Reading 2

Unit 3- Reading 2

Page 41

Fighting bacteria

Long ago, people did not understand Infection. They did not understand illness. They did not know that illnesses could be transferred from one person to another. They believed that bad air caused infections and illnesses.

People tried using plants and animals from their environment to cure infections and illnesses. Usually, they did not help. People did not know that bacteria caused infections and diseases. They did not know that bacteria existed.

THE DISCOVERY OF BACTERIA

Antony van Leeuwenhoek first observed bacteria in 1676.

Nearly 200 years later, scientists learned that bacteria were linked to many of the terrible diseases that humans suffered from. However, they did not know how to cure these diseases. Instead, scientists tried to develop ways to prevent many of these diseases.

PASTEURIZATION

In 1859, Louis Pasteur developed a procedure to make milk from farm animals safe to drink.

He found that bacteria in the milk could be destroyed whenever the milk was heated to a high temperature. This heating process was called pasteurization. Pasteur had ideas for destroying bacteria in other situations. For instance, he found that one reaction of carbolic acid (a strong chemical) was to destroy bacteria on laboratory equipment.

CARBOLIC ACID

Joseph Lister was a surgeon.

He lived around the same time as Pasteur. He knew that surgery was dangerous. Patients often developed infections where their skin was cut. Many patients died from these infections. Lister analyzed Pasteur’s ideas. He wondered if chemicals could prevent infections in surgery patients.

He tried the carbolic acid. Before each surgery, he sprayed a weak mix of the acid on the surgery tools. He sprayed it on a patient’s skin. And he sprayed it on the bandages that the patient would wear after the surgery. He saw that the acid spray was very effective in preventing infections. The acid spray made surgery safer for patients.

His patients reacted very well to the treatment.

PENICILLIN

Scientists had developed several effective ways to prevent bacteria from causing harmful diseases. But they had not yet found ways to cure people who were already ill from a disease. They knew that high heat and chemicals would destroy bacteria. But they knew doctors could not heat a patient’s body to a high temperature.

Doctors could not spray a person’s lungs with acid. These acts might kill the bacteria, but they would also kill the patient.

In 1928, scientist Alexander Fleming noticed a reaction when bacteria touched a certain fungus (a plant-like growth). The bacteria were destroyed. Just as important, the fungus was harmless to humans. This fungus was penicillin.

Soon penicillin was put into medicines for patients to swallow.

Penicillin could cure many diseases. The penicillin helped the patient’s body destroy harmful bacteria. This kind of medicine was called an antibiotic. In the following years, many other antibiotics were created.

First, scientists discovered bacteria.

Then they developed ways to prevent bacteria from causing harm. Finally, they found cures for many of the illnesses and infections caused by bacteria.