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Infectious Disease > Week 9 > Flashcards

Week 9 Flashcards

1
Q

Parasites

A

either protozoa or helminth that lives on or in a host and gets its food from or at the expense of its host

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2
Q

Protozoa - 4 kinds

A

unicellular eukaryotes

1) Amoebas
2) Sporozoans
3) Flagellates
4) Ciliates

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3
Q

Amoebas (3)

motility?

A

pseudopod mobility

1) Entamoeba histolytica
2) Naegleria fowleri
3) Acanthamoeba

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4
Q

Entamoeba histolytica

Transmission

A

fecal-oral

Cysts ingested and differentiate in ileum to trophozoites → invade colon epithelium → local necrosis, hematogenous spread → intestinal/extraintestinal amebiasis

INVASIVE + HEMATOGENOUS SPREAD

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5
Q

Entamoeba histolytica

Trophozoite stage vs. Infective cyst stage

A

Trophozoite stage: pseudopods allow organism to move along intestinal wall and take up nutrients

Infective cyst stage: cysts ingested and cause infection

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6
Q

Entamoeba histolytica

Presentation (3 possibilities)

A

1) Asymptomatic carrier (most common)
2) Intestinal amebiasis
3) Liver abscess

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7
Q

Entamoeba histolytica

asymptomatic carrier

A

(most common) - cysts in stool → highly contagious, cysts can survive outside host

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8
Q

Entamoeba histolytica

Intestinal amebiasis

A

subacute onset over weeks
Bloody diarrhea**, INVASIVE
Abdominal pain, nausea, vomiting

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9
Q

Entamoeba histolytica

Liver abscess

A

“anchovy paste” liver abscess

Dull RUQ pain, elevated LFTs

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10
Q

Entamoeba histolytica

Diagnosis - 2 characteristic findings

A

antigen testing + parasite in stool or extraintestinal sites, asymptomatic carriers will have cysts in stool

***FLASK SHAPED ULCERS on biopsy - colonic lesions with mucosal ulceration and submucosal invasion

**TROPHOZOITES with INGESTED RBCs

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11
Q

Entamoeba histolytica

Treatment (3)

A

metronidazole (invasive colitis) + paromomycin, iodoquinol

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12
Q

Naegleria fowleri

Transmission

A

enter through nose from water sources, ascends olfactory nerve through cribriform plate → into frontal lobe

Typically infection in summer months (warmer water)

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13
Q

Naegleria fowleri

Presentation

A

causes rapidly fatal meningoencephalitis

Severe headache, fever, vomiting

SX 5-8 days after contact

Nearly 100% lethal

Affects healthy young adults and children with recent exposure to warm freshwater

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14
Q

Naegleria fowleri

Diagnosis

A

organisms in CSF samples

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15
Q

Naegleria fowleri

TX

A

amphotericin B (rarely effective) - always fatal

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16
Q

Acanthamoeba

Transmission

A

nasopharyngeal route (similar to Naegleria fowleri), or breaks in skin

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17
Q

Acanthamoeba

Presentation (2)

A

1) granulomatous amebic encephalitis (especially IMMUNOCOMPROMISED)
- Headache, nausea, vomiting, etc.

2) Keratitis (associated with CONTACT LENSES)

**Can cause death

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18
Q

Sporozoans include what amoebas? (3)

motility?

A

no pseudopod, flagellar, or ciliary motility

1) Cryptosporidium
2) Toxoplasma gondii
3) Plasmodium spp

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19
Q

Cryptosporidium

Transmission

A

fecal-oral transmission
Oocytes ingested → sporozoites released in small intestine and differentiate into trophozoites

Trophozoites attach to intestinal wall → oocysts passed out of GI tract

INTRACELLULAR replication within intestinal wall

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20
Q

Cryptosporidium

Risks for infection

A

drinking water supplies, swimming pools, recreational water facilities

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21
Q

Cryptosporidium

Presentation?

