Introduction to Microbiology

• Microbiology is the study of organisms too small to be seen with the naked eye.

Microbes

• Microbes, also known as Microorganisms, are commonly called "germs" or "bugs.”
• Microbes include bacteria, viruses, fungi, algae, protozoa, and helminths.
• Prions ("infectious proteins") are a recent addition to the list of microbes.

Disciplines of Microbiology

• Bacteriology is the study of bacteria.
• Mycology is the study of fungi and yeast.
• Virology is the study of viruses.
• Parasitology is the study of parasitic protozoans and helminths.
• Immunology is the study of the humoral and cellular immune response to disease agents and allergens.

Importance of Microbiology

• Microbes play biological roles as decomposers, recyclers, and symbionts.
• They aid in animal digestion, especially in ruminants.
• Microbes are used in food microbiology to produce yogurt, cheese, beer, and bread.
• Microbes ensure food safety by preventing putrefaction and disease.
• Microbes are used in pharmaceuticals to produce complex drug molecules like insulin.
• Bioremediation uses microbes to clean up pollution.
• Some bacteria and viruses are pathogenic and can cause sickness.
• Fundamental biology relies on microbes to work out most biochemical pathways.

History of Microbiology

• Anton Van Leeuwenhoek discovered 'animalcules'.
• Robert Hooke discovered cells.
• Schwann developed the cell theory.
• Robert Koch lived from 1843-1910.
• Rudolf Virchow stated cells arise from pre-existing ones.
• Carolus Linnaeus developed classification systems.
• Ferdinand Cohn discovered endospores.
• Louis Pasteur developed vaccines, pasteurization, and the germ theory.
• Edward Jenner developed vaccines.
• Jablot Louis disproved spontaneous generation.
• Francesco Redi disproved spontaneous generation.
• Alexander Fleming (1929) accidentally discovered penicillin.
• Paul Ehrlich (1890s) worked with vaccines.
• Joseph Lord Lister developed antiseptics for surgical wound infections, and is known as the Father of Antiseptic Surgery.
• Walter Hesse (1846-1911) used agar as a solidifying agent for hardening media, which is extracted from seaweeds and red algae.
• Rechard Petri (1852-1921) used the agar dish to provide a large area for growth.
• Gram (1853-1935) introduced staining methods to demonstrate and distinguish between Gram-positive and Gram-negative bacteria.
• Raymond Sabouraud (1890-1910) developed culture media to study yeast and molds.
• Dimitri Ivanovski (1892) discovered that the tobacco mosaic virus could pass through filters used to remove bacteria.
• Selman Waksman (1940) discovered antibiotics such as tetracycline and streptomycin.
• Reska (1938) created the first electron microscope.
• Watson, Crick, Franklin, and Wilkins discovered the structure of DNA.

Spontaneous Generation

• Aristotle (384-322 B.C.) proposed spontaneous generation, the idea that living things can arise from nonliving matter.
• Francesco Redi's experiments showed that when decaying meat was kept isolated from flies, maggots never developed.
• Meat exposed to flies was soon infested and as a result, scientists began to doubt Aristotle's theory.
• Louis Pasteur disproved Abiogenesis and is considered the Father of Microbiology.
• Pasteur showed microbes caused fermentation, leading to the discovery of Germ Theory
• Pasteur studied spoilage of wine and dairy products, introducing pasteurization to prevent it.
• Pasteur used cotton plugs in cultures to prevent airborne contamination and devised Aseptic Technique.
• His discovery of pasteurization led to the introduction of the "germ theory of disease" in 1864.
• Pasteur stated that diseases are caused by the growth of microbes in the body and not by sins, bad character, or poverty.

Germ Theory of Diseases

• Robert Koch (1843-1910), using criteria developed by Jacob Henle (1809-1895), established the relationship between Bacillus anthracis and anthrax.
• Koch's Postulates are still used to establish the link between a microorganism and a particular disease.
• The causative agent must be present in all affected organisms but absent in healthy individuals.
• The agent must be capable of being isolated and cultured in pure form.
• When the cultured agent is introduced to a healthy, susceptible organism, the same disease must occur.
• Additionally, the same causative agent must be isolated again from the affected host.

Golden Age of Microbiology

• The period from 1860 to 1900 is named the Golden Age of Microbiology.
• Rapid advances spearheaded by Louis Pasteur and Robert Koch led to the establishment of microbiology as a science.
• Scientists looked for answers including if Is spontaneous generation of microbial life is possible involving Aristotle, Jablot, Redis, Louis Pasteur, what causes fermentation involving Louis Pasteur, what causes disease involving Louis Pasteur, Robert Koch, and how can we prevent infection and disease

Emerging Infectious Diseases (EID)

• EIDs are new diseases and the increasing incidence of old ones.
• Factors include evolutionary changes in existing organisms.
• The spread of known diseases into geographic areas is often due to modern transportation.
• Ecological changes resulting in the introduction of unusual agents.
• The emergence of antimicrobial resistance is a major factor.

Specific EIDs

• West Nile Encephalitis was first diagnosed in Uganda in 1937 and appeared in New York City in 1999.
• Invasive Group A Streptococcus is known as the "flesh-eating bacteria.”
• Escherichia coli 0157:H7 causes "bloody diarrhea" and hemorrhagic uremic syndrome (HUS).
• Bovine Spongiform Encephalopathy (BSE) or "mad cow" disease is caused by prions.
• Acquired Immunodeficiency Syndrome (AIDS) is is caused by HIV has hit Africa the hardest.
• Anthrax caused by Bacillus anthracis was sensationalized in 2001 when spores were disseminated via mail.
• H5N1 Avian Influenza is also known as Bird Flu.
• Three flu pandemics have occurred in the past century: the Spanish flu of 1918, Asian flu of 1957, and the 1968 Hong Kong flu.
• Smallpox is a contagious disease caused by a virus and is said to have originated over 3,000 years ago in India or Egypt.
• H1N1 Swine Influenza A is also known as Swine Flu.
• Ebola was first observed in 1976.
• There are diseases on the rise like AIDS, Avian Influenza, Ebola, Marburg, Cholera, Rift Valley Fever, Typhoid, Tuberculosis, Leptospirosis, Malaria, and Dengue, and on the decline, like Guinea worm, Smallpox, Yaws, Poliomyelitis, Measles, Leprosy, and Neonatal tetanus.