General aspects – Remember definition: organisms frequently found on or within body of healthy individuals – Most are bacteria, but some are viruses, fungi, and protozoa

American Legion Convention in 1976 in Philadelphia hotel – Respiratory distress and fever – 200 affected – 34 died

General Aspects Ecology – Found throughout the environment Very simple nutritional requirements – Not usually in normal flora unless hospitalized or immunocompromised

Diversity of species Ecology – Found worldwide in soil, water, vegetation, and microbial flora of animals and humans – Some are always associated with disease

Comparison of Meningococcus and Gonococcus Pathobiology Similarities: – Both diploccocci – Share about 80% DNA – Neither makes exotoxin; both make endotoxin – Both are relatively good colonizers

Staphylococci Important human pathogen – Causes both relatively minor and serious diseases One of the hardiest of the non￾sporeforming bacteria – Can exist on dry surfaces for a long period – Relatively heat-resistant; temperature range

Production of Ab and Activation of Macrophages and Cytotoxic T Cells T-Dependent T-Independent

Definition – Soluble substances that alter normal metabolism of host cells with deleterious effects on the host Host range – Known for bacteria, but possible that they play a role in diseases caused by fungi

生物统计学：《生物统计附试验设计》课程教材（第三版）附录 常用生物统计方法的SAS程序

真核微生物（Eukarya） 又称真细菌（eubacteria），包括普通细菌、放线菌、蓝细菌、 枝原体、立克次氏体和衣原体等 古生菌在进化谱系上与真细菌及真核生物相互并列，且与后者关系 更近，而其细胞构造却与真细菌较为接近，同属于原核生物