A

Self-limiting WATERY diarrhea

Immunocompromised → protracted, severe watery diarrhea

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22
Q

Cryptosporidium

Diagnosis

A

stool samples with ACID-FAST oocysts

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23
Q

Cryptosporidium

TX (3)

A

**supportive

Nitazoxanide (children)

Antiretroviral therapy (HIV) (CD4 > 100)

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24
Q

Toxoplasma gondii

Transmission (3)

A

Cysts in undercooked meat
Oocysts in cat feces
Transplacentally to fetus

**Obligate INTRACELLULAR parasitic protozoa

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25
Q

Toxoplasma gondii

Risks for infection

A

common infection in US

Change litter box daily (don’t do it if you’re pregnant)

Uncooked meat (high incidence in France)

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26
Q

Toxoplasma gondii

Presentation (4)

A

1) Asymptomatic
2) Mononucleosis-like illness (sore throat, fever, swollen lymph nodes)
3) TOXOPLASMOSIS
4) Congenital toxoplasmosis

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27
Q

Toxoplasma gondii

TOXOPLASMOSIS

A

Immunocompromised → cysts rupture and release tachyzoites = TOXOPLASMOSIS

**TRIAD = Chorioretinitis, encephalitis, pneumonitis

Most common cause of encephalitis in HIV patients

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28
Q

Toxoplasma gondii

Congenital Toxoplasmosis

A

Pregnant woman infected WITHOUT previous exposure → can cross placenta causing congenital toxoplasmosis

**chorioretinitis, HYDROCEPHALUS, intracranial calcifications (MULTIPLE ring-enhancing lesions in cortex and basal ganglia on head CT)

Blueberry muffin rash, hepato- splenomegaly, hyperbilirubinemia, lymphadenopathy

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29
Q

Toxoplasma gondii

Treatment

A

pyrimethamine, Sulfadiazine, Leucovorin

Prophylaxis: TMP/SMX

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30
Q

Plasmodium spp

A

hematologic infection - parasites in blood cells (Infects RBCs)

> 0.5 million deaths/year, ½ children under age of 5 in Africa

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31
Q

Plasmodium spp

Transmission

A

Anopheles mosquito

Mosquito bite release sporozoites into bloodstream → LIVER, infects hepatocytes → sporocytes divide into merozoites and released from hepatocytes

→ infect RBCs → merozoites develop into trophozoites → infected RBCs less flexible → destroyed in spleen (splenomegaly) or RBCs burst and release parasite

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32
Q

Plasmodium spp

Presentation

A

Malaria

Anemia, fever, chills

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33
Q

P. malariae presentation? infects what type of RBCs?

A

cyclical symptoms (every 3 days), only infect mature RBCs

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34
Q

P. vivax and P. ovale presentation? infects what type of RBCs?

A

“relapsing infection” (every 2 days) and infects only reticulocytes (immature RBCs)

Schuffner dots unique to P. vivax/ovale - brick red dots in host erythrocytes

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35
Q

P. falciparum

presentation? infects what type of RBCs?

A

most severe, infects ALL RBCs

Make RBCs stick to capillary and venule walls → occlusion, hemorrhage

  • Brain (cerebral malaria)
  • Kidneys (renal failure)
  • Lung (pulmonary edema)

Sickle cell trait, thalassemia, and glucose-6-phosphate dehydrogenase deficiency confers protection

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36
Q

P. Malaria has what trophozoite and what gametocyte shape?

A

Trophozoite → band or rectangular

Gametocyte shapes → round

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37
Q

P. vivax and P. ovale have what trophozoite and what gametocyte shape?

A

Trophozoite → large, irregular rings

Gametocyte shapes → round

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38
Q

P. falciparum has what trophozoite and what gametocyte shape?

A

Trophozoites → small rings

Gametocytes → banana-like

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39
Q

Flagellates include what amoebas? (5)

Motility?

A

whip-like flagella motility

1) Giardia Lamblia
2) Trichomonas vaginalis
3) Leishmania spp
4) Trypanosoma cruzi
5) Trypanosoma brucei

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40
Q

Giardia Lamblia

Transmission

A

fecal-oral

10-25 cysts required for infection

Cysts ingested → become trophozoites in duodenum that attach to duodenal villi

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41
Q

Giardia Lamblia

Risks for infection

A

travelers, daycares, homosexual men, hikers, campers - chlorination NOT effective, only boiling/iodine

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42
Q

Giardia Lamblia

Presentation

A

Diarrhea - foul smelling, fatty stools

Malabsorption AND hypersecretion

Most common cause of nonbacterial diarrhea in USA

NONINVASIVE destruction of villi

Can cause lactase deficiency

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43
Q

Giardia Lamblia

Diagnosis

A

tear shaped cysts in stool, owl eye nuclei (two nuclei) and four flagella or antigen testing

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44
Q

Giardia Lamblia

TX

A

metronidazole

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45
Q

Trichomonas vaginalis

Transmission

A

*Sexually transmitted

Lacks cyst form, rarely leaves host

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46
Q

Trichomonas vaginalis

Presentation (3)

A

1) Asymptomatic carrier
2) Acute vaginitis
3) Urethritis (men)

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47
Q

Trichomonas vaginalis

Acute vaginitis - symptoms?

