PARA Flashcards by MS ICA

ECOFRIENDLY fecal fixative:

Formalin
Schaudinn’s
Polyvinyl alcohol
Merthiolate-iodine-formalin

Polyvinyl alcohol

How well did you know this?

Not at all

Perfectly

The formalin–ether (ethyl acetate) concentration procedure for feces is used to demonstrate:

Motility of helminth larvae
Protozoan cysts and helminth eggs
Formation of amoebic pseudopods
Trophozoites

Protozoan cysts and helminth eggs

How well did you know this?

Not at all

Perfectly

Layers obtained in the formalin ether sedimentation technique (top to bottom):

Sediment > formalin > debris > ether
Sediment > debris > formalin > ether
Ether > formalin > debris > sediment
Ether > debris > formalin > sediment

Ether > debris > formalin > sediment

How well did you know this?

Not at all

Perfectly

“Cultures of parasites are different from bacterial cultures; no quality control is needed.” This statement is:

True, if two tubes of media are set up for each patient
True, if the media are checked every 24 hours
False, unless two different types of media are used
False, and organism and media controls need to be set up

False, and organism and media controls need to be set up

Duplicate cultures should be set up, and specific American Type Culture Collection (ATCC) strains should be cultured along with the patient specimens to confirm that the culture system is operating properly. This approach is somewhat different from that used in diagnostic bacteriology and mycology.

How well did you know this?

Not at all

Perfectly

Charcot–Leyden crystals in stool may be associated with an immune response and are thought to be formed from the breakdown products of:

Neutrophils
Eosinophils
Lymphocytes
Monocytes

Eosinophils

How well did you know this?

Not at all

Perfectly

A mother states that she has observed her 4-year-old son scratching his anal area frequently. The most likely cause of this condition is:

Trichomonas vaginalis
Enterobius vermicularis
Ascaris lumbricoides
Necator americanus
Entamoeba histolytica

Enterobius vermicularis

How well did you know this?

Not at all

Perfectly

The term internal autoinfection can be associated with the following parasites:

Cryptosporidium spp. and Giardia lamblia
Cystoisospora belli and Strongyloides stercoralis
Cryptosporidium spp. and Strongyloides stercoralis
Giardia lamblia and Cystoisospora belli

Cryptosporidium spp. and Strongyloides stercoralis

Both Cryptosporidium and S. stercoralis have an internal autoinfection capability in their life cycles. This means that the cycle and infection can continue even after the patient has left the endemic area. In the case of Cryptosporidium, the cycle continues in patients who are immunocompromised and unable to self-cure.

How well did you know this?

Not at all

Perfectly

Larva with heart to lung migration, except:

Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura

Trichuris trichiura

How well did you know this?

Not at all

Perfectly

Triad of infection or unholy 3, except:

Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura

Strongyloides stercoralis

How well did you know this?

Not at all

Perfectly

Visceral larva migrans is associated with which of the following organisms?

Toxocara—serology
Onchocerca—skin snips
Dracunculus—skin biopsy
Angiostrongylus—CSF examination

Toxocara—serology

How well did you know this?

Not at all

Perfectly

Ingestion of which of the following eggs will result in infection?

Strongyloides stercoralis
Opisthorchis sinensis
Toxocara canis
Schistosoma japonicum

Toxocara canis

The eggs of T. canis are infectious for humans and cause visceral larva migrans. These ascarid eggs of the dog can infect humans; the eggs hatch and the larvae wander through the deep tissues, occasionally the eye. In this case, the human becomes the accidental intermediate host.

How well did you know this?

Not at all

Perfectly

A helminth egg is described as having terminal polar plugs. The most likely helminth is:

Hookworm
Trichuris trichiura
Fasciola hepatica
Diphyllobothrium latum

Trichuris trichiura

How well did you know this?

Not at all

Perfectly

You are working in a rural medical clinic in China and a 3-year- old girl is brought in by her mother. The child appears emaciated and, upon testing, is found to have a hemoglobin level of 5 g/dL. Her feet and ankles are swollen, and there is an extensive rash on her feet, ankles, and knees. The most likely parasitic infection that causes the child’s condition is:

Schistosomiasis
Cercarial dermatitis
Hookworm infection
Ascariasis

Hookworm infection

How well did you know this?

Not at all

Perfectly

May be associated with vertical transmission and congenital infections:

Ascaris lumbricoides
Ancylostoma duodenale
Necator americanus
Enterobius vermicularis

Ancylostoma duodenale

How well did you know this?

