铜绿假单胞菌和白假丝酵母﹝俗称白色念珠菌）这两种条件致病菌可共存于人体。两者间存在复杂的相互关系，即跨界相互作用：铜绿假单胞菌抑制白色念珠菌形态转换，抑制其生物膜形成并毒杀其菌丝；白色念珠菌则抑制铜绿假单胞菌绿脓菌素形成并抑制其丛集运动。本文综述了跨界相互作用可能存在的3种机制：信号转导通路、生物膜和毒性因子的作用。铜绿假单胞菌通过信号分子N-3-氧代十二烷酰-L-同型丝氨酸内酯（3-oxo-C12-HSL）抑制白色念珠菌形态转换，而白色念珠菌通过信号分子法呢醇抑制铜绿假单胞菌绿脓菌素生成和丛集运动，即存在信号分子介导的跨界相互作用。跨界相互作用影响铜绿假单胞菌和白色念珠菌各自的致病性。如能充分利用跨界相互作用，将有助于优化治疗的选择。

Pseudomonas aeruginosa and Candida albicans can coexist in human body. There is a complex interaction between the two opportunistic pathogens which was defined as cross-kingdom interaction: Pseudomonas aeruginosa inhibits the morphological change of Candida albicans, the formation of bacterial biofilm and kill the hypha, and Candida albicans inhibits the formation of pyocyanine of Pseudomonas aeruginosa and the swarming motility. Cross-kingdom interaction may exist three mechanisms: quorum sensing, biofilm and toxicity. By secretion of signaling molecule N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL), Pseudomonas aeruginosa inhibits conversion of Candida albicans from yeast to hypha. By secretion of signaling molecule farnesol, Candida albicans inhibits the formation of pyocyanie and swarming motility. It suggests that the cross-kingdom interaction is partly mediated by signal molecules. Due to the presence of cross-kingdom interaction, the pathogenicity of Pseudomonas aeruginosa and Candida albicans is impacted, helpful in choosing the better treatment.