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Chapter 1 microbiology as a science
This document provides an overview of microbiology and its relevance to healthcare. It defines microbiology as the study of microorganisms such as bacteria, viruses, and fungi. It discusses pioneers in microbiology like Van Leeuwenhoek, Pasteur, and Koch and how they advanced the germ theory of disease. The document also summarizes Koch's postulates, exceptions to the postulates, and careers in microbiology like medical and clinical microbiology.
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Chapter 1 microbiology as a science
- 2. MICROBIOLOGY - The Science Preparedby: Sherleen Jane D. Fernandez, LPT
- 3. LEARNING OBJECTIVES: Definemicrobiology, pathogen, nonpathogen, and opportunistic pathogen. Differentiate between acellular microbes and microorganisms and list several examples of each. List several reasons why microbes are important (e.g., as a source of antibiotics). Explain the relationship between microbes and infectious diseases. List some of the contributions of Leuwenhoek, Pasteur, and Koch to microbiology. Differentiate between biogenesis and abiogenesis. Explain the germ theory of disease. Outline Koch’s Postulates and cite some circumstances in which they may apply. Discuss two medically related fields of microbiology. Differentiate between infectious diseases and microbial intoxications.
- 4. What is Microbiology? Microbiology - isthe study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa.
- 5. TYPES OF BACTERIA PATHOGENS Disease causing microorganisms also known as infectious agents. 3% of known microbes “Microbial enemies” NON-PATHOGENS Microbes that do not cause disease Some are beneficial to us whereas others have no effect on us at all “Microbial allies”
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- 9. • We have,living on and in our bodies (skin and in our mouth and gastrointestinal tract), approximately 10 times as many microbes as the total number of cells that make up our bodies. Indigenous Microbiota
- 10. • Some ofthe microbes that colonize (inhabit) our bodies are known as opportunistic pathogens (or opportunists). Although these microbes usually do not cause us any problems, they have the potential to cause infections if they gain access to the part of our anatomy where they do not belong.
- 11. • Microbes areessential for life on this planet as we know it. For example, some microbes produce oxygen by the process known as photosynthesis.
- 12. • Many microbesare involved in the decomposition of dead organisms and the waste products of living organisms. Decomposition Decomposers or Saprophytes
- 13. • Some microbes arecapable of decomposing industrial wastes (oil spills, for example).
- 14. • Many microbes areinvolved in elemental cycles, such as the carbon, nitrogen, oxygen, sulphur, and phosphorous cycles.
- 15. • Algae andbacteria serve as food for tiny animals. Then, larger animals eat the smaller creatures, and so on.
- 16. • Some microbeslive in the intestinal tracts of animals, where they aid in the digestion of food and, in some cases, produce substances that are of value to the host animal.
- 17. • Many microbesare essential in various food and beverage industries, whereas others are used to produce certain enzymes and chemicals.
- 18. • Some bacteriaand fungi produce antibiotics that are used to treat patients with infectious diseases
- 19. Antibiotic era Wehave all heard of the Pre-Antibiotic Era, prior to the 1940’s when millions of people died from common bacterial infections because antibiotics were not used to treat them. In the last 50 years we have enjoyed the luxury of knowing that bacterial infections can almost always be cured by using antibiotics. We are now in the Antibiotic Era.
- 20. Post-Antibiotic Era Aswe enter the 21st Century, we are gradually slipping into the Post-Antibiotic Era, a time when antibiotics no longer work because bacteria have become resistant to all the antibiotics. The change will not come as suddenly as the start of the Antibiotic Era, because the change to antibiotic resistant germs has been slow, up until now. New strains are rapidly developing
- 21. • Microbes areessential in the field of genetic engineering. • For many years, microbes have been used as “cell odels”.
- 22. • Finally, wecome to diseases. Microbes cause two categories of diseases: infectious diseases and microbial intoxications.
- 24. MICROBIOLOGY & INFECTIOUSDISEASE Today microbiology is mentioned frequently in the news. It affects many facets of our daily lives, including: The air we breathe The food we eat The hospitals where we go for treatment of illness and injury The natural disasters which sometimes occur without warning
- 25. THE RELEVANCE OF MICROBIOLOGYTO HEALTH CARE • There has always been disease. • For generations, little could be done to treat or prevent disease. • Advances in public health awareness lessened the effects of infection. • Infectious disease utilizes a large percentage of health care. • Health care professionals need to understand how pathogens cause disease.
- 26. …THE RELEVANCE OF MICROBIOLOGYTO HEALTH CARE • The discovery of antibiotics began to prevent serious infection. • Vaccination and better sanitation practices reduced the incidence of infectious diseases. • For a time, most infectious diseases were thought to be under control.