Not at all

Perfectly

The parasites penetrate the skin and cause cutaneous larva migrans (CLM), also referred to as creeping eruption:

Ancylostoma duodenale and Necator americanus
Ancylostoma braziliense and Ancylostoma caninum
Toxocara cati and Toxocara canis
Brugia malayi and Loa loa

Ancylostoma braziliense and Ancylostoma caninum

How well did you know this?

Not at all

Perfectly

An immunosuppressed man has several episodes of pneumonia, intestinal pain, sepsis with gram-negative rods, and a history of military service in Southeast Asia 20 years earlier. The most likely cause is infection with:

Trypanosoma cruzi
Strongyloides stercoralis
Paragonimus westermani
Naegleria fowleri

Strongyloides stercoralis

How well did you know this?

Not at all

Perfectly

Characteristics of the rhabditiform (noninfective) larvae of Strongyloides stercoralis include a:

Short buccal capsule and large genital primordial
Long buccal capsule and pointed tail
Short buccal capsule and small genital primordium
Small genital primordium and notch in tail

Short buccal capsule and large genital primordial

How well did you know this?

Not at all

Perfectly

When the undercooked meat is digested in the stomach, the larvae are resistant to the gastric pH and pass to the intestine, where they invade the mucosa:

Ascaris
Enterobius
Trichuris
Trichinella

Trichinella

How well did you know this?

Not at all

Perfectly

A 45-year-old hunter developed fever, myalgia, and periorbital edema. He has a history of bear meat consumption. The most likely causative agent is:

Toxoplasma gondii
Taenia solium
Hymenolepis nana
Trichinella spiralis

Trichinella spiralis

How well did you know this?

Not at all

Perfectly

After returning from a 2-year stay in India, a patient has eosinophilia, an enlarged left spermatic cord, and bilateral inguinal lymphadenopathy. The most likely clinical specimen and organism match is:

Thin blood films—Leishmania
Urine—concentration for Trichomonas vaginalis
Thick blood films—microfilariae
Thin blood films—Babesia

Thick blood films—microfilariae

How well did you know this?

Not at all

Perfectly

The most common identified species of filarial worms that infect humans:

Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti

Wuchereria bancrofti

How well did you know this?

Not at all

Perfectly

Which microfilariae are usually not found circulating in the peripheral blood?

Brugia malayi
Wuchereria bancrofti
Onchocerca volvulus
Loa loa

Onchocerca volvulus

How well did you know this?

Not at all

Perfectly

Which of the following statements is true regarding onchocerciasis?

The adult worm is present in the blood
The microfilariae are in the blood during the late evening hours
The diagnostic test of choice is the skin snip
The parasite resides in the deep lymphatics

The diagnostic test of choice is the skin snip

How well did you know this?

Not at all

Perfectly

The tail is often referred to as a “shepherd’s crook.”

Brugia malayi
Mansonella perstans
Mansonella streptocerca
Onchocerca volvulus

Mansonella streptocerca

How well did you know this?

Not at all

Perfectly

The worm has a characteristic, thick cuticle and a large uterus that fills the body cavity and contains rhabditoid larvae. Ancylostoma caninum Dracunculus medinensis Strongyloides stercoralis Trichinella spiralis

Dracunculus medinensis

The worms are incapable of maturation within the human host and migrate aimlessly, causing tissue damage and inflammation. Brugia malayi Dracunculus medinensis Gnathostoma spinigerum Trichinella spiralis

Gnathostoma spinigerum

Which parasite causes eosinophilic meningoencephalitis, a form of larva migrans causing fever, headache, stiff neck, and increased cells in the spinal fluid? Necator americanus Angiostrongylus cantonensis Strongyloides stercoralis Ancylostoma braziliense

Angiostrongylus cantonensis

The examination of sputum may be necessary to diagnose infection with: Paragonimus westermani Trichinella spiralis Wuchereria bancrofti Fasciola hepatica

Paragonimus westermani

Largest of the INTESTINAL trematodes, and infection is acquired by ingestion of raw water chestnuts or caltrop: Fasciolopsis buski Fasciola gigantica Heterophyes heterophyes Metagonimus yokogawai

Fasciolopsis buski

Eggs are operculated with slight opercular shoulders, yellow-brown, embryonated: Fasciola hepatica Heterophyes heterophyes Paragonimus westermani Schistosma japonicum

