Pseudomonas aeruginosa inhibits in-vitro Candida biofilm development

Abstract

BackgroundElucidation of the communal behavior of microbes in mixed species biofilms may have a major impact on understanding infectious diseases and for the therapeutics. Although, the structure and the properties of monospecies biofilms and their role in disease have been extensively studied during the last decade, the interactions within mixed biofilms consisting of bacteria and fungi such as Candida spp. have not been illustrated in depth. Hence, the aim of this study was to evaluate the interspecies interactions of Pseudomonas aeruginosa and six different species of Candida comprising C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. dubliniensis in dual species biofilm development.ResultsA significant reduction in colony forming units (CFU) of C. parapsilosis (90 min), C. albicans and C. tropicalis (90 min, 24 h and 48 h), C. dubliniensis and C. glabrata, (24 h and 48 h) was noted when co-cultured with P. aeruginosa in comparison to their monospecies counterparts (P < 0.05). A simultaneous significant reduction in P. aeruginosa numbers grown with C. albicans (90 min and 48 h), C. krusei (90 min, 24 h and 48 h),C. glabrata, (24 h and 48 h), and an elevation of P. aeruginosa numbers co-cultured with C. tropicalis (48 h) was noted (P < 0.05). When data from all Candida spp. and P. aeruginosa were pooled, highly significant mutual inhibition of biofilm formation was noted (Candida P < 0.001, P. aeruginosa P < 0.01). Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) analyses confirmed scanty architecture in dual species biofilm in spite of dense colonization in monospecies counterparts.ConclusionsP. aeruginosa and Candida in a dual species environment mutually suppress biofilm development, both quantitatively and qualitatively. These findings provide a foundation to clarify the molecular basis of bacterial-fungal interactions, and to understand the pathobiology of mixed bacterial-fungal infections.

Current understanding of multi‐species biofilms

“…Toxic substances are secreted by many microbial species to kill or inhibit the growth of other species. For example, P. aeruginosa is reported to kill Candida in multi-species biofilms by using virulence factors which are well characterized in human infections [53][54]. Tong et al reported that Streptococcus oligofermentans uses L-amino acid oxidase to generate hydrogen peroxide (H 2 O 2 ) from peptone and suppress the growth of S. mutans in a peptone-rich multi-species biofilms [55].…”

Inhibition of co-colonizing cystic fibrosis-associated pathogens by Pseudomonas aeruginosa and Burkholderia multivorans

“…aeruginosa inhibited the growth of all Candida species tested, some of the yeast species were in turn capable of inhibiting Ps. aeruginosa (Bandara et al, 2010;Treat et al, 2007). Therefore, the factors contributing to the inhibition by Ps.…”

Microbial metabolic exchange in 3D

“…Although the human immune system is partially responsible for controlling C. albicans infections, microbes commonly coisolated from patients suffering from such infections have been shown to produce metabolites capable of modulating C. albicans virulence (Hogan and Kolter, 2002;Morales and Hogan, 2010). As one such organism, P. aeruginosa uses a variety of physical and chemical methods to limit the growth of C. albicans (Gibson et al, 2009;Bandara et al, 2010). It attaches exclusively to the hyphal germ tubes of C. albicans and secretes several virulence factors, including 3-oxo-C12 homoserine lactone and pyocyanin, to inhibit growth of C. albicans (Hogan et al, 2004).…”