Med. Microbiology Mod:1 History & Chemistry of Microbiology

• Leeuwenhoek observations of microbes introduces most types of microorganisms to the world - protozoa
• Developed the first microscope, his profound observational skills and his detailed reports over a 50 year period and his discovery of many types of microorganisms “beasties”.

Because he was using a simple microscope, protozoa are bigger than bacteria.

• Bacteria
• Archaea
• Fungi
• Protozoa
• Algae
• Small multi-cellular animals.

• Prokaryotic – any unicellular microorganism that lacks a nucleus. Classification includes bacteria and archea.
• Eukaryotic – an organism made up of cells containing a nucleus composed of genetic material surrounded by a distinct membrane. Classification includes animals, plants, algae, fungi and protozoa.

• Is spontaneous generation of microbial life possible?
• What causes fermentation?
• What causes disease?
• How can we prevent infection & disease?

• The theory was developed by Aristotle, answer was widely accepted for over 2000 years because it seems to explain a variety of commonly observed phenomena, such as he appearance of maggot on spoiled meat.
• Fancesco Redi (late 1600s) demonstrated by a series of experiments using decaying meat what kept isolated from flies, maggots never developed, whereas meat exposed to flies was soon infested. As a result of experiments such as these, scientists began to doubt Aristotle’s theory and adopt the view that animals come only from other animals.

Pasteur determined that yeast ferment grape juice to produce alcohol, and that bacteria ferment grape juice to produce acids.

Pasteur’s discovery that bacteria are responsible for spoiling wine led naturally to his hypothesis in 1857 that microorganisms are also responsible for diseases. This idea came to be know as the germ theory of diease. Because a particular disease is typically accompanied by the same symptoms in all affected individuals, early investigators suspected that diseases such as cholera, tuberculosis and anthrax are each caused by a specific ger, called a pathogen.

• Modern principles of hygiene, involving sewage and water treatment, personal cleanliness, and pest control were improved.
• Use of antiseptics (Ignas Semmelweis), clean nursing practices (Florence Nighingale), adequate sewage treatment and a pure water supply (John Snow), vaccines (Edward Jenner), and chemotherapy ( Paul Ehrlich) help prevent infections & diseases.
• The development of principles in good hygiene started the foundations for infection control and epidemiology. Vaccines began the field of immunology. Ehrlich began the field of chemotheraphy.

• Fancesco Redi (late 1600s) demonstrated by a series of experiments using decaying meat what kept isolated from flies, maggots never developed, whereas meat exposed to flies was soon infested. As a result of experiments such as these, scientists began to doubt Aristotle’s theory and adopt the view that animals come only from other animals.
• John T. Needham boiled beef gravy and infusions of plant material in vials, which he then tightly sealed with corks. Some days later, Needham observed that the vials were cloudy, and examination revealed an abundance of “microscopical animals of most dimensions.”  As he explained it, there must be a “life force” that causes inanimate matter to spontaneously come to life because he had heated the vials sufficiently to kill everything.     
• Spallanzani (Lazzaro), an Italian Catholic priest, contradicted Needham’s finding. He boiled infusions for almost an hour and sealed the vials by melting their slender necks closed.  His infusion remained clear unless he broke the seal.  He concluded 3 things:  Needham either had failed to heat his vials sufficiently to kill all microbes or had not sealed them tightly enough.  Microorganisms (MO) exist in the air and can contaminate experiments.  And Spontaneous generation of MO doesn’t occur; all living things arise from other living things. 
• Pasteur boiled infusions long enough to kill everything. But instead of sealing the flask, he bent their necks into an S-shape, which allowed air to enter while preventing the introduction of dust and microbes into the broth.  He reported that his swan-neck flasks remained free of microbes even 18 moths later.  He broke the necks off some flasks, exposing the liquid in them directly to the air, and he carefully tilted oters so that the liquid touched the dust that had accumulated in their necks.  The next day, all these flask were cloudy with microbes.  He concluded that the microbes in the liquid were the progeny of microbes that had been on the dust particles in the air.

• A group of observation leads a scientist to ask a question about some phenomenon.
• The scientist generates a hypothesis – that is, a potential answer to the question.
• Scientist designs and conducts an experiment to test the hypothesis.
• Based on the observed results of the experiment, the scientist either accepts, rejects or modifies the hypothesis.

Pasteur’s discovery that anaerobic bacteria fermented grape juice into acids suggested a method for preventing the spoilage of whine. His name became a household word when he developed pasteurization, a process of heating the grape juice just enough to kill most contaminating bacteria without changing the juice’s basic

• Because of his many, varied and significant accomplishments in working with microbes, Pasteur may be considered the Father of Microbiology.
• In debunking spontaneous generation, discovery that anaerobic bacteria fermented grapes juice and yeast fermentation made alcohol, pasteurization processes, and in producing vaccines.

• Discovered the anthrax bacterium.
• Found the cause of tuberculosis was a rod-shaped bacterium, Mycobacterium tuberculosis.
• Developed method of isolation of bacteria, technique still used today.
• The use of steam to sterile growth media.
• The first photography of bacteria in diseased tissue.
• Simple staining techniques for bacterial cells and flagella.
• Koch’s postulate

• aka Koch’s postulate – each postulate must be satisfied before the cause of an infectious disease is proven.
• The suspected causative agent must be hound in every case of the disease and be absent from healthy hosts.
• The agent must be isolated and grown outside the host.
• When the agent is introduced o a healthy, susceptible house, the host must get the disease.
• The same agent must be found in the diseased experimental host.

• The Gram stain is still the most widely used staining technique. It is one of the first steps carried out when bacteria are being identified, and it is one of the procedures you will learn in lab. 
• His procedure involves the application of a series of dyes, leaves some microbes purple and others pink. We use the procedure to separate bacteria into either Gram positive or Gram negative groups.

insistence on hand washing by medical staff.

modified and advanced the idea of antisepsis in health care setting. Because the founder of antiseptic surgery, and opened new fields of research into antisepsis and disinfection.

introduced cleanliness and other antiseptic techniques into nursing practice. Instrumental in setting standards for hygiene that saved innumerable lives during the Crimean War of 1854.  She founded the Nightingale School for Nurses, the first of its kind in the world.

Strong belief there was a critical need for adequate sewage treatment and a pure water supply. His study was the foundation for 2 branches of microbiology – infection control and epidemiology, which is the study of the occurrence, distribution and spread of disease in humans.

Developed the first vaccine for small pox. Began the field of immunology – the study of the body’s specific defenses against pathogens.

Discovered that chemicals could be used to kill MO deferentially. His discoveries began the branch of medical microbiology known as chemotherapy.

• Edward Jenner – developed the first vaccine (small pox).
• Louis Pasteur – later capitalized on Jenner’s work by producing weakened strains of various pathogens for use in preventing the serious diseases they cause. (cholera, anthrax and rabies).

A branch of medical microbiology in which chemicals are studies for their potential to destroy pathogenic MO.

• What are the basic chemical reactions of life? (biochemistry)
• How do genes work? (molecular biology)
• What roles do MO play in the environment?  (bio-remediation & nutrient recycling). 
• How do we defend against disease?  (immunology, chemotherapy)

A.  Bacteria

Cilium

Flagellum

• 3 - Pseudopod
• 4 - Nucleus

Microbes only on dust in the neck's bend.