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93 Cards in this Set
- Front
- Back
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What is Mutualism
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A relationship in which tow organisms live in the same environment and both experience benefit from the relationship
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What is Commensalism
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'eating from the same table'
using the same (shared) resources without direct benefit from one or the other |
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What is Parasitism?
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two species occupy the same environment and one feeds off another to the detriment of the host.
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What is Parasitdoism?
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Occurs when the parasite is so damaging to the host that the relationship results in the destruction of the host from the inside out.
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What are the most common parasitic infections worldwide?
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Toxoplasmosis
ascariasis |
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What are the three parasitic infections that cause the greatest mortality?
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-Schistosomiasis
-Malaria -Amebiasis |
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What stages are drug-resistant and how do they confer increased damage to the host?
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-Cysts and spore stages
They require: -longer drug durations -higher doses -cyclical regimens -multiple drug combos (all confer increased risk for toxicity) |
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What do Entamoeba histolytica and Entamoeba dispar cause?
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They are GI tract protozoa.
-E. histolytica is infectious -E. dispar is not (thus does not need to be treated) |
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What are the two most common GU infections (from protozoa)?
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-Vesicular schistosomiasis (schistosoma haematobium)
-Trichomoniasis (Trichomonas vaginalis) |
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What are the two most common blood infections caused by Protozoa?
How do these affect the liver? |
-Plasmodium species (malaria)
-Trypanosoma species (African sleeping sickness and Chagas disease) They cause hepatosplenomegaly: due to their blood borne nature |
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What organism causes Chagas disease and what are the symptoms?
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-Trypansoma cruzi
-fever -swelling at site of innoculation -periorbital swelling Chronic: -Cardiac dysrhythmias -heart failure -Dilated esophagus or colon |
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What are the obstacles to treating Chagas disease?
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Trypansoma cruzi is intracellular.
-difficult to get the drug inside the cell to treat the infection. |
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What are the mose widely recognized protozoal CNS or ocular infectors?
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-Plasmodium
-Trypansomoa -Toxoplasma -Antamoeba |
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What are some side effects that occur if you decide to treat CNS or Ocular protazoal infections?
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-increased inflammation and other problems due to dead debris
-impaired outflow of fluid causing increased pressure (in the CNS or the eye) |
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What are some side effects of occular infections?
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-partial or complete vision loss
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What are some side effects of CNS infections?
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-seizures
-mental deterioration -coma -death |
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What is the best way to classify the most prevalent Protozoa species?
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By the means that they infect humans.
-food prep/handling/water -insect bites -sexually |
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Which Protozoan organisms are transmitted sexually?
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-Trichomoniasis
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Which protozoan organisms are transmittied via insect bite?
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-Plasmodium species (malaria)
-Tryposonoma species (chagas and sleeping sickness) -leishmaniasis (sand fly) |
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Which protozoan organisms are transmittied via food/water/handling things improperly?
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-amebiasis
-giardiasis -toxoplasmosis -cryptosporidiosis -cyclosporiasis |
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What are the major ways that Toxoplasmosis can be transmitted?
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-eating undercooked meats
-accidental ingestion of cysts from infected cat feces |
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Who are at greater risk for infectious complications from toxoplasmosis?
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-Neonates (mental retardation, impaired vision or blindness)
-Immunosupressed patients |
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What are the two forms of protozoa and how do they differ?
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1. Trophozoites
-they are actively motile but rarely infectious. 2. Cysts - cause infection -resistant to drug tx |
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What occurs in the exo-erythrocyce cycle of Plasmodium infection?
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-follows an infected mosquito bite.
-plasmodium sporozoites enter circulation and infect the liver cells -Replicate asexually |
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Which forms of Plasmodium persist in the liver for short verses long periods of time?
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Short:
-P. falciparum -P. Malarie Long: -P. ovale P. vivax |
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What occurs in the erythrocyte cycle of Plasmodium infection?
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-Liver schizont ruptures and trophozoites are released
-infect RBCs *antimalarial drugs primarily act at this stage and are capable of killing only Active species of this stage |
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What occurs in the Sporogenic Cycle of Plasmodium infections?
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-a mosquito bites and takes up the infection (gametocytes)
-this is the sexual stage of replication and the formation of sporozoites. |
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What are the routes of transmissionof Helminths to humans?
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-Skin penetration
-consumption -Ectoparasitic transmission (bite) -Fecal-oral |
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What are the two phyla of Helminths?
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-Platyhelminths (flat worms)
includes: *Trematodes (Flukes) *Cestodes (tapeworms) 2. Nematodes (round worms) |
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What is the most common Trematode infection worldwide?
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Schistosoma mansoni
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What is the primary vector for trematode transmission? (specificially Nanophyetus salmincola)
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Fresh water fish
-salmon -trout -white fish |
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What is the major effective treatment for trematode infections?
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-Praziquantel
-albendazole is also used |
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What are the 2 ways humans can get cestode infections (tapeworms)
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-eating tainted vegetation infected with eggs
-Difinitive host: eating the tissue/meat of animals infected with the cysts |
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How can one prevent cestode infections?
