AUTHOR=Camarillo-Márquez Omar , Córdova-Alcántara Itzel M. , Hernández-Rodríguez Cesar H. , García-Pérez Blanca E. , Martínez-Rivera María A. , Rodríguez-Tovar Aida V. 

TITLE=Antagonistic Interaction of Staphylococcus aureus Toward Candida glabrata During in vitro Biofilm Formation Is Caused by an Apoptotic Mechanism

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02031

DOI=10.3389/fmicb.2018.02031

ISSN=1664-302X

ABSTRACT=<p><bold>Background:</bold> Infections caused by <italic>Candida</italic> species and <italic>Staphylococcus aureus</italic> are associated with biofilm formation. <italic>C. albicans–S. aureus</italic> interactions are synergistic due to the significant increase in mixed biofilms and improved resistance to vancomycin of <italic>S. aureus</italic>. <italic>C. glabrata</italic> and <italic>S. aureus</italic> both are nosocomial pathogens that cause opportunistic infections in similar host niches. However, there is scarce information concerning the interaction between these last microorganisms.</p><p><bold>Results:</bold> The relationship between <italic>C. glabrata</italic> and <italic>S. aureus</italic> was evaluated by estimating the viability of both microorganisms in co-culture of planktonic cells and in single and mixed biofilms. An antagonistic behavior of <italic>S. aureus</italic> and their cell-free bacterial supernatant (CFBS) toward <italic>C. glabrata</italic>, both in planktonic form and in biofilms, was demonstrated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM) images showed yeast cells surrounded by bacteria, alterations in intracytoplasmic membranes, and non-viable blastoconidia with intact cell walls. Concomitantly, <italic>S. aureus</italic> cells remained viable and unaltered. The antagonistic activity of <italic>S. aureus</italic> toward <italic>C. glabrata</italic> was not due to cell-to-cell contact but the presence of CFBS, which causes a significant decrement in yeast viability and the formation of numerous lipid droplets (LDs), reactive oxygen species (ROS) accumulation, as well as nuclear alterations, and DNA fragmentation indicating the induction of an apoptotic mechanism.</p><p><bold>Conclusion:</bold> Our results demonstrate that the <italic>S. aureus</italic> CFBS causes cell death in <italic>C. glabrata</italic> by an apoptotic mechanism.</p>