EUKARYOTIC-MICROBES.pptx

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins
Burton's Microbiology
for the Health Sciences
Chapter 5. Microbial Diversity
Part 2: Eucaryotic Microbes

Chapter 5 Outline
•Fungi
– Characteristics
– Classification
– Medical Significance
•Lichens
•Slime Moulds
•Introduction
•Algae
– Characteristics and
Classification
– Medical Significance
•Protozoa
– Characteristics
– Classification and Medical
Significance

Meet the
Microbes:
Eukaryotes
Image: Aspergillus fumigatus , CDC
Aspergillus
fumigatus
From the Virtual Microbiology Classroom on ScienceProfOnline.com

Algae
Characteristics and Classification
•Algae are photosynthetic, eukaryotic organisms.
•All algal cells consist of cytoplasm, a cell wall (usually), a
cell membrane, a nucleus, plastids, ribosomes,
mitochondria, and Golgi bodies.
– Some have a pellicle, a stigma, and/or flagella
•Algae range in size from unicellular microorganisms to
large, multi-cellular.
•Algae produce energy by photosynthesis.
– Some may use organic nutrients.

Algae
Characteristics and Classification, cont.
•Algae may be arranged in colonies or strands.
•Most algal cell walls contain cellulose.
•Depending on their photosynthetic pigments, algae are
classified as green, golden, brown, or red algae.
•Algae include: diatoms, dinoflagellates, desmids, Spirogyra,
Chlamydomonas,Volvox, and Euglena.

Algae are an important source
of food, iodine, fertilizers,
emulsifiers, and stabilizers and
gelling agents for jams and
culture media.

Algae: Medical Significance
•One genus of algae, Prototheca, is a very rare cause of
human infections
•Causes protothecosis
•Algae in several other genera secrete toxic substances called
phycotoxins
– Poisonous to humans, fish, and other animals
– If ingested by humans, the phycotoxins produced by the
dinoflagellates that cause “red tides” can lead to a disease called
paralytic shellfish poisoning.

Common PondWater Algae and Protozoa

Protozoa
Characteristics
• Protozoa are nonphotosynthetic, eucaryotic
organisms.
• Most protozoa are unicellular and free-living;
found in soil and water.
• Most protozoa are more animal-like than
plant-like.
• All protozoal cells possess a variety of
eucaryotic structures/organelles.
• Protozoa cannot make their own food; they
ingest whole algae, yeasts, bacteria, and

Protozoa
Characteristics, cont.
•Protozoa do not have cell walls, but
some possess a thickened cell
membrane called a “pellicle,” which
serves the same purpose –
protection.
•Some flagellates and ciliates ingest
food through a primitive mouth or
opening called a cytostome.

A typical protozoan life cycle has 2 stages – a
trophozoite and a cyst.
• The trophozoite is the motile, feeding, dividing
stage.
• The cyst is the nonmotile, dormant, survival
stage.
• Some protozoa are parasites.
• Parasitic protozoa cause many human diseases,
such as malaria, giardiasis, and
trypanosomiasis.

•Protozoa are divided into groups, based on their
method of locomotion:
– Amebae move by means of pseudopodia (“false feet”) –
example: Entamoeba histolytica, the cause of amebic
dysentery.
– Ciliates move by means of hairlike cilia – example:
Balantidium coli, the cause of balantidiasis.
– Flagellates move by means of whiplike flagella – example:
Giardia lamblia, the cause of giardiasis.
– Sporozoa have no visible means of locomotion – example:
Plasmodium spp., which cause malaria.

ProtozoaThat Cause Human Diseases
Photomicrograph of a B. coli trophozoite
(Arrows are pointing to the cilia).
SEM of a Giardia lamblia trophozoite.

Image: Textbook, Microbiology, with
Diseases by Taxonomy, R. Bauman.
Protozoan Life Cycle

Inflammatory disorder of
the intestine, especially
the colon, that results in
severe diarrhea containing
mucus and/or blood in the
feces.
Untreated, dysentery can
be fatal due to massive
dehydration.
Can be caused by
bacteria, protozans or
parasitic worms.
Image: Source Unknown
Disease, Please: Dysentery

• Pathogenic species that feed off
the intestinal lining.
• Infection results from eating
food / drinking water
contaminated by the organism -
usually from feces.
• Chronic infection may result in
malnourishment, blocking
absorption of food across their
intestinal wall.
Protozoan Species:
Giardia lamblia (aka G. intestinalis)
Images: Public Health Image Library, (PHIL) #11649; #11632 & #3394 From the Virtual Microbiology Classroom on ScienceProfOnline.com
My dog Lulu was diagnosed with
Giardia. The vet ordered an
ELISA test on a stool sample.
Unlike a routine flotation stool
check that gets parasite eggs and
cysts to float to the top of a
solution, the ELISA test looks
for a specific antigen (or protein)
of the Giardia organism.
Giardiasis is typically treated
over several days with the drug
Metronidazole.

