mycology exam 3

Ameba

Single-celled parasite that moves by means of cytoplasm extensions called

pseudopods (false feet)

Trophozoite

The motile feeding stage of amebas that multiply by binary fission

Cyst

The non-motile, non-feeding stage of amebas that are capable of survival

outside their hosts and of initiating human infection

Karyosome

Central mass of chromatin inside select amebic

nuclei

Peripheral chromatin

Ring of chromatin that surrounds the nuclei of

select amebas

Chromatoid bar

Oblong structures containing condensed RNA

material in the cytoplasm of select amebic cysts

Glycogen mass

A cytoplasmic area without defined borders that is

believed to represent stored food and is usually visible

in young cysts

Excystation

The transformation of amebic cysts into amebic

trophozoites

ileocecal area of the intestine

Encystation

The transformation of amebic trophozoites into amebic

cysts

Specimen of choice for recovering intestinal amebas

stool

Specimen of choice for recovering extraintestinal amebas – varies by

species but includes:

Mouth scrapings

• Cerebrospinal fluid (CSF)/brain tissue

• Corneal scrapings

Entamoeba histolytica/ Entamoeba

dispar TROPH

Ingests RBCs

avg size: 12-25 um

one nucleus, pseudopodia

Entamoeba histolytica /

Entamoeba dispar

CYST

1-4 nuclei, mature cysts have 4

avg size 12-28 um

Entamoeba histolytica /

Entamoeba dispar other info

toxic megacolon

Entamoeba hartmanni -

Trophozoite

one nucleus

ingested bacteria may be present

avg size 8-12 um

Entamoeba hartmanni - Cyst

avg size 7-9 um

1-4 nuclei

smiley face

rounded chromatoid bars

Entamoeba coli - Trophozoite

avg size 18-27 um

pseudopods

one nucleus

large, irregular karyosome

Entamoeba coli - Cyst

avg size 12-25um

1-8 nuclei

large, irregular karyosome

Endolimax nana - Trophozoite

avg size 7-10 um

one nucleus

pseudopods

Endolimax nana - Cyst

avg size 7-10 um

NO peripheral chromatin

1-4 nuclei, 4 most common

Iodamoeba bütschlii -

Trophozoite

avg size 12-18 um

one nucleus

NO peripheral chromatin

bacteria, yeast, other debris may be found in cytoplasm

Iodamoeba bütschlii - Cyst

avg size 8-12 um

one nnucleus

well defined glycogen mass

naegleria fowleri- trophozoite

sluglike, blunt psedopods

one nucleus

one central karyosome

ameboid: pseudopods, large karyosome, 8-22 um

AMEBOFLAGELLATE: flagella, 7-15um

Naegleria fowleri - Cyst

9-12um, cyst wall

central karyosome, peripheral chromatin

Naegleria fowleri other info

CSF giemsa stain for dx

Three known morphologic forms:

• Ameboid trophozoite

• Flagellate form

• Cyst

• Ameboid trophs are only form known in humans.

Warm bodies of water, including lakes, streams, ponds, swimming pools

• Contaminated dust

• Highest prevalence – summer months

• It grows best at higher temperatures up to 115°F (46°C)

Primary amebic meningoencephalitis (PAM)

Acanthamoeba Species -

Trophozoite

avg size 25 um

sluggish, spinelike pseudopods

one nucleus

Acanthamoeba Species - Cyst

DOUBLE CELL WALL (outside has ragged edges)

8-25um

acanthomoeba other info

DOUBLE CELL WALL

CSF – standard methods

• Other samples:

• Brain tissue

• Corneal scrapings

EYE INFECTION-contacts

Granulomatous amebic encephalitis (GAE)

• Slowly developing symptoms include:

• Headaches

• Seizures

• Stiff neck

• Nausea and vomiting

Sporozoa

A group of protozoa that have no obvious means

of locomotion

Macrogametocyte

Female sex cell of Plasmodium spp

Microgametocyte

Male sex cell of Plasmodium spp.

Merozoite

Asexual sporozoa trophozoite

Ring form

Ringlike structure that appears initially after

invasion of RBC by Plasmodium spp

Schizogony

Asexual multiplication that occurs in humans prior

to invasion of the red blood cells

Schizont

Morphologic form responsible for the development

and maturing of merozoites critical to parasite

survival

Sporogony

Sexual multiplication that occurs in mosquitoes

Sporozoite

Infective stage transferred by vector

Immature schizonts

Growing chromatin and

visible cytoplasmic

material surrounds the

growing chromatin.

mature schizont

Fully developed

merozoites emerge

(asexual sporozoa

trophozoites)

Cytoplasmic material is

presumed to be absent

except with Plasmodium

vivax.

plasmodium life cycle

Vector is the mosquito genus Anopheles.

 Vector transfers the infective *sporozoites

with blood meal.