- 27. …THE RELEVANCE OF MICROBIOLOGYTO HEALTH CARE • Diseases once thought to be under control are reappearing • Pathogens are showing increasing resistance to antibiotics. • New diseases are emerging and organisms that were thought to be harmless have been discovered to cause disease in certain circumstances. • A fundamental understanding of microbiology has never been more relevant.
- 28. INFECTIOUS DISEASE • Onlya tiny fraction of microorganisms cause infections. • A microorganism that causes an infection is called a pathogen. • Only a fraction of pathogens affect humans.
- 29. …INFECTIOUS DISEASE • Thepotential of a pathogen to cause disease is referred to as its degree of virulence. • Many bacteria and some fungi are part of the normal microbial flora of the body. • They naturally colonize the skin and mucosal surfaces. • Most of the time, these organisms are completely harmless.
- 30. ...INFECTIOUS DISEASE • Somepathogens are always highly virulent. • Highly virulent pathogens are always associated with disease. Most pathogens can be looked at from the following 3 perspectives: 1. Epidemiology 2. Pathogenesis 3. Host defense
- 31. EPIDEMIOLOGY In epidemiology, pathogensare studied by how well they meet the five requirements of infection: • Entry (Get in) • Establishment (Stay in) • Defeat the host defense • Damage the host • Be transmissible
- 32. EPIDEMIOLOGY In epidemiology,pathogens are classified by the transmission mechanisms they use. Such as: • Air • Food or water • Insect vectors • Person-to-person contact Pathogens can also be classified according to their geographic distribution
- 33. EPIDEMIOLOGY • Providing thebest care for infected individuals and protection of others involves a clear understanding of the 5 requirements for infection. • Knowing how an organism gains entry and how it spreads are vital to care for infected individuals It allows for the implementation of strategies to limit spread. It also helps in understanding of the spread of disease.
- 34. EPIDEMIOLOGY Epidemics are causedby a variety of factors, including the following: • Poor socioeconomic conditions • Ignorance of how infections occur • Poor hygiene • Natural disasters
- 35. PATHOGENESIS Virulence factors arerequired for a pathogen to do the following: Persist in the patient Cause disease Escape or defeat host defenses
- 36. PATHOGENESIS Pathogens employ avariety of methods to accomplish infection. Bacterial pathogens can: • Produce digestive enzymes • Produce toxins
- 37. PATHOGENESIS Symptoms can beassociated with particular types of infection: Coughing – respiratory infection Diarrhea – digestive infection Nervous system dysfunction – central nervous system
- 38. HOST DEFENSE • Infectionis a complex and competitive struggle. • It can be characterized as pathogens versus host defense. • The outcome of this struggle depends on the success or failure of the host defense. Failure of the host defense = infection
- 39. HOST DEFENSE Many pathogenshave developed methods to defeat host defenses. Some directly attack host defenses Some change their looks (a form of camouflage) Some hide
- 40. TREATMENT OF INFECTIOUSDISEASES Many potent and successful tools are available to defeat infection. These include: 1. Antibiotics 2. Disinfectants and antiseptics Antibiotics are toxic chemicals and therefore must act selectively. They must kill the disease-causing microorganisms but not harm the patient.
- 41. TREATMENT OF INFECTIOUSDISEASES • Treatments are easier for bacterial infections than for fungal and viral diseases. • Viruses are intracellular parasites so either: 1. They must be attacked before entry into a host cell. or 2. The infected host cells must be killed to kill the virus.
- 42. TREATMENT OF INFECTIOUSDISEASES The best treatment of disease is PREVENTION.
- 43. TREATMENT OF INFECTIOUSDISEASES Public health measures include: • Disinfection of water supplies • Monitoring food supplies • Proper hygiene and sanitation • Proper waste removal and treatment • Insect and pest control
- 44. TREATMENT OF INFECTIOUSDISEASES • Immunization requires that we understand immune mechanisms and that we design vaccines that will successfully stimulate protection. Immunization also requires: Public health control of the immunization of children Design and development of new vaccines An ability to ensure the safety of vaccines
- 45. FIRST MICROORGANISMS ONEARTH Fossils of primitive microorganisms date back about 3.5 billion years ago. Candidates for the first microorganisms on Earth are archaea and cyanobacteria.
- 46. EARLIEST KNOWN INFECTIOUSDISEASES Infectious diseases of humans and animals have existed for as long as humans and animals have inhabited the planet. Earliest known account of pestilence occurred in Egypt in about 3180 BC.