• A type of amoebae.
• Eat and move by extending
parts of their bodies to
form pseudopods (SUE-
dough-pods).
• Exists asymptomatically in
10% of world’s population.
• When disease develops, can
be fatal (kills 100,000
annually).
• Feeds on the lining of the
gut. Irritation created can
lead to condition known as
amoebic dysentery.
Protozoan Species: Entamoeba histolytica
(ENT-ah-MEE-bah HISS-tow-LIT-ick-ah)
Image: E. histolytica spore, CDC; E. histolytica life
cycle, Mariana Ruiz; E. histolytica trophozoite, CDC From the Virtual Microbiology Classroom on ScienceProfOnline.com

• Toxoplasma gondii.
• Can get from contaminated water,
eating undercooked infected meat
(especially pork, lamb & venison), or
contact with cat feces that contain
Toxoplasma.
• Mild symptoms are flu-like.
• Pregnant women and people with
compromised immune systems could
develop serious health problems.
• Severe toxoplasmosis can damage
the brain, eyes and other organs.
Severe cases are more likely in
individuals who have weak immune
systems.
Disease: Toxoplasmosis

• Life-threatening disease
caused by Plasmodium
protozoan parasites
transmitted through the bites
of infected mosquitoes.
• Symptoms include fever, chills,
and flu-like illness. Left
untreated can cause coma and
death if progresses to
cerebral malaria.
Disease: Malaria

Fungi
Characteristics
•The study of fungi is called mycology; scientists who study fungi
are called mycologists.
•Fungi are found virtually everywhere.
•Some fungi are harmful, some are beneficial.
•Fungi represent a diverse group of eucaryotic organisms that
include yeasts, moulds, and fleshy fungi (e.g., mushrooms).
•Fungi are the “garbage disposers” of nature.
•Fungi are not plants – they are not photosynthetic.

Fungi
Characteristics, cont.
•Fungal cell walls contain a polysaccharide called chitin.
•Some fungi are unicellular, while others grow as filaments
called hyphae.
– Hyphae intertwine to form a mass called a mycelium.
•Some fungi have septate hyphae (the hyphae are divided
into cells by cross walls or septa).
•Some fungi have aseptate hyphae (the hyphae do not have
septa).

Fungi
Reproduction
•Depending on the species, fungal cells can reproduce by
budding, hyphal extension, or the formation of spores.
– There are 2 general categories of spores:
• Sexual spores
• Asexual spores (also called conidia)
– Some fungi produce both asexual and sexual spores.

Fungal Colonies andTerms
Relating to Hyphae

Fungi
Classification
•Classification of fungi is based primarily on
their mode of sexual reproduction and the
type of sexual spore they produce.
•Deuteromycotina or Deuteromycetes include
the medically important moulds such as
Aspergillus and Penicillium.
–Fungi in this phylum have no mode of sexual
reproduction or the mode of sexual reproduction
is not known.

Microscopic Appearance ofVarious Fungi
Aspergillus fumigatus Aspergilus flavus
Penicillium sp. Curvularia sp.
Scopulariopsis sp.
Histoplasma capsulatum

Fungi: Yeasts
•Yeasts are eucaryotic, unicellular organisms that lack
mycelia.
•Individual yeast cells, also referred to as blastospores or
blastoconidia, can only be observed using a microscope.
•Yeasts usually reproduce by budding, but occasionally by a
type of spore formation.
•A string of elongated buds is known as a pseudohypha (not
really a hypha).
•Some yeasts produce thick-walled, spore-like structures
called chlamydospores (or chlamydoconidia).

Gram-Stained Clinical Specimen Containing
BuddingYeast Cells

Microscopic Appearance of theYeast
Candida albicans
A = Chlamydospores
B = Pseudohyphae
C = Budding yeast cells
(blastospores)

Fungi: Yeasts, cont.
•Yeasts are found in soil and water and on the
skins of many fruits and vegetables.
–Yeasts have been used for centuries to make wine
and beer.
–Saccharomyces cerevisiae is a yeast used in baking.
–Candida albicans is the yeast most frequently
isolated from human clinical specimens, and is also
the fungus most frequently isolated from human
clinical specimens.

Fungi: Yeasts, cont.
•Yeast colonies may be difficult to distinguish from bacterial
colonies.
– A simple wet mount can be used to differentiate yeast colonies
from bacterial colonies.
• Yeasts are larger than bacteria and are usually oval-shaped.
• Yeasts are often observed in the process of budding.
• Bacteria do not bud.

