Influence of Streptococcus mitis and Streptococcus sanguinis on virulence of Candida albicans: in vitro and in vivo studies

Abstract

The aim was to evaluate in vitro possible interactions, gene expression, and biofilm formation in species of Candida albicans, Streptococcus mitis, and Streptococcus sanguinis and their in vivo pathogenicity. The in vitro analysis evaluated the effects of S. mitis and S. sanguinis on C. albicans's biofilm formation by CFU count, filamentation capacity, and adhesion (ALS1, ALS3, HWP1) and transcriptional regulatory gene (BCR1, CPH1, EFG1) expression. In vivo studies evaluated the pathogenicity of the interaction of the microorganisms on Galleria mellonella, with analyses of the CFU per milliliter count and filamentation. In vitro results indicated that there was an observed decrease in CFU (79.4-71.5%) in multi-species biofilms. The interaction with S. mitis inhibited filamentation, which seems to increase its virulence factor with over-expression of genes ALS1, ALS3, and HWP1 as well the interaction with S. sanguinis as ALS3 and HWP1. S. mitis upregulated BRC1, CPH1, and EFG1. The histological images of in vivo study indicate an increase in the filamentation of C. albicans when in interaction with the other species. It was concluded that S. mitis interaction suggests increased virulence factors of C. albicans, with periods of lower virulence and proto-cooperation in the interaction with S. sanguinis.

The Role of Candida albicans Virulence Factors in the Formation of Multispecies Biofilms With Bacterial Periodontal Pathogens

“…Hence, the question remains whether or not a group of early colonizers modulates fungal biofilm formation to influence oral health or disease progression in the host organism. Furthermