miscellaneous protozoa Flashcards
(69 cards)
what are the 4 groups of Miscellaneous protozoa
- ciliates
- hairlike cytoplasmic extensions called cilia (used for movement)
- human pathogen: Balantidium coli (intestinal spp.) - sporozoa
- live in intestine or tissues (intestinal or tissue infection)
- subclass: Coccidia
- reproduce in two ways: outside the body (asexual) and inside the body (sexual).
[Asexual reproduction (outside the body) – They multiply without needing a partner. This happens in the environment, like in contaminated food, water, or soil.
Sexual reproduction (inside the body) – Once inside a human or animal, they reproduce by combining genetic material, creating new parasite cells that continue the infection.]
- blastocystea
- intially considered a yeast but now a sporozoa
-example: Blastocystis hominis - pneumocystis jiroveci
- former name: Pneumocystis carinii
- as fungi
- cause lung infections, esp in ppl with weak immune system
examples of Intestinal species and Tissue species in simple
Intestinal species:
○ Isospora belli
○ Sarcocystis spp.
○ Cryptosporidium parvum
Tissue species
○ Toxoplasma gondii
2 New Genera under Miscellaneous Protozoa
Cyclospora cayetanensis
- stomach infections
Microsporidia
- known to produce intestinal disease in humans
- recent discoveries so no exact classifications yet
coccidia
Group of protozoan parasites in which asexual replication occurs outside a human host
When inside the human host, they replicate through sexual
Balantidium coli (Balantidiasis) lab diagnosis
Stool Examination (Wet Prep & Permanent Stains):
Detects trophozoites and cysts in stool.
Multiple samples required = accurate detection.
Sigmoidoscopy Material:
Patients with sigmoido-rectal infections to detect parasites in the intestine.
Isospora belli (Isosporiasis) lab diagnosis
Stool & Duodenal Content Examination:
Specimen of choice to detect oocysts in different stages (immature, partially mature, fully mature).
Intestinal Biopsy:
Detect intracellular forms of the parasite in case of low infection levels. [In such cases, doctors may take a small sample of the intestine (biopsy) to check for parasites inside the intestinal cells.]
Direct Wet Preparations & Concentration Methods:
Used when oocyst numbers are low
Iodine staining can enhance visibility.
Enterotest (String Test):
Helps collect parasites from the small intestine when stool samples fail to detect them.
Biopsy materialmore direct than stool = higher possibility to detect
Sheather’s Sugar Flotation:
Helps separate oocysts from stool for better detection.
Staining Techniques:
- Modified Acid-Fast Stain → Confirms oocysts in stool.
- Auramine-Rhodamine Stain → Used for preliminary detection.
Sarcocystis spp. (Sarcocystosis) lab diagnosis
Stool Examination (Wet Prep):
Detects mature oocysts in stool in wet prep. (mature ooocyst is the diagnostic stage)
Sporocysts may be seen singly or in pairs cemented together.
Routine Histologic Methods:
Muscle Biopsy
Used in cases of muscle infections to detect sarcocysts (cyst stage) in muscle tissues.
Cryptosporidium parvum (Cryptosporidiosis) lab diagnosis
Stool Examination (Oocyst Detection):
Iodine Stain
Modified Acid-Fast Stain
Formalin-Fixed Smears Stained with Giemsa
Serologic Tests (Antigen & Antibody Detection):
Enzyme-Linked Immunosorbent Assay (ELISA)
Indirect Immunofluorescence Assay (IFA)
Modified Zinc Sulfate Flotation & Sheather’s Sugar Flotation (Stool Concentration Techniques):
Separates oocysts from stool for better visualization.
Esp when the sample is under the phase contrast microscopy
Intestinal Biopsy:
Detects merozoites and gametocytes in intestinal tissue (not seen in stool samples).
Blastocystis hominis (Blastocystis Infection) lab diagnosis
Stool Examination:
- Iodine Wet Preparation → Detects peripheral cytoplasm (1 or more nuclei = light yellow) and central vacuole (does not stain, appears clear and transparent)
- Permanent Stain Preparation → Nuclei stain dark, while the vacuole may or may not stain (able to not stain at all to very apparent)
Saline (like water) Preparations Not Recommended:
Can lyse the organism, leading to false-negative results.
