Transcript Microbiology

Ch 12
The Eukaryotes:
Fungi, Algae,
Protozoa, and
Helminths
Copyright © 2010 Pearson Education, Inc.
Student Learning Outcomes
 List the defining characteristics of fungi.
 Identify two beneficial and two harmful effects of fungi.
 List the defining characteristics of protozoa.
 Differentiate an intermediate host from a definitive host.
 List the distinguishing characteristics of the two classes of
parasitic helminths, and give an example of each.
 Provide a rationale for the elaborate life cycles of parasitic
worms.
 Define arthropod vector.
 Differentiate between a tick and a mosquito, and name a
disease transmitted by each.
Copyright © 2010 Pearson Education, Inc.
FUNGI
 Chemoheterotroph, aerobic
(molds) or facultatively
anaerobic (yeasts)
 Mycology: Study of fungi
 Most fungi decomposers, few
are parasites of plants and
animals.
 # of serious fungal infections
increasing
Fig. 12.1
Copyright © 2010
Pearson Education,
Review
Table
12.2Inc.
Characteristics of Fungi
 Hyphae: Filaments of cells,
mostly septate
 Mycelium: Mass of hyphae.
 Molds: mostly filamentous.
 Yeasts: nonfilamentous, unicellular fungi.
 Budding yeasts divide asymmetrically.
 Dimorphic fungi: yeasts like 37C, molds 25C.
 Fungal spores differ from bacterial spores. Form from
aerial hyphae.
 Growth in acidic, low-moisture, high osmotic pressure
environments.
 Metabolize complex carbohydrates (e.g.: lignin).
Copyright © 2010 Pearson Education, Inc.
Economic Effects of Fungi
 Saccharomyces cerevisiae: Bread, wine, HBV
vaccine
 Trichoderma: Cellulase
 Taxomyces: Taxol
 Entomophaga: Biocontrol
 Paecilomyces: Kills termites
 Mold spoilage
Copyright © 2010 Pearson Education, Inc.
Fungal Diseases – Mycoses
1. Systemic mycosis: infection deep within body,
affects many tissues and organs. Histoplasmosis and
coccidiomycosis.
2. Subcutaneous mycosis: Saprophytic fungi, e.g.:
Sporotrichosis.
3. Cutaneous mycosis = Dermatomycosis: affects
keratin-containing tissues (hair, nails, skin).
4. Superficial mycosis: localized on hair shafts and
superficial skin cells.
Opportunistic mycoses:
 caused by normal microbiota or fungi that are not
usually pathogenic (E.g.: Candidiasis and
Pneumocystis pneumonia)
 usually systemic.
Copyright © 2010 Pearson Education, Inc.
Human eyelash
with unknown
fungus infection.
Minimal damage to
skin or underlying
tissues.
However, impaired
IS can encourage
the infecting fungus
to proliferate.
Copyright © 2010 Pearson Education, Inc.
ALGAE
Mostly photoautotrophs,
mostly in ocean
Diatoms
 Unicellular, store
energy in form of oil
 Domoic acid  Neurological disease
 Ingestion of mussels that fed on diatomes (also
affects birds and sealions)
Dinoflagellates (plankton)
 Some produce neurotoxins: red tide
 Kills fish, marine mammals, and humans, e.g.:
parasitic shellfish poisoning (PSP)
Copyright © 2010 Pearson Education, Inc.
PROTOZOA
Unicellular,
eukaryotic
chemoheterotrophs. Large and diverse group. Few
are pathogenic.
Found in soil and water and as normal microbiota in
animals.
Trophozoite: Vegetative form (feeding and growing).
Asexual reproduction via fission, budding, or
schizogony (multiple fission).
Sexual reproduction via conjugation.
Some protozoa can produce a cyst that provides
protection during adverse environmental conditions.
Copyright © 2010 Pearson Education, Inc.
