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Prokaryotes, Eukaryotes, and Non-living Infectious Particles Introduction to Microbiology Common Pathogens
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The Prokaryotes
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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
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Alphaproteobacteria Rickettsiaceae; Cell Symbionts
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Bartonella – causes cat scratch disease
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Betaproteobacteria Aerobic or facultative bacteria that are often highly versatile in their degradation capacities Contains mostly human pathogens – Example: Neisseria species.
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Figure 24.7 The Betaproteobacteria Bordetella – Chemoheterotrophic; rods – B. pertussis Burkholderia – Nosocomial infections
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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.
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Figure 11.7 The Gammaproteobacteria Pseudomonadales – Pseudomonas Opportunistic pathogens Metabolically diverse Polar flagella
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Figure 11.8 The Gammaproteobacteria Vibrionales – Found in coastal water Vibrio cholerae causes cholera V. parahaemolyticus causes gastroenteritis
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The Gammaproteobacteria Enterobacteriales (enterics) – Peritrichous flagella; facultatively anaerobic Enterobacter Erwinia Escherichia Klebsiella Proteus Salmonella Serratia Shigella Yersinia
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Figure 11.9b More Gammaproteobacteria
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Yersinia Pestis – causative agent of the Black Plague
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Yersinia enterocolitica Causes Yersinosis; enterocolitis. Zoonotic disease.
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Figure 11.12 The Epsilonproteobacteria Helicobacter – Multiple flagella – Peptic ulcers – Stomach cancer
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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.
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Epsilonproteobacteria Campylobacter jejuni – causes food borne intestinal illness.
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Gram-Positive Bacteria - Firmicutes Low G + C Gram-positive
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Figure 11.15 Clostridiales Gram positive; spore producers; obilgate anaerobes Clostridium
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Gangrene – caused by C. perfringens
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Figure 11.18 Bacillales Gram positive; aerobic of facultative anaerobes; Bacillus, Listeria and Staphylococcus Staphylococcus – Cocci
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Staph Infection
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[Insert Figure 11.19] Figure 11.19 Lactobacillales Generally aerotolerant anaerobes; lack an electron- transport chain – Lactobacillus – Streptococcus – Enterococcus – Listeria
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Actinobacteria High G + C Gram-positive
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Actinobacteria Actinomyces Corynebacterium Frankia Gardnerella Mycobacterium Nocardia Propionibacterium Streptomyces
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Figure 11.24b Chlamydias obligate intacelluar parasites; unique life cycles Chlamydia trachomatis – Trachoma – STI, urethritis Chlamydophila pneumoniae Chlamydophila psittaci – Psittacosis
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Figure 11.24a Life Cycle of the Chlamydias
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Figure 11.25 Spirochetes All posses axial filaments Borrelia Leptospira Treponema
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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
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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
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Domain Archaea Extremophiles Hyperthermophiles – Pyrodictium – Sulfolobus Methanogens – Methanobacterium Extreme halophiles – Halobacterium
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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
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The Eukaryotes: Fungi, Algae, Protozoa, and Helminths
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KingdomFungi Nutritional TypeChemoheterotroph MulticellularityAll, except yeasts Cellular Arrangement Unicellular, filamentous, fleshy Food Acquisition MethodAbsorptive Characteristic FeaturesSexual and asexual spores Embryo FormationNone Mycology is the study of fungi Fungi
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Figure 12.2 Molds The fungal thallus consists of hyphae; a mass of hyphae is a mycelium.
