Medical Microbiology

Medical MicrobiologyThe HistoryEQ: Who are the major contributors to the development of Microbiology?

What is Microbiology?

They study of microbes or microorganisms

Microbes, or microorganisms are minute living things that are usually unable to be viewed with the naked eye.

What are some of examples of microbes? Bacteria, fungi, protozoa, algae, viruses, and some are

parasites (helminths)

Some are pathogenic


Microbres When you hear the word bacteria, what comes to your mind?


Not all bacteria cause disease

Most bacterial species cannot cause disease

Figure 1. Gram stain of a species of Micrococcus, commonly isolated from the skin and nasal membranes of humans. Figures from: http://textbookofbacteriology.net/normalflora.html

Microbes

Many species play beneficial roles

Production of antibiotics and foodstuffs

Decompose organic waste

Produce industrial chemicals such as ethyl alcohol and acetone

Produce fermented foods such as vinegar, cheese, and bread

Can microorganisms be good for us, beneficial? Explain your answer


Ancient Microbiological History

Ancient people recognized many factors involved in diseases.

Most ancient people documented that some diseases are communicable

Example: When Black Death struck Europe entire villages were abandoned in an effort to escape the highly infectious plague (1347 A.D)

No medical knowledge existed in Medieval England to cope with the disease.

Ancient Microbiological History

The Romans were a hygienic bunch and were concerned with health and cleanliness (waste and sewage).

The Romans invented the first underground sewage system

Ancient Microbiological History The Romans understood that sewage could cause disease therefore

decided to build an underground sewage system which is an idea we still use today.

A network of pipes brought clean water into the city of Rome and removed waste.

Waste flushed from the latrines flowed through a central channel into the main sewage system and thence into a nearby river or stream.

The public bath houses was the place where people went to socialize and do business as well as getting clean.

History of Microbiology? Discovering organisms

First microbes were observed in 1673

Robert Hooke- In 1665 reported that living things were composed of little boxes or cells devised the compound microscope and illumination system

Antoni van Leeuwenhoek- (1673-1723)

He is considered the father of bacteriology Made simple microscopes and began observing with them (1674) Discovered bacteria (he called them animalcules)

Leeuwenhoek's microscope consisted simply of:

A) a screw for adjusting the height of the object being examined

B) a metal plate serving as the body

C) a skewer to impale the object and rotate it

D) the lens itself, which was spherical

History of Microbiology: The Theories

Spontaneous Generation

Many believed in spontaneous generation:

Aristotle synthesized the hypothesis which stated that some vital force contained in given organic matter can create living organisms from inanimate objects.

In basic terms spontaneous generation stated that living organisms arise from non living matter.

Spontaneous Generation Spontaneous generation was disproved in 1668 by Italian Scientist, Francesco

Redi.

What are the steps to the scientific method?

If your were Francesco Redi, what experimental design would you create to disprove spontaneous generation?

Redi’s Experiment:

Redi’s question: Where do maggots come from?

Hypothesized: Redi suspected that flies landing on the meat laid eggs that eventually grew into maggots

Experiment: Placed meat in three separate jars


Disproving Spontaneous Generation: Redi’s Experiment


Jar #1 Jar #2 Jar #3• Left open • Maggots developed• Flies were observed

laying eggs on the meat in the open jar

• Covered with netting • Maggots appeared on

the netting• Flies were observed

laying eggs on the netting

• Sealed • No maggots

developed

John Needham- revived the theory of spontaneous generation in 1745

Needham theorized that if he took chicken broth and heated it, all living things in it would die.

After heating some broth, he let a flask cool and sit at a constant temperature. The development of a thick turbid solution of microorganisms in the flask was strong proof to Needham of the existence of spontaneous generation.

Spontaneous Generation


The Question: What causes tiny living things to appear in decaying broth?

Lazzaro Spallanzani (1729-1799) In 1776 he demonstrated that microorganisms were already in

the solution, the container, or the air

He took solutions which he knew would "breed" organisms and boiled them for up to an hour. The flasks were hermetically sealed to keep out contaminated air.

Spontaneous GenerationThe Question: What causes tiny living things to appear in decaying broth?