A
  • burning, itching, dysuria, frequency)
  • STRAWBERRY CERVIX
  • GREEN, foul-smelling vaginal discharge
  • Vaginal pH > 4.5
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48
Q

Trichomonas vaginalis

Diagnosis

A

vaginal wet mount shows motile pear-shaped flagellated trophozoites (corkscrew motility)

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49
Q

Trichomonas vaginalis

TX

A

Metronidazole

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50
Q

Leishmania spp

Transmission
intra or extracellular?

A

blood sucking bite of female sandfly

Intracellular parasites in macrophages

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51
Q

Leishmania spp

Presentation (3)

A

1) Visceral leishmaniasis = Black Fever
2) Cutaneous leishmaniasis
3) Mucocutaneous leishmaniasis

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52
Q

Visceral leishmaniasis = Black Fever

A

Intermittent/spiking fever
Splenomegaly
Pancytopenia
Skin hyperpigmentation (“black fever”)

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53
Q

Cutaneous leishmaniasis

A

Erythematous papule at sandfly bite which expands and ulcerates

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54
Q

Mucocutaneous leishmaniasis

A

Lesions confined to skin, mucous membranes, and cartilage

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55
Q

Leishmania spp

Diagnosis

A

tissue biopsy with macrophages containing amastigotes (non motile, non flagellated form)

Outside of macrophages, Leishmania spp. Flagellated

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56
Q

Leishmania - Treatment?

A

sodium stibogluconate, liposomal amphotericin B

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57
Q

Trypanosoma cruzi

Transmission

A

painless bite and defecation of Reduviid bug (“kissing bug”)

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58
Q

Trypanosoma cruzi

Presentation: Acute

A

Chagoma = inflammation at bite site

Romana’s sign = swelling/inflammation around eyelids when organisms enter conjunctiva

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59
Q

Trypanosoma cruzi

Presentation: Chronic

A 
Dilated cardiomyopathy with apical atrophy
Cardiac arrhythmias
Megacolon
Megaesophagus
Achalasia
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60
Q

Trypanosoma cruzi

Diagnosis

A

flagellated trypomastigotes on blood smear (acute) or non flagellated amastigotes within cells on biopsy

Chronic infection → parasitemia below detectable levels

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61
Q

Trypanosoma cruzi

TX

A

benznidazole and nifurtimox

Chronic = supportive care

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62
Q

Trypanosoma brucei

Transmission

A

painful bite of infected tsetse fly

Found in Sub-Saharan Africa

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63
Q

Trypanosoma brucei

Presentation: Early vs. Late

A

causes African sleeping sickness

Early: intermittent fever, malaise, and headache

Late: CNS involvement, daytime somnolence, nighttime insomnia, persistent headaches

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64
Q

Trypanosoma brucei

Diagnosis

A

mobile trypanosomes on blood smear

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65
Q

Trypanosoma brucei

TX

A

suramin (early), melarsoprol (late, CNS)

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66
Q

Primary host

A

host in which parasite reaches maturity and sexually reproduces within

67
Q

Secondary host/Intermediate host

A

host that harbors parasite only for a short transition period

68
Q

Reservoir host

A

host in which parasite can live indefinitely with no harmful effects

69
Q

Dead-end/Incidental host

A

intermediate host that does not allow transmission to definitive host → prevent parasite from completing its development

70
Q

Helminths

A

parasitic worms

1) Platyhelminthes (flatworms)
2) Nematodes (roundworms)

71
Q

Platyhelminthes (flatworms)

include what 2 classes of wormies?

A

1) Cestodes (tapeworms)

2) Trematodes (flukes)

72
Q

Cestodes (tapeworms) include what?