Cyclospora cayetanensis (Cyclosporiasis) lab diagnosis
Stool Examination:
Non-Traditional Concentration Methods → Does not use formalin to prevent destruction of oocysts.
Sporulation Observation:
Oocysts sporulate best at room temperature.
Addition of 5% Potassium Dichromate → Helps sporocysts become visible.
Flotation Methods:
Phase Contrast Microscopy & Bright-Field Microscopy → Best for isolating oocysts.
Modified Acid-Fast Stain:
Helps confirm the presence of oocysts.
Autofluorescence Test:
Oocysts autofluoresce under UV light, making detection easier.
Microsporidia (Microsporidiosis) lab diagnosis
Serologic Tests:
Detects some species-specific antibodies in blood.
Cell Culture:
Some species will grow in culture
Staining:
detest all or part of the spore microscopically
Thin Smear with Trichrome & Acid-Fast Stain:
show desired spores
Giemsa-Stained Biopsy Material & Fecal Concentrates:
- readily shows the spores
Transmission Electron Microscopy (TEM)
for speciation of the microsporidia
Toxoplasma gondii (Toxoplasmosis) lab diagnosis
Serologic Tests (Antibody Detection):
- Double-Sandwich ELISA
→ Detects IgM antibodies in congenital infections.
- Indirect Hemagglutination (IHA) & ELISA
→ Detects IgG antibodies for past infections.
Indirect Fluorescent Antibody (IFA) Test:
→ Detects both IgM & IgG levels.
Microscopic Examination:
Detects tachyzoites and bradyzoite cysts in human tissue samples.
Animal Inoculation:
Rarely used, involves injecting suspected infected tissue into lab animals to confirm infection.
Pneumocystis jiroveci (Pneumocystis Pneumonia - PCP) lab diagnosis
Respiratory Sample Collection:
Sputum
Bronchoalveolar Lavage (BAL)
Tracheal Aspirates
Bronchial Brushings
Lung Tissue Samples
Staining Techniques:
Giemsa & Iron Hematoxylin Stains
Histologic Procedures:
Gomori’s Methenamine Silver Stain
Monoclonal Fluorescent Stain:
this test only happens when there is only small no. of organisms present in Isospora belli
enterotest
(there is low infection)
Balantidium coli life cycle
Infection:
Humans ingest infective cysts in contaminated food or water.
- infective form - cyst
Excystation:
In the small intestine, cysts excyst, and trophozoites emerge.
Trophozoite Activity:
Trophozoites reside in the
- cecal region,
- terminal ileum,
- mucosa/submucosa of the large intestine
Multiplication:
Trophozoites divide by binary fission, producing two young trophozoites.
Encystation:
In the lumen of the intestine, trophozoites encyst, mature, and are excreted in feces.
Cyst Survival: Cysts can survive for weeks in the environment, unlike delicate trophozoites.
Comparison: Life cycle is similar to Entamoeba histolytica but differs in that B. coli does not undergo nuclear multiplication in the cyst phase.
Isospora belli life cycle
Infection:
Humans ingest mature (sporulated) oocysts from contaminated food or water.
- infective and diagnostic stage - mature or sporulated oocysts
Excystation:
Oocysts excyst in the small intestine, releasing sporozoites.
Asexual Reproduction:
Sporozoites undergo schizogony in intestinal mucosal cells, producing merozoites.
Sexual Reproduction:
Gametogony occurs in the same intestinal cells, forming macrogametocytes and microgametocytes.
Gametocyte Fusion:
Gametocytes fuse to form oocysts, which are excreted in feces.
Immature Oocysts:
Immature oocysts may be excreted but cannot infect until they mature outside the host.
Sarcocystis Species life cycle
Infection through Meat:
Humans ingest uncooked pig or cattle meat containing sarcocysts.
Definitive Host:
Humans are the definitive host for sexual reproduction (gametogony).
Intermediate Host: Humans can also serve as an intermediate host where sarcocysts develop in striated muscle.
Ingestion of Oocysts:
Humans can ingest oocysts from other animals not having an intermediate host, which also leads to infection.
