Introduction Fall 16 PDF

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Introduction Fall 16...

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Dr. Deborah V. Harbour 8/2016

Chapter 1: Introduction and History of Microbiology Objectives for chapter 1. 1. Define microbiology. What are the microorganisms: names, sizes 2. Discuss classification and phylogeny. 3. Discuss cell types and properties 4. Role of microbes in the world 5. History of Microbiology A. What is Microbiology? 1. Study of living organisms which are too small to be seen with the unaided eye, i.e., requires magnification by microscopes. a. Most bacteria are in the micrometer range (10-6M) and require oil immersion to view; eukaryotic cells are usually larger. b. Most viruses are in nanometer range (10-9M); need electron microscope 2. What are the microorganisms (microbes) that are studied in this course? a. Bacteria and Archaea (prokaryotes; unicellular) b. Fungi – yeast and mold (unicellular and multicellular, respectively) c. Protists – protozoa (unicellular) and algae (unicellular and multicellular) d. Helminths - worms with microscopic products of life cycle (animals) e. Viruses (virion) – noncellular; protein and nucleic acid f. Prions – proteins 3. Microorganisms are unicellular but may grow as colonies on agar and other media a. bacteria – clones ; derived from single cell to a macroscopic colony b. yeast and mold – grow in colonies also. B.

Microorganisms are the most numerous, ubiquitous, and diverse form of life on earth and bulk weight of all other life forms combined. Bacteria exhibit characteristics common to biological systems including: a. Reproduction (does not mean sexual can be binomial), metabolism, organization, growth – increase in size (here means increase in number), movement and/or irritability, transport in and out of cell, storage and cell support, and adaptability – ability to respond to environmental stimuli, b. Viruses are very small often only nucleic acid with a protein coat. Most believe they do not fit the definition of life. Viruses are not cells so they are obligate intracellular organisms, i.e., they infect host cells and depend on hosts’ cellular machinery to replicate themselves.

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Role of Microbes in World. Why is it important to study Microbiology? 1. Microbiology ecology – interactions of microbes and the environment. a. Decomposition - responsible for decay and putrification of carcasses and other organic materials. b. Recycle vital elements - convert carbon, nitrogen, oxygen, sulfur, phosphorus into forms that plants and animals can use. Extract ores for use. c. Photosynthetic bacteria use CO2 to produce carbohydrates & oxygen (O2). d. Bioremediation – turn pollutants into food or produce enzymes to break down toxins and pollution, such as oil spills, radioactive waste. e. Sewage treatment – convert organic material in water to CO2, nitrates, sulfates, phosphates, ammonia, methane and hydrogen sulfide. f. Insect control – insect pathogens kill these pests. Bacillus thuringiensis g. Agricultural microbiology - nitrogen fixing bacteria are important in the growth of many plants such as legumes. Pathogens for plants and livestock.

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Industrial microbiology – study of microbial activities useful to humankind. a. Food - fermentation to ale and wine from sugar. Others are making of bread, yogurt and cheese. b. Antibiotics (Streptomyces, Penicillium, others) – chemotherapy, inhibit growth of bacteria. c. Biofuels production Biotechnology – use of microbes to produce desired products (genetic engineering) a. Human proteins and enzymes – insulin, growth hormone b. Vaccines – Hepatitis B vaccine and others produced by vector c. Gene therapy – constant production of lacking gene product by vector d. Genomics – study of entire microbial genome and expression of genes Interactions with Humans a. Microbiome - symbiotic ecosystem of normal microbes inhabiting the body – protection and other functions b. Medical microbiology – infectious disease caused by microbes; biofilms may lead to chronic infection and antimicrobial resistance. a. Top 10 all-cause mortality included respiratory and sepsis in the U.S. b. Microbes contribute to cancer and possibly heart disease and diabetes death. c. Emerging (new) and Re-emerging (old coming back) Infectious Disease d. Biological weapons – use of pathogens or their products as a weapon. e. Immunology and vaccines – immunity and resistance of fighting off infection f. Epidemiology and Public Health – tracking infectious disease in populations.

