prokaryotes, eukaryotes, and non-living infectious particles
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Prokaryotes, Eukaryotes, and Non-living Infectious Particles. Introduction to Microbiology Common Pathogens. The Prokaryotes. Proteobacteria. All Gram-negative Many pathogens. Also organisms that do nitrogen fixation Most use flagella for movement; some non-motile or use gliding motility - PowerPoint PPT PresentationTRANSCRIPT
Prokaryotes, Eukaryotes, and Non-living Infectious Particles
Introduction to MicrobiologyCommon Pathogens
The Prokaryotes
Proteobacteria
• All Gram-negative• Many pathogens. Also organisms that do
nitrogen fixation• Most use flagella for movement; some non-
motile or use gliding motility• Alpha, Beta, Gamma, Delta and Epsilon
Alphaproteobacteria Rickettsiaceae; Cell Symbionts
Bartonella – causes cat scratch disease
Betaproteobacteria
• Aerobic or facultative bacteria that are often highly versatile in their degradation capacities
• Contains mostly human pathogens– Example: Neisseria species.
Figure 24.7
The Betaproteobacteria• Bordetella
– Chemoheterotrophic; rods
– B. pertussis
• Burkholderia– Nosocomial
infections
Gammaproteobateria
• Class of several medically, ecologically and scientifically important groups of bacteria
• Includes Pseudomonas aeruginosa, Vibrio species (Cholera), E. coli, Salmonella species, Shigella species, etc.
Figure 11.7
The Gammaproteobacteria
• Pseudomonadales– Pseudomonas
• Opportunistic pathogens
• Metabolically diverse
• Polar flagella
Figure 11.8
The Gammaproteobacteria• Vibrionales
– Found in coastal water
• Vibrio cholerae causes cholera
• V. parahaemolyticus causes gastroenteritis
The Gammaproteobacteria• Enterobacteriales
(enterics)– Peritrichous flagella;
facultatively anaerobic
• Enterobacter• Erwinia• Escherichia• Klebsiella• Proteus• Salmonella• Serratia• Shigella• Yersinia
Figure 11.9b
More Gammaproteobacteria
Yersinia Pestis – causative agent of the Black Plague
Yersinia enterocoliticaCauses Yersinosis; enterocolitis. Zoonotic disease.
Figure 11.12
The Epsilonproteobacteria
• Helicobacter– Multiple flagella – Peptic ulcers– Stomach cancer
Epsilonproteobacteria
• Mainly the curved/spirilla• Most of the known species inhabit the
digestive tract of animals and serve as symbionts or pathogens(– Helicobacter spp. in the stomach– Campylobacter spp. in the duodenum.
Epsilonproteobacteria
• Campylobacter jejuni – causes food borne intestinal illness.
Gram-Positive Bacteria - Firmicutes
• Low G + C• Gram-positive
Figure 11.15
ClostridialesGram positive; spore producers; obilgate
anaerobes• Clostridium
Gangrene – caused by C. perfringens
Figure 11.18
Bacillales Gram positive; aerobic of facultative anaerobes; Bacillus, Listeria
and Staphylococcus
• Staphylococcus– Cocci
Staph Infection
[Insert Figure 11.19]
Figure 11.19
Lactobacillales• Generally
aerotolerant anaerobes; lack an electron-transport chain– Lactobacillus– Streptococcus– Enterococcus– Listeria
Actinobacteria
• High G + C• Gram-positive
Actinobacteria
• Actinomyces• Corynebacterium• Frankia• Gardnerella• Mycobacterium• Nocardia• Propionibacterium• Streptomyces
Figure 11.24b
Chlamydiasobligate intacelluar parasites; unique life cycles
• Chlamydia trachomatis– Trachoma– STI, urethritis
• Chlamydophila pneumoniae
• Chlamydophila psittaci – Psittacosis
Figure 11.24a
Life Cycle of the Chlamydias
Figure 11.25
SpirochetesAll posses axial filaments
• Borrelia• Leptospira• Treponema
Bacteroidetes
• Gram negative, non-sporeforming, anaerobic, and rod-shaped bacteria that are widely distributed in the environment, including in soil, in sediments, sea water and in the guts and on the skin of animals.
