Summary Microbiology: with Diseases by Body System PDF

Preview

Summary

Download Summary Microbiology: with Diseases by Body System PDF

Description

Microbiology (55-237) Learning Objectives for Midterm 1 Chapter 1- Microbiology Basics/Types of Microbes 1. Sorts of organisms -

-

-

-

-

Bacteria/Archaea: 0.5-5micrometers. Prokaryotes (no nucleus), smaller than eukaryotes, reproduce asexually, live singly or in pairs, chains or clusters, bacteria walls are composed of polysaccharides called peptidoglycan, archaea do not have these walls; thrive in extreme conditions. Fungi: Eukaryotes (nucleus +genetic material), differ from plants- get their nutrients from other organisms, differ from animals- have cell wall. MOLDS: Multicellular, intertwining filaments, sexual/asexual spores. Ex: Penicillin. YEASTS: Unicellular, asexual budding (cell within a cell within a cell…), some sexual spores. Ex: Saccharomyces Cerevisiae- bread, Candida Albicansoral/vaginal infections. Protozoa: Single- celled eukaryotes, similar to animal cells in nutritional needs +cellular structure, live freely in water but can live in animal host, mostly asexual. 3 methods of locomotion: Pseudopods (blobs that flow with direction of travel), Cilia (short filaments that vibrate/beat to propel itself- like a tank), Flagella (long tail that corkscrews to propel- like sperm) Algae: Unicellular or multicellular photosynthetic eukaryotes, categorized by pigmentation +composition of cell wall. LARGE ALGAE: seaweed, kelp- in oceans. UNICELLULAR ALGAE: found in freshwater ponds, lakes, rivers, stagnant water… Virus: Smallest size, only visible with electron microscope, acellular composed of small amounts of genetic material surrounded by protein walls. Prions: Abnormal protein. Viroids: Mostly affect plants

2. Some parasitic worms are important in the diagnosis of certain diseases. Microscopic eggs and immature stages of the worm can be detected in body fluids and excretions. 3. Relative size (from smallest to large): Viroid, virus, prions, algae, fungi, bacteria, protozoan. 4. Viruses, Prions and Viroids are parasitic particles that live/take over animal (or plant) cell hosts. 6. The 3 domains are the 3 major categories of living matter: Bacteria, Archaea, and Eukaryotes. 7. How microbes are detrimental to humans: -

Bacterial Infections (TB, Petussis, Meningococcal, Streptococcal, Staphylococcal…) Viral Infections (Cold/flu, HIV/AIDS, MMR, Polio, Hep C, Herpes, Ebola, Mononucleosis…) Fungal Infections (Yeast infections, ringworm, athlete’s foot, nail fungus…) Parasitic Infection (Tape worm, Malaria, amebiasis…) Prions: (Creutzfeldt-Jakob’s disease, mad cow…) Toxins and allergens: Molds, a type of fungus Water/Food contaminations (Salmonella, E. Coli, Cholera…)

8. How microbes are beneficial to humans: -

Saccharomyces Cerevisiae- used to make bread, beer! Probiotics: Taken to restore normal flora Molds/ bacteria to make dairy products (cheese, yogurt, sour cream..) Antibiotics!

9. Human flora/microbiome is the body’s natural bacterial count found in mucosa membranes (mouth/saliva, eyes), GI, GU and Resp. tracts. These beneficial bacteria help maintain our health as they play a role in the first line of defense mechanism and immunity.

Chapter 1 (continue) - Introduction to Studying Microbes 1. Spontaneous Generation contains 3 major theories, according to Aristotle: Asexual reproduction, Sexual reproduction and Abiogenesis (arise from non-living matter). * 3 scientists experimented and drew conclusions related to this statement. Probably not needed for midterm but you never know! Redi (meat and flies- animals come from animals). Needham (Broth, plant matter and heat- there is a life force that causes inanimate objects to spontaneously come to life). Spallanzani (Proved Needham’s theory wrong, concluded that microorganisms exist in air that can contaminate and all living things come from living things). Fermentation; Louis Pasteur: Proceeded only when living cells were present (Studied the formation of alcohol throughout various experiments with yeasts and grape juice. Pasteurization was the later process of heating the juice to kill off bad bacteria. 2. Challenges in studying microorganisms: Different organisms growing in varied conditions produce different end products. The very small sizes of most microorganisms often make it difficult to see (also they’re colourless so stains are needed). Different types exhibit few or no visible differences. 3. Development of the microscope and microbiology techniques were crucial to the advancement of science and medicine. Microscopes allowed scientists to better visualize the characteristics of microorganisms that then allowed them to study them (figure out their mechanisms of actions, their effects on humans, foods, animals, vegetation). 4. Koch’s postulates: an ‘agent’ is merely a ‘suspect’ before the postulates have been fulfilled. Every case must be satisfied before the cause of an infectious disease is proven. There are 4 steps: -

The suspect causative agent must be found in every case of the disease and be absent from healthy hosts. The agent must be isolated and grown outside the host. When the agent is introduced to a healthy, susceptible host, the host must get the disease. The same agent must be found in the diseased experimental host.

5. Bacteria and other cultures are grown in labs, cultivated and isolated in petri/agar dishes. They are either grown in a broth or on a solid surface. Dyes and stains are used to identify and characterize microorganisms.

6. A pure culture is the growth/cultivation and isolation of a single strain of a particular microorganisms. 8. Infection prevention, control, epidemiology, handwashing- Nightingale, Snow, Lister, Semmelweis. Cowpox/Smallpox vaccines- Jenner. Pasteur advanced this. 10. Sub-disciplines of microbiology include: -

Medical Microbiology (immunology, epidemiology, microbe pathology…) Environmental Microbiology (biochemistry; exotic, plant, ocean, soil microbiology…) Applied Microbiology (drug research; industrial and food microbiology, various therapies…) General Microbiology (study of general bacteria and viruses) Chapter 2- Cell Building Blocks

1. Covalent bonds: Sharing of electrons. Hydrogen bonds: Electrical attraction between partially charged H+ atoms and full negative charged molecules. 2. Metabolism encompasses all chemical reactions involved in maintaining the living state of cells and the organism. Catabolic: decomposition reactions, release energy. Anabolic: Synthesis reactions, requires energy. Exchange reaction: forming and/or breaking covalent bonds and exo/endothermic steps. 3. Enzymes are used to catalyze and speed up a chemical reaction. 4. Qualities of water: -

Surface tension: allows for transport of dissolved materials in/out of cells. Solvent: used to dissolve salts and other electrolytes. Liquid form across a wide range of temperature. Absorb: heat and conducts electricity. Easily adaptive to moderate temperature fluctuations. Participates in most chemical reactions.

5. Acids: Low pH, release H+ atoms, anions. Base: High pH, binds to/accepts H+ atoms, cations. Salts: Contain anions and cations in molecular structure therefore helps neutralize both acids and bases. 6. Organic Macromolecules: -

-

Lipids: Hydrophobic, aka triglycerides (3 fatty acids, 1 glycerol). Categories include: Trans fats, non- saturated and saturated fats, cholesterols, steroids… Carbohydrates: Mono, Di, Poly- saccharides. Provide energy. Proteins: Required for structure, function and regulation of most organ tissues. Include aminoacids, primary structures (linear chain), secondary structures (helix), tertiary structures (pleated sheet, globular structure), and quaternary structure (many structures in one molecule. Nucleic acids: Adenine, Thymine and Cytosine, Guanine bind together (AT, CG) to create a unique sequence forming an individual’s genetic code.

7. DNA: Deoxyribonucleic acid carries the genetic code in its double-helix structure. It’s the main blueprint. RNA: Ribonucleic acid, is a singular helix copy of a specific section of DNA. This copied section is used by the cells. 8. AT(D, M)P: Adenosine tri/di/monophosphate. Energy sources used in reactions.

Chapter 4- Microscopy 1. Metric units of length: nanometer, micrometer, millimeter, centimeter, decimeter, meter. (Draw stair scale for cheat sheet). 3. The use of microscopy allows scientists to see all microorganisms. 4. Magnification: Increases size of objects. Resolution: Ability to distinguish objects close together (sharpens the image). Contrast: Difference in intensity between 2 objects or an object and its background. 5. Stains and dyes are used since microorganisms are colourless. 6. Stains: -

-

Simple stains: single, basic dyes in which the samples are soaked or smeared. Determines the shape, size and arrangement of the microorganism. Differential stains: Use of more than 1 dye to determine the different cells, chemicals and structures. These include:  Gram stains: Purple (positive), Pink (negative)  Acid-fast stains: If the spread is fast (pink), slow (blue)  Endospore stains: uses heat to infuse the dyes in organisms with impermeable walls.  Histological stains: delineates features of histological specimens (cancer cells) Special Stains: Reveal special microbial structures.  Negative (capsule): stains the background rather than the organism (acid dyes are repulsed by negative charged molecules)  Flagellar: certain molecules bind to the flagella to increase the diameter, contrast and to change the colour of the tiny flagella.  Fluorescent: use of UV light and stains.

