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30 Cards in this Set

  • Front
  • Back
Which of the following is/are characteristic of adult T cell lymphoma?
A. peripheral CD4+/CD25+ flower cells
B. hypercalcemia
C. high serum IL-2 receptor
D. A & B
E. A, B, C
E. A, B, C.
Patients can also have skin rash and extreme thirst. Interestingly, the neoplastic cells express CD25, which is the IL-2 receptor, as well as high levels of free IL-2 receptor
in the serum. The usual incubation time for ATCL is 20-30 years.
QCCP2, HTLV-I
Which test is the primary screening test for HIV?
A. serum enzyme-linked immunosorbent assay
B. Western blot
C. quantitative HIV RNA
D. CD4 count
E. p24 antigen detection
A. serum enzyme-linked immunosorbent assay.
The extremely high sensitivity of the serum ELISA test makes it the screening test of choice. There can be a window period between the infection and seroconversion,
usually 6-8 weeks, leading to possible false negative results. The confirmation of a positive result is usually done with Western blot, which is read positive if at least two
bands (p24, gp41, and gp120/160) are positive.
QCCP2, HTLV-3 [HIV-1 and -2]
Which of the following HIV tests is the assay for determining response to anti-retrovirals?
A. serum ELISA
B. Western blot
C. quantitative HIV RNA
D. CD4 count
E. p24 antigen detection
C. quantitative HIV RNA.
Quantitative HIV RNA is an assessment of viral load. Quantitation of RNA levels is an excellent prognostic tool to predict progression, especially long-term.
QCCP2, HIV
Which test is the best choice for the detection of HIV infection shortly after an infection?
A. serum ELISA
B. Western blot
C. quantitative HIV RNA
D. CD4 count
E. p24 antigen detection
C. quantitative HIV RNA.
The sensitivity of quantitative HIV RNA approaches 100%; however, the specificity is less. In a confirmatory test, you would like optimal specificity, unlike screening tests
where you would like the sensitivity to be high.
QCCP2, HIV
Which of the following organisms is detectable with modified acid-fast stains?
A. Cryptosporidium
B. Cyclospora
C. Isospora
D. A & B
E. A, B, C
E. A, B, C.
All of the above parasites are potentially positive for acid-fast staining, improving the chances of detection notably. The related organism microsporidium is not acid-fast
and may require more invasive means for diagnosis.
QCCP2, Parasites, specimens
Which of the following organisms can be detected with the “adhesive tape” test?
A. Giardia lamblia
B. Enterobius vermicularis
C. Strongyloides stercoralis
D. Onchocerca volvulus
E. Brugia malayi
B. E.
The adult female worm migrates to the anal verge at night to lay eggs. This accounts for the nocturnal anal pruritus that is a symptom of enterobial infection. Some of the
eggs that are laid by the female worm can be collected with adhesive tape applied to the anus at night.
QCCP2, Cellophane tape
Which parasite can be specifically detected serologically after a recent infection?
A. Paragonimus westermanii
B. Strongyloides stercoralis
C. Brugia malayi
D. Taenia solium
E. Toxoplasma gondii
E. T.
For the most part, specific serology beyond elevated IgE following parasitic infection is not available. The exception is Toxoplasma, which is a potentially catastrophic cause
of transplacental (the “T” in TORCH) infection if it is primarily acquired by a woman during pregnancy.
QCCP2, Laboratory methods
What is the principal means of distinguishing Entamoeba histolytica from Entamoeba hartmanii by light microscopy?
A. size of trophozoite
B. appearance of karyosome
C. appearance of nuclear chromatin
D. number of nuclei in cyst form
E. appearance of chromatoidal bars in cyst
A. size of trophozoite.
The only selection that is different between the related organisms is the size of the trophozoite. Entamoeba histolytica is roughly twice the size at 20-30 microns diameter
than E. hartmanii, which is only 5-10 microns in diameter. Also, though non-specific, E. histolytica tends to be the most common trophozoite to contain ingested RBCs.
QCCP2, T3.16, Amoeba that resemble E. histolytica
What is the most common site of extraintestinal amebic abscess?
A. lungs
B. liver
C. brain
D. spleen
E. bladder
B. liver.
The gray-white purulence or anchovy paste amebic abscess is most often in the liver, though the brain and spleen are not uncommon sites for abscess formation.
QCCP2, E. histolytica
What's the fastest way to identify Iodamoeba butschlii?
A. the presence of ingested red blood cells in the trophozoite form
B. culture on a lawn of inactivated E coli
C. its small (5-10 micron) size
D. the prominent vacuole in the cyst form
E. the presence of up to 8 nuclei in the cyst form
D. the prominent vacuole in the cyst form.
Iodamoeba beutschlii, at risk of sounding indelicate, has a “butt” or a large clear vacuole in the cyst form. Naegleria is grown on inactivated E. coli, Entamoeba hartmanii is
small, and Entamoeba coli has up to 8 nuclei in the cyst form.
QCCP2, Protozoa
Which organism causes granulomatous amebic encephalitis?
