Assessment PARA Flashcards
ECOFRIENDLY fecal fixative:
Formalin
Schaudinn’s
Polyvinyl alcohol
Merthiolate-iodine-formalin
Polyvinyl alcohol
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
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
“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
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
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
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.
Larva with heart to lung migration, except:
Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura
Trichuris trichiura
Triad of infection or unholy 3, except:
Ascaris lumbricoides
Hookworms
Strongyloides stercoralis
Trichuris trichiura
Strongyloides stercoralis
Visceral larva migrans is associated with which of the following organisms?
Toxocara—serology
Onchocerca—skin snips
Dracunculus—skin biopsy
Angiostrongylus—CSF examination
Toxocara—serology
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.
A helminth egg is described as having terminal polar plugs. The most likely helminth is:
Hookworm
Trichuris trichiura
Fasciola hepatica
Diphyllobothrium latum
Trichuris trichiura
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
May be associated with vertical transmission and congenital infections:
Ascaris lumbricoides
Ancylostoma duodenale
Necator americanus
Enterobius vermicularis
Ancylostoma duodenale
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
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
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
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
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
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
The most common identified species of filarial worms that infect
humans:
Brugia malayi
Loa loa
Onchocerca volvulus
Wuchereria bancrofti
Wuchereria bancrofti
Which microfilariae are usually not found circulating in the peripheral blood?
Brugia malayi
Wuchereria bancrofti
Onchocerca volvulus
Loa loa
Onchocerca volvulus
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 lateevening 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
The tail is often referred to as a “shepherd’s crook.”
Brugia malayi
Mansonella perstans
Mansonella streptocerca
Onchocerca volvulus
Mansonella streptocerca
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
Hydrogen peroxide
Methanol
Acetone
10% formalin
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 10% FORMALIN and then removing it.
If surgical removal is not feasible:
PAIR (PUNCTURE, ASPIRATION, INFECTION, AND REINJECTION)
Used for the inactivation of hydatid sand by injecting the cyst with a CYSTICIDAL AGENT
HYPERTONIC 30% SALINE
*0.5% CETRIMIDE
*70 TO 95% ETHANOL
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, andperiodic 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
Which of the following is associated with LOEFFLER’S SYNDROME:
Ascaris lumbricoides
Enterobius vermicularis
Trichuris trichiura
Wuchereria bancrofti
Ascaris lumbricoides
LOEFFLER’S SYNDROME: transient pulmonary infiltration; day-to-day clearing in 3 to 14 days; associated with marked peripheral eosinophilia