Heterophyes heterophyes

Severe infections may cause obstruction of the biliary ducts, resulting in enlargement and tenderness of the liver, cirrhosis, cholecystitis (inflammation of the gallbladder), and cholangiocarcinoma (cancerous growth in bile duct epithelium). C. sinensis and O. viverrini H. heterophyes and M. yokogawai P. westermani and P, mexicanus S. japonicum and S. mansoni

C. sinensis and O. viverrini

A 32-year-old male tourist traveled to Senegal for 1 month. During the trip, he swam in the Gambia river. Two months after his return, he began complaining of intermittent lower abdominal pain with dysuria. Laboratory results of ova and parasites revealed eggs with a terminal spine. Which of the following parasites is the cause of the patient’s symptoms? Schistosoma mansoni Schistosoma haematobium Ascaris lumbricoides Taenia solium

Schistosoma haematobium

Resembles egg of S. haematobium, but acid-fast positive: S. japonicum S. intercalatum S. mansoni S. mekongi

S. intercalatum

Schistosoma intercalatum eggs are found in: Stool Urine Both of these None of these

Stool S. intercalatum eggs are only found in feces, not in urine specimens.

Examination of 24-hour unpreserved urine specimen is sometimes helpful in the recovery of: Trichomonas vaginalis trophozoites Schistosoma haematobium eggs Strongyloides stercoralis larvae Enterobius vermicularis eggs

Schistosoma haematobium eggs

The miracidial hatching test helps to demonstrate the viability of eggs of: Taenia species Schistosoma species Hookworm species Opisthorchis species

Schistosoma species

Two helminth eggs that may resemble one another are: Diphyllobothrium latum and Paragonimus westermani Opisthorchis sinensis and Fasciolopsis buski Taenia saginata and Hymenolepis nana Ascaris lumbricoides and Trichostrongylus

Diphyllobothrium latum and Paragonimus westermani

Eating poorly cooked pork can lead to an infection with: Taenia solium and Trichinella spiralis Taenia saginata and Hymenolepis nana Trichuris trichiura and Hymenolepis diminuta Diphyllobothrium latum and Ascaris lumbricoides

Taenia solium and Trichinella spiralis

Several Papua New Guinea villagers known to eat pork during celebrations were reported to be suffering from an outbreak of epileptiform seizures. One of the first things you should investigate is: The prevalence of Ascaris infections in the population The prevalence of schistosomiasis in the population The presence of Trypanosoma brucei gambiense in the villagers The presence of Giardia cysts in the drinking water The presence of Taenia solium in the pigs

The presence of Taenia solium in the pigs

An operculated cestode egg that can be recovered from human feces is: Clonorchis sinensis Diphyllobothrium latum Paragonimus westermani Dipylidium caninum

Diphyllobothrium latum D. latum is the only operculated cestode egg that is found in humans; the infection is acquired from the ingestion of raw freshwater fish.

Humans acquire infections with Diphyllobothrium latum adult worms by: Ingestion of freshwater crabs Skin penetration of cercariae Ingestion of water chestnuts Ingestion of raw freshwater fish

Ingestion of raw freshwater fish

In infections with Taenia solium, humans can serve as the: Definitive host Intermediate host Either the definitive or the intermediate host None of these options

Either the definitive or the intermediate host If humans ingest T. solium cysticerci in uncooked or rare pork, the adult tapeworm will mature within the intestine (human will serve as definitive host); if eggs from the adult tapeworm are ingested, then the cysticerci will develop in human tissues (accidental intermediate host), causing cysticercosis.

In a condition resulting from the accidental ingestion of eggs, the human becomes the intermediate rather than the definitive host. The correct answer is: Trichinosis Strongyloidiasis Ascariasis Cysticercosis

Cysticercosis

Humans can serve as both the intermediate and definitive host in infections caused by: Enterobius vermicularis Hymenolepis nana Schistosoma japonicum Ascaris lumbricoides

Hymenolepis nana

Infection is more frequent in populations living in conditions of poverty or poor hygiene, in day care centers, and in persons living in institutional settings or prisons. D. latum D. caninum H. nana T. saginata

H. nana

The eggs (70 to 85 μm by 60 to 80 μm) are large, ovoid, yellowish, and moderately thick-shelled. The eggs contain a six-hooked oncosphere with the absence of polar filaments in the space between the oncosphere and the eggshell. H. diminuta H. nana Both of these None of these

H. diminuta

Eggs are small and have polar filaments present in the space between the oncospheres and the eggshell. H. diminuta H. nana Both of these None of these

H. nana

The adult tapeworm of Echinococcus granulosus is found in the intestine of: Dogs Sheep Humans Cattle

Dogs Although the hydatid cysts are found in sheep or in humans (accidental intermediate host), the adult tapeworms of E. granulosus are found in the intestine of the dog.