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-cook meat thourughly
-wash vegetation with clean water prior to ingestion |
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What is the most common helminthic parasitic infection worldwide?
Name some associations |
Ascaris Lumbricoides
-is a nematode (round worm) -young children at greater risk -impaired growht -impaired intellectual development |
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Which MOA for antiparasite drugs is least toxic to the host?
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-targeting essential enzymes found ONLY in parasites
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antiparasite drugs with which MOA are generally not used?
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-Targeting biochemial functions essential to both parasite and host.
-due to potential toxicity to host |
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Which form, aerobic or anarobic species, are suseptible to metronidazole? Why?
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Anaerobic
-metronidazole is a pro-drug which is transformed to its active metabolite using anaerobic metabolism. |
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What is P-gp?
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it is a drug efflux protein found on luminal cells
-fx to pump out drugs percieved to be toxic -reduces bioavailability |
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Which parasites have P-gp as a means of drug resistance?
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-Entamoeba histolytica
(resistant to ementine) -Plasmodium falciparum (chloroquine) |
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Which drugs block P-gp proteins?
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-antagonize drug efflux proteins
*Na channel blockers *Ca channel blockers (non-dihydropyridines = verapamil and diltiazem) |
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What are folate antagonists used for? What is special about them?
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Used as antimalarial drugs
- must use a combination therapy of two folate antagonists with different MOAs to prevent resistance from enzyme mutations |
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Which class of drugs is generally first line treatment for protozoal infections?
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Nitroimidazoles
- such as metronidazole treats: -Giardiasis -Amebiasis -Trichomoniasis |
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What is the tx for amebiasis? What organism causes it?
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-Entamoeba histolytica
Asymptomatic = luminal Symptomatic = luminal + syst |
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What are the three luminal agents used to treat amebiasis?
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-Diloxanide
-Iodoquinol (MC) -Paromomycin |
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What agents are used to treat systemic amebiasis?
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-Metronidazole
-Tinidazole (more expensive) |
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What are the pros and cons of iodoquinol?
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Pro: has low bioA, so it stays in the lumen and treats amebiasis in the lumen
Con: -increases intestinal zinc abs -decreases absorption of other metals (chelator) |
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Which luminal agentused for amebiasis is contraIndicated in pregnancy?
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Diloxanide Furoate.
-not commercially available in the US. |
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Describe Paromomycin Sulfate.
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-used as a luminal agent to treat asymptomatic amebiasis
-Aminoclycoside antibiotic -Used for tapeworms during pregnancy |
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What are the three categories of systemic anti-protozoal agents?
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-Metronidazole and tinidazole
-Erythromycin and Tetracycline - Dehydroemetine and emetine |
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What is the main use for Metronidazole?
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-used to treat AnAerobic bacteria and protozoa.
-primary use is for Trichmonoas vaginalis |
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What is the route of administration for Metronidazole?
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-Topical for bacterial vaginosis
-Oral for vaginal trichonomiasis MOST EFFECTIVE -ContraIndicated in the first trimester of pregnancy. Category B in 2nd and 3rd Tri. |
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What are the adverse effects of Metronidazole?
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-Disulfiram like reaction with alcohol.
-metallic taste -Altered CNS fx (insomnia, weakness, dizzyness, vertigo) with long course or high dose -thrush, dysuria, rash, dark urine, neutropenia |
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Which drugs are antibacterial against protozoal infections?
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Metronidazole
paromomycin tetracycline doxycycline erythromycin |
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Which drugs are used if a patient cannot take Metronidazole?
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-Erythromycin (moderate inf)
-Tetracycline (severe inf) |
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What is Dehydroemetine? when should it be used?
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-A systemic agent for protozoal infections
-Use only if metronidazole, tetracycline and erythromycin are ineffective or contraI |
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How is Dehydroemetine administered?
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IM or SubQ injections
-Orally is contraindicated, induces emesis. - |
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What are the side effects of Dehydroemetine?
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-Cardiovascular Toxicity
*avoid in pts w/ renal or cardiac diseases -muscle weakness -NVD |
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If Dehydroemetine must be used for extraintestinal amebiasis, what else must be done?
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- must use a luminal agent in combination with Dehydroemetine
** must follow up with a 21 day course of Chloroquine! |
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How is treatment of Giardia different than Amebiasis?
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-Both use Metronidazole-
*Giardia is less dose (1g) compared with amebiasis (2-3g per day) *Giardia uses only metronidazole, not a combo with a luminal agent as is done in ambeiasis |
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What drugs are used for Giardiasis if metronidazole is ineffective?
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-Nitazoxanide
-Paromomycin -Albendazole |
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What is the drug of choice for Trichomonas vaginalis?
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-Metronidazole
-tinidazole |
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In which stage to antimalarial drugs work?
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-All kill the asexual erythrocyte stage
-few work against the liver stage |
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Which forms of Plasmodium remain in the liver for longer periods of time?
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-P. vivax
-P. ovale -must treat with 2 antimalarial drugs 1. Chloroquine- to treat the erythrocyte stage 2. Primaquine- to treat liver/tissue schizonts (14days) |
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What is Chloroquine used for?
