Infectious diseases are caused by viruses, bacteria, fungi (yeasts and molds), protozoa (single-celled animals), and worms. In shape, bacteria may be round (cocci, Fig. 1), rod-shaped (bacilli, Fig. 2), or curved (vibrios and spirochetes, see Fig. 2). They may be named according to their shape and by the arrangements they form (see Fig. 1). They also are described according to the dyes they take up when stained in the laboratory. The most common laboratory bacterial stain is the Gram stain, with which gram-positive organisms stain purple and gram-negative organisms stain red (see Fig. 1). Microorganisms often produce disease by means of the toxins (poisons) they release. The presence of harmful microorganisms or their toxins in the body is termed sepsis.
FIGURE 1. Round bacteria (cocci), Gram stained. (Reprinted with permission from Cohen BJ, Wood DL. Memmler's The Human Body in Health and Disease. 9th Ed. Philadelphia: Lippincott Williams & Wilkins, 2000.)
FIGURE 2. Rod-shaped and curved bacteria. (Reprinted with permission from Cohen BJ, Wood DL. Memmler's The Human Body in Health and Disease. 9th Ed. Philadelphia: Lippincott Williams & Wilkins, 2000.)
责任编辑：admin
上一篇：医学文章阅读——Neoplasia
下一篇：医学文章阅读——Emergency Care
微信公众号搜索“译员”关注我们，每天为您推送翻译理论和技巧，外语学习及翻译招聘信息。