Surgery is the most common form of treatment for hydatid disease. The procedure involves surgical removal of cysts or inactivation of hydatid sand by injecting the cyst with __________ and then removing it. 10% formalin 70% ethanol 95% ethanol Acetone

10% formalin

Most lethal of all helminthic diseases: Taenia saginata Taenia solium Echinococcus granulosus Echinococcus multilocularis

Echinococcus multilocularis

Tapeworm that causes coenurosis in humans: Echinococcus multilocularis Spirometra mansonoides Taenia multiceps Taenia solium

Taenia multiceps

An Entamoeba histolytica trophozoite has the following characteristics: Central karyosome in the nucleus, ingested RBCs, and clear pseudopodia Ingested RBCs, clear pseudopodia, and uneven chromatin on the nuclear membrane Ingested RBCs, clear pseudopodia, and large glycogen vacuoles in cytoplasm Large, blotlike karyosome, ingested white blood cells (WBCs), and granular pseudopods

Central karyosome in the nucleus, ingested RBCs, and clear pseudopodia

A patient has been diagnosed as having amebiasis but continues to be asymptomatic. The physician has asked for an explanation and recommendations regarding follow-up. Suggestions should include: Consideration of Entamoeba histolytica versus Entamoeba dispar A request for an additional three stools for culture Initiating therapy, regardless of the patient’s asymptomatic status Performance of barium x-ray studies

Consideration of Entamoeba histolytica versus Entamoeba dispar

A Gram stain from a gum lesion showed what appeared to be amoebae. A trichrome smear showed amoebae with a single nucleus and partially digested PMNs. The correct identification is: Trichomonas tenax Entamoeba histolytica/E. dispar Entamoeba polecki Entamoeba gingivalis

Entamoeba gingivalis

If the granules are on one side, the nucleus may appear to have a “basket nucleus” arrangement of chromatin, more commonly seen in the cyst stage. D. fragilis E. gingivalis E. nana I. butschlii

I. butschlii

Cysts of Iodamoeba bütschlii typically have: Chromatoidal bars with rounded ends A heavily vacuolated cytoplasm A large glycogen vacuole Many ingested bacteria and yeast cells

A large glycogen vacuole

A 12-year-old girl is brought to the emergency department with meningitis and a history of swimming in a warm-water spring. Motile amoebae that measure 10 μ in size are seen in the CSF and are most likely: Iodamoeba bütschlii trophozoites Dientamoeba fragilis trophozoites Naegleria fowleri trophozoites Endolimax nana trophozoites

Naegleria fowleri trophozoites

Which of the following causes granulomatous amebic encephalitis (GAE), primarily in immunosuppressed, chronically ill, or otherwise debilitated individuals? Acanthamoeba Dientamoeba Iodamoeba Naegleria

Acanthamoeba

Eye infections with Acanthamoeba spp. have most commonly been traced to: Use of soft contact lenses Use of hard contact lenses Use of contaminated lens care solutions Failure to remove lenses while swimming

Use of contaminated lens care solutions

Select the most sensitive recovery method for Acanthamoeba spp. from lens care solutions or corneal biopsies. The trichrome staining method The use of monoclonal reagents for the detection of antibody The use of non-nutrient agar cultures seeded with Escherichia coli The Giemsa’s stain method

The use of non-nutrient agar cultures seeded with Escherichia coli

Which of the following is the best technique to identify Dientamoeba fragilis in stool? Formalin concentrate Trichrome-stained smear Modified acid-fast–stained smear Giemsa’s stain

Trichrome-stained smear

Trophozoites are teardrop shaped and have been described as “someone looking at you" C. mesnili D. fragilis G. lamblia T. vaginalis

G. lamblia

The organism is found most commonly in the CRYPTS IN THE DUODENUM: Cryptosporidium Isospora spp. Giardia lamblia Entamoeba histolytica

