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NBME Micro > Microbiology: Parisitology > Flashcards

Microbiology: Parisitology Flashcards

1
Q

What are the key aspects of treating Trichomonas vaginalis infections?

A

Metronidazole should be given to both the patient and the sexual partner for prophylaxis; screen for STIs as well

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2
Q

What pathological findings are seen in schistosomiasis?

A

Hepatosplenomegaly, liver and spleen fibrosis, portal hypertension

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3
Q

Which nematodes are transmitted through bites?

A

Loa loa, Onchocerca volvulus, Wuchereria bancrofti (Lay LOW to avoid getting bitten)

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4
Q

What are the characteristics of a heavy infection with Trichuris trichiura?

A

Loose stools, rectal prolapse (usually in children), and anemia

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5
Q

What are the 4 tissue nematodes?

A

Toxocara, Onchocerca, Loa loa, Wuchereria

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6
Q

Why should pregnant women avoid cat litter boxes?

A

Cat feces may contain Toxoplasma oocysts, which can cross the placenta and cause birth defects

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7
Q

How is visceral larva migrans treated?

A

Bendazoles (diagnosis: Toxocara canis infection)

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8
Q

What are 2 different presentations of leishmaniasis?

A

Cutaneous: skin ulcers; visceral (kala-azar): spiking fevers, hepatosplenomegaly, pancytopenia

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9
Q

How is Chagas disease transmitted?

A

Triatomine insect (“kissing”), with a painless bite, much like a kiss; the insect defecates around the mouth or eyes; there is fecal transmission into the bite or mucosa

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10
Q

What is the treatment of choice for Wuchereria bancrofti infection?

A

Diethylcarbamazine

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11
Q

What complications of chronic Trypanosoma cruzi infections characterize Chagas disease?

A

Dilated cardiomyopathy with apical atrophy; megaesophagus; megacolon

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12
Q

Elephantiasis is a feature of which helminthic infection?

A

Wuchereria bancrofti infection

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13
Q

What infections can the blood-sucking insects known as lice transmit to humans?

A

Rickettsia prowazekii (typhus), Borrelia recurrentis (relapsing fever), and Bartonella quintana (trench fever)

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14
Q

Name the helminth that causes portal hypertension.

A

Schistosoma mansoni or Schistosoma japonicum

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15
Q

In a patient with river blindness caused by Onchocerca volvulus, anaphylaxis may develop as a result of exposure to what?

A

Microfilaria

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16
Q

How do you treat hookworm infections?

A

Bendazoles or pyrantel pamoate

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17
Q

What is the common name for Ancylostoma duodenale and Necator americanus?

A

Hookworms

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18
Q

A woman from a rural area has new-onset skin swelling and conjunctival worms. You suspect a nematode infection. How is the organism responsible acquired?

A

By way of deer, horse, and mango flies (diagnosis: Loa loa infection)

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19
Q

What lab finding might be expected with a hookworm infection?

A

Microcytic anemia

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20
Q

A patient had cercariae penetrate his skin while swimming in a freshwater lake. Years later, he has painless hematuria. Why is this concerning?

A

He could have squamous cell carcinoma of the bladder from a chronic Schistosoma haematobium infection

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21
Q

How does a patient acquire an infection with Trypanosoma cruzi?

A

From the painless bite by a triatomine insect (“kissing” bug), which deposits feces containing the protozoa

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22
Q

What treatment is used in life-threatening forms of malaria?

A

IV quinidine or artesunate

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23
Q

What is the treatment of choice for African sleeping sickness with CNS involvement?

A

Melarsoprol (versus suramin for blood-borne disease); “I sure am mellow when I’m sleeping”; remember melatonin helps with sleep

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24
Q

What test is used to diagnose malaria, and what findings are expected?

A

Blood smear, look for trophozoite ring forms and RBC schizonts with merozoites

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25
Q

How do you treat an infection with Strongyloides stercoralis?

A

Ivermectin or bendazoles

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26
Q

Name the helminth that causes biliary tract disease and is associated with cholangiocarcinoma.

A

Clonorchis sinensis

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27
Q

A woman bitten by a deerfly exhibits skin swelling and worms in the conjunctiva. What is the treatment for this condition?

A

Diethylcarbamazine; (diagnosis: Loa loa infection)

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28
Q

How are infections with Clonorchis sinensis treated?

A

Praziquantel

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29
Q

What is the mechanism that causes the itching that occurs in scabies?

A

Mites burrow into the stratum corneum, which causes pruritus

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30
Q

What is the mode of transmission of Diphyllobothrium latum?

A

Ingestion of larvae in uncooked freshwater fish

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31
Q

How is Cryptosporidium diarrhea treated in immunocompetent patients?