- 47. PIONEERS IN THESCIENCE OF MICROBIOLOGY
- 48. ANTON VAN LEEUWENHOEK (1632-17230 • “Fatherof Microbiology” • Not a trained scientist! • Made many simple single-lens microscopes • Observed ”animalcules” (bacteria and protozoa)
- 49. LOUIS PASTEUR (1822-1895) • Frenchchemist who made numerous contributions to microbiology • Investigated different fermentation products • Developed the pasteurization process • Discovered life forms that could exist without oxygen (anaerobes) • Developed several vaccines, including rabies and anthrax vaccines
- 50. LOUIS PASTEUR • Pasteurlaid the foundation of aseptic techniques, techniques that prevent contamination by unwanted microbes. These techniques are based on Pasteur’s idea that microbes can be killed by heat and that procedures can be designed to inhibit the access of airborne microbes to nutrient environment. • He disapprove the idea that microorganisms spontaneously generated from non-living matter.
- 51. Pasteur discoveredforms of life that could exist in the absence of oxygen. Pasteur discovered the “Germ Theory of Disease”.
- 52. ROBERT KOCH (1843-1910) • Germanphysician who made numerous contributions to microbiology • Made significant contributions to the germ theory of disease • Discovered that Bacillus anthracis produced spores • Developed methods of fixing and staining bacteria • Developed methods to cultivate bacteria
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- 54. Koch’s Postulates: 1. Aparticular microbe must be found in all cases of the disease and must not be present in healthy animals or humans. 2. The microbe must be isolated from the diseased animal or human and grown in pure culture in the laboratory. 3. The same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible laboratory animals. 4. The same microbe must be recovered from the experimentally infected animals and grown again in pure culture.
- 56. If anorganism fulfill Koch’s postulates, it has been proven to be the cause of that particular infectious disease. Koch’s Postulates helped prove the germ theory of disease. Koch gave a tremendous boost to the development of microbiology by stressing laboratory culture and identification of microorganisms. Circumstances do exist in which Koch’s Postulates cannot be fulfilled.
- 57. Exceptions to Koch’sPostulates: To fulfil Koch’s Postulates, it is necessary to grow the pathogen in the laboratory (in vitro) in or on artificial culture media. However, some pathogens will not grow on artificial media.
- 58. To fulfilKoch’s Postulates, it is necessary to infect laboratory animals with the pathogen being studied. However, many pathogens are species-specific, meaning that they infect only one species of animal.
- 59. Some diseases, calledsynergistic infections or polymicrobial infections, are caused not by one particular microbe, but by the combined effects of two or more different microbes.
- 60. Another difficultythat is sometimes encountered while attempting to fulfil Koch’s Postulates is that certain pathogens become altered when grown in vitro.
- 61. The Golden Ageof Microbiology (1857-1914) • Many disease producing organisms were discovered. • Microbial metabolism studies undertaken. • Microbiological techniques refined. • A better understanding of the role of immunity and ways to control and prevent infection by microbes.
- 62. CAREERS IN MICROBIOLOGY •A microbiologist is a scientist who studies microbes. • There are many career fields within the science of microbiology (e.g., bacteriology, phycology, protozoology, mycology, parasitology, and virology).
- 63. Medical & ClinicalMicrobiology Involves the study of pathogens, the disease they cause and the body’s defenses against disease. Concerned with epidemiology, transmission of pathogens, disease-prevention measures, aseptic techniques, treatment of infectious diseases, immunology, and production of vaccines.
- 64. Your future career: NURSE Putyour name here, RN
Editor's Notes
- #2 A little progress each day adds up the biggest result
- #5 This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents. Micro means very small – anything so small that it must be viewed with a microscope. Therefore, MICROBIOLOGY can be defined as the study of microbes.
- #7 Acellular microbes also known Cellular microbes includes the less complex prokaryotes (organism composed of cell that lack true nucleus) and the more complex eukaryotes (organisms composed of cells that contain a true nucleus)
- #9 Although they are very small, microbes play significant roles in our lives.
- #10 10 trillion cells x 10 = 100 trillion microbes. - 500 to 1,000 different species of microbes live on and in us. Indigenous microbiota – the microbes that live on and in our body, benefits us For example, the IM inhibit the growth of pathogens in those areas of the body where they live by occupying space, depleting the food supply and secreting materials that may prevent or reduce the growth of pathogens.
- #11 For example, a bacterium called Escherichia coli lives in our intestinal tracts. This organism does not cause us any harm as long as it remains in our intestinal tract, but can cause disease if it gains access to our urinary bladder, bloodstream, or a wound. Other opportunists strike when a person becomes run-down, stressed out, or debilitated (weakened) as a result of some disease or condition. Thus, opportunistic can be thought of as a microbes awaiting the opportunity to cause disease.
- #12 Actually, microbes contribute more oxygen to our atmosphere than plants do. Thus, organisms that require oxygen – human for example – owe a debt of gratitude to the algae and cyanobacteria (a group of photosynthetic bacteria) that produce oxygen.