A

Platyhelminthes (flatworms)

1) Taenia solium (pork tapeworm)
2) Taenia saginata (beef tapeworm)
3) Echinococcus (dog tapeworm)
4) Diphyllobothrium (fish tapeworm)

73
Q

Trematodes (flukes) include what?

A

Platyhelminthes (flatworms)

1) Schistosoma (blood flukes) = Schistosomiasis
2) Clonorchis sinensis (Asian liver fluke)
3) Paragonimus westermani (lung fluke)

74
Q

Nematodes (roundworms)

include what worms?

6 intestinal roundworms
2 tissue roundworms

A

Intestinal roundworms:

1) Enterobius vermicularis (pinworm)
2) Ascaris lumbricoides: giant roundworm
3) Trichinella spiralis
4) Trichuris trichiura: whipworm
5) Strongyloides stercoralis
6) Necator americanus (hookworm)

Tissue roundworms:

1) Onchocerca volvulus = River blindness
2) Wuchereria bancrofti

75
Q

Taenia solium (pork tapeworm)

Transmission - two main routes?

A

Intestinal infection: ingestion from undercooked pork → mature into adults in small intestine, consume food ingested by host

Tissue infection: ingested as eggs from feces → eggs hatch in SI, penetrate intestinal wall → travel to other tissues (brain, skeletal muscle, eye)

76
Q

Taenia solium (pork tapeworm)

Appearance

A

4 suckers + circle of hooklets

77
Q

Taenia solium (pork tapeworm)

Presentation

A

1) Intestinal infection

2) Tissue infection: cysts grow slowly and can cause seizures, neurological deficits and blindness

78
Q

Taenia solium (pork tapeworm)

Diagnosis

A

proglottids and eggs in stool or calcified cysticerci in muscle or brain on imaging

79
Q

Taenia solium (pork tapeworm)

Treatment

A

praziquantel, albendazole + corticosteroids

80
Q

Taenia saginata (beef tapeworm)

Transmission

A

ingestion via undercooked beef → intestinal infection, attachment to small intestine wall → eggs passed in feces

81
Q

Taenia saginata (beef tapeworm)

Presentation

A

Typically asymptomatic**
Malnutrition
Abdominal discomfort

82
Q

Taenia saginata (beef tapeworm)

Appearance

A

4 suckers + NO hooklets

83
Q

Taenia saginata (beef tapeworm)

Diagnosis

A

identification of proglottids and eggs in stool

84
Q

Taenia saginata (beef tapeworm)

TX

A

praziquantel

85
Q

Echinococcus (dog tapeworm)

Transmission

A

ingestion of eggs found in dog feces

Eggs → hatch into larvae → small intestine → penetrate and travel to other tissues

86
Q

Echinococcus (dog tapeworm)

Presentation

A

tissue infection

HYDATID CYSTS in liver, lung, brain

  • Cysts grow and cause organ displacement/ dysfunction
  • “EGGSHELL” calcification (typically liver)
  • Release of cyst contents can cause severe ANAPHYLAXIS and spread of infection

Common in sheepherders

87
Q

Echinococcus (dog tapeworm)

Treatment

A

albendazole

Inject larvicidal solution into cysts during surgery

88
Q

Diphyllobothrium (fish tapeworm)

Transmission

A

ingestion of undercooked freshwater fish → larvae mature into adults in SI → consume food/B12

89
Q

Diphyllobothrium (fish tapeworm)

Presentation

A

Usually asymptomatic
Malnutrition
Megaloblastic anemia (B12 deficiency)

90
Q

Diphyllobothrium (fish tapeworm)

Diagnosis

A

proglottids and eggs in stool

91
Q

Diphyllobothrium (fish tapeworm)

TX

A

praziquantel

92
Q

Schistosoma (blood flukes) = Schistosomiasis

Life cycle

A

Trematodes (flukes)

humans and snails

Snails excrete cercariae into fresh water that then PENETRATE human SKIN and enter blood → LIVER → mature into adults

Adults migrate against portal flow to venous plexuses - release eggs
EGGS CAUSE PATHOLOGY → cause acute inflammatory response, passed into feces or urine, etc.