A

Nitazoxanide; otherwise, prevent by water filtration

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32
Q

Taenia solium, Diphyllobothrium latum, and Echinococcus granulosus are examples of what type of organism?

A

Cestodes (tapeworms)

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33
Q

How is Strongyloides stercoralis transmitted?

A

Larvae from soil penetrate the skin.

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34
Q

How is Toxocara canis transmitted?

A

Via the fecal-oral route

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35
Q

What are the characteristics of a Clonorchis sinensis infection?

A

Biliary tract inflammation and pigmented gallstones

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36
Q

Name 4 other nematodes that can be acquired via the same route as Ascaris.

A

Enterobius, Toxocara, Trichinella, and Trichuris are acquired by ingestion, similar to Ascaris

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37
Q

How can you distinguish Schistosoma mansoni from Schistosoma hematobium?

A

Schistosoma mansoni has an egg with a lateral spine; Schistosoma haematobium has an egg with a terminal spine

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38
Q

What is the classic triad of congenital toxoplasmosis?

A

Chorioretinitis, hydrocephalus, and intracranial calcifications

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39
Q

Which 2 species of Plasmodium form dormant hypnozoites in the liver, leading to relapsing malaria?

A

P vivax and P ovale

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40
Q

What is the mode of transmission of intestinal Taenia solium?

A

Consumption of undercooked pork containing encysted larvae

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41
Q

What is the treatment for the tapeworm infection associated with vitamin B12 deficiency and anemia?

A

Praziquantel; (diagnosis: Diphyllobothrium latum infection)

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42
Q

How are acute infections of Trypanosoma cruzi treated?

A

Benznidazole or nifurtimox (cruzing in my Benz, with a fur coat on) to treat T cruzi

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43
Q

What is the mode of transmission of Ancylostomaspp and Necator americanus infestations?

A

Larvae penetrate the skin

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44
Q

For school-aged children who are diagnosed with head lice, how is their school attendance generally affected?

A

Minimally, if at all; most children with head lice can continue to attend school while receiving treatment at home

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45
Q

How can scabies be treated?

A

Permethrin cream, laundering of all bedding and clothing, and treating close contacts

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46
Q

What are the possible intestinal complications associated with Ascaris lumbricoides infections?

A

Ileocecal valve obstruction, intestinal perforation, biliary obstruction

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47
Q

Name the helminth(s) that classically cause(s) microcytic anemia.

A

Ancylostoma and Necator

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48
Q

A boy contracted a rapidly fatal meningoencephalitis after swimming in a freshwater lake. What is the most appropriate diagnostic test for his condition?

A

Test for amoebas in the cerebrospinal fluid (diagnosis: Naegleria fowleri)

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49
Q

How does Trichinella spiralis cause muscle inflammation?

A

Larvae enter the bloodstream and are encysted in striated muscle cells, leading to inflammation of the muscle

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50
Q

How are diarrhea-causing protozoans transmitted?

A

Via oocysts/cysts in contaminated water

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51
Q

How does an infection with Diphyllobothrium latum cause megaloblastic anemia?

A

The tapeworm competes for vitamin B12 in the intestines

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52
Q

Name 2 other nematodes that can be acquired via the same route as Strongyloides.

A

Ancylostoma and Necator are acquired through the skin similar to Strongyloides

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53
Q

What is the mode of transmission of a Strongyloides stercoralis infestation?

A

Larvae found in the soil penetrate the skin and infect the intestines

54
Q

What group of people are at risk for severe infections of babesiosis?

A

Patients with asplenia

55
Q

What are the presenting signs and symptoms of Pediculus humanus/Phthirus pubis infections?

A

Severe pruritus with excoriations; may arise on the scalp and neck (head lice), axillae and waistband (body lice), or perianal and pubic regions (pubic lice)

56
Q

With which anti-malarials is it important to screen for G6PD deficiency prior to use?

A

Quinidine, artesunate, primaquine

57
Q

How is transmission of Taenia solium different in terms of its presentation as a tapeworm versus cysticercosis/neurocysticercosis?

A

Tapeworms are acquired through ingestion of larvae; cysticercosis/neurocysticercosis develop through ingestion of eggs

58
Q

How is African sleeping sickness transmitted?

A

Trypomastigotes are transmitted through the bite of a tsetse fly

59
Q

How does scabies present?

A

Pruritis and serpiginous burrows between fingers and toes

60
Q

Where might Plasmodium vivax and P ovale remain dormant in the body, and in what form do they remain dormant?

A

The liver as hypnozoites

61
Q

How is Naegleria fowleri transmitted?