- #13 Decomposition is the process by which organic substances are broken down into simpler organic matter. A saprophyte or saprotroph is an organism which gets its energy from dead and decaying organic matter. This may be decaying pieces of plants or animals. Imagine living in a world with no decomposers? Saprophytes aid in fertilization by returning inorganic nutrients to the soil. They break down dead and dying organic materias (plants and animals) into nitrates, phosphates, and other chemicals necessary for the growth of plants.
- #14 Thus, we can use microbes – genetically engineered microbes, in some cases – to clean up after ourselves. BIOREMEDIATION
- #15 Knowledge of these microbes is important to farmers who practice crop rotation to replenish nutrients in their fields and to gardeners who keep compost pits as a source of natural fertilizer.
- #16 Thus, microbes serve as important links in food chains.
- #17 E.g: E. coli – human intestinal tract – produce vitamin K and B1, absorbed by the human body. Although termites eat wood, they cannot digest it. *cellulose-eating protozoa in their intestinal tract – where they get their nutrients
- #18 BIOTECHNOLOGY - the exploitation of biological processes for industrial and other purposes, especially the genetic manipulation of microorganisms for the production of antibiotics, hormones, etc.
- #19 Antibiotics - a medicine (such as penicillin or its derivatives) that inhibits the growth of or destroys microorganisms.
- #21 In the next 5-10 years we will start noticing the change much more dramatically.
- #22 *Microbiologists have engineered bacteria and yeast to produce a variety of useful substances, such as insulin, growth hormones, and vaccines.
- #23 Health care professionals must be aware of: Infectious disease Pathogens that caused them Source of the pathogen How are these diseases are transmitted How to protect yourself and your patients from these diseases
- #24 Infectious: Gas gangrene Gangrene is the death of body tissue. Clostridial myonecrosis, a type of gas gangrene, is a fast-spreading and potentially life-threatening form of gangrene caused by a bacterial infection from Clostridium bacteria. The infection causes toxins to form in the tissues, cells, and blood vessels of the body. These bacteria will release toxins that cause tissue death and release a gas. Most gangrene infections occur in situations where open wounds from an injury or surgery are exposed to bacteria. Non-traumatic gas gangrene, a more rare form of gas gangrene, can develop when blood flow to body tissues is compromised and bacteria gets inside. There is a greater risk in people who have a peripheral vascular disease, atherosclerosis, or diabetes mellitus. MI: Staphylococcal food poisoning Foodborne botulism
- #30 Pathogens can be categorized based on their degree of virulence.
- #32 Epidemiology is the study of factors determining the frequency and distribution of disease.
- #33 Some are found worldwide, others are restricted to certain geographic areas.
- #37 Sometimes, damage associated with an infection is due to over active host defenses. Viral pathogens can kill the host cells.
- #42 Fungal cells are very similar to human cells so very few chemicals are selectively toxic.
- #43 Prevention involves public health measures and immunization.
- #47 Rabies, anthrax, botulism, measles, smallpox, thypoid fever, thypus fever,worm infections, syphilis
- #49 FATHER OF BACTERIOLOGY, FATHER OF PROTOZOOLOGY Fabric merchant, minor city official in Holland 500 microscopes, 200 – 300x its size
- #51 -
- #52 He introduced the terms aerobes and anaerobes The theory that specific microbes cause specific infectious disease. Anthrax – Bacillus anthracis Tuberculosis – Mycobacterium tuberculosis
- #53 He discovered M. tuberculosis and V. cholerae
- #56 A particular microbe must be found in all cases of the disease and must not be present in healthy animals or humans. The microbe must be isolated from the diseased animal or human and grown in pure culture in the laboratory. The same disease must be produced when microbes from the pure culture are inoculated into healthy susceptible laboratory animals. The same microbe must be recovered from the experimentally infected animals and grown again in pure culture.
- #58 1. Such pathoges include viruses, ricketsias, chlamydias because they can only multiply and survive only within the living host cells.
- #59 For example, some pathogens that infects human will infect only humans. X human volunteers – ethical considerations
- #60 Necrotizing ulcerative gingivitis and bacterial vaginosis. It is difficult to reproduce such synergistic infections in the laboratory.
- #61 Some become less pathogenic, whereas others become nonpathogens. Thus, they will no longer infect animals after being cultured on artificial media.
- #62 The period from 1860 to 1900 is often named the Golden Age of Microbiology. During this period, rapid advances, spear-headed by Louis Pasteur and Robert Koch, led to the establishment of microbiology as a science.
- #63 Bacteriologst – study the structures, functions and activities of bacteria. Phycologist – algae Protozoologist – protozoa and their activities Mycologist – fungi Parasitologists – parasites Virologist – prions, viroids and acellular infectious agents that are even smaller than viruses.