*Gram staining- especially in bacteria, it’s important to determine if a certain type of bacteria is positive or negative to then give an antibiotic accordingly to its gram stain. Each have their own different structures and each antibiotic have a slightly different mechanisms of actions* 7. LIGHT MICROSCOPY uses various lights to see the microorganisms: -

-

Bright field (specimens appear dark compared to a light background):  Simple Microscope: Contains single magnifying lens (up to 300x)  Compound Microscope: Uses a series of magnifying lenses. Light waves pass through the specimen. (up to 2000x) Dark field (specimens appear light compared to a dark background) Phase Microscopes (used when specimens could be damaged or altered by attaching them to slides or staining them)  Phase-Contrast microscope: Produce sharply defined images (used for cilia and flagella)  Differential Interference Contrast Microscope: Use prisms to split light beams into their component wavelengths, increasing the contrast and producing a three-dimensional appearance.

-

-

Fluorescence Microscopes (Use a UV light source to increase the resolution. Some specimens are naturally fluorescent, like pseudomonas and photosynthetic organisms while others are stained with fluorescent dyes. Bright neon colours appear on dark background). Confocal Microscopes (Also uses UV/fluorescence dyes but these microscopes use UV lasers to illuminate the chemicals of a single plane while the rest of the specimen remains dark, creating optical slices which are then digitized to create a 3D structure.)

ELECTRON MICROSCOPIES can magnify objects 10,000x to 100,000x with good resolution to observe the smallest bacteria, viruses, internal cellular structures and even molecules and large atoms. -

-

Transmission Electron Microscopes: Generates a beam of electrons that produces an image on a fluorescent screen. The electrons pass through the specimen, through magnetic fields that manipulate and focus on the beam and then onto a fluorescent screen that absorb electrons, changing that energy into visible light. Produces a 2D image. Scanning Electron Microscopes: Also uses magnetic fields within a vacuum tube to manipulate a beam of electrons. Instead of passing electrons through a specimen, the SEM rapidly focuses them back and forth across the specimen’s surface, which has been coated with a metal. The whole specimen can be observed in a realistic 3D image. Chapter 6- Culturing Microbes

1. Clinical Specimens: are samples of human material that is collected then examined/tested in presence of microorganisms. -

Skin (any accessible membrane including eyes, ears, nose, throat, vagina, cervix, urethra, open wound...): use of sterile swab brushed across the surface. Blood: Needle aspiration from veins. Cerebrospinal Fluid: Needle aspiration from subarachnoid space. Stomach: Intubation. Urine: Aseptic collection- midstream collection, clean catch method, catheter. Lungs: Sputum by coughing or use of suctioning. Diseased Tissue: Biopsy- removal by surgery.

2. Appropriate clinical specimen collection and transport: Clinical Specimens are then transported in a special transport media that are chemically formulated to maintain the relative abundance of different microbial species or to maintain an anaerobic environment. All specimens must be labelled properly and promptly transported to the lab to avoid the death of the pathogens and to minimize any risk of contamination.

3. The 6 I’s in studying microbiology: -

Inoculation: The sample is placed into a container (streak plates/petri dishes, pour-plate with a broth or solid surface) Incubation: Specimens are placed in a controlled environment to promote growth. Isolation: Used to separate the specimens to promote isolated cultures, easier for identification purposes. Inspection: Cultures are observed under microscopes to categorize the sample. Information Gathering: Further tests to provide specific details about a microbe. Identification: Main goal is to attach a name to the specific microbe sample.

4. Pure culture: Cultures that contain only one strain or one specific sample. Mixed culture: Many pathogens are cultivated and grown in the same area/dish. Contaminated culture: A culture that has acquired an unwanted, foreign microorganism. (How? Cross contamination by not following aseptic techniques). 6. Physical forms of media: -

Solid: Cultures grown on a solid surface. Semisolid: Cultures grown in a viscous substance. Liquid: Cultures grown in a broth.

7. Chemically defined media: The exact chemical compositions are known to then provide all essentials to promote their growth. The environment provides nutrients/energy sources, water, the right amount of oxygen and other required physical conditions such as the right pH, temperature and osmotic pressure. Complex media: The exact chemical composition of the complex medium is unknown therefore by adding other pre-digested yeasts, beef broths, soy or proteins, such as those found in milk, it promotes a wider variety of microorganism growth. 8. Enriched media: Contains complex organic substances that are required to promote specific microorganism growth. 9. Functional type Medias: -

Enrichment media: includes many complex substances, growth factors required by fastidious microbial species. Selective media: includes ingredients that kill (or inhibit growth) of certain microbes, while others can grow in/on it. Differential media: allows us to distinguish between different types of microbes, based on how they grow (e.g., colour of colonies, change in colour of medium). Transport media: helps maintain and preserve specimens prior to analysis. Reducing media: prevent oxygen accumulation (toxic to some microbes).

14. Preservation and long-term storage -

Deep Freezing: (-50C to -95C). Can be restored years later by thawing. Lyophilisation: The process of removing water from frozen cultures using an intense vacuum....