Colonies of C. albicans on Blood Agar

Gram-Stained Clinical Specimen Containing
Yeasts, Bacteria, andWhite Blood Cells

Fungi: Moulds
•Often spelled “molds.”
•Moulds are often seen in water and soil and
growing on food.
•Moulds produce cytoplasmic filaments called
hyphae.
–Aerial hyphae extend above the surface of whatever
the mould is growing on.
–Vegetative hyphae grow beneath the surface.

Fungi: Moulds, cont.
•Moulds have great commercial importance.
– Some produce antibiotics.
• Examples: Penicillium and Cephalosporium
– Some moulds are used to produce large quantities of enzymes that are
used commercially.
– The flavor of cheeses like bleu cheese, Roquefort, camembert, and
limburger are due to moulds that grow in them.

Fungi: Fleshy Fungi
•Include mushrooms, toadstools, puffballs and bracket
fungi
•Consist of a network of filaments or strands (the
mycelium) that grows in soil or on rotting logs
•The fruiting body that grows above the ground forms and
releases spores
•Some mushrooms are edible; some are extremely toxic

Fungi
Medical Significance
•A variety of fungi including yeasts, moulds, and some fleshy
fungi, are of medical, veterinary and agricultural importance
because of the diseases they cause in humans, animals, and
plants.
•The infectious diseases of humans and animals that are
caused by moulds are called mycoses.
•Fungal infections of humans are categorized as superficial,
cutaneous, subcutaneous, and systemic mycoses.

Superficial and Cutaneous Mycoses
•Superficial mycoses are fungal infections of the outermost
areas of the human body – hair, nails and epidermis.
•Cutaneous mycoses are fungal infections of the living layer of
the skin, the dermis.
– A group of moulds collectively referred to as dermatophytes cause
tinea (“ringworm”) infections.
– Note that “ringworm” infections have nothing to do with worms.
– The yeast, Candida albicans, can also cause cutaneous, oral, and
vaginal infections.

Subcutaneous and Systemic Mycoses
•Subcutaneous and systemic mycoses are more severe types
of fungal infections.
•Subcutaneous mycoses are fungal infections of the dermis
and underlying tissues. Example: Madura foot.
•Systemic mycoses are fungal infections of the internal
organs of the body.
– Spores of some pathogenic fungi may be inhaled with dust from
contaminated soil or dried bird or bat feces.They may also enter
through wounds of the hands and feet.

Subcutaneous and Systemic Mycoses, cont.
•Examples of deep-seated pulmonary infections include
blastomycosis, coccidioidomycosis, cryptococcosis, and
histoplasmosis.
•Inhalation of common bread moulds like Rhizopus and Mucor
spp. can cause disease and even death in immunosuppressed
patients.
•Diagnosis of mycoses is accomplished by culture techniques
and immunodiagnostic procedures.
– Yeasts are identified using a series of biochemical tests.
– Moulds are identified using a combination of macroscopic and
microscopic observations.

Fungal Infections:
Types of Mycoses
 Superficial Mycoses: Most patients are not
even aware that they have condition. Fungi
only growing on dead skin, hair and nails.
Fungus doesn’t secretes metabolites into
body.
 Cutaneous Mycoses: Fungi growing and
secreting metabolites into the skin. Person
is definitely aware of the infection. An
example of this is Epidermophyton floccosum,
one of the causes of athlete's foot.
 Subcutaneous Mycoses: Fungus must be
traumatically implanted into the body.
 Systemic Mycoses: Fungi are inhaled into
the lungs and subsequently are transported
to other internal organs, usually through the
bloodstream.

Dimorphic Fungi
•A few fungi, including some pathogens, can live as
either yeasts or moulds, depending on growth
conditions.This phenomenon is known as
dimorphism and the fungi are called dimorphic fungi.
– When grown in vitro at body temperature (37oC),
dimorphic fungi grow as yeasts and produce yeast
colonies.
– When grown in vitro at room temperature (25oC),
dimorphic fungi exist as moulds, producing mould
colonies.
– In vivo, dimorphic fungi exist as yeasts.

Dimorphic Fungi, cont.
• Dimorphic fungi that cause human
diseases include:
– Histoplasma capsulatum
(histoplasmosis)
– Sporothrix schenckii
(sporotrichosis)
– Coccidioides immitis
(coccidioidomycosis)
– Blastomyces dermatitidis
(blastomycosis)

Fungi
Heterotrophic (consumers)
digest their food
externally, secrete
digestive enzymes and
then absorb nutrient
molecules into their cells.
Examples: yeasts, molds,
and mushrooms.
Fungi are also used
extensively by humans:
• yeasts responsible for
fermentation of beer & bread
• mushroom farming is big industry
• produce some antibiotics

Fungal Infections
Also called mycoses (singular mycosis)
A fungus is actually a primitive vegetable.
Mushrooms, mold and mildew are examples.
You are more likely to get a fungal infection if you
have a weakened immune system or take
antibiotics.
Fungi can be difficult to kill. For skin and nail
infections medication applied directly to the
infected area. Oral antifungal medicines available
for serious infections.