A. Naegleria
B. Acanthamoeba
C. Entamoeba histolytica
D. Entamoeba hartmanii
E. Iodamoeba
B. A .
Acanthamoeba is known for causing GAE as well as a severe keratitis in contact lens users who make their own contact lens cleaning solution or use tap water.
QCCP2, Acanthamoeba
What is the non-pathogenic flagellate that must be distinguished from Giardia lamblia?
A. Chilomastix mesneli
B. Dientamoeba fragilis
C. Trichomonas vaginalis
D. Trypanosoma cruzi
E. Leishmania donovani
A. C .
Unlike the “falling leaf” motility of Giardia, C. mesneli has a rotary motion and a cyst form with only one nucleus (Giardia cysts have 4. The other choices are all pathogenic
organisms.
, QCCP2, Chilomastix mesneli
Which amoeba is most often seen as a coinfection with Enterobius vermicularis?
A. Naegleria
B. Acanthamoeba
C. Entamoeba histolytica
D. Dientamoeba
E. Iodamoeba
D. D.
With two nuclei and a fractured central karyosome, Dientamoeba is often seen coinfecting with Enterobius. Like Enterobius, D. fragilis causes diarrhea and pruritus ani.
QCCP2, Dientamoeba
What feature of Leishmania spp helps to distinguish them from Histoplasmaor Toxoplasma?
A. small intracellular amastigotes
B. bar-like kinetoplast
C. central axostyle
D. external flagellum
E. extracellular forms
B. bar-like kinetoplast.
Especially in the intracellular amastigote forms of the three organisms, the one feature of Leishmania that helps to distinguish it from the others is the bar-like kinetoplast
adjacent to the nucleus. Specific culture media, such as Novy-MacNeal-Nicolle medium, can be used to isolate Leishmania where the flagellated promastigote form can be
identified.
QCCP2, Leishmania
Which species of Leishmania is most commonly associated with mucocutaneous leishmaniasis?
A. L. major
B. L. tropica
C. L. brazilensis
D. L. donovani
E. L. mexicana
C. L.
A number of species of Leishmania are pathogenic, often causing distinct disease entities. L. tropica and L. major are associated with solitary cutaneous lesions, while L.
donovani is associated with systemic disease (Kala-azar). L. mexicana is the causative agent of the self-limiting Chiclero ulcer of the ear lobe, while L. brazilensis causes
mucosal and cutaneous lesions.
QCCP2, Leishmania
What characteristic feature of T. cruzi trypomastigotes helps distinguish it from T. brucei in peripheral blood smears?
A. undulating flagellum
B. central kinetoplast
C. culture on Novy-MacNeal-Nicolle medium
D. presence in lymph nodes
E. “C” shape
E. “C” shape.
The other features mentioned are shared to some extent by both species of trypanosomes. The characteristic “C” shape (remember - Cruzi, Chagas, “C”-shape) helps to
identify Trypanosoma cruzi compared to the more randomly curved trypomastigotes of T. brucei.
QCCP2, Trypanosoma spp
The only medically significant ciliate organism is:
A. Entamoeba histolytica
B. Balantidium coli
C. Cryptosporidium parvum
D. Chilomastix mesneli
E. Cyclospora cayetenensis
B. B .
A 50-70 micron organism with circumferential ciliation and a lenticulate nucleus, B. coli is the most medically significant ciliate (and the only one you probably have to be
aware of).
QCCP2, Ciliates
Where can Cryptosporidium be found in an infected host?
A. adherent to small intestinal brush border
B. within an intracellular apical vacuole
C. interdigitated between enterocytes
D. in foveolar gland crypts of the stomach
E. intracytoplasmically within enterocytes
B. within an intracellular apical vacuole.
On light microscopy, the Cryptosporidia appear to be small (8-15 micron), round organisms attached to the extracellular brush border. However, ultrastructural studies
have determined that the organism is located in a unique position within an intracellular, yet extracytoplasmic apical vacuole. Very strange. Isospora interdigitates,
Microsporidium is intracellular, and Strongyloides is found within the crypt epithelium.
QCCP2, Cryptosporidiosis
Which of the following organisms is in the differential diagnosis of the bradyzoite of Toxoplasma gondii?
A. Leishmania
B. Histoplasma
C. Trypanosoma
D. A & B
E. A, B, C
E. A, B, C.
The bradyzoite forms of Toxoplasma are small intracellular organisms seen within the cytoplasm of histiocytes, while the tachyzoites are curved extracellular organisms. A
histiocyte filled with Toxoplasma bradyzoites resembles Leishmania, Histoplasma, Trypanosoma, and Coccidioides, and must be distinguished.
QCCP2, Toxoplasma
What test best helps to differentiate pregnant women at a lower risk for intrauterine Toxoplasma infection?
A. anti-Toxoplasma IgM
B. PCR of CSF
C. Giemsa staining
D. anti-Toxoplasma IgG
E. amniotic fluid serology
D. anti-Toxoplasma IgG.
Less than 1/5 of pregnant women have been previously infected by Toxoplasma, a fact which is confirmed with positive IgG anti-toxo serology. These previously infected
women are at an extremely low risk of transplacental transmission of Toxoplasma compared to those who have not been previously exposed.