Giardia lamblia

Infection mimics acute viral enteritis, bacillary dysentery, bacterial or other food poisonings, acute intestinal amebiasis, or “traveler’s diarrhea” C. mesnili D. fragilis E. hartmanni G. lamblia

G. lamblia

One of the following protozoan organisms has been implicated in waterborne and foodborne outbreaks. The suspect organism is: Pentatrichomonas hominis Giardia lamblia Balantidium coli Dientamoeba fragilis

Giardia lamblia

Organisms that should be considered in a waterborne outbreak of diarrheal disease include: Giardia lamblia and Cryptosporidium spp. Endolimax nana and Entamoeba histolytica Blastocystis hominis and Trichomonas vaginalis Toxoplasma gondii and Schistosoma mansoni

Giardia lamblia and Cryptosporidium spp.

Organisms that should be considered in a nursery school outbreak of diarrhea include: Endolimax nana, Giardia lamblia, and Entamoeba coli Giardia lamblia, Dientamoeba fragilis, and Cryptosporidium spp. Cryptosporidium spp., Trichomonas vaginalis, and Entamoeba coli Pentatrichomonas hominis, Dientamoeba fragilis, and Endolimax nana

Giardia lamblia, Dientamoeba fragilis, and Cryptosporidium spp. G. lamblia, D. fragilis, and Cryptosporidium have been implicated in nursery school outbreaks. Among the many protozoa and coccidia found in the human, these three organisms have become the most likely parasites in this type of setting.

Fecal immunoassays have become more commonly used to diagnose infections with: Endolimax nana and Blastocystis hominis Giardia lamblia and Cryptosporidium spp. Ascaris lumbricoides and Trichuris trichiura Strongyloides stercoralis and Trichomonas vaginalis

Giardia lamblia and Cryptosporidium spp. Rapid fecal immunoassays have become more widely used for the diagnosis of infections with G. lamblia and Cryptosporidium. For these two organisms, the fecal immunoassays are more sensitive than the routine O&P examination.

Cysts have a single nucleus and a typical curved cytostomal fibril, called the shepherd’s crook: C. mesnili D. fragilis G. lamblia I. butschlii

C. mesnili

The life cycle and mode of transmission of this protozoan are not known, although transmission in helminth eggs (e.g., Ascaris and Enterobius spp.) has been postulated: C. mesnili D. fragilis G. lamblia I. butschlii

D. fragilis

Parasitic organisms that are most often transmitted sexually include: Entamoeba gingivalis Dientamoeba fragilis Trichomonas vaginalis Diphyllobothrium latum

Trichomonas vaginalis

Which specimen is the LEAST likely to provide recovery of Trichomonas vaginalis? Urine Urethral discharge Vaginal discharge Feces

Feces

A sexually active 24-year-old woman complains of vaginal itching and vaginal discharge. To verify your tentative diagnosis of trichomoniasis, you should include which of the following in your workup? Specific serologic test Ova and parasite fecal smear Wet mount of vaginal fluid Enzyme-linked immunoassay (ELISA) test of serum Stool culture

Wet mount of vaginal fluid

A 60-year-old Brazilian patient with cardiac irregularities and congestive heart failure suddenly dies. Examination of the myocardium revealed numerous amastigotes, an indication that the cause of death was most likely: Leishmaniasis with Leishmania donovani Leishmaniasis with Leishmania braziliense Trypanosomiasis with Trypanosoma gambiense Trypanosomiasis with Trypanosoma cruzi

Trypanosomiasis with Trypanosoma cruzi T. cruzi, the cause of Chagas disease, has two forms within the human: the trypomastigote in the blood and the amastigote in the striated muscle (usually cardiac muscle and intestinal tract muscle).

When malaria smears are requested, what patient information should be obtained? Diet, age, sex Age, antimalarial medication, sex Travel history, antimalarial medication, date of return to United States Fever patterns, travel history, diet

Travel history, antimalarial medication, date of return to United States

Massive hemolysis, blackwater fever, and central nervous system involvement are most common with: Plasmodium vivax Plasmodium falciparum Plasmodium malariae Plasmodium ovale

Plasmodium falciparum

An apparently fatigued but alert 38-year-old woman has spent 6 months as a teacher in a rural Thailand village school. Her chief complaints include frequent headaches, occasional nausea and vomiting, and periodic fever. You suspect malaria and indeed find parasites in red blood cells in a thin blood smear. To rule out the dangerous falciparum form of malaria, which one of the following choices is NOT consistent with a diagnosis of Plasmodium falciparum malaria based on a microscopic examination of the blood smear? Red blood cells containing trophozoites with Schuffner’s dots Red blood cells containing >1 parasite per RBC Banana-shaped or crescent-shaped gametocytes Parasites within normal-sized red blood cells Parasites with double nuclei

