Antibiotics
...ns of inhibiting the growth of or killing bacteria and other microorganisms. These organisms can be bacteria, viruses, fungi, or animals called protozoa. A particular group of these agents is made up of drugs called antibiotics, from the Greek word anti ("against") and bios ("life"). Some antibiotics are produced from living organisms such as bacteria, fungi, and molds. Others are wholly or in part synthetic - that is, produced artificially. Penicillin is perhaps the best known antibiotic. Its discovery and later development is among mankind's greatest achievements. Antibiotics have enabled the medical profession to treat effectively many infectious diseases, including some that were once life-threatening. How Antibiotics Work ? Antibiotics can be bacteriostatic (bacteria stopped from multiplying) or bactericidal (bacteria killed). To perform either of these functions, antibiotics must be brought into contact with the bacteria. It is believed that antibiotics interfere with the surface of bacteria cells, causing a change in their ability to reproduce. Testing the action of an antibiotic in the laboratory shows how much exposure to the drug is necessary to halt reproduction or to kill the bacteria. Although a large amount of an antibiotic taken at one time might kill the bacteria causing an illness, such a dose usually would make the person suffer from illness caused by the drug. Therefore, antibiotics are given in a series of smaller amounts. This assures that the bacteria are either killed or reduced enough in numbers so that the body can repel them. When too little antibiotic is taken, bacteria can often develop methods to protect themselves against it . The next time the antibiotic is needed against these bacteria, it will not be effective. Taking in Antibiotics. To work against infecting organisms, an antibiotic can be applied externally, such as to a cut on the skin's surface, or internally, reaching There are dozens of antibiotics. The following are in common use: Penicillins. The various types of penicillins make up a large group of antibacterial antibiotics of which only those from benzyl penicillin are naturally produced from molds. Penicillin G and ampicillin are in this class. Another penicillin, called piperacillin, has been shown to be effective against 92 percent of infections without causing serious side effects. Penicillins are often given in combination with some of the following categories of drugs. Cephalosporins. Similar to the penicillins, cephalosporins are often given when a sensitivity (allergic reaction) to the former is known or suspected in a patient. Cefotaxime sodium is a kind of cephalosporin that is very effective in combating deep infections such as those that occur in bones and those resulting from surgery. Aminoglycoside. Aminoglycosides include streptomycin and neomycin. These drugs are used to treat tuberculosis, bubonic plague, and other infections. Because of potentially serious side effects, such as interference with hearing and their ability to make one sensitive to sunlight, these drugs are given with caution. Tetracyclines. Tetracyclines are effective against pneumonia, typhus, and other bacteria-caused illness but can harm the function of the liver and kidneys. Tetracycline in a special gel base is used to treat many eye infections. Macrolides. Macrolides are often used in patients who appear to be sensitive to penicillin. Erythromycin is the best known medicine in this group. Polypeptides. The class of antibiotics called polypeptides is quite toxic (poisonous) and is used mostly on the surface of the skin (topically). Bacitracin is in this category. Resistance and Side Effects. An antibiotic acts by limiting or stopping (and therefore killing) the growth of a specific microorganism. It probably accomplishes this by interfering with the wall of the bacteria cell at which it is targeted while at the same time having little effect on the body's normal cells. When one is exposed continually to an antibiotic for an illness of long duration (such as rheumatic fever), the targeted bacteria may develop its own defense against the drug. An enzyme that can destroy the drug may be produced by the bacteria, or the cell wall can become resistant to being broken by the action of the antibiotic. When this happens, and it does most frequently in response to long or frequent treatment with penicillin or streptomycin, the patient is said to be "fast" against the drug. For example, one may be penicillin-fast, meaning penicillin is no longer able to help fight the infection and another type of antibiotic must be given. Allergic reactions to antibiotics are usually seen as rashes on the skin, but severe anemia (too few red blood cells), stomach disorders, and deafness can occasionally result. It was once thought that allergic reactions to antibiotics - penicillin in particular - were frequent and permanent. Recent studies suggest, however, that many people outgrow their sensitivity or never were allergic. The large number of antibiotics that are now available offers a choice of treatment that can, in most instances, avoid allergy-causing drugs. It is well to remember that all drugs can cause both wanted and unwanted effects on the body. The u...