Sexual and Asexual Reproduction:
Both reproduction types occur in humans, depending on whether they are the definitive or intermediate host.
Cryptosporidium parvum life cycle
Infection:
Humans ingest mature oocysts from contaminated food or water.
Excystation:
Sporozoites emerge in the upper gastrointestinal tract and invade epithelial cells of the gut.
Reproduction:
Both asexual (schizogony) and sexual reproduction (gametogony) occur within epithelial cells.
Autoinfection:
The thin-shelled oocyst causes autoinfection by rupturing inside the host and reinfecting epithelial cells.
Excretion of Oocysts:
The thick-shelled oocyst is excreted in feces, which can infect a new host.
Two Forms of Oocysts:
- Thin-shelled oocysts: Cause autoinfection.
- Thick-shelled oocysts: Excreted, remain intact, and infect new hosts.
Blastocystis hominis life cycle
Reproduction:
Reproduces by sporulation or binary fission.
Sexual and Asexual Reproduction:
Exhibits both types of reproduction, with pseudopod extension and retraction for movement and feeding.
Cyclospora cayetanensis life cycle
Infection:
Humans ingest oocysts from contaminated food or water.
Excystation:
In the small intestine, sporozoites are released and invade epithelial cells.
Asexual Reproduction:
Sporozoites undergo schizogony, producing merozoites.
Sexual Reproduction:
Macrogametocytes and microgametocytes form oocysts.
Oocyst Excretion:
Oocysts are excreted in feces.
Oocyst Maturation:
Immature oocysts mature outside the body in one or more weeks, becoming capable of infecting a new host.
Microsporidia life cycle
Transmission:
Can be direct or involve an intermediate host.
Infection:
Humans are infected when spores inject sporoplasm into host cells.
Reproduction:
New spores form within infected host cells and are released, leading to new infections.
Spores in Environment:
Spores are excreted in feces or urine and can infect other hosts (e.g., carnivorous animals).
Toxoplasma gondii life cycle
Definitive Host:
Cats (or other felines).
Intermediate Host:
Rodents (mice or rats).
Infection in Cats:
Cats ingest infected rodents, releasing bradyzoites that convert to tachyzoites.
Reproduction in Cats:
Sexual reproduction occurs in the gut of the cat, producing immature oocysts, which are shed in feces
Oocyst Maturation:
Oocysts mature outside the host within 1–5 days.
Infection in Rodents:
Rodents ingest mature oocysts, leading to tachyzoite formation in the intestinal epithelium, which migrate to the brain or muscle, where they form cysts filled with bradyzoites.
Cycle Continuation:
Cats ingest infected rodents, and the cycle repeats.
Pneumocystis jiroveci life cycle
Life Cycle Status: The life cycle of Pneumocystis jiroveci is still considered unknown, but some presumptions can be made about its progression once inside the host.
Steps in the Life Cycle:
Trophozoite Residence:
Once inside the host, P. jiroveci resides in the alveolar spaces of the lung tissue.
Mature Cysts:
Mature cysts rupture, releasing trophozoites that actively grow, multiply, and feed within the host.
Trophozoite to Precyst/Cyst Conversion:
Trophozoites eventually convert into precysts and cysts, which may be found in organs such as the spleen, lymph nodes, and bone marrow.
clinical symptoms of Balantidium coli
Asymptomatic Carrier State:
Some individuals are asymptomatic carriers of B. coli, similar to carriers of Entamoeba histolytica.
Balantidiasis:
Symptoms can range from mild colitis and diarrhea to severe balantidiasis.
- Full-blown Balantidiasis:
Resembles amebic dysentery.
Abscesses and ulcers may form in the mucosa and submucosa of the large intestine.
Secondary bacterial infections may occur.
- Acute Infection:
Symptoms include up to 15 liquid stools per day, containing pus, mucus, and blood.
- Chronic Infection:
May result in a tender colon, anemia, cachexia, and alternating diarrhea and constipation.
Extraintestinal Infections:
B. coli may invade areas other than the intestine, such as:
Liver
Lungs
Pleura
Mesenteric nodes
Urogenital tract
These invasions are rare.
