Antibiotics are produced by microorganisms, such as bacteria or fungi, which prevent the growth and multiplication of deleterious bacteria. Years ago it was discovered that this antibiotic material could be collected and purified and then used to kill harmful bacteria in humans. Today some antibiotics are produced synthetically, a more efficient and cheaper method.
Drugs other than antibiotics also interfere with the growth and multiplication of harmful bacteria. They are called chemotherapeutic agents, and sulfonamide (usually called sulfa) is an important member of this group. Sulfa was developed before penicillin, the first antibiotic, and is still useful in certain types of infections. In general, most people use the word antibiotic to include all of these drugs.
There are many varieties of antibiotics, but no antibiotic is effective against every type of bacteria. In fact, this is good because the human body contains many useful, friendly bacteria and it could be dangerous if these were killed.
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