 Sporozoites enter liver to multiply.

 Schizogony (asexual multiplication)

 Also known as **exoerythrocytic cycle

Liver cells rupture to release merozoites.

 Merozoites infect red blood cells.

 *Erythrocytic cycle

 Merozoites can go on to:

 Infect new RBCs

 Develop into microgametocytes and

macrogametocytes

 Be destroyed by the immune system

Timing of blood collection

in between paroxysms

p. vivax

paroxysms Q 48hrs

p.ovale

paroxysms Q 48 hrs

p.malariae

paroxysms Q 72hrs

p.falciparum

q 36-48 hrs

Plasmodium vivax

AKA: Benign tertian malaria, vivax malaria

infects young RBCs causing distorted shape

ring form-single chromatin dot with ring surrounding vacuole

Most widely distributed of the Plasmodium

species and found in tropical, subtropical, and

temperate regions

Paroxysms occur every 48 hours.

avg 16 merozoites

plasmodium ovale

AKA Benign tertian

malaria, Ovale malaria

Differences from P.

vivax:

 Larger ring

 Thicker & more

amoeboid ring

 Multiple rings can

infect 1 RBC

avg 8 merozoites per infected RBC

infects only young and immature cells, causing deformed, ragged edge cells

ROSETTE APPEARANCE of merozoite

Found primarily in tropical Africa as well as Asia

and South America

Q 48hr

Plasmodium malariae

BAND FORM, BIRDS EYE

6-12 merozoites

only infects mature RBCs, no distortion

Rings seen less often.

 Developing trophozoites and immature and

mature schizonts are more common.

Found in subtropic and temperate regions

There are no known relapses.

Plasmodium falciparum

Synonyms:

 Black water fever

 Malignant tertian malaria

 Aestivoautumnal malaria

 Subtertian malaria

 Falicparum malaria

avg 24 merozoites

Ring form: HEADPHONE configuration

CRESCENT SHAPE

may infect all age RBCs, no distortion

Infections – in late summer and early fall

 Epidemiology

 Limited to tropical and subtropical regions

36 to 48 paroxysms

 Deadliest form of malaria

• Large amounts of toxic cellular debris

• May enter kidneys, brain, and liver

• May result in coma and death

Plasmodium knowlesi

can form bands

Babesia spp

Develops within RBC, from the trophozoite, to

form a Maltese cross appearance

 Produces sporozoites, which are taken up by

the tick vector

Vector is a tick of the genus Ixodes

Humans considered accidental host

 Merozoites undergo binary fission to produce

more sporozoites that ultimately infect new

RBCs.

Specimen of choice – Giemsa-stained

peripheral blood films

 Thick blood smear for screening

 Thin blood smear for differentiating Babesia

species from Plasmodium species

 Timing of blood collection not critical

Babesia microti and

Babesia divergens

MALTESE CROSS

Trophozoite

• Resembles the ring form of Plasmodium species

• Absence of malarial pigment and dots

Merozoite

• Four trophozoites mature to

form a Maltese cross.

• Sexual stage occurs in the

tick (vector).

• Asexual stage occurs in

animals and humans.

Specimen of choice – Giemsa-stained

peripheral blood film

• Thick and thin blood films

B. divergens tends to be more severe and fatal if

untreated

B. microti

Southeast New

England, Midwest

and Mexico

• Most common tick

vector – Ixodes

scapularis

• Primary reservoir –

white-footed mouse

B. divergens

European countries

• Has been found in the

Nantucket area

• Tick vector – Ixodes ricinus

• Reservoir hosts – cattle and

rabbits

Axostyle

Rod-like support structure in select flagellates

Axoneme

Intracellular portion of a flagellum

Cytostome

Rudimentary mouth present in some flagellates

Median bodies

Comma-shaped structures inside Giardia

intestinalis

 Structure associated with energy, metabolism, or

support

Undulating membrane

Fin-like structure

Costa

Rod-like structure located at the base of the

undulating membrane

Flagellate life cycle

troph, cyst form

Ingestion of infected cysts when present =

initiation of human intestinal infection

Trophozoites in intestinal tract

 Actively multiply by asexual binary fission

 Changes in intestinal environment –

excystation, when cysts are present

Giardia intestinalis troph

troph: BILATERAL SYMMETRY

avg size: 10-15um

falling leaf motility

2 ovoid nuclei, each w a large karyosome, 2 median bodies, 2 axonemes, sucking disk

Giardia intestinalis cyst

10-12um

immature cyst has 2 nuclei, mature has 4

median bodies

Chilomastix mesnili

Trophozoite

avg length: 8-15um

PEAR SHAPED

four flagella

Chilomastix mesnili - Cyst

7-10um x3-7um

clear hyaline knob

LEMON SHAPED

Dientamoeba fragilis

Trophozoite

contains ingested bacteria

8-12um

2 nuclei

Symptoms vary and include:

 Diarrhea and abdominal pain

– Diarrhea alternating with constipation

 Bloody or mucoid stools

Possible theory: D. fragilis may be transmitted

via select helminth eggs (Chapter 8):

• Enterobius vermicularis (pinworm)

• Ascaris lumbricoides (large intestinal roundworm)

Only known morphologic form – trophozoites

Trichomonas vaginalis

Trophozoite

costa, axostyle, undulating membrane ½ body length, 4 flagella

8-15um

Hemoflagellate

Single-celled parasite that moves by means of tail-

like extensions of cytoplasm known as a flagellum

(pl. flagella) that resides in blood and tissue

Blepharoplast

Basal body structure located in the cytoplasm of

the hemoflagellates

Kinetoplast

An umbrella term that refers to the blepharoplast

and small parabasal body located in the cytoplasm

of the hemoflagellates

Chaga’s Disease

A common name for the disease caused by

Trypanosoma cruzi

Amastigote

Oval, non-flagellated morphologic form found in some of the

hemoflagellate life cycles

Promastigote

Long, slender hemoflagellate morphologic form containing a free

flagellum

Epimastigote

Long, spindle-shaped, hemoflagellate morphologic form equipped with

a free flagellum and an undulating membrane that extends over ½ the

body length.

Trypomastigote

Long and slender to study hemoflagellate morphologic form of

Trypanosoma spp. that typically looks like the letter C or U on

permanent stain. It has a full body length undulating membrane.

espundia

leishmaniasis braziliensis

Leishmania braziliensis Complex

Biopsy of infected ulcer = specimen of choice

• Microscopy:

 Specimen of choice for recovery of amastigotes

Arthropod vector

• Sand fly species: Lutzomyia and

Psychodopygus

Infective stage for human

• Promastigotes

Leishmania donovani Complex

Screening test: Montenegro skin test

Darkening of the skin (kala-azar – black fever)

Trypanosoma brucei gambiense

West African sleeping sickness

Tsetse fly: Glossina palpalis and

Glossina tachinoides

Diagnostic stage for humans

• Trypomastigotes

 Infective stage for tsetse fly

• Trypomastigotes – tsetse fly picks them up during

blood meal.

West African (Gambian) sleeping sickness

• Painful chancre surrounded by white halo at bite site

lymphadenopathy

Winterbottom’s sign

Trypanosoma brucei rhodesiense

Synonyms:

 East African

sleeping sickness

 Rhodesian

trypanosomaisis

Giemsa-stained blood preparations

• Trypomastigotes*

 Microscopic examination of CSF

• Trypomastigotes

Tsetse fly species: Glossina morsitans and Glossina

pallidipes

Reservoir hosts:

• Cattle

• Sheep

• Wild game animals

Trypanosoma cruzi

Chaga’s disease

 American trypanosomiasis

Arthropod vector

• Kissing (reduviid) bug

 Mode of transmission

• Kissing bug defecates near blood meal

site.

• Kissing bug subsequently rubs it into the

skin via the scratch in preparation for its

blood meal.

Central and South America

• Highest prevalence – Brazil

Erythematous nodule

(chagoma)

Myocarditis

• Enlargement of the colon (megacolon) or esophagus

(megaesophagus)

Balantidium coli - Trophozoite

CILIA!!!!

35-50um

2 nuclei

cystosome mouth

Balantidium coli

Cyst

52-55um

2 nuclei

DOUBLE CYST WALL

Isospora belli (AKA Cystoisospora)

Oocyst

double cell wall

2 mature sporocysts each contain 4 sporozoites

30×12um

Cryptosporidium parvum

Oocyst

4-6um

ROSETTE SHAPE

4 sporozoites

waterparks, community swimming pools, day care

Blastocystis hominis

Vacuolated Form

Whole vacuole pushes nuclei to edge of cell

5-32um

Cyclospora cayetanensis

Oocyst

Oocysts to autofluoresce under ultraviolet

light microscopy

7-10um

2 sporocysts each w 2 sporozoites

Microsporidia Spore

TUBULES

1-5um

Most cases occur in AIDS patients.

• Haiti

• Zambia

• Uganda

• The United Kingdom

• The U.S.

• The Netherlands

Toxoplasma gondii

Tachyzoites and Bradyzoites

crescent shape

Serologic methods performed on blood

samples

Definitive host – cat

 Intermediate hosts –

rats or mice

nfected child may experience:

– Hydrocephaly, microcephaly

Pneumocystis jiroveci

Trophozoite

2-4um

ameboid shape

4-8 nuclei

Pneumocystis jiroveci

Cyst

4-8 nuclei

4-12 um

AIDS patients often develop Kaposi’s sarcoma

(malignant skin disease).