• Bacteroides are found in the mouth and large intestine
• Cytophaga: Cellulose-degrading in soil
Figure 11.26
Fusobacteria- Fusobacterium is a Gram-
negative non-sporeforming bacterium that is widely known and studied as a human and animal pathogen.
- Fusobacterium's exceptional ability to adhere with both Gram-negative and Gram-positive plaque microorganisms in biofilms (specifically in soft tissue) has made it a highly invasive pathogen.
- Primarily given attention for its peridontal implications
- Strains of Fusobacterium have been identified as pathogen to many parts of the body
Domain Archaea
Extremophiles• Hyperthermophiles
– Pyrodictium– Sulfolobus
• Methanogens– Methanobacterium
• Extreme halophiles– Halobacterium
Microbial Diversity
• PCR indicates up to 10,000 bacteria per gram of soil.
• Many bacteria have not been identified because they– Haven't been cultured– Need special nutrients– Are a part of complex food chains requiring the
products of other bacteria– Need to be cultured to understand their metabolism
and ecological role
The Eukaryotes: Fungi, Algae, Protozoa, and Helminths
Kingdom Fungi
Nutritional Type Chemoheterotroph
Multicellularity All, except yeasts
Cellular ArrangementUnicellular, filamentous, fleshy
Food Acquisition Method Absorptive
Characteristic Features Sexual and asexual spores
Embryo Formation None
Mycology is the study of fungi
Fungi
Figure 12.2
Molds
• The fungal thallus consists of hyphae; a mass of hyphae is a mycelium.
Figure 12.3
Yeasts
• Unicellular fungi• Fission yeasts divide symmetrically• Budding yeasts divide asymmetrically
Figure 12.4
Fungal Dimorphism
• Pathogenic dimorphic fungi are yeastlike at 37°C and moldlike at 25°C
Medically Important Phyla of Fungi
• Zygomycota – saprophtyic molds (bread mold); mucor• Ascomycota – sac fungi; Candida albicans and
Aspergillus flavus• Anamorphs – produce asexual spores only; ringworm
(tinea) and dermatophytes– Basidiomycota – club fungi– Teleomorphic fungi – produce sexual and asexual
spores• Cryptococcus (yeast-like state causes disease)
Zycomycota - Mucormycosis
Dermatophyte – capable of utilizing keratin
Cryptococcus
Candidiasis
Kingdom Protist
Nutritional Type Photoautotroph
Multicellularity Some
Cellular ArrangementUnicellular, colonial, filamentous, tissues
Food Acquisition Method Diffusion
Characteristic Features Pigments
Embryo Formation None
Algae
Diatoms – produce neurotoxins
Figure 12.13
Dinoflagellates• Cellulose in plasma
membrane• Unicellular• Chlorophyll a and c,
carotene, xanthins• Store starch• Some are symbionts in
marine animals• Neurotoxins cause
paralytic shellfish poisoning
Figure 12.14
Oomycota• Decomposers and
plant parasites– Phytophthora
infestans responsible for Irish potato blight
– P. cinnamoni infects Eucalyptus
– P. ramorum causes sudden oak death
Kingdom Protist
Nutritional Type Chemoheterotroph
Multicellularity None
Cellular Arrangement Unicellular
Food Acquisition Method Absorptive; ingestive
Characteristic Features Motility; some form cysts
Embryo Formation None
Protozoa
Medically Important Phyla of Protozoa
• Archaezoa• Microspora• Amoebozoa• Apicomplexa• Ciliophora• Euglenozoa
Figure 12.16b
Archaezoa• No mitochondria• Multiple flagella• Giardia lamblia• Trichomonas
vaginalis (no cyst stage)
Figure 12.16c, d
Archaezoa
Microspora Opportunistic parasites. Intracelluar development and
spore formation• Microsporidia
Figure 12.17a
Amoebozoa• Move by
pseudopods• Entamoeba• Acanthamoeba
Apicomplexa
• Nonmotile• Intracellular parasites• Complex life cycles• Plasmodium• Babesia• Cryptosporidium• Cyclospora
2
3
67
8
Figure 12.18
The Life Cycle of Plasmodium vivax
Clinical Focus, p. 355
Cryptosporidium
Figure 12.19
Ciliates• Move by cilia• Complex cells• Balantidium
