Candida Albicans Regulates The Association Of Acinetobacter Baumannii With Lung Epithelial Cell

Background:The interactions between fungi and bacteria have become a hot topic of research.Both Candida albicans and Acinetobacter baumannii are common opportunistic pathogens and often occupy the same ecological niche.The cross-kingdom effects of Candida albicans and Acinetobacter baumannii have been investigated,but the effect of Candida albicans on the association of Acinetobacter baumannii with lung epithelial cells has not been reported.Objective:The purpose of this study was to study the effect of Candida albicans on the adhesion of Acinetobacter baumannii to lung epithelial cells and explore the possible mechanism.Method:First of all,we compared the CFU of Acinetobacter baumannii association with lung epithelial cell between single species group and dual-species group,and then we explored the role of formaldehyde fixation on the adhesion of Acinetobacter baumannii to lung epithelial cells.Furthermore,we explored the role of soluble chemicals on regulating the growth and the adhesion ability of Acinetobacter Baumannii.Results:Candida albicans increased the colony number of Acinetobacter baumannii adhering to lung epithelial cells.Though the cells were fixed with formaldehyde,the adhesion of Acinetobacter baumannii to lung epithelial cells still increased in the presence of Candida albicans compared to that in the absence of Candida albicans.In vitro co-culture of C.albicans and Acinetobacter baumannii,the result showed that C.albicans could increase the growth level of Acinetobacter baumannii,which was independent of direct contact with the bacteria.Interestingly,the adhesion of Acinetobacter baumannii to lung epithelial cells increased with the increase of the maximum infection number.The number of adherent colonies of Acinetobacter baumannii to lung epithelial cells was both increased by the supernatant of Candida albicans culture medium and Candida albicans-lung epithelial cell culture.Moreover,the expression of outer membrane protein A was elevated by Candida albicans supernatant.Conclusion:Candida albicans promotes the adhesion of Acinetobacter baumannii to lung epithelial cells,which may be due to the increase of the growth level of Acinetobacter baumannii and the expression level of OmpA mediated by some soluble chemical,and then the adhesion of Acinetobacter baumannii to lung epithelial cells increases.