QCCP2, Toxoplasma
Which species of Plasmodium is responsible for quartan (72-hour) fevers?
A. P. falciparum
B. P. vivax
C. P. malariae
D. A & B
E. A, B, C
C. P. .
P. malariae differs from the other species of Plasmodium by having 72 hour or quartan fever spikes rather than the 48 hour tertian fevers. P. malariae can also have
nephrotic syndrome and prefers to infect older red blood cells.
QCCP2, Plasmodium spp
Where do Plasmodium sporozoites proliferate?
A. liver
B. red blood cells
C. bone marrow
D. within nucleated erythrocyte precursors
E. freely within the blood
A. liver.
After sporozoites are introduced into the blood stream by an anopheline mosquito, they travel to the liver to proliferate. The infected hepatocytes rupture and release the
merozoites, which infect RBCs. Hypnozoites are the forms that maintain a latent infection in the liver.
QCCP2, Plasmodium
Individuals who lack the Duffy antigen on the surfaces of their red blood cells are protected against which species of Plasmodium?
A. P. vivax
B. P. falciparum
C. P. malariae
D. A & B
E. A, B, C
A. P. The Duffy antigen is the receptor for P. vivax; therefore, loss of the receptor affords some protection against infection. G6PD deficiency provides some protection against all
species of Plasmodium, while sickle cell trait protects individuals predominantly against P. falciparum.
QCCP2, Plasmodium
Which form of Plasmodium is described as intraerythrocytic collections of numerous organisms?
A. merozoites
B. schizonts
C. hypnozoites
D. trophozoites
E. bradyzoites
B. schizonts.
The schizont is the form that contains numerous merozoites within the erythrocyte. With the rupture of the schizont, merozoites are released to infect other RBCs. The
hemolysis corresponds to the clinical fever spikes.
QCCP2, Plasmodium
All of the following features of Plasmodium falciparum are helpful in distinguishing it from P. vivax or P. ovale, except:
A. multiple ring forms within an erythrocyte
B. applique trophozoite forms
C. enlarged infected red blood cells
D. banana-shaped gametocytes
E. double chromatin dots in ring forms
C. enlarged infected RBCs.
Unlike P. ovale and P. vivax, P. falciparum-infected RBCs tend not to be enlarged. Schuffner dots are also a characteristic of P. vivax and P. ovale.
QCCP2, Plasmodium
Extraerythrocytic ring forms are characteristic of which organisms?
A. Babesia microti
B. Plasmodium falciparum
C. Plasmodium vivax
D. Plasmodium ovale
E. Plasmodium malariae
A. B .
Only Babesia has extraerythrocytic forms. In addition, there aren't gametocytes or schizonts present in the peripheral blood with babesiosis.
QCCP2, Babesia microti
Which of the following organisms is/are commonly seen coinfecting patients with babesiosis?
A. Borrelia burgdorfei
B. Ehrlichia chaffeensis
C. microfilariae
D. A & B
E. A, B, C
D. A & B.
Lyme disease, babesiosis, ehrlichiosis, and even some flaviviruses are transmitted by the deer tick, Ixodes scapularis, on the east coast and the western black-legged tick,
Ixodes pacificus, on the west coast.
QCCP2, Babesia microti
Which of the following is the most common AIDS-defining illness?
A. cryptosporidiosis
B. Pneumocystis pneumonia
C. esophageal candidiasis
D. Kaposi sarcoma
E. toxoplasmosis
B. P pneumonia.
PCP, or Pneumocystis carinii pneumonia, is the most common AIDS-defining illness. Now renamed Pneumocystis jiroveckii, the organism presents with a characteristic
bilateral “bat-wing” distribution of lung opacity with frothy alveolar exudate. Within the exudate, the organisms can be seen either in relief (Wright-Giemsa) or as positivelystaining
“crushed ping-pong balls” (GMS).
QCCP2, Pneumocystis
Which nematode has a characteristic double-operculated egg?
A. Trichuris trichuria
B. Ascaris lumbricoides
C. Necator americanus
D. Ancylostoma duodenale
E. Strongyloides stercoralis
A. T.
Trichuris, the whipworm, has an extremely tapered anterior end and double-operculated egg. It may coinfect with Ascaris.
QCCP2, Trichuris
Which nematode has a characteristic mammilated bile-stained egg?
A. Trichuris
B. Ascaris
C. Necator
D. Ancylostoma
E. Strongyloides
B. A.
Without the unique outer shell, Ascaris eggs resemble those of hookworms or Strongyloides. Ascaris is also significant for its lifecycle - eggs are ingested, hatch in the
intestine, migrate to the lungs, and, after being expectorated, are in turn swallowed and take up residence in the duodenum. During the lung stage, they can cause the
hypereosinophilic Loeffler syndrome.
QCCP2, Ascaris