Red blood cells containing trophozoites with Schuffner’s dots

Plasmodium vivax and Plasmodium ovale are similar because they: Exhibit Schüffner’s dots and have a true relapse in the life cycle Commonly have appliqué forms in the red cells Have true stippling, do not have a relapse stage, and infect old red cells Have no malarial pigment and multiple rings

Exhibit Schüffner’s dots and have a true relapse in the life cycle

Key characteristics of infection with Plasmodium knowlesi include: Rapid erythrocytic cycle (24 hr), will infect all ages of RBCs, and can cause serious disease Erythrocytic cycle limited to young RBCs and causes a relatively benign disease The possibility of a true relapse from the liver, infection in older RBCs, and causes serious disease Extended life cycle (72 hr), will infect all ages of RBCs, and disease is similar to that caused by P. ovale

Rapid erythrocytic cycle (24 hr), will infect all ages of RBCs, and can cause serious disease Key characteristics of an infection with Plasmodium knowlesi include a rapid life cycle (24 hr), the potential to infect all ages of RBCs, and the possibility of serious symptoms similar to those seen with P. falciparum infections. There is no relapse from the liver with this species.

Early ring stages of the fifth human malaria, Plasmodium knowlesi, resemble those of: Plasmodium malariae Plasmodium ovale Plasmodium falciparum Plasmodium vivax

Plasmodium falciparum

Older developing stages (trophs, schizonts) of the fifth human malaria, Plasmodium knowlesi, resemble those of: Plasmodium malariae Plasmodium ovale Plasmodium falciparum Plasmodium vivax

Plasmodium malariae

A patient is being seen in the emergency department for a low-grade fever, headache, and general malaise after returning from Africa on a photographic safari. The physician has requested blood for malaria; the laboratory would like to have patient information regarding: Specific travel history and body temperature every 4 hours Liver function tests and prophylactic medication history Transfusion history and body temperature every 4 hours Prophylactic medication history and specific travel history

Prophylactic medication history and specific travel history If the patient has malaria and has been taking prophylaxis (often sporadically), the number of parasites on the blood smear will be reduced and examination of routine thick and thin blood films should be more exhaustive. Also specific geographic travel history may help to determine whether chloroquine-resistant Plasmodium falciparum may be a factor.

Recommended stain for all parasitic blood works: Giemsa Wright Modified acid fast stain Modified trichrome stain

Giemsa

There are few procedures considered STAT in parasitology. The most obvious situation would be: Ova and parasite examination for giardiasis Baermann’s concentration for strongyloidiasis Culture of amoebic keratitis Blood films for malaria

Blood films for malaria

Babesia has been implicated in disease from both splenectomized and nonsplenectomized patients. Morphologically, the parasites resemble: Plasmodium falciparum rings Leishmania donovani amastigotes Microsporidial spores Trypanosoma cruzi trypomastigotes

Plasmodium falciparum rings

Oocysts survive in the environment for several months to more than 1 year and are resistant to disinfectants, freezing, and drying. However, they are killed by heating to 70°C for 10 minutes. Balamuthia mandrillaris Pentatrichomonas hominis Isospora belli Toxoplasma gondii

Toxoplasma gondii

When staining Cystoisospora belli oocysts with modified acid-fast stains, the important difference between these methods and the acid-fast stains used for acid-fast bacilli (AFB) is: The staining time is much longer with regular AFB acid-fast stains The decolorizer is weaker than acid alcohol used for AFB decolorizing A counterstain must be used for the modified methods The stain is more concentrated when staining for AFB

The decolorizer is weaker than acid alcohol used for AFB decolorizing

Patients with severe diarrhea should use “enteric precautions” to prevent nosocomial infections with: Giardia lamblia Ascaris lumbricoides Cystoisospora belli Cryptosporidium spp.

Cryptosporidium spp. Cryptosporidium oocysts (unlike those of C. belli) are immediately infective when passed in stool, and nosocomial infections have been well documented with this coccidian.

