia
Metronidazole (Flagyl)
DOC for Trichomonas vaginalis
Metronidazole (Flagyl)
DOC for Toxoplasma gondii
Pyrimethamine (Daraprim) + Sulfadiazine + folinic acid
DOC for Pneumocystis jiroveci
TMP/SMX + folinic acid
DOC for roundworms (Nematodes) Ascaris lumbricoides (roundworm) Enterobius vermicularis (pinworm) Necator americanus (hookworm)
Pyrantel pamoate (Antiminth)
DOC for tapeworms (cestodes)
Praziquantel (Biltricide)
DOC for flukes (trematodes)
Praziquantel (Biltricide)
What is the only fluke not treated by Praziquantel?
Sheep liver fluke Fasciola hepatica
Use triclabendazole or bithionol instead