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-Malaria tx against P. ovale, P. vivax, P. malariae once daily
-Malaria prevention: against P. falciparum that are chloroquine-susceptible (travel) (once weekly dose to prevent) |
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What are the side effects of Chloroquine?
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-Vivid Dreams
-Pruritis (use antihistamies at the same time as ingesting drug) -High Doses: *cardiomyopathy, AV block, blood dyscrasias, CNS toxicity |
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When is Chloroquine ContraIndicated?
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-Patients with previous retinal or filed vision changes.
- Regular eye exas recommended to patients. |
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When is Quinine Used?
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-for malaria against P. falciparum that is resistant to chloroquine
-Is a blood agent -Used for SEVERE malaria |
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What are the dosing considerations for Quinine?
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-long term tx causes increased risk for toxicity
-Combine with doxycycline or clindamycin and dose for 3 days. -As monotherapy, give for no more than 7 days. -IV administration |
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What should be monitored in patients taking Quinine?
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-Monitor for Cardio toxicity, especially when give IV
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What are the serious adverse effects of Quinine?
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-Thrombocytopenia
-Hemolytic anemia -Cinchonism -HSN reactions (rash, urticaria, angioedema, bronchospasm) -Blood Dyscrasias |
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What are the adverse drug reactions of Quinine?
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-Hypoglycemia (insulin release)
-Severe hypOtension * if rapid IV infusion -Sterile Abscesses and tetanus *after IM injection -Uterine Contractions *dont use during pregnancy!! |
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What is Mefloquine?
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Is an antimalarial agent much like quinine.
-Drug of Choice for prophylaxis -Not used in treatment |
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What are the contraindications of Mefloquine use?
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History of:
-dysrhythmias, conduction def -Neuro disorders, seizures, psychiatric disorders -sensitivity to related drugs such as quinine. |
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What is Atovaquone?
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-Drug used for Prophylaxis of malaria
-travelers in areas that are P. falciparum chloroquine-resistant |
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When is Atovaquone used for mono tx and whed to use in combo?
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Monotherapy:
P jiroveci pneumonia Combo: with folic acid antagonst (Proguanil) for malaria |
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What are the Artemisins drug class?
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-Artemether
-Artesunate -Dihydroartemisinin First line for multiple drug resistant malaria |
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What is special about the Artemisins?
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-Rapidly acting
-works against all four malarial parasites -not used for pro therapy |
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What is adventagous about the Atovaquone and Proguanil combo for malaria prophylaxis?
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Can begin as late as 2 days prior to arrival in an endemic area.
-Proguanil has synergic activity agains liver forms of malaira...not enough to treat them though |
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What is the MOA for the folate antagonist drugs used for malaria? (Proguanil and Pyrimethamine)
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-Selective inhibition of plasmodial dihydrofolate reductase.
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Besides malaria, when is Pyrimethamine used? what is the drug?
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-is an anti-folate drug
-used for tx of toxoplasmosis in combo w/ clindamycin or sulfadiazine |
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What are the drugs of choice for malaria prophylaxis?
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-Chloroquine in areas that are P. falciparum chloroquine-sensitive
Areas that are P. falciparum chloroquine-resistant, use: -Mefloquine -Atovaquone+Proguanil -Doxycycline |
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What is the use of Primaquine?
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-Antimalarial tx for P. vivax and P. ovale ONLY after suspected exposure
-Do G6PD testing before the drug is prescribed |
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When/Where is Chloroquine NOT and effective antimalarial drug
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KENYA
-Do not prescribe chloroquine to travelers going to Kenya as malaria prophylaxis |
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What are the general dosing considerations for malaria prophylaxis for travelers?
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Before travel:
-two weeks before, once weekly dose --two days before, begin the daily dosing After: 4 weeks for once weekly drugs 7 days for daily drugs |
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Which antimalarial drugs are weekly? what is their half-lives?
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-Mefloquine (3 weeks)
Chloroquine (1-2 mo) |
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Which antimalarial drugs are daily dosed?
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Doxycycline
Atovaquone/proguanil |
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Which is the drug of choice for prevention of Trypanosomiasis (African sleeping sickness)?
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-Pentamidine
-used a prohylaxis |
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What is the route of administration for Pentamidine?
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-used to prevent african sleeping sickness
- ROA= parenteral -IV preferred, IM accepted |
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What is Suramin?
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-Drug for African sleeping sickness
-DOC for east african sleeping sickness (T. brucei rhodesiense) -second line for west african sleeping sickness (T. brucei gambiense) |
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What is the tx for Chagas Dz?
What are its SE? |
Nifurtimox
-SE= NVD, abd pain, fever, rash, restlessness, insomnia, neuropathies and seizures |
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What is the tx for Toxoplasmosis?
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-Pyrimethamine + sulfadiazine
-two folic acid inhibitors ** contraindicated in pregnancy |
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What is the DOC for toxoplasmosis in pregnancy?
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Spriamycin
MOA: binds to 50s rib subunit Unless active fetal infection has already taken place...then use pyrimethamine+sulfasalazine |
