Question 1

The Acanthamoeba organism is motile and has spinelike pseudopods,a single round nucleus in the cyst form,and a large karyosome in the nucleus of the troph.An estimated 70% of clinical cases of Acanthamoeba keratitis are misdiagnosed as __________ keratitis.

A)bacterial
B)fungal
C)prion
D)viral

Accepted Answer

An estimated 70% of patients with clinical Acanthamoeba keratitis are misdiagnosed as having viral keratitis.In addition,the average time to diagnosis keratitis as a result of an Acanthamoeba infection can average 2.5 weeks longer for noncontact lens wearers than for contact lens wearers.

Question 2

The CSF would reveal which of the following results in infections caused by N.fowleri?&#10;A)Increased glucose,increased protein,and positive Gram stain&#10;B)Decreased glucose,decreased protein,and negative Gram stain&#10;C)Decreased glucose,increased protein,and negative Gram stain&#10;D)Increased glucose,decreased protein,and positive Gram stain

Accepted Answer

An analysis of the CSF of N.fowleri infections will show decreased glucose and increased protein concentrations.The leukocyte count will range from several hundred to greater than 20,000 cells per mm³.Although Gram stains and bacterial cultures of CSF will be negative,serious patient complications can occur as the result of incorrect therapy if false-positive Gram stains are reported.

Question 3

MATCHING&#10;Match the infectious stage of T.gondii with the appropriate description.&#10;a.Crescent-shaped&#10;b.Oocysts from cat feces&#10;c.Tissue cysts&#10;Tachyzoites

Accepted Answer

Tachyzoites are the fast-multiplying form of T.gondii that cause acute infection.

Answer: B 
 Oocysts from cat feces are the environmentally persistent form of T.gondii and can infect humans and animals through consumption of contaminated food or water.

Answer: C 
 Tissue cysts are the slow-growing, dormant form of T.gondii that can persist for the life of the host and cause reactivation of infection under certain conditions.

Question 4

A 15-year-old male was diving in a lake when he inhaled some of the stagnate water.Five days later he was admitted to the hospital,comatose,and in critical condition.A cerebrospinal fluid (CSF)specimen was taken,and several motile amoebae were observed.The patient would most likely be diagnosed with which of the following conditions?

A)Granulomatous amebic encephalitis
B)Primary amebic meningoencephalitis
C)Secondary amebic encephalitis
D)Chronic granulomatous meningitis

Accepted Answer

Naegleria fowleri trophozoites can be found in water or moist soil.The amoebae may enter the nasal cavity by the inhalation or aspiration of water,dust,or aerosols containing the trophozoites or cysts.N.fowleri is incapable of survival in clean,chlorinated water.After inhalation or aspiration,the organisms then penetrate the nasal mucosa,probably through phagocytosis of the olfactory epithelium cells,and migrate via the olfactory nerves to the brain,causing a primary amebic meningoencephalitis.

Question 5

Trichomoniasis is the primary nonviral sexually transmitted disease worldwide.One complication of this infection is:&#10;A)keratitis.&#10;B)endometritis.&#10;C)meningitis.&#10;D)appendicitis.

Accepted Answer

Trichomoniasis is the primary nonviral sexually transmitted disease worldwide.Infection with Trichomonas vaginalis has major health consequences for women,including complications in pregnancy,association with cervical cancer,and a predisposition to human immunodeficiency viral (HIV)infection.Although vaginitis is the most common finding in women with trichomoniasis,other complications include the distension of a fallopian tube with pus,endometritis,infertility,low birth weight,and cervical erosion.In addition,an increased association with HIV transmission and cervical dysplasia has been reported.

Question 6

The troph of the motile T.vaginalis organism measures 7 to 23 mm long and 5 to 15 mm wide.The recommended treatment of choice for this urogenital infection is:&#10;A)tetracycline.&#10;B)metronidazole.&#10;C)penicillin.&#10;D)ketoconazole.

Accepted Answer

Metronidazole is recommended for the treatment of urogenital trichomoniasis,although resistance to both metronidazole and other nitroimidazoles has been reported.T.vaginalis is pear-shaped and measures 7 to 23 mm long (averaging 13 mm)and 5 to 15 mm wide.

Question 7

Tissues suspected of containing Acanthamoeba cysts can be observed using various stains.A cyst that stains black has most likely been stained with the __________ stain.&#10;A)methenamine silver&#10;B)periodic acid-Schiff (PAS)&#10;C)Giemsa&#10;D)Wright's

Accepted Answer

In infections caused by Acanthamoeba spp. ,PAS stains the cyst wall red and methenamine silver stains the cyst black.

Question 8

A 26-year-old woman has an odorous vaginal discharge,lower abdominal pain,and difficulty urinating.Vaginal secretions are collected and sent to the laboratory for examination 3 hours after collection.No motile organisms are observed on the wet preparation;however,T.vaginalis is suspected.Which one of the following statements explains this discrepancy?

A)The infection is most likely bacterial;therefore a Gram stain should have been performed.
B)The specimen should have been refrigerated before examination;consequently,the organism was compromised.
C)The time between collection and the microscopic examination was prolonged,resulting in loss of motility.
D)No discrepancy is present;this organism in nonmotile.

Accepted Answer

The identification of T.vaginalis is often based on the examination of wet preparations of vaginal and urethral discharges and prostatic secretions.This examination must be performed within 10 to 20 minutes after sample collection;if not,the organisms lose motility and may not be identified.Several specimens may have to be examined for the detection of the organisms.

Question 9

MATCHING&#10;Match the infectious stage of T.gondii with the appropriate description.&#10;a.Crescent-shaped&#10;b.Oocysts from cat feces&#10;c.Tissue cysts&#10;Sporozoites

Accepted Answer

Sporozoites are the infectious stage of Toxoplasma gondii found within oocysts, which are shed in cat feces.

Question 10

Primates,as well as dogs,sheep,and horses,have died of central nervous system (CNS)infections with which organism?&#10;A)N.fowleri&#10;B)Acanthamoeba spp.&#10;C)Toxoplasma gondii&#10;D)Balamuthia mandrillaris

Accepted Answer

B.mandrillaris is uncommon and was thought to be a harmless soil organism,with no relevance for infecting mammals.However,since B.mandrillaris was first recognized at the San Diego Wild Animal Park when a gibbon died of meningoencephalitis,a number of primates,as well as dogs,sheep,and horses,have died of CNS infection caused by this organism.Approximately 100 cases of human amebic encephalitis worldwide have been identified with approximately one-half of the cases diagnosed in the United States.Death can occur from a week to several months after the onset of symptoms.Patients eventually die with a massive CNS infection.

Question 11

MATCHING&#10;Match the infectious stage of T.gondii with the appropriate description.&#10;a.Crescent-shaped&#10;b.Oocysts from cat feces&#10;c.Tissue cysts&#10;Bradyzoites

Accepted Answer

The answer of MATCHING&#10;Match the infectious stage of T.gondii with...

Question 12

Laboratory diagnosis of T.gondii is confirmed by:&#10;A)Giemsa stain.&#10;B)tissue culture.&#10;C)serologic testing.&#10;D)Western blot.

Accepted Answer

The answer of Laboratory diagnosis of T.gondii is confirmed by:&#10;A)Giemsa...

Deck 48: Protozoa From Other Body Sites