Microbiology Lecture Notes PDF

MICROBIOLOGY MR. REGINALD ARTHUR-MENSAH JNR Sunday, February 7, 2021 1  COURSE OUTLINE » General characteristics of the » Host-parasite relationship Bacterial cell...

MICROBIOLOGY MR. REGINALD ARTHUR-MENSAH JNR Sunday, February 7, 2021 1  COURSE OUTLINE » General characteristics of the » Host-parasite relationship Bacterial cell » Immune system » Classification of micro-organisms » Methods of taking specimen » Microbial infections » Interpretation of common laboratory » Definitions and basic principles of results sterilization and disinfection » Chain of infection » Ecology and habitat conditions suitable for growth of aerobes and anaerobes » Infection prevention » Pathogenesis of parasitic infections Sunday, February 7, 2021 2  THINGS TO NOTE… » Attendance to lectures is essential for success. Students who miss lectures usually do not perform best. » To gain the most from lectures, it is best to read any relevant text material beforehand, READ WIDE on the course outline, test questions can take any form. » Concentrate during lectures, do not simply sit back passively, listen attentively and make your own LEGIBLE notes, do not make SKETCHY notes. » During lectures, concentrate on what is being said, E.g. points emphasized by tone of voice and be sure to capture all the main ideas, concepts and definitions. 3 » FEEL FREE TO ASK QUESTIONS during class when you don’t understand something, it is very likely others in the class don’t understand and you will be the one to help them. » When studying your notes it is a good idea to emphasize the most important points with a highlighter as when reading a textbook. » I’ll take recap of previous lectures anytime we have a class. » POP QUIZ, CLASS QUIZZES can happen at any time so be prepared. » Class sessions are to be very interactive as much as possible, No QUIETNESS please. 4 Some microbial interactions… Sunday, February 7, 2021 5 Sunday, February 7, 2021 6 The human microbiome plays an important role in the control of vital homeostatic mechanisms in the body. These include enhanced metabolism, resistance to infection and inflammation, prevention against autoimmunity as well as an effect on the gut-brain axis. SCFA, Short-Chain fatty acid. 7 Sunday, February 7, 2021 8 Euprymna scolopes, the bobtail squid Sunday, February 7, 2021 A blood fed, Aedes aegypti mosquito 10 Sunday, February 7, 2021 11 Sunday, February 7, 2021 A patient on a ventilator due to COVID-19 12  WHAT HAS CHANGED OUR WORLD!!! Sunday, February 7, 2021 13  Handwashing Sunday, February 7, 2021 14  Wear face mask Sunday, February 7, 2021 15  Use hand sanitizer Sunday, February 7, 2021 16  Don’t touch your face! Sunday, February 7, 2021 17  Physical distancing Sunday, February 7, 2021 18  INTRODUCTION AND BRIEF HISTORY Sunday, February 7, 2021 19 » The importance of microbiology cannot be overemphasized because society benefits from these microorganisms immensely. » Microorganisms are everywhere: almost every natural surface is colonized by them, from the human body to the deep ocean. » Used in bread making, cheese production, yoghurt, beer production, antibiotics, vaccines, vitamins, enzymes etc. » They are also involved in food spoilage. Sunday, February 7, 2021 20 »Also make possible the carbon, oxygen, nitrogen and sulfur cycle in the terrestrial and aquatic ecosystems. »We swallow millions of microbes everyday with no ill effects. We depend on some to help us digest our food. »Responsible for human, animal and plant diseases. Sunday, February 7, 2021 21 »Microbiology is the study of all organisms too small to be seen clearly with the unaided eye. ▪ It is the study of microorganisms. ▪ Bacteria, viruses, algae, fungi, protozoa. Sunday, February 7, 2021 22 Classification of microorganisms » Before the existence of microbes was known, all organisms were grouped into either the animal kingdom or the plant kingdom. » When microscopic organisms with characteristics of animals and plants were discovered late in the seventeenth century, a new system of classification was needed. » Still, biologists couldn’t agree on the criteria for classifying these new organisms until the late 1970s. » In 1978, Carl Woese devised a system of classification based on the cellular organization of organisms. It groups all organisms in three domains as follows: 23 » Bacteria (cell walls contain a protein–carbohydrate complex called peptidoglycan) » Archaea (cell walls, if present, lack peptidoglycan) » Eukarya, which includes the following: ▪ Protists (slime molds, protozoa, and algae) ▪ Fungi (unicellular yeasts, multicellular molds, and mushrooms) ▪ Plants (mosses, ferns, conifers, and flowering plants) ▪ Animals (sponges, worms, insects, and