Invasion by and multiplication of pathogenic microorganisms in a bodily part or tissue,which may produce subsequent tissue injury and progress to overt disease through a variety of cellular or toxic mechanisms.

• 传染致病微生物侵入人体的某部分或组织，并且不断繁殖，接着造成组织损坏，最后通过一系列细胞或中毒机制发展为显性症状