Medically Important Protozoa
1. Arcaezoa (lack mitochondria)
 Trichomonas and
 Giardia
2. Microspora (no mitochondria and no microtubules)
– diarrhea and keratoconjunctivitis in AIDS patients
3. Amoebozoa (move via pseudopodia)
 Entamoeba (dysentery) and Acanthamoeba
4. Apicomplexa: not mobile, intracellular
 Plasmodium, Babesia, Toxoplasma, Cryptosporidium
5. Euglenozoa: Hemoflagellates
 Trypanosoma
Copyright © 2010 Pearson Education, Inc.
Amoebozoa
 Move by
pseudopods
 Entamoeba
 Acanthamoeba
Copyright © 2010 Pearson Education, Inc.
The Life Cycle of Plasmodium vivax
2
3
8
7
6
Fig 12.18
Euglenozoa
 Move by flagella
 Hemoflagellates
 Trypanosoma spp.
 Sleeping
sickness
 Chagas’
disease
Fig 23..22
Copyright © 2010 Pearson Education, Inc.
HELMINTHS (Parasitic Worm)
 Kingdom: Animalia
 Phylum: Platyhelminthes
(flatworms)
Class: Trematodes (flukes)
Class: Cestodes (tapeworms)
 Phylum: Nematoda (roundworms)
 few are human parasites
 Anatomy and life cycle modified for
parasitism
 Adult stage in definitive host.
 Each larval stage in specific
intermediate host.
Copyright © 2010 Pearson Education, Inc.
Life Cycle of Helminths
 Monoecious (hermaphroditic)
 Male and female reproductive systems in one animal
 Dioecious
 Separate male and female
 Egg  larva(e)  adult
Copyright © 2010 Pearson Education, Inc.
Platyhelminths
 Dorsoventrally flattened
Trematode, or fluke: Oral and ventral sucker attaches
to host tissue
 Cestode, or tapeworm: Scolex (head), proglottids
4 suckers and
rostellum with hooks
Fig 12.26
Gravid proglottid with
uterine branches
Taenia solium
Taenia saginata
Copyright © 2010 Pearson Education, Inc.
Human definitive host;
pig or cattle intermediate host.
Echinococcus granulosus
Fig. 12. 27
Human as
Human is ….
Definitive Host
Taenia saginata
Cysticerci in beef
muscle
Intermediate Host
Echinococcus
granulosus
Adult in dog
Nematodes
Roundworms have a complete digestive system
Eggs infective for humans:
 Ascaris lumbricoides: Ascariasis. 2nd most
common worm infection in US. (Most common
worldwide; > 1 bio infected)
 Enterobius vermicularis (pinworm). Most
common worm infection in US (30% of
children, 16% of adults infected)
.
Copyright © 2010 Pearson Education, Inc.

Pinworm / Enterobius vermicularis
Fig12.28
Copyright © 2010 Pearson Education, Inc.
Diagnosing Pinworm Disease
Do test immediately
after waking up.
Several samples
might need to be
examined.
Since scratching of
the anal area is
common, samples
taken from under the
fingernails may also
contain eggs.
pinworm paddle
Larvae Infective for Humans
Hookworms
Ancylostoma duodenale and
Necator americanus
Copyright © 2010 Pearson Education, Inc.
Fig 25.23
Trichinellosis:
The Life Cycle of Trichinella spiralis
The Heartworm Dirofilaria immitis
Primarily in dogs and cats  human heart failure,
also in human lungs
Spread via mosquitoes
Fig 12.29
Copyright © 2010 Pearson Education, Inc.
ARTHROPODS AS VECTORS
Kingdom: Animalia
 Phylum: Arthropoda (exoskeleton, jointed legs, segmented body)
 Class: Insecta (6 legs)
 Lice, fleas, mosquitoes
 Class: Arachnida (8 legs)
 Mites and ticks
 Arthropods that carry diseases are called vectors.
 Elimination of vectorborne
diseases best via control or
eradication of vectors.
Copyright © 2010 Pearson Education, Inc.
Arthropod Vectors
 Mechanical transmission
 Biological transmission
 Microbe multiplies in vector
 Definitive host
 Microbe’s sexual reproduction in vector
Copyright © 2010 Pearson Education, Inc.
Fig 12.32