Key Figures in the History of Microbiology

A Brief History of Microbiology

• The debate over spontaneous generation was challenged by Anton Lavoisier, who proposed the concept of biogenesis, stating that living cells can arise only from preexisting living cells.
• Rudolf Virchow demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but air itself does not create microbes.
• Louis Pasteur showed that microorganisms can be present in nonliving matter (solids, liquids, and air) and demonstrated that microbial life can be destroyed by heat.
• Pasteur's work provided evidence that microorganisms cannot originate from mystical forces present in nonliving materials, concluding that any appearance of "spontaneous" life in nonliving solutions can be attributed to microorganisms that were already present in the air or in the fluids themselves.

The Golden Age of Microbiology

• The period from 1857 to 1914 is known as the Golden Age of Microbiology, led by Louis Pasteur and Robert Koch.
• During this period, discoveries were made about agents of many diseases and the role of immunity in preventing and curing disease.

Fermentation and Pasteurization

• Louis Pasteur discovered that microorganisms called yeasts convert sugars into alcohol in the absence of air (fermentation).
• In the presence of air, bacteria change the alcohol into vinegar (acetic acid).
• The solution to the spoilage problem was to heat the liquor just enough to kill the bacteria that caused the spoilage, a process known as pasteurization.

Germ Theory of Disease

• The realization that yeasts play a crucial role in fermentation led to the possibility that microorganisms might cause disease, forming the Germ Theory of Disease.
• Joseph Lister applied the germ theory of disease to medical procedures, reducing the incidence of infections and deaths by treating surgical wounds with a phenol solution.
• Robert Koch provided the first proof that bacteria can cause a disease, leading to the discovery of Bacillus anthracis in the blood of cattle that had died of anthrax.

Vaccination

• Edward Jenner made an experiment to find a way to protect people from smallpox, discovering that vaccination with cowpox could provide immunity.
• Louis Pasteur discovered why vaccinations work, finding that microorganisms with decreased virulence can induce immunity against subsequent infections by their virulent counterparts.
• Pasteur used the term vaccine for cultures of avirulent microorganisms used for preventive inoculation.

Current Applications of Microbiology in Pharmacy

• Chemotherapy is the treatment of disease by using chemical substances, with chemicals produced naturally by bacteria and fungi called antibiotics, and chemotherapeutic agents prepared from chemicals in the laboratory called synthetic drugs.
• Paul Ehrlich discovered salvarsan, an arsenic derivative effective against syphilis, and speculated about a "magical bullet" that could hunt down and destroy a pathogen.
• The first synthetic drugs were developed, including sulfa drugs, and antibiotics were discovered, including penicillin.

Antibiotics

• The first antibiotic was discovered by Alexander Fleming, who found that the mold Penicillium notatum (later renamed Penicillium chrysogenum) produced an active inhibitor, penicillin.
• Since then, thousands of other antibiotics have been discovered, but many antimicrobial chemicals are too toxic to humans for practical use.
• The emergence and spread of new strains of microorganisms that are resistant to antibiotics is a growing concern, with vancomycin-resistant Staphylococcus aureus and Enterococcus faecalis alarming health care professionals.