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Figure 12.3 Yeasts Unicellular fungi Fission yeasts divide symmetrically Budding yeasts divide asymmetrically
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Figure 12.4 Fungal Dimorphism Pathogenic dimorphic fungi are yeastlike at 37°C and moldlike at 25°C
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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)
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Zycomycota - Mucormycosis
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Dermatophyte – capable of utilizing keratin
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Cryptococcus
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Aspergillosis
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Candidiasis
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KingdomProtist Nutritional TypePhotoautotroph MulticellularitySome Cellular Arrangement Unicellular, colonial, filamentous, tissues Food Acquisition MethodDiffusion Characteristic FeaturesPigments Embryo FormationNone Algae
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Diatoms – produce neurotoxins
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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
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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
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KingdomProtist Nutritional TypeChemoheterotroph MulticellularityNone Cellular ArrangementUnicellular Food Acquisition MethodAbsorptive; ingestive Characteristic FeaturesMotility; some form cysts Embryo FormationNone Protozoa
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Medically Important Phyla of Protozoa Archaezoa Microspora Amoebozoa Apicomplexa Ciliophora Euglenozoa
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Figure 12.16b Archaezoa No mitochondria Multiple flagella Giardia lamblia Trichomonas vaginalis (no cyst stage)
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Figure 12.16c, d Archaezoa
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Microspora Opportunistic parasites. Intracelluar development and spore formation Microsporidia
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Figure 12.17a Amoebozoa Move by pseudopods Entamoeba Acanthamoeba
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Apicomplexa Nonmotile Intracellular parasites Complex life cycles Plasmodium Babesia Cryptosporidium Cyclospora
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2 3 6 7 8 Figure 12.18 The Life Cycle of Plasmodium vivax
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Clinical Focus, p. 355 Cryptosporidium
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Figure 12.19 Ciliates Move by cilia Complex cells Balantidium coli is the only human parasite
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Figure 12.20 Euglenozoa Move by flagella Euglenoids – Photoautotrophs
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Figure 23.22 Euglenozoa Move by flagella Hemoflagellates – Trypanosoma spp. Sleeping sickness Chagas’ disease
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KingdomAnimalia Nutritional TypeChemoheterotroph MulticellularityAll Cellular ArrangementTissues and organs Food Acquisition MethodIngestive; absorptive Characteristic FeaturesElaborate life cycles Embryo FormationAll Helminths
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Helminths (Parasitic Worms) Kingdom: Animalia – Phylum: Platyhelminthes (flatworms) Class: Trematodes (flukes) – Tissue and blood flukes Class: Cestodes (tapeworms) – Phylum: Nematoda (roundworms)
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Characteristics of Helminths Reduced digestive system Reduced nervous system Reduced locomotion Complex reproduction
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Figure 12.25 The Life Cycle of Trematodes
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Figure 12.26 Cestodes, or Tapeworms
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Human as Definitive Host – parasite reaches maturity Taenia saginataCysticerci in beef muscle Intermediate Host – only some of the parasite’s developmental stages are complete Echinococcus granulosus Adult in dog
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Figure 12.28 Nematodes
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Figure 12.29 The Heartworm Dirofilaria immitis
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Ascaris and Pinworm
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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
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Figure 12.31 Arthropods as Vectors
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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
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Structure Figure 13.2a Nucleic acid – DNA or RNA Capsid – Capsomeres Envelope Spikes
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Figure 13.3 Morphology of an Enveloped Virus
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Figure 13.4 Morphology of a Helical Virus
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Figure 13.5 Morphology of a Complex Virus
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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.
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Figure 13.6 Growing Viruses Viruses must be grown in living cells – Bacteriophages form plaques on a lawn of bacteria
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Figure 13.7 Growing Viruses Animal viruses may be grown in living animals or in embryonated eggs
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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
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The Lytic Cycle 1 2 3 Figure 13.11
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4 The Lytic Cycle Continued
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Figure 13.12 The Lysogenic Cycle
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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)
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Virus remains in asymptomatic host cell for long periods – Cold sores, shingles Latent Viral Infections Figure 13.21
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Disease processes occurs over a long period; generally is fatal – Subacute sclerosing panencephalit is (measles virus) Persistent Viral Infections Figure 13.21
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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
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Normal Protein vs. Prion
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Scrapie
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Creutzfeldt-Jakob
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