History of Microbiology and Germ Theory

Romans (Varro)

Ancient civilization contributing to early microbiological thought.

Microscopy

Study of small objects using magnification tools.

Hooke (1665)

First to observe and describe cells.

Leeuwenhoek (~1700)

Discovered microorganisms, termed them 'animalcules'.

Cell Theory

All living things are composed of cells.

Spontaneous Generation

Theory that life arises from non-living matter.

Redi (1668)

Demonstrated maggots do not arise from meat.

Pasteur (1861)

Developed swan-necked flask experiment disproving spontaneous generation.

Miasma Theory of Disease

Belief that diseases are caused by 'bad air'.

Florence Nightingale

Pioneer in sanitation and nursing practices.

Germ Theory of Disease

Microorganisms can cause diseases in hosts.

Fracastoro (1546)

Proposed 'seminaria' as seeds of disease.

John Snow (1854)

Traced cholera outbreak to contaminated water pump.

Cholera

Disease caused by Vibrio cholerae bacterium.

Vibrio cholerae

Gram-negative, comma-shaped bacterium causing cholera.

Contaminated Water

Primary transmission route for cholera infection.

Symptoms of Cholera

Include watery diarrhea and 'rice-water stools'.

Enterotoxin

Toxin produced by cholera bacterium affecting intestinal cells.

Koch's Postulates

Criteria to establish causative agent of disease.

Pure Culture Techniques

Methods to isolate and grow microorganisms.

Agar

Gelatinous substance derived from algae for culturing.

Exceptions to Koch's Postulates

Not all diseases follow Koch's criteria.

Treponema pallidum

Bacterium causing syphilis, cannot be cultured.

Mycobacterium leprae

Bacterium causing leprosy, grows in armadillos.

HIV

Human immunodeficiency virus affecting only humans.