Chapter 49 - Other Protozoa Flashcards
Free-Living Amebae
- what are the three most common encountered genera?
- Naegleria
- Acanthamoeba
- Balamuthia
Free-Living Amebae
- What part of the body do they target?
- What are some examples of diseases?
Tend to cause infections of the central nervous system (CNS).
- Primary amebic meningoencephalitis (PAM)
- Granulomatous amebic encephalitis (GAE)
Naegleria fowleri
- What well-known name does this go by?
- What is its path of entry?
- what disease is it responsible for?
- The brain eating amoeba
- Amebae enter the nasal cavity and migrate to the brain.
- Rapidly causes fatal PAM
Naegleria fowleri
- the two trophozoite forms are?
- Amoeboid
- Flagellate
Naegleria fowleri
- describe the shape and cell wall of the cysts.
- Cysts are round with a thick double wall.
Acanthamoeba spp.
- what are the stages and where can they be observed?
- No flagellate stage is known.
- Cysts and trophozoites can be observed in samples.
Acanthamoeba spp.
- What are the two main infections caused by this species?
- what is the main difference between the two?
Granulomatous amebic encephalitis
- Is associated with underlying disease (no freshwater contact).
- May take several weeks or months to establish disease.
Amebic keratitis
- Is associated with direct exposure to contaminated material or solutions.
- Wearing contacts is the leading risk factor.
Acanthamoeba spp.
- what are the 4 main ways to diagnose?
- Culture with nonnutrient plates overlaid with Escherichia coli
- Cerebrospinal fluid (CSF) examination
- Cytospin slides preparations using bronchoalveolar lavage (BAL)
- Tissue biopsy
Naegleria fowleri
vs. Acanthamoeba spp.
- how many forms?
- what are those forms?
- what diseases does each cause?
- water/not water related?
N. fowleri
- 3 forms
- Trophozoite forms are:
- – Amoeboid
- – Flagellate
- Cysts are round with a thick double wall
- Rapidly causes fatal PAM.
- Water related
Acanthamoeba
- 2 forms
- No flagellate stage is known.
- Cysts and trophozoites.
- Granulomatous amebic encephalitis and amebic keratitis
- Not water related
Balamuthia mandrillaris
- what disease does it cause?
- what is the prognosis for the host?
- Is a rare cause of human amebic encephalitis.
- Death may occur 1 week to several months after symptoms
Balamuthia mandrillaris
- what other amoeba is this similar to?
- how is it differentiated?
- Balamuthia is differentiated from Acanthamoeba on the basis of nuclear morphologic characteristics (multiple nucleoli compared with only one).
Balamuthia mandrillaris
- how is it cultured?
- Can be cultured using monkey kidney cells and mucosal replicating cells (MRC), human epidermoid carcinoma (HEp-2), and macrophages.
Balamuthia mandrillaris
- what are the layers of the cyst?
- appear to have 3 layers
- Outer wrinkled ectocyst
- Middle structure-less mesocyst
- Inner thin edocyst
Trichomonas vaginalis
- describe the shape and size
- describe the membrane,
- pear-shaped
- 7-23um length
- 5-15um length
- undulating membrane that extends half the length of the body
Trichomonas vaginalis
- what are the number of nuclei?
- what is the visibility under a microscope?
- 1 nuclei
- not seen in unstained mounts
Trichomonas vaginalis
- describe its motility
- how many flagella do they have and where are they located?
- jerky and rapid
- 3-5 anterior flagella, 1 posterior
- no free posterior flagellum
Trichomonas vaginalis
- what samples are they seen in?
- what is their infective stage?
- seen in urine, urethral discharge, and vaginal smears
- infective stage the troph
Trichomonas vaginalis
- where is it usually found?
- what are the clinical findings?
- at what stage is it seen in clinical findings?
- vagina in females, urethra and prostate in males
- leukorrhea, pruritus vulvae (white urethral discharge in males)
- seen in clinical settings only as a troph
Trichomonas vaginalis
- how is it acquired?
- how long can it live?
- Acquired primarily through sexual intercourse
- Capable of survival for extended periods
Toxoplasma gondii
- what is the broad range of hosts it infects?
- what is its definitive host?
- Infects most warm blooded animals
- Cats are definitive host
Toxoplasma gondii
- what are the 6 steps to its life cycle?
- Cats ingest oocysts
- Organisms released and invade epithelial cells of small intestine.
- Asexual cycle
- Sexual cycle with formation of oocysts
- Oocysts excreted (Uninfective)
- One to five days become infective
Toxoplasma gondii
- what are the three different stages to its life cycle?
Tachyzoites - Cresent shaped - One end more rounded than the other - Geimsa is the stain of choice Bradyzoides - Found within tissue cysts - PAS positive Oocysts - Contain sporozoites
Toxoplasma gondii
- diagnosis?
- Serologic method (most common):
- Identifies Toxoplasma gondii antibodies.
- Polymerase chain reaction (PCR)
- Examination of biopsy specimens, buffy coats, or CSF
- Isolation in tissue culture or laboratory animals
Toxoplasmosis
- symptoms for the immunocompetent?
- No clinical symptoms are observed in most patients.
- Some will have an acute infection (e.g., lymphadenopathy).
Toxoplasmosis
- symptoms for the immunocompromised?
- CNS is primarily involved.
- Myocarditis can develop.
- Pneumonitis is prevalent.
Toxoplasmosis, congenital
- when is the fetus at the highest?
- what are the symptoms?
- Is severe if the mother acquires the organism during the first or second trimester.
- Symptoms include retinochoroiditis, cerebral calcification, and hydrocephaly.
Toxoplasmosis, ocular
- what type of infection develops?
- Congenital or acquired chorioretinitis infection develops.