vertebrates) Sunday, February 7, 2021 24 »Disciplines of study within microbiology include: ▪ Immunology ▪ Bacteriology ▪ Epidemiology ▪ Mycology ▪ Biotechnology ▪ Bioremediation ▪ Parasitology ▪ Virology Sunday, February 7, 2021 25  Anthony van Leeuwenhoek of Delft Holland, was the first person to observe and describe microorganisms accurately [1632-1723]. Sunday, February 7, 2021 26 Conflict over spontaneous generation » Spontaneous generation ▪ Aristotle believed [384 – 322 BC] » This view was finally challenged by the Italian physician, Francesco Redi, [1626-1697]. He carried out experiments on decaying meat and its ability to produce maggots. » Louis Pasteur [1822-1895] settled this matter once and for all. Sunday, February 7, 2021 27 Louis Pasteur’s experiment Filtered air through cotton and objects resembling plant spores were trapped. If a piece of the cotton was placed in sterile medium, microbial growth occurred. Next, he placed nutrient solution in flasks, heated their necks and bent them into variety of curves while keeping the ends of the necks open. Boiled solutions and allowed to cool. No growth took place though contents were exposed to air, because dust and germs had been trapped on the walls of the curved necks. If necks were broken, growth commenced immediately. Sunday, February 7, 2021 28 Sunday, February 7, 2021 29 Spontaneous generation of microbes by Francesco Redi Sunday, February 7, 2021 30  English physicist John Tyndall [1820-1893] also debunked spontaneous generation in 1877 by demonstrating that dust did indeed carry germs and that if dust was absent, broth remained sterile even if directly exposed to air. Sunday, February 7, 2021 Louis Pasteur John Tyndall 31 Microorganisms and diseases » It took many years for scientists to establish the connection between microorganisms and diseases. » Introduced the germ theory of diseases. » Agostini Bassi [1773-1856] first showed microorganisms could cause disease when he demonstrated in 1835 that silkworm disease was due to fungal infection. » In 1845, M. J. Berkeley proved that the great Potato Blight disease of Ireland was caused by a fungus. 32 »Indirect evidence that microorganisms were agents of human disease came from work of the English surgeon Joseph Lister [1827-1912] on the prevention of wound infections. »Developed a system of antiseptic surgery designed to prevent microorganisms from entering wounds. Instruments were heat sterilized and phenol was used on surgical dressings and at times sprayed over the surgical area. Sunday, February 7, 2021 33 »Remarkably successful and transformed surgery after Lister published his findings in 1867. »This also provided indirect evidence for the role of microorganisms in disease because phenol which killed bacteria also prevented wound infections. Sunday, February 7, 2021 34 English Surgeon, Joseph Lister Sunday, February 7, 2021 35 »First direct demonstration of the role of microorganisms in causing diseases came from the study of anthrax by German Physician Robert Koch [1843-1910]. »He used the criteria proposed by his former teacher, Jacob Henle [1809- 1885] to establish the relationship between Bacillus anthracis and Anthrax and published his findings in 1876. Sunday, February 7, 2021 36 »Koch injected healthy mice with material from diseased animals and the mice became ill. After transferring anthrax by inoculation through a series of 20 mice, he incubated a piece of spleen containing the anthrax Bacillus in beef serum. The bacilli grew, reproduced and produced spores. When the isolated bacilli or spores were injected into mice, anthrax developed. »His criteria for proving the relationship between a microorganism and disease became known as Koch’s postulates. Sunday, February 7, 2021 37  » The microorganism must be present in every case of the disease but absent from healthy organisms. » The suspected microorganism must be isolated and grown in a pure culture. » The same disease must result when the isolated microorganism is inoculated into a healthy host. » The same microorganism must be isolated again from the diseased host. Sunday, February 7, 2021 Robert Koch 38  Robert Koch examining a specimen in his laboratory. Sunday, February 7, 2021 39 Sunday, February 7, 2021 Koch’s postulate 40 Sunday, February 7, 2021 41  Other experiments to disprove the spontaneous generation of microbes. Sunday, February 7, 2021 42 Nomenclature » The system of nomenclature (naming) for organisms in use today was established in 1735 by Carolus Linnaeus. » Scientific names are latinized because Latin was the language traditionally used by scholars. » Scientific nomenclature assigns each organism two names; ▪ The genus (plural: genera) is the first name and is always capitalized; ▪ The specific epithet (species name) follows and is not capitalized. 