Diseases & Conditions


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Bacteria


Neither plants nor animals, bacteria are microbes whose nuclei are not enclosed in thin tissue like plants or animals. Some bacteria feed on other organisms, some make their own food (as plants do), and some bacteria do both. Some need air to survive and others exist without air (anaerobic). Some move by themselves, and others cannot move at all. Bacteria also come in a variety of shapes, colors, sizes, and ways of living. Some of the more serious types of bacterial infections include GONORRHEA, MENINGITIS, WHOOPING COUGH, PNEUMONIA, and TUBERCULOSIS. Bacteria are of incredible importance because of their extreme flexibility, capacity for rapid growth and reproduction, and their ancient age—the oldest known fossils are those of bacteria-like organisms that lived nearly three-and-a-half billion years ago. It is important to remember that not all bacteria are harmful; most are helpful, such as those that break down dead plant and animal matter in the soil. Some (like the actinomycetes) produce antibiotics such as streptomycin and nocardicin. Plants cannot grow without nitrogen, and bacteria help nitrogen to form in the soil. Bacteria are also used to make cheese out of milk, and leather out of animal hide. Grazing animals use bacteria in their stomachs to digest grass. Bacteria can be found in the air, the water, food, and everyday objects. Since few of these are harmful, humans are seldom bothered by them. When harmful bacteria do enter the body, the immune system most of the time can kill the invading microbes. Unfortunately, bacteria are beginning to become resistant to many of the antibiotics doctors use to treat the infections. A 1996 World Health Organization report found that drug-resistant strains of microbes causing MALARIA, TUBERCULOSIS, PNEUMONIA, CHOLERA, and diarrhea are on the rise. Strong new types of microbes in the United States cause up to 60 percent of hospital-acquired infections, the report adds. The problem occurs when antibiotics are prescribed when they are not needed, or when patients do not take the full course of medication, allowing a few microbes to survive.