A

Acquired from warm freshwater lakes; enters the CNS through the cribriform plate

62
Q

Name the parasite that is associated with the development of hematuria and squamous cell bladder cancer.

A

Schistosoma haematobium

63
Q

What form of the nematode is excreted in the stool of an individual infected with Strongyloides stercoralis?

A

Rhabditiform larvae

64
Q

How is giardiasis treated?

A

Metronidazole

65
Q

How is Schistosoma transmitted to humans?

A

Through penetration of the skin by cercariae (eg, while swimming or bathing)

66
Q

In patients with Plasmodium falciparum infections, RBCs tend to occlude capillaries in which 3 organs?

A

Kidneys, lungs, and brain (cerebral malaria)

67
Q

How does Cryptosporidium present in immunocompetent hosts?

A

Mild, watery diarrhea

68
Q

A man bitten by a female black fly experiences skin hyperpigmentation and blindness. What is the diagnosis?

A

Onchocerca volvulus infection (black flies, black skin nodules, “black sight”)

69
Q

Before using chloroquine to treat malaria, what should be verified about the patient’s particular strain of malaria?

A

That the strain is sensitive to chloroquine; some have developed resistance to this drug, and other agents should be used instead

70
Q

Name 2 nematodes that can be acquired via a similar route as Loa loa.

A

Onchocerca volvulus and Wuchereria bancrofti (acquired via insect bites)

71
Q

What is a possible fatal complication of Onchocerca infections?

A

Allergic reaction to the microfilaria

72
Q

What is the mode of transmission of an Ascaris lumbricoides infestation?

A

Fecal-oral route (“knobby-coated” eggs are visible in feces under a microscope)

73
Q

What are the 6 intestinal nematodes?

A

Enterobius, Ascaris, Strongyloides, Ancylostoma/Necator, Trichinella, Trichuris

74
Q

In what populations is scabies common?

A

Children, prison inmates, and nursing home residents (crowded conditions)

75
Q

What methods are used to diagnose an Entamoeba histolytica infection in a blood sample?

A

Serology and serum antigen testing

76
Q

What disease is associated with a Clonorchis sinensis infection?

A

Cholangiocarcinoma

77
Q

How is an Enterobius infection diagnosed?

A

Tape test to look for the presence of eggs stuck to the tape

78
Q

How is Entamoeba histolytica transmitted?

A

Via cysts in the water

79
Q

How does treatment of amebiasis differ between symptomatic and asymptomatic patients?

A

Symptomatic: use metronidazole; asymptomatic: use paromomycin or iodoquinol

80
Q

What is the treatment of choice of congenital toxoplasmosis?

A

Sulfadiazine + pyrimethamine

81
Q

What protozoan infection is characterized by bloody diarrhea, RUQ abdominal pain, and liver abscesses?

A

Entamoeba histolytica infection

82
Q

How is cysticercosis transmitted?

A

By ingestion of food contaminated with human feces containing Taenia solium eggs

83
Q

Name the parasite that forms hydatid liver cysts

A

Echinococcus granulosus

84
Q

What is the most common clinical presentation of Trichuris trichiura infection?

A

Asymptomatic

85
Q

How does toxoplasmosis present in immunocompetent adults?

A

As a mononucleosis-like syndrome but without heterophile antibodies

86
Q

Toxoplasma causes severe disease in what 2 patient populations?

A

Patients with AIDS (reactivation) and neonates (congenital toxoplasmosis)

87
Q

A man is bitten by a sandfly and develops spiking fevers, hepatosplenomegaly, and pancytopenia. What is the most appropriate treatment for this condition?

A

Amphotericin B with sodium stibogluconate (diagnosis: visceral leishmaniasis, or kala-azar)

88
Q

How does African sleeping sickness present?

A

Recurrent fevers, somnolence, coma, lymphadenopathy

89
Q

What acid-fast organism causes watery diarrhea in healthy patients?

A

Cryptosporidium

90
Q

What is the intermediate host of Schistosoma flukes?

A

Snails

91
Q

Enterobius vermicularis causes infection of what organ?

A

The intestines (although it typically manifests as anal pruritus)

92
Q

How do you treat Onchocerca volvulus infections?

A

Ivermectin (for river blindness)

93
Q

What is the treatment for Trichinella spiralis infection?

A

Bendazoles

94
Q

Name the parasite that causes brain cysts and seizures.

A

Taenia solium (neurocysticercosis)

95
Q

What are 2 other classic findings associated with the infection causing river blindness?

A

Skin changes and loss of elastic fibers; (diagnosis: Onchocerca volvulus infection)

96
Q

What is the common name for Enterobius vermicularis?