Evade immune system via molecular mimicry

93
Q

Schistosoma (blood flukes)

Presentation (6)

A

1) Cercarial dermatitis (swimmer’s itch)
2) Acute schistosomiasis
3) Chronic schistosomiasis (months to years after infection)
4) Intestinal schistosomiasis
5) Hepatosplenic schistosomiasis
6) GU Schistosomiasis

94
Q

Schistosoma (blood flukes)

Cercarial dermatitis (swimmer’s itch)

A

within days of infection due to cercariae penetrating skin - **can be seen in USA

95
Q

Schistosoma (blood flukes)

Acute schistosomiasis

A

1-2 months after infection - serum sickness-like disease

Cough, fever, chills, abdominal pain, dysentery, lymphadenopathy

96
Q

Schistosoma (blood flukes)

Intestinal schistosomiasis

A

chronic/intermittent abdominal pain, poor appetite, diarrhea, intestinal bleeding and iron deficiency

97
Q

Schistosoma (blood flukes)

Hepatosplenic schistosomiasis

A

hepatomegaly, splenomegaly, periportal fibrosis, portal HTN

98
Q

Schistosoma (blood flukes)

GU Schistosomiasis

A

hematuria, eggs excreted in urine, dysuria, urinary frequency
Can lead to squamous cell carcinoma of bladder

99
Q

Schistosoma (blood flukes) - DX

A

eggs or stool in urine, clinical presentation

100
Q

Enterobius vermicularis

A

(pinworm)

Intestinal round worm
-Most common helminth in the US

Symptoms: perianal itching

101
Q

Enterobius vermicularis (pinworm)

Transmission

A

fecal-oral

Ingest eggs → hatch in duodenum/jejunum → mature in ileum and large intestine

Adults mate in colon, at night, females migrate out of rectum to perianal skin and lay eggs

102
Q

Enterobius vermicularis (pinworm)

Diagnosis

A

“Scotch tape” test for eggs

Eggs NOT found in stool

103
Q

Enterobius vermicularis (pinworm)

TX

A

benzimidazoles, pyrantel pamoate

104
Q

Ascaris lumbricoides

A

giant roundworm
intestinal roundworm

One of most common helminthic infections worldwide, highest prevalence in tropical countries

105
Q

Ascaris lumbricoides: giant roundworm

Transmission

A

Fecal-oral transmission

Ingestion of ova → hatch in SI → release larvae that penetrate intestinal wall and migrate hematogenously or via lymphatics to lungs

Larvae mature in alveoli and ascend bronchial tree and are swallowed → back in SI → mature into adult worms

106
Q

Ascaris lumbricoides: giant roundworm

Symptoms (5)

A

1) Asymptomatic (most)
2) Respiratory symptoms
3) Nutritional deficiencies
4) Obstruction of bowel lumen
5) If in biliary tree → biliary colic, cholecystitis, ascending cholangitis, obstructive jaundice

107
Q

Ascaris lumbricoides: giant roundworm

Respiratory symptoms

A

Loeffler’s syndrome (hypersensitive eosinophilic pneumonitis)

Dry cough, burning/substernal discomfort, dyspnea, fever, wheezing

108
Q

Ascaris lumbricoides: giant roundworm

Diagnosis

A

stool microscopy with identification of eggs

109
Q

Ascaris lumbricoides: giant roundworm

TX

A

benzimidazoles, ivermectin

110
Q

Trichinella spiralis

Transmission

A

Caused by ingestion of undercooked meat containing larvae of T. spiralis from animal

Gastric acid/pepsin in stomach causes larvae to be released from cysts → small bowel mucosa

Adults in SI migrate to striated muscles

111
Q

Trichinella spiralis

Domestic vs. Sylvatic cycle

A

Domestic cycle: involves pigs, rodents

Sylvatic cycle: involves many animals (bears, moose, wild boars)

112
Q

Trichinella spiralis

Symptoms (3)

A

1) Trichinosis
2) Intestinal phase
3) Invasive phase

113
Q

Trichinella spiralis

Trichinosis

A

associated with consumption of raw or undercooked meat (especially PIGS)

114
Q

Trichinella spiralis

Intestinal phase

A

diarrhea, abdominal pain, nausea (occurs within 1 week of inoculation)

115
Q

Trichinella spiralis

Invasive phase

A

myalgia, periorbital edema, eosinophilia, splinter hemorrhages, fever (occurs within 4 weeks)

