Introduction and History of Microbiology PDF

Introduction and history of microbiology (First Microbiology Lecture) By Prof. Dr. Zainalabideen A. Al-Abdulla, DTM&H., MRCPI, Ph.D (Oxon), FRCPath. (U.K.) 2024/2025 Learning Objectives 1. Recommended textbook: Burton’s Microbiology for the Hea...

Introduction and history of microbiology (First Microbiology Lecture) By Prof. Dr. Zainalabideen A. Al-Abdulla, DTM&H., MRCPI, Ph.D (Oxon), FRCPath. (U.K.) 2024/2025 Learning Objectives 1. Recommended textbook: Burton’s Microbiology for the Health Sciences by P.G. Engelkirk, J. Buben- Engelkirk, and R. Fader; Eleventh or Tenth Edition. 2. What is microbiology? 3. To know the famous pioneers in the science of microbiology 4. To generally classify the different types of Microbes. 5. Why to study microbiology? 6. To understand what is medical microbiology?, and what is clinical microbiology? 7. To introduce the branches and specialty of microbiology. What is microbiology? It is an advanced biology that studies living organisms (microorganisms) as well as nonliving elements (acellular microbes). The former are all bacteria, all archaea, all protozoa, some algae, and some fungi. The latter, are microbes including viruses and prions. - Primitive microbes existed on earth since 3.5 billion years ago, while humans (homo sapiens) exited only for the past 100,000 years or so. - Bacteria and protozoa were the first microbes to be observed by humans. - Then it took about 200 years to discover their connection in causing infectious diseases. Pioneers in the Science of microbiology Aton van Leeuwenhoek (1632-1723) - The first person to see live bacteria and protozoa, so "he is referred to as the “Father of Microbiology, Bacteriology or Protozoology” - He was not a scientist (merchant from Holland), but had a hobby in a tiny glass lenses which he grinded and mounted in metal frames creating what today are known as single-lens microscope or simple microscope. Louis Pasteur (1822-1895) - He was a French chemist. - He is considered the founder of microbiology and modern medicine due to his numerous contributions. - Examples: Yeasts convert the glucose in grapes to ethyl alcohol (ethanol) by fermentation. Introduced the word “aerobes” (organisms that require oxygen) and “anaerobes” (organisms that do not require oxygen”. Developed a process called “pasteurization” to kill microbes (63-65 Celsius for 30 min. or 73-75 Celsius for 15 seconds). cont./... Cont./… Louis Pasteur Germ theory: Specific microbes cause specific infectious diseases such as Bacillus anthracis causes anthrax, and Mycobacterium tuberculosis causes tuberculosis. He developed vaccines against animal diseases such as anthrax in sheep, and rabies in dogs and then to treat human rabies (he treated a 9-year old boy “Joseph Meister”). To honor him “Pasteur Institute was created in 1888 in Paris as a center for infectious diseases and teaching (e.g. Yersin was a student of it who discovered later the bacterium of plaque (Yersinia ) Robert Koch (1843-1910) - He was a German physician. - He made numerous contributions: Koch’s Postulates: He proved scientifically that B. anthracis truly causes anthrax and discovered their spores (resistant thick wall cells). Developed methods for fixing and staining bacteria and cultivating them on solid media in Petri dish. He was able to produce by culture one type of organisms “pure culture” He discovered Vibrio cholerae that cause cholera cont./… Koch’s Postulates (1884) 1- A particular microbe must be found in a disease. 2- The microbe must be grown in a pure culture. 3- The isolated microbe must cause the same disease in laboratory animals. 4- The same microbe is recovered from the laboratory animals and grown again in a pure culture. Exceptions to Koch’s Postulate - Pathogens can not be grown in ordinary cultures such as obligate intracellular organism (viruses, Chlamydia, and Rickettsia). - The special organisms (fastidious) have special laboratory requirements (as Spirochetes of syphilis). Microbes - The microbes that can cause disease are known as “pathogens”, while those which can not cause a disease are called “nonpathogens” - Only 3% of microbes are pathogenic. - Some nonpathogenic microbes are beneficial to us (microbial allies), while those that harm us (microbial enemies). - The microbes that live on and in the human body are referred to as our “indigenous microbiota”. Why study microbiology? - Microbes live in and on human’s body are 10 times more than body cells (100 trillions vs. 10 trillions). For example they live on/in the skin, mouth, intestinal tract, and others. - These microbes are of 500-1000 species (indigenous microbiota = human microbiome or human biome). Some of these microbes are known as opportunistic pathogens since they can cause disease under certain circumstances or outside their normal habitat, e.g. E. coli out side the intestine becomes pathogenic as in urinary tract (urinary tract infection). Cont./…microbiology study - The human microbiome can inhibit the growth of pathogens (beneficial; so do not kill them by certain agents such as unnecessary use of antibiotics). - Others produce oxygen to earth (photosynthesis) such as algae, and cyanobacteria. - Some microbes decompose dead organisms and waste products (decomposers or saprophytes). Some genetically engineered microbes are used to - clean environments such as oil spills in seas which is known as (bioremediation). cont./... cont./…microbiology study - Intestinal bacteria such as E. coli produces vitamin K and vitamin B12. - Biotechnology: Some organisms can be used to produce useful substances such as insulin or growth hormone. This is done by insertion of specific gene or genes in microbes to manufacture specific substances - Antibiotics are produced by some organisms that can inhibit or kill other organisms. - Microbes can cause infectious diseases or microbial intoxication (see the Figure) Microbes share in manufacturing process 1. Food, e.g. acidophilus milk 2. Alcoholic beverages 3. Chemicals e.g. ethanol 4. Antibiotics, e.g. penicillin, tetracycline, etc. Medical and clinical microbiology Medical microbiology - Deals with microbiology and medicine. - It involves the study of pathogens, the diseases they cause and the body’s defenses against these disease. - It is concerned with epidemiology, transmission of pathogens, prevention, aseptic technique, treatment, immunology and production of vaccines. Clinical microbiology (Diagnostic microbiology) - It is a branch of medical microbiology. - It is concerned with laboratory diagnosis of human infectious diseases. Branches of microbiology Microbiologists: study microbes. Bacteriologists: Study structure, functions, and activities of bacteria. Phycologists: Study algae Protozoologists: Study protozoa and their activities. Mycologists: Study fungi Virologists: Study viruses and their effects on cells. Virologists and biologists are involved in genetic engineering (transfer of genetic materials- will be studied later) Parasitologists: Study arthropods, helminthes, and some protozoa Theory of Spontaneous generation (Abiogenesis) - This theory stated that life can arise spontaneously from nonliving materials (abiogenesis). - It was debated for two centuries (1650-1850). - Louis Pasteur and John Tyndall disproved the theory of abiogenesis. - Abiogenesis was replaced by another theory stating that life can only arise from preexisting life (biogenesis). This theory was first proposed a German scientist (Rudolf Virchow) in 1858. 7. NOTE ANSWER ALL THE 10 MCQ QUESTIONS IN YOUR BOOK (BURTON’S MICROBIOLOGY for the HEALTH SCIENCES, Eleventh/Tenth Editions)