43 » Scientific names can, among other things, ▪ Describe an organism, ▪ Honor a researcher, or ▪ Identify the habitat of a species. » e.g., consider Staphylococcus aureus, a bacterium commonly found on human skin. Staphylo- describes the clustered arrangement of the cells; - coccus indicates that they are shaped like spheres. The specific epithet, aureus, is Latin for golden, the color of many colonies of this bacterium. Sunday, February 7, 2021 44 »The genus of the bacterium Escherichia coli (esh′er-IK-e¯-ah KO¯ - lI¯, or KO¯ -le¯) is named after a physician, Theodor Escherich, whereas its specific epithet, coli, reminds us that E. coli live in the colon, or large intestine. Sunday, February 7, 2021 45  PROKARYOTE CELL STRUCTURE AND FUNCTIONS » A unicellular organism have cells lacking membrane-bound nuclei. E.g. bacteria, algae Size, Shape and Arrangement » Most bacteria have one or two shapes. » Cocci (Coccus) are spherical cells. Can exist as individual cells or in characteristic arrangement useful in bacterial identification. Sunday, February 7, 2021 47 » Diplococci (Diplococcus) when cocci divide and remain together to form pairs. » Long chains of cocci result when cells adhere after repeated divisions in one plane, often seen in the genera Streptococcus, Enterococcus and Lactococcus. 48 » Staphylococcus divides in random planes to generate irregular grapelike clumps. » Members of the genus Micrococcus often divide in two planes to form square groups of four cells called Tetrads. 49 » Genus Sarcina, Cocci divide in three planes producing cubical packets of eight cells. Sunday, February 7, 2021 50 ▪Try this Sunday, February 7, 2021 51 » Other common types of bacterial shape is rod shape often called Bacilli (Bacillus). Shape of rod’s end may be flat, rounded, cigar-shaped or bifurcated. May occur single or remain together after division to form pairs or chains. » Coccobacilli Sunday, February 7, 2021 52  Bacilli megaterium—rods in chains Sunday, February 7, 2021 53 » Few rod-shaped bacteria, Vibrios are curved to form distinctive commas or incomplete spirals. Sunday, February 7, 2021 54 » Actinomycetes characteristically form long multinucleate filaments or hyphae that branch to produce a network called a mycelium. » Many bacteria are shaped like long rods twisted into spirals or helices. They are spirilla if rigid and spirochetes when flexible. » A few bacteria are flat. » Some bacteria are variable in shape and lack a single characteristic form. These are called pleomorphic. 55  R. rubrum—spiral-shaped spirilla Actinomyces—a filamentous bacterium Leptospira interrogans—a spirochete Sunday, February 7, 2021 56 Sunday, February 7, 2021 57  Haloquadratum walsbyi, a square archaeon Sunday, February 7, 2021 58 Sunday, February 7, 2021 59 » Bacteria vary in size as much as in shape. » The smallest (e.g. members of genus Mycoplasma) are about 0.3 µm in diameter. » Nanobacteria and utramicrobacteria appear to range from around 0.2 µm to less than 0.05 µm in diameter. » E. coli, a Bacillus is 1.1 to 1.5 µm wide by 2 to 6 µm long. Sunday, February 7, 2021 60 »Some spirochates occasionally reach 500 µm in length and cyanobacterium, Osillatoria is about 7 µm in diameter. »Epulopiscium fishelsoni grows as large as 600 by 80 µm. Sunday, February 7, 2021 61  PROKARYOTE CELL ORGANIZATION » Bounded by a chemically complex cell wall. » Separated from it by a periplasmic space lies the plasma membrane. » Genetic material is the nucleoid, not separated from cytoplasm by membranes. » Ribosomes and inclusion bodies scattered about in the cytoplasmic matrix. » Flagella for locomotion. » Pili for attachment to surfaces and mating. » Some are surrounded by a capsule or slime layer external to the cell wall. Sunday, February 7, 2021 62 Sunday, February 7, 2021 Prokaryote cell organization 63  Morphology of a prokaryotic cell. Sunday, February 7, 2021 64 Plasma membrane Selectively permeable membrane, mechanical boundary of cell, nutrient and waste transport, location of many metabolic processes (respiration, photosynthesis), detection of environmental cues for chemotaxis. Gas Vacuole Buoyancy for floating in aquatic environments Ribosomes Protein synthesis Inclusion bodies Storage of carbon, phosphate and other substances Nucleoid Localization of genetic material Periplasmic space Contains hydrolytic enzymes and binding proteins for nutrient processing and uptake Cell wall Shape and protection from lysis in dilute solutions Capsules and slime layers Resistance to phagocytosis, adherence to surfaces Fimbriae and pili Attachment to surfaces, bacterial mating Flagella Movement Endospore Survival under harsh conditions 65