Antibiotic

An antibiotic is a naturally occurring chemical that kills or inhibits the growth of bacteria. Today, antibiotics are used to treat infections and to fight a wide range of bacteria. However, the overuse of antibiotics has caused bacteria that are resistant to antibiotics to become more widespread, and in many cases, the antibiotics have become ineffective.

When a person gets an infection, microscopic bacteria have entered the body through an opening or a wound. After quickly finding an abundant supply of food inside, these bacteria reproduce in great numbers and release toxins or poisons as they grow. These toxins can interfere with cell functions or even destroy human cells.

THE HISTORY OF ANTIBIOTICS

Antibiotic drugs have been developed to fight and kill bacteria. They are derived from other organisms, like molds, that are naturally harmful to bacteria. Certain molds produce their own toxins that destroy bacterial cells. This may be the means by which a mold would defend itself against bacterial invasion. As early as 1871, the English surgeon Joseph Lister (1827–1912) noted that certain organic compounds seemed to act against bacteria. However, it was not until 1928 that the Scottish doctor Alexander Fleming (1881–1955) made the important discovery that would eventually lead to the development of penicillin (synthetically produced antibiotics derived from molds and used to treat a wide variety of diseases). While he was growing cultures of bacteria in petri dishes for experiments, Fleming accidentally left several dishes uncovered for a few days. He then noticed that a green mold had gotten into one dish (having traveled through the air as a mold spore) and had destroyed or dissolved the bacteria. Examining the situation with his trained eye, Fleming realized that he had come upon a natural substance that could kill bacteria. His later experiments with mice showed that his new "penicillin" killed only the bacteria and did not harm the animals' cells. Since he was unable to purify and concentrate more penicillin, he published a paper that received little attention. It was not until 1940 that penicillin was taken up experimentally by others who, by 1942, were beginning to make it in large amounts. Fleming's discovery would eventually lead to the steady production of several different lifesaving antibiotics.

HOW ANTIBIOTICS WORK

The key to why an antibiotic works is that it is selectively toxic or poisonous. That is, it works against certain life forms and not others. It does this by interfering with the cell wall of each new bacterial cell, and this eventually kills the cell. Since animal and human cells do not have cell walls, it is not harmful to these types of cells. However, when an antibiotic encounters a bacterial cell, it joins with its cell wall, leaving a gap in the cell wall so that it no longer can protect its contents, which then spill out. Other antibiotics bind to the ribosomes (particles that act in protein synthesis) in a bacterial cell and stop them from making proteins (which a cell needs to stay alive).

BACTERIOCIDAL AND BACTERIOSTATIC ANTIBIOTICS

There are two types of antibiotics: some antibiotics are bacteriocidal while others are bacteriostatic. Bacteriocidal agents kill bacteria, while bacteriostatic agents slow them down so that the host's immune system has a better chance to defeat them. Today's many antibiotics can be broad-spectrum agents or narrow-spectrum agents. As it sounds, one is effective against a broad range of bacteria while the other works against only a few. There also are many different "families" of antibiotics, some of which are synthetic or man-made. However, no matter how different they are from one another, when a patient is given an antibiotic injection or takes an antibiotic pill, the antibiotic prevents bacterial cells from growing and dividing normally.

ANTIBIOTIC RESISTANT BACTERIA

Bacteria may seem easy to kill with modern medicine. Yet these invisible agents of disease can reproduce every twenty minutes and have proven capable of becoming resistant to antibiotics. They do this by mutations, or changes. that occur in a cell's genetic material. More and more, antibiotic resistant bacteria are becoming increasingly common due largely, it has been shown, to their routine use by farmers who give antibiotics to their livestock and chickens to prevent them from getting sick. Unfortunately, because people then consume the meat of these animals, humans are ingesting some of the antibiotics given to the animals. It has been shown that overuse of antibiotics in both humans and in animals speeds up the development of antibiotic resistant bacteria.

Without antibiotics, humans still would be subject to the terrible diseases that killed millions of people in the past. Before 1950, bacterial diseases like diphtheria, tuberculosis, pneumonia, blood poisoning, food poisoning, bacterial meningitis, and scarlet fever were sure killers. This victory over bacteria may be coming to an end since humans are now faced with the real possibility that entire populations of bacteria are mutating to the point where they will be resistant to any antibiotic available.