Parasite stages that are immediately infective for humans on passage from the gastrointestinal tract include: Schistosoma spp. eggs Toxoplasma gondii bradyzoites Giardia lamblia trophozoites Cryptosporidium spp. oocysts

Cryptosporidium spp. oocysts Cryptosporidium spp. oocysts are immediately infectious when passed in the stool, regardless of the stool consistency (formed—liquid).

In an outbreak of diarrheal disease traced to a municipal water supply, the most likely causative agent is: Cryptosporidium spp. Cystoisospora belli Entamoeba histolytica Dientamoeba fragilis

Cryptosporidium spp. Cryptosporidium oocysts have been transmitted through contaminated municipal water supplies. Such outbreaks have been well documented.

Oocysts of Cryptosporidium spp. can be detected in stool specimens using: Modified Ziehl–Neelsen acid-fast stain Gram stain Methenamine silver stain Trichrome stain

Modified Ziehl–Neelsen acid-fast stain

Sporadic mini-outbreaks of diarrheal disease have been associated with the ingestion of strawberries, raspberries, fresh basil, mesclun (baby lettuce leaves), and snow peas. The most likely causative agent is: Dientamoeba fragilis Cystoisospora belli Cyclospora cayetanensis Schistosoma mansoni

Cyclospora cayetanensis

Examination of a modified acid-fast stained fecal smear reveals round structures measuring approximately 8–10 μm, some of which are stained and some of which are not. They do not appear to show any internal morphology. The patient is symptomatic with diarrhea, and the cause may be: Blastocystis hominis Polymorphonuclear leukocytes Large yeast cells Cyclospora cayetanensis

Cyclospora cayetanensis One of the newer coccidian parasites, C. cayetanensis, has been implicated in cases of human diarrhea. The recommended stains are modified acid-fast stains, and the organisms are quite variable in their staining characteristics. The oocysts are immature when passed (no internal morphology) and they measure about 8–10 μm.

Autofluorescence requires no stain and is recommended for the identification of: Entamoeba histolytica cysts Toxoplasma gondii tachyzoites Dientamoeba fragilis trophozoites Cyclospora cayetanensis oocysts

Cyclospora cayetanensis oocysts

Primary infections with the microsporidia may originate in: The lung The nervous system The gastrointestinal tract Mucocutaneous lesions

The gastrointestinal tract

The microsporidia are protozoans (now classified with the fungi) that have been implicated in human disease primarily in: Immunocompromised patients Pediatric patients under the age of 5 years Adult patients with congenital immunodeficiencies Patients who have been traveling in the tropics

Immunocompromised patients

A transplant patient on immunosuppressive drugs developed increasing diarrhea. The most likely combination of disease and diagnostic procedure is: Trichinosis and trichrome stain Microsporidiosis and modified trichrome stain Paragonimiasis and wet preparation Toxoplasmosis and Gram stain

Microsporidiosis and modified trichrome stain

Microsporidia have been identified as causing severe diarrhea, disseminated disease in other body sites, and ocular infections. Routes of infection have been identified as: Ingestion Inhalation Direct contamination from the environment Ingestion, inhalation, and direct contamination

Ingestion, inhalation, and direct contamination

Confirmation of an infection with microsporidia can be achieved by seeing: The oocyst wall Sporozoites within the spore Evidence of the polar tubule Organisms stained with modified acid-fast stains

Evidence of the polar tubule Confirmation of an infection with microsporidial spores can be achieved by seeing evidence of the polar tubule within the spores (horizontal or diagonal line across/within the spore).

Microsporidial infections can be confirmed using: Light microscopy and modified trichrome stains Phase contrast microscopy and routine trichrome stains Electron microscopy and modified acid-fast stains Fluorescence microscopy and hematoxylin stains

Light microscopy and modified trichrome stains An infection with microsporidia can be confirmed using modified trichrome stains (10X the normal dye content found in routine trichrome stains) and light microscopy. The internal polar tubule will be visible within some of the spores; this will serve as confirmation of the infection.

All of the following are sexually transmitted protozoans except: Trichomonas vaginalis Entamoeba histolytica Giardia lamblia Cryptosporidium spp. Balantidium coli

Balantidium coli The World Health Organization has ranked trichomoniasis as the most prevalent, nonviral, sexually transmitted disease in the world with an estimated 172 million new cases a year. The intestinal protozoa Giardia lamblia, Entamoeba histolytica, and Cryptosporidium spp. are significant causes of STDs, especially among homosexual populations.

PARA Flashcards

(101 cards)