116
Q

Trichinella spiralis

Diagnosis

A

clinical symptoms + serology or larvae on muscle biopsy

117
Q

Trichinella spiralis

TX

A

benzimidazoles

118
Q

Trichuris trichiura

A

whipworm

Intestinal parasite associated with poor hygiene in tropical climates

119
Q

Trichuris trichiura (whipworm)

Transmission

A

fecal-oral

Unembryoated eggs passed in stool → become infective → ingest via food or hands contaminated with soil
→ eggs hatch and release mature larvae → mature into adult worms → establish in COLON

120
Q

Trichuris trichiura (whipworm)

Symptoms

A

Asymptomatic (most)
Stools may contain mucus and blood
Nocturnal bowel movements
Rectal prolapse

121
Q

Trichuris trichiura (whipworm)

Diagnosis

A

stool examination for eggs (FOOTBALL/barrel shape)

122
Q

Trichuris trichiura (whipworm)

TX

A

Benzimidazoles

123
Q

Strongyloides stercoralis

Transmission

A

fecal-cutaneous

Penetrate skin of feet → local itching → enter bloodstream and lungs (pneumonia)

Swallowed → mature into adults in SI → invade mucosa and lay eggs

Larvae hatch from eggs embed within intestinal wall → inflammation and pain (diarrhea)

Can have autoinfection by penetrating intestinal wall to re-enter bloodstream

124
Q

Strongyloides stercoralis

Symptoms

A

pneumonia + gastroenteritis

125
Q

Strongyloides stercoralis

DX

A

LARVAE seen in stool (not eggs) + eosinophilia

126
Q

Strongyloides stercoralis

TX

A

benzimidazoles, ivermectin

127
Q

Necator americanus (hookworm)

Symptoms

A

Pneumonia
Gastroenteritis
Anemia (secretion of anticoagulant + consumption of blood by worm)

128
Q

Necator americanus (hookworm)

Transmission

A

fecal-cutaneous

Infective larvae penetrate skin of FEET → local itching, eventually enter bloodstream → transported to LUNGS → enter alveoli

Cause respiratory tract inflammation (pneumonia) → SWALLOW larvae → mature into adults in SMALL INTESTINE and attach to mucosa via cutting plates of teeth

Adults mate in lumen of intestine → eggs shed in feces

129
Q

Necator americanus (hookworm)

Diagnosis

A

detection of EGGS (not larvae) in stool + eosinophilia

130
Q

Onchocerca volvulus

Transmission

A

Human = only definitive host

Female black fly bite release onchocerca volvulus larvae → mature into adult form in subcutaneous tissue

Adults mate and release microfilariae

131
Q

Onchocerca volvulus

Symptoms (3)

A
  • Fibrosis around adult worms
  • Inflammation due to microfilariae → thick, scaling, hyperpigmented pruritic rash (“lizard skin”)

-River blindness: when microfilariae reach eye
MAJOR cause of blindness

132
Q

Onchocerca volvulus

Diagnosis

A

skin biopsy with microfilariae

133
Q

Onchocerca volvulus

TX

A

ivermectin

134
Q

Wuchereria bancrofti

Symptoms

A

1) Lymphatic filariasis

2) Tropical pulmonary eosinophilia

135
Q

Wuchereria bancrofti

Lymphatic filariasis

A

lymphedema and elephantiasis (scrotum, arms, breast)

ONLY adult worms causes elephantiasis (not microfilariae)

136
Q

Wuchereria bancrofti

Tropical pulmonary eosinophilia

A

caused by microfilariae in lung → immediate hypersensitivity reaction, increased IgE, eosinophilia, coughing, wheezing at night

137
Q

Wuchereria bancrofti

Transmission

A

female mosquito deposits larvae in skin → enter lymph nodes → after 1 year larvae mature into adult worms and trigger inflammation, fever, lymphadenopathy → obstruction of lymphatics

Mosquito transmission

138
Q

Wuchereria bancrofti

Diagnosis

A

blood with microfilariae

139
Q

Wuchereria bancrofti TX

A

diethylcarbamazine

140
Q

Nitroimidazoles - Metronidazole

Therapeutic use

A

GET GAP on the Metro

Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, Anaerobes (bacteroides, C. diff - BELOW the diaphragm), H. Pylori

141
Q

Nitroimidazoles - Metronidazole

Mechanism of action

A

pro-drug targets enzyme unique to parasite

Generates free radicals → cytotoxic intermediates that inhibit DNA synthesis

142
Q

Nitroimidazoles - Metronidazole

Toxicity

A

disulfiram-like reactions, metallic taste, headache, nausea

143
Q

Nitazoxanide

used for what?