Biogenesis In 1858 German scientist, Rudolf Virchow challenged

spontaneous generation with his concept of biogenesis

Living organisms arise from pre-existing life

Virchow presented his idea to the scientific community, but could not back it up with a convincing experiment


Settlement of Spontaneous Generation

In 1861, a French scientist by the name of Louis Pasteur demonstrated where microorganisms came from

Father of Medical Microbiology

Demonstrated the microorganisms exist in the air and could contaminate sterile solutions by passing air through cotton filters

The filter trapped tiny particles floating in the air


http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27

Louis Pasteur’s Swan neck flask experiment

http://www.microbiologytext.com/index.php?module=Book&func=displayarticle&art_id=27

History of Microbiology: The Theories French chemist Louis Pasteur’s design of

this experiment settled the argument.

Louis Pasteur performed numerous experiments to discover why wine and dairy products became sour

He found that bacteria were to blame (lactic acid fermentation)

Pasteur called attention to the importance of microorganisms in everyday life and stirred scientists to think that if bacteria could make the wine “sick,” then perhaps they could cause human illness.

Louis Pasteur’s experiments


Golden Age of Microbiology1857- 1914

Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity and antimicrobial medicine

Germ Theory of Disease

Germ theory states that specific microscopic organisms are the cause of specific diseases.

Pasteur and The Germ Theory of Disease

Pasteur showed that microbes are responsible for fermentation

Microbial growth is also responsible for spoilage of food

Pasteur demonstrated that spoilage bacteria could be killed with heat (pasteurization)

Discovered that weak forms of disease could be used as an immunization against stronger forms and that rabies was transmitted by viruses too small to be seen under the microscopes of the time Developed vaccines for anthrax (1881)and rabies (1885)


1835: Agostino Bassi- showed a silkworm diseases was caused by a fungus

1865: Pasteur- believed that another silkworm disease was caused by a protozoan

1840s: Ignaz Semmelwise- advocated hand washing to prevent transmission of fever from one OB patient to another

http://www.youtube.com/watch?v=KSLCkT2ttXQ



Germ Theory of Disease 1860s: Joseph Lister- He is the father of antiseptic

surgery.

He used a chemical disinfectant (carbolic acid) to prevent surgical wound infections after reading Pasteur’s work showing microbes are in the air, can spoil food, and cause animal disease.

The Germ Theory of Disease: Robert Koch

1867: Robert Koch- provided proof that bacterium causes anthrax and provided the experimental steps, Koch’s postulates, used to prove that a specific microbe causes a specific disease.

Koch’s Postulates Pathogen must be

present in all cases of disease

Pathogen must be isolated and grown in lab in pure culture

Pathogen from pure cultures must cause disease when inoculated into healthy, susceptible lab animal

Same pathogen must be isolated from the diseased lab animal


Immunology: History of Vaccination A precursor of smallpox vaccination was variolation (The Germ Theory of Disease was not known at this time)

An early Asian method which introduced dried scabs of smallpox patients and was later modified in Europe

Modification consisted of injecting infectious material under the skin

First tested among abandoned children and prisoners

When it was declared safe, members of the English royal family were inoculated

Smallpox vaccine 1796: Edward Jenner is credited with the development

of the smallpox vaccine

Folk wisdom suggested that dairy maids who had contracted cowpox seemed to be immune to smallpox

Infection with the cowpox virus produced a much less severe form of disease than smallpox

Smallpox Vaccine: Jenner conducted an

experiment in which he used scabs from the cowpox lesions on the arm of a dairy maid, Sarah Nelmes to create a small pox vaccine

He then used the material to vaccinate an 8 year old boy, James Phipps

After being vaccinated Phipps appeared to develop immunity to the smallpox virus.

Smallpox vaccine continued Later Jenner vaccinated his own son and several other

children

He obtained similar results

Worldwide elimination of smallpox was achieved in 1978

Called vaccination from vacca for cow

The protection is called immunity

Discovery of Penicillin 1928: Alexander Fleming

discovered the first antibiotic.

He observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus.

1940s: Penicillin was tested clinically and mass produced and was available towards the end of World War II

Development of Agar Angelina Hesse developed the use of Agar to grow

microorganisms. She was the wife of Walter Hesse who worked in Koch’s

laboratory Advantages of agar- It was not attacked by most bacteria. Agar is better than gelatin because of its higher melting point

(96°c) and solidifying (40–45°c) points.

Medical Microbiology

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