Introduction to Microbiology PDF

Introduction to Microbiology Biomedical Science Benjamin Tighe Intended Learning Outcomes By the end of the session students should be able to: State the main division of micro-organisms into bacteria, viruses, fungi and protozoa, and distinguish between eukaryotes and prokaryotes. Recogni...

Introduction to Microbiology Biomedical Science Benjamin Tighe Intended Learning Outcomes By the end of the session students should be able to: State the main division of micro-organisms into bacteria, viruses, fungi and protozoa, and distinguish between eukaryotes and prokaryotes. Recognise the importance of microorganisms in health and disease Explain how micro-organisms cause disease Describe the conditions typically needed for microbial growth Become familiar with terms associated with micro-organisms Microbiology The study of organisms too small to be seen clearly with the naked eye (0.1-0.2mm diameter) Known as micro-organisms or microbes Includes: 1. Bacteria 2. Viruses 3. Fungi 4. Algae 5. Protozoa Questions before we start? We know we have microbes as part of our normal microflora Are they everywhere? Do we have a standardised ‘normal microflora’? 103 and 104 – which figure is associated with: A.) Human cells that make up the human body B.) Number of microbes that inhabit the human body Why study about microbiology? Why study about microbiology? Health Disease Prevention Manipulation of the host Infection Clinical appearance Host response Infection control Treatment / management / resistance Medical connection Local / global impact Eukaryotes and Prokaryotes – take 10 minutes to complete the main features of Eukaryotes and Prokaryotes Eukaryotes Prokaryotes Eukaryotes Large & complex Has clearly defined nucleus Membrane bound organelles Single or multi-cellular Prokaryotes Small & simple Have a nucleoid with no membrane Lacks internal membrane structure Always unicellular  Bacteria Fungi Micro- organisms Viruses Protozoa / parasites Micro-organisms in Health (countering microbephobia) Put on the discussion board why microbes support us in health? Valdes A.M., Walter J., Segal E., Spector T.D. Role of the gut microbiota in nutrition and health. BMJ. 2018;361:k2179. doi: 10.1136/bmj.k2179. Accessed December 2020 What gives rise to the variety in the proportion of microbes that live with us? Humans are born…….. Microbial introduction and the establishment of microbiome is a random process influenced by Establishment of the many factor like: microbiome starts at…….. 1. Mode of delivery 2. Diet The microbiome……….with 3. … age 4. … The study of human 5. … microbiome diversity started 6. … with Antonie Van 7. … Leeuwenhoek (1)  Obesity Disease Emerging disease Impact on conditions Metabolic impact e.g. diabetes Loss of function Quality of life Transmission Death Cost burden Emotional impact Poly-pharmacy How do micro-organisms cause disease? How Micro-organisms cause disease: The disease potential of micro- organisms is related to their Products Antigenic nature Defences The host Accessed December 2020 How do micro-organisms cause disease Endotoxins How do micro-organisms cause disease Exotoxins How do micro-organisms cause disease Metabolites How do micro-organisms cause disease Enzymes How do micro-organisms cause disease Toxins – complete the following table Comparison of main features of exotoxins and endotoxins Property Exotoxin Endotoxin Source Origin Chemistry Toxicity Clinical effects Antigenicity Integrity of bacterial cell Microbial Enzymes Define an enzyme Key features of enzymes Microbial enzymes support invasiveness Invasiveness – Allowing easy spread Protection Degrades host response Microbial Enzymes Enzymes are a form of catalyst which bacteria use to break down materials or synthesise their energy and building requirements Enzymes are capable of producing changes in other substances without undergoing change themselves Invasiveness – Allowing easy spread Protection Degrades host response Metabolites Products of metabolism Most relevant in dentistry – Streptococcus mutans and production of organic acids which leads to dissolution of enamel and commences caries process.  Please go to Introduction to Microbiology Workbook and complete the table referring to terms associated with Microbiology Environmental Microbial Growth Considerations Temperature pH Water Light Nutrition Respiration Temperature Please go to Introduction to Microbiology Workbook and complete the table referring to the environmental microbial growth factors The graph shows growth rate of bacteria as a function of temperature The graph shows growth rate of bacteria as a function of pH Moisture 80% + of the microbial cell is water & drying is tolerated differently by different species E.g. Staphylococci may survive outside the host in a dry environment for days whereas Treponema pallidum die in seconds Bacteria may not grow in dehydrated food, but growth may recommence once water is added Light All parasitic micro-organisms grow and survive best in darkness, therefore ultra violet light is lethal and may be used in some types of sterilisation X-rays will also damage microbe DNA and can be used to sterilise medical supplies  Nutrition Basic requirements similar to those of higher forms of life they require an energy and nitrogen, carbon, water and sulphur source Different enzyme systems which are specific in breakdown of certain nutrient compounds (nutrient recycling) Microbial growth can be enhanced by enriching the growth medium with specific nutrients and can be retarded using growth inhibitors Respiration refer to bacteria lecture References 1. Van Leeuwenhoek A. An abstract of a letter from Antonie van Leeuwenhoek. About animals in the scrurf of the teeth. Philosophical Transactions of the Royal Society of London. 1683;14:568-574 2. Valdes A.M., Walter J., Segal E., Spector T.D. Role of the gut microbiota in nutrition and health. BMJ. 2018;361:k2179. doi: 10.1136/bmj.k2179. Recommended Reading The following books are useful for further reading on some of the topics in infectious disease, but it is not essential for you to buy these: Oral Microbiology. P Marsh, M Martin (Wright, 1999). ISBN: 9780702061066. Essential Microbiology for Dentistry, 5th edition. L Samaranayake (Elsevier, 2011). ISBN: 0702074357