抗生素 Antibiotics

An antibiotic is a drug that kills or slows the growth of bacteria. Antibiotics are one class of antimicrobials,
a larger group which also includes anti-viral, anti-fungal, and
anti-parasitic drugs. They are relatively harmless to the host, and
therefore can be used to treat infections. The term, coined by Selman Waksman,
originally described only those formulations derived from living
organisms, in contrast to "chemotherapeutic agents", which are purely
synthetic. Nowadays the term "antibiotic" is also applied to synthetic antimicrobials, such as the sulfa drugs. Antibiotics are generally small molecules with a molecular weight less than 2000. They are not enzymes. Some antibiotics have been derived from mould, for example the penicillin class.

        wikipedia：Antibiotic Antimicrobiobial .

抗生素殺菌作用主要有4種機制：

• 抑制細菌細胞壁的合成：抑制細胞壁的合成會導致細菌細胞破裂死亡，以這種方式作用的抗菌藥物包括青黴素類和頭孢菌素類，哺乳動物的細胞沒有細胞壁，不受這些藥物的影響。
• 與細胞膜相互作用：一些抗菌素與細胞的細胞膜相互作用而影響膜的滲透性，這對細胞具有致命的作用。以這種方式作用的抗生素有多粘菌素和短桿菌素。
• 干擾蛋白質的合成：干擾蛋白質的合成意味著細胞存活所必需的酶不能被合成。干擾蛋白質合成的抗生素包括福黴素類、氨基糖苷類、四環素類和氯黴素。
• 抑制核酸的轉錄和複製：抑制核酸的功能阻止了細胞分裂和/或所需酶的合成。以這種方式作用的抗生素包括萘啶酸和二氯基吖啶。

抗生素可以分為:
   * β-內醘胺類抗生素 β-Lactam
          o 青黴素類 Penicillins
          o 頭孢菌素類 Cephalosporins
          o 非典型的β-內醘胺類抗生素
    * 四環素類抗生素 Tetracycline
    * 氨基糖苷類抗生素 Aminoglycoside
    * 大環內酯類抗生素 Macrolide
    * 氯黴素類抗生素 Chloramphenicol