A

Cryptosporidiosis in non-AIDS patients

144
Q

Tinidazole

A

longer half life, better tolerated than Metronidazole

145
Q

Paromomycin

Mechanism?

A

aminoglycoside abx

Mechanism of action: binds A site of 30S ribosome, inhibits protein synthesis (bactericidal) - concentrates in gut

146
Q

Paromomycin - uses?

A

entamoeba histolytica, leishmania donovani, giardia

minimal toxicity

147
Q

Pentamidine - used for…

A

used for treatment/prophylaxis of P. jirovecii infection in patients with sulfa allergies
Minimal side effects

148
Q

Pyrimethamine - mechanism and use?

A

antifolate that acts synergistically to target enzymes involved in folate synthesis → impair parasite DNA synthesis

Use: Malaria

149
Q

Benzimidazoles - use?

A

Mebendazole, Albendazole

NEMATODES - Ascaris, Necator (hookworm), Enterobius (pinworm), Trichuriasis (whipworm)

150
Q

Mebendazole

A

poor absorption, concentrates in GI tract, excreted in bile

Used to treat nematode infections isolated to GI tract

151
Q

Albendazole

A

better absorption, distributed into tissues

152
Q

Benzimidazoles

Mechanism?

A

inhibit microtubule assemble by binding interface of alpha-beta tubulin dimer

Selectively bind to parasite tubulin

Widespread resistance exists

153
Q

Pyrantel Pamoate

Therapeutic use

A

NEMATODES - Ascariasis (roundworm), Enterobiasis (pinworm), Hookworm

154
Q

Pyrantel Pamoate

Mechanism of action

A

ACh receptor agonist → spastic paralysis of worm

155
Q

Praziquantel

Use?

A

Cysticercosis (pork tapeworm, Taenia solium) Cystic hydatid disease (echinococcus

156
Q

Praziquantel

Mechanism?

A

Ca2+ ionophore→induce paralysis, detachment, excretion

Induces tegmental damage - activates host immune system

**DO NOT use if neurocysticercosis - can cause permanent damage

157
Q

Quinolones

Mechanism?

A

act against erythrocytic stage of infection, block detoxification of heme into hemozoin → heme accumulates and is toxic to plasmodium

158
Q

Chloroquine

A

used for all except falciparum (widespread resistance)

Toxicity: retinopathy, pruritus, hepatotoxicity, cardiac disorders

MUST exclude G-6-PD deficiency

159
Q

Primaquine

A

used for P. ovale or P. vivax - activity against hypnozoites which can remain dormant in liver for months to years

MUST exclude G-6-PD deficiency

160
Q

Mefloquine

A

treatment or prophylaxis for P. falciparum or P. vivax

Used for prophylaxis during pregnancy

Rarely used due to psychotic disturbances as side effects

161
Q

Quinine - use and mechanism

A

treatment and cure of erythrocytic stages of chloroquine resistant and MDR P. falciparum malaria

Mechanism: inhibit parasite feeding mechanism, generate oxidative stress

162
Q

Quinine - toxicity

A 
Cinchonism - visual dysfunction, tinnitus, nausea, vomiting
Stimulates pancreatic B-cells
Hypotension
MUST exclude G-6-PD deficiency
CONTRAINDICATED in pregnancy
163
Q

Atovaquone with Proguanil

Use?
Mechanism?

A

Use: drug resistant P. falciparum, PCP pneumonia

Mechanism:

  • Atovaquone → block electron transport chain of P. falciparum
  • Proguanil → inhibit parasite dihydrofolate reductase and potentiate mitochondrial toxicity of atovaquone
164
Q

Artemisinin

Mechanism and use?

A

Mechanism: bind iron, break down peroxide bridges → generate free radicals

Use: Fastest parasite clearance times of any antimalarial and act rapidly killing blood stages of ALL Plasmodium species

-Often combined with other drugs to prevent resistance

Infectious Disease (9 decks)

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