Most pharmacies today carry many antibiotics for treating bacterial diseases, yet until World War II, no such medicines existed. Not until the 19th century was it discovered that bacteria could cause disease. Much of modern medicine rests on the pioneering work of the researchers discussed here.
In 1677, Dutch tradesman Anton van Leeuwenhoek first observed bacteria. His hand-held microscopes magnified objects much better than other microscopes of his day did. In the sticky plaque of his own teeth, he observed "many little living animalcules, very prettily a moving."
In 1850, Hungarian physician Ignaz Semmelweis instructed his medical students to wash their hands between seeing patients. This first simple antiseptic procedure spared thousands of new mothers from deadly puerperal (pyoo-UHR-puhr-uhl), or child-bed, fever.
In 1861, French chemist Louis Pasteur proved that germs did not grow by spontaneous generation. He also showed that heating broth can kill bacteria and sterilize the broth. By sterilizing his hands, surgical instruments, and his patient's incisions with carbolic acid, British surgeon Joseph Lister applied Pasteur's ideas. This action greatly reduced the loss of life from infection.
In 1876, Robert Koch, a German physician, was the first to prove the link between a bacterium and a disease. He isolated Bacillus anthracis from a sick animal and established the bacterium's role in the disease anthrax. Within 20 years, Koch and colleagues across Europe and the United States had discovered the causal agents for dozens of infectious diseases.
The growing knowledge of bacteria and disease in the late 1800s encouraged researchers to look for safer antibacterial drugs, because heavy metals such as mercury often harmed the patient.
In 1910, German physician Paul Erlich developed the compound Salversan, which sucessfully treated syphilis. In 1928, British microscopist Alexander Fleming accidentally discovered the antibacterial effect of penicillium mold, which was to become the source of penicillin, the first mass-produced antibiotic.
During the last half of the 20th century, many new antibiotics were created. More recently, molecular techniques have opened a new era of medical research for the treatment of bacterial diseases. Computer programs are now commonly used to design more-effective antibiotics and vaccines. This advancement is especially important because of the increasing numbers of bacteria that are not affected by traditional antibiotics, such as penicillin and streptomycin.
1. Identify two conclusions drawn from Louis Pasteur's 1861 experiment.
2. Critical Thinking Is hand washing still an important way to prevent the spread of disease? Explain.
3. Critical Thinking It was once believed that poisonous vapors called miasmas caused disease. Why do you think this belief existed?
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Bacteria are important in many industries. Bacillus thuringiensis, or Bt, is commonly sold as an organic pesticide to kill pests, such as the corn earworm caterpillar in (a). After an oil spill, cleanup crews spray fertilizer, which encourages the growth of naturally occurring prokaryotes to break down the oily sludge (b).
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