A

Pinworm

97
Q

A patient has unilateral, nontender periorbital swelling after recent travel to Bolivia. How do you confirm the diagnosis?

A

Observe trypomastigotes on blood smear (this patient has the Romaña sign of acute Chagas disease)

98
Q

What is the mechanism of anemia in hookworm infestations?

A

The worms suck blood through the intestinal walls, leading to a microcytic anemia

99
Q

Describe the phenomenon of autoinfection with Strongyloides stercoralis infection

A

Some larvae penetrate the colonic wall and enter the blood circulation without leaving the body

100
Q

How is an infection with Schistosoma spp. treated?

A

Praziquantel

101
Q

Which fluke is transmitted in undercooked fish?

A

Clonorchis sinensis

102
Q

Name the helminth that causes vitamin B12 deficiency.

A

Diphyllobothrium latum

103
Q

How is a diagnosis of visceral leishmaniasis made?

A

Blood smear showing macrophages containing amastigotes

104
Q

How is a lice infection treated?

A

Pyrethroids, ivermectin lotion, malathion, and/or nit combing

105
Q

How is an Entamoeba histolytica infection diagnosed from a stool sample?

A

Stool antigen testing and/or visualization of trophozoites (with engulfed RBCs in the cytoplasm) or cysts (up to 4 nuclei each)

106
Q

What are the diagnostic findings of Trichomonas vaginalis infection?

A

Motile trophozoites on wet mount and/or “strawberry cervix” on exam

107
Q

What is the common name for Ascaris lumbricoides?

A

Giant roundworm

108
Q

Which nematodes are transmitted cutaneously?

A

Strongyloides, Ancylostoma, Necator (They get into your feet from the SANd)

109
Q

Name the helminth that causes perianal pruritus.

A

Enterobius

110
Q

Which nematodes are transmitted by ingestion of contaminated food?

A

Enterobius, Ascaris, Toxocara, Trichinella, Trichuris (you’ll get sick if you EATTT these)

111
Q

Name the parasite that causes myalgias and periorbital edema.

A

Trichinella spiralis (trichinosis)

112
Q

What is the Romaña sign?

A

Unilateral periorbital swelling indicative of acute Trypanosoma cruzi infections

113
Q

What disease can develop secondary to chronic infection with Schistosoma?

A

Squamous cell bladder cancer (with Schistosoma haematobium)

114
Q

What organism causes scabies?

A

Sarcoptes scabiei

115
Q

How can you diagnose babesiosis?

A

With a blood smear (look for “Maltese cross” or ring forms) or polymerase chain reaction test

116
Q

What is the treatment for pinworm infection?

A

Pyrantel pamoate or bendazoles (because worms are bendy)

117
Q

How is Trichomonas vaginalis transmitted?

A

Sexually (T vaginalis can only exist inside the human body to be able to form cysts)

118
Q

How do you treat neurocysticerosis?

A

Albendazole

119
Q

What protozoan infection is characterized by a foul-smelling, itching, burning vaginitis with green discharge?

A

Trichomoniasis (Trichomonas vaginalis)

120
Q

Where do the insects prefer to live in a patient with lice?

A

Scalp and neck (head lice); waistline and axillae (body lice)

121
Q

What are the findings on colon biopsy of a patient with an Entamoeba histolytica infection?

A

Flask-shaped ulcers

122
Q

In what region of the world is Babesia infection most common?

A

Northeastern United States

123
Q

How do you treat the dormant form of malaria?

A

Primaquine

124
Q

In a patient with confirmed Toxocara canis infection, which organs tend to be infected most often?

A

Heart (leading to myocarditis), liver, eyes (visual impairment), and CNS (leading to seizures and/or coma)

125
Q

What is noted in the blood smear of patients with African sleeping sickness?

A

Trypomastigotes (Trypanosoma brucei)

126
Q

How does the fever pattern differ in malaria caused by Plasmodium vivax, P ovale, P falciparum, and P malariae?

A

P malariae: every 72 hours (quartan); P vivax/P ovale: every 48 hours (tertian); P falciparum: irregular

127
Q

How is cutaneous larva migrans acquired?

A

Penetration of exposed skin (often feet) by hookworms

128
Q

What is the mode of transmission of the Plasmodium species that cause malaria?

A

Bite of the female Anopheles mosquitoes, which usually occurs at night

129
Q

What disease is transmitted in a similar manner to babesiosis?

A

Lyme disease; both are transmitted by Ixodes ticks

130
Q

What is the treatment of choice for a blood-borne Trypanosoma brucei infection?

A

Suramin (versus melarsoprol for CNS disease); “I sure am mellow when I’m sleeping”; remember melatonin helps with sleep

NBME Micro (36 decks)

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