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Infectious Disease 1. Approximately 13 - 15 million people die/yr from preventable infectious diseases a. The top six killers are respiratory disease (influenza and pneumonia), Tuberculosis, AIDS, Diarrheal disease, Malaria, Hepatitis and Measles b. Mostly in children, poor and unavailable medical care. 2. Nosocomial infections (health care acquired) a. Compromised patient population is continuously susceptible to opportunistic infection or other pathogens. b. Those immunocompromised with transplants, having blood transfusions, defective immune function, newborns and older population are at risk. c. We are performing more procedures that encourage infections, particularly in hospitals. Nosocomial infections kill ~90,000 (directly and indirectly) each year in the U.S. 3. Emerging and Reemerging diseases – new diseases (emerging) or diseases once thought to be under control but are now becoming more prominent (re-emerging) for various reasons: a. Adaptation to new environments because of a change in geography, climate, (no population (herd) immunity) – AIDS, West Nile Virus, Measles, Monkey Pox. b. New technology – fecal contamination in slaughterhouses, fields bring exposure to Salmonella, E.coli. Water contamination by Cryptosporidium and Giardia are not killed with usual water treatment methods. c. Adaptation to new hosts (mutations) – Influenza, SARS Coronavirus. d. Humans encroaching into new environments – Hantavirus, Ebola virus. e. New forms or new portals of entry – variant Creutzfeldt Jakob disease in humans thought to be contracted from eating beef from cows with mad cow disease f. Resistance to current antimicrobial agents – malaria, TB, hospital strains g. Lack on control through climate change or no vaccinations, other.

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Morbidity and Mortality Infectious Diseases – different for developing and developed 1. Morbidity – illness Most common infectious disease in U.S. – diarrhea, sexually transmitted diseases 2 Mortality – death 2

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Core Concepts and new discoveries in microbiology we will discuss throughout semester 1. Biofilms 2. Antimicrobial resistance and Gene transfer 3. Mutation, adaptation and immune evasion 4. Immunocompromised individuals 5. Vaccines 6. Biotechnology (includes vaccines and gene therapy) 7. Microbiome and Normal Microbiota in health and disease 8. Emerging and re-emerging infections 7. Persistent infectious disease and cancer

History of Microbiology A Leeuwenhoek (1673) – discovered microorganisms by visual observation using simple microscopes (magnifying glasses) that he created. Father of Bacteriology. B.

Hooke (1665) - Theory of Biogenesis (Cell theory) – cells from cells, life from life

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Most scientists of the day believed in the Spontaneous Generation Theory - life from nonliving material (abigenesis). Rotting flesh bred maggots, flies came from manure, and wheat bred mice.

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Francesco Redi – among the first to disprove spontaneous generation by using experimental theory. Showed that maggots did not emerge de novo from putrified meat if the meat was covered.

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Jablot, Needham, Spallanzani – life did not arise spontaneously. Air was the source of the microbes which helped to disprove spontaneous generation. Prevented growth in meat by covering, broth by either sealing after heating or heating the air leading into the broth preventing entry of any new live microbes.

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Pasteur – contaminating organisms in broth infusions were introduced from the air in the form of dust particles. Discovered fermentation and pasteurization.

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Germ Theory of Disease – Pasteur and Koch were the fathers of the Germ Theory of Disease. Proved that infectious diseases are caused by microorganisms.

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Koch’s postulates (see text) a. Agent causing infectious disease; isolated in pure culture; cause the same disease in another. b. Can not always be met today a. Some organisms cannot be grown in pure culture b. Viral cancer - can’t insert DNA into host genome, unethical c. C. botulinum causes disease by release of toxin, d. Chronic infection (hepatitis) can’t be proved this way. e. Latent infection – organisms become dormant and cannot be measured.

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Semmelweis – Cited handwashing as important in iatrogenic disease and was criticized.

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Lister – believed that sepsis was caused by microbes. Developed antiseptic surgery using carbolic acid (phenol) to clean wounds, dressings and instruments. Significantly reduced gangrene.

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Antibiotics (treatment of infections) - Fleming discovered penicillin through serendipitous means

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Vaccination (helps prevent disease) - Edward Jenner developed smallpox vaccine by using cowpox lesions from dairy maids; Pasteur

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