Epidemiology of Mycoses
Transmission and Prevalence of Fungal Infections
• It is your immune system that
keeps you safe from fungal
infection.
• Mycoses are typically acquired via
inhalation, trauma or ingestion.
• Since usually not contagious,
difficult to report incidence, other
than epidemics or when they effect
a specific population (such as AIDS
patients).
Image: Source unknown

True Fungal Pathogens vs. Opportunistic Fungi
There are only four types of fungi that are
considered true pathogens…
- Blastomyces dermatitidis
- Coccidioides immitis
- Histoplasma capsulatum
- Paracoccidioides brasiliensis
… the rest are considered opportunistic.
What’s the difference?
• True pathogenic fungi have the ability to
actively attack and invade tissues of healthy
individuals. Have specific enzymes and proteins
that help them survive and reproduce within
the body.
• Oppurtunistic fungi do not cause disease in
healthy individuals, but can cause disease in
those with weakened immune system. Pathogen:
Blastomyces
Opportunist:
Aspergillus

True Fungal Pathogen
Species: Blastomyces dermatitidis
(blast-o-MICE-ease dur-ma-TID-id-iss)
• What Is Blastomycosis?
Caused by fungus found in soil in the eastern and
central US.
Infection occurs by inhalation of spores. Once
inhaled, fungus grows and may disseminate through
blood to other organs.
• Pulmonary Blastidiomycosis
Resolves on its own in most people. In immune
compromised can cause respiratory failure.
• Disseminated Blastidiomycosis
If disseminates from lungs, can result in wart-like
or recessed skin lesions (cutaneous blastidiomycosis) or
damage to bones (osteoarticular blastidiomycosis).
AIDS patients are prone to develop meningitis from
infection.

Opportunistic Fungal Pathogen
Species: Aspergillus fumigatus
• Can cause disease aspergillosis.
• Has become leading infectious cause of
death in leukemia and bone marrow
transplant patients.
• Can result in:
- allergic reaction
- pulmonary mass
- systemic infection
- can also exacerbate asthma
• Five things increase a persons risk of
experiencing opportunistic mycoses:
• Invasive medical procedures
• Medical therapies that weaken the immune system
• Certain preexisting conditions / Immune
compromised
• Specific lifestyle factors

Lichens and Slime Moulds
•Lichens are observed as colored, often circular patches
on tree trunks and rocks.
– Lichens are composed of an alga and a fungus living in a
mutualistic relationship.
– Lichens are classified as protists.
•Slime moulds are found in soil and on rotting logs.
– Slime moulds have both fungal and protozoal
characteristics.
– Slime moulds are classified as protists.

DifferentTypes of Lichens

Helminths
Helminths are parasitic
worms that live inside their
host.
Examples: hook, whip, pin, heart
and round worms
Belong to the Kingdom Animalia.
Live in and feed off living hosts.
Receive nourishment and
protection while disrupting their
hosts' nutrient absorption,
causing weakness and disease.
Many types of helminths live in
the digestive tract of their
host. These are referred to as
intestinal parasites.
Watch a video clip,
called
Worm in My Butt,
of a man describing
his helminth
infection.

You are
my host!
I am burrowing
up through your
feet, to your
throat, where
you’ll swallow me.
I live and grow,
with my teeth
hooked into the
lining of your
intestine!
Ancylostoma duodenale

• Two species commonly infect
humans: Ancylostoma duodenale and
Necator americanus.
• Infect > 600 million worldwide.
• Eggs in fecally-contaminated soil
mature into larvae.
• Larvae penetrate skin of foot
(sometimes causing “ground itch”), ride
the lymph system to the right side of
heart, and pumped into lungs, are
coughed up, and are then swallowed.
• Enter digestive system, and mature
into adult worms in small intestines.
• Worms suck blood voraciously.
Cause anemia, loss of iron & protein,
and damage mucosa.
Helminth: Hookworms

• Parasitic nematode worm (helminth) that lives in
small intestine of host.
• Taeniasis is the infection of humans with adult
tapeworm of Taenia saginata (beef)
• or Taenia solium (pork).
• People with taeniasis may not know they have an
infection because symptoms are usually mild or
absent.
• T. solium tapeworm infections can lead to
cysticercosis, a disease that can cause seizures,
so it is important to seek treatment.
Images: Tapeworm scolex, T. Port; Tapeworm life cycle, CDC,
Tapeworm segments on cat’s tail, Worms in Cats website.
Helminth: Tapeworms

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