coli is the only human parasite
Figure 12.20
Euglenozoa
• Move by flagella• Euglenoids
– Photoautotrophs
Figure 23.22
Euglenozoa• Move by flagella• Hemoflagellates
– Trypanosoma spp.• Sleeping
sickness• Chagas’ disease
Kingdom Animalia
Nutritional Type Chemoheterotroph
Multicellularity All
Cellular Arrangement Tissues and organs
Food Acquisition Method Ingestive; absorptive
Characteristic Features Elaborate life cycles
Embryo Formation All
Helminths
Helminths (Parasitic Worms)
• Kingdom: Animalia– Phylum: Platyhelminthes (flatworms)
• Class: Trematodes (flukes)– Tissue and blood flukes
• Class: Cestodes (tapeworms)
– Phylum: Nematoda (roundworms)
Characteristics of Helminths
• Reduced digestive system• Reduced nervous system• Reduced locomotion• Complex reproduction
Figure 12.25
The Life Cycle of Trematodes
Figure 12.26
Cestodes, or Tapeworms
Human as
Definitive Host – parasite reaches maturity
Taenia saginata Cysticerci in beef muscle
Intermediate Host – only some of the parasite’s developmental stages are complete
Echinococcus granulosus
Adult in dog
Figure 12.28
Nematodes
Figure 12.29
The Heartworm Dirofilaria immitis
Ascaris and Pinworm
Arthropods as Vectors
• May transmit diseases (vectors) • Kingdom: Animalia
– Phylum: Arthropoda (exoskeleton, jointed legs)• Class: Insecta (6 legs)
– Lice, fleas, mosquitoes
• Class: Arachnida (8 legs)– Mites and ticks
Figure 12.31
Arthropods as Vectors
Viruses
• Obligatory intracellular parasites• Contain DNA or RNA• Contain a protein coat• Some are enclosed by an envelope• Some viruses have spikes• Most viruses infect only specific types of cells
in one host• Host range is determined by specific host
attachment sites and cellular factors
Structure
Figure 13.2a
• Nucleic acid– DNA or RNA
• Capsid– Capsomeres
• Envelope• Spikes
Figure 13.3
Morphology of an Enveloped Virus
Figure 13.4
Morphology of a Helical Virus
Figure 13.5
Morphology of a Complex Virus
Taxonomy of Viruses
• Family names end in -viridae.• Genus names end in -virus.• Viral species: A group of viruses sharing the
same genetic information and ecological niche (host). Common names are used for species.
• Subspecies are designated by a number.
Figure 13.6
Growing Viruses• Viruses must be
grown in living cells– Bacteriophages
form plaques on a lawn of bacteria
Figure 13.7
Growing Viruses• Animal viruses
may be grown in living animals or in embryonated eggs
Virus Identification
• Cytopathic effects• Serological tests
– Detect antibodies against viruses in a patient– Use antibodies to identify viruses in neutralization
tests, viral hemagglutination, and Western blot
• Nucleic acids– RFLPs– PCR
The Lytic Cycle
1
2
3
Figure 13.11
4
Figure 13.11
The Lytic Cycle Continued
Figure 13.12
The Lysogenic Cycle
Oncogenic Viruses – Viruses that can induce cancer
• Oncogenic DNA viruses– Adenoviridae– Herpesviridae– Poxviridae– Papovaviridae– Hepadnaviridae
• Oncogenic RNA viruses– Retroviridae– Viral RNA is transcribed to
DNA, which can integrate into host DNA
– HTLV-1 (Human T-cell Lymphotropic Virus; linked to leukemia)
– HTLV-2 (Human T-cell Lymphotropic Virus; linked to hairy cell leukemia)
• Virus remains in asymptomatic host cell for long periods– Cold sores,
shingles
Latent Viral Infections
Figure 13.21
• Disease processes occurs over a long period; generally is fatal– Subacute
sclerosing panencephalitis (measles virus)
Persistent Viral Infections
Figure 13.21
Prions
• Proteinaceous Infectious particle• Inherited and transmissible by ingestion,
transplant, and surgical instruments– Spongiform encephalopathies: Sheep scrapie,
Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome, Kuru, fatal familial insomnia, mad cow disease
Normal Protein vs. Prion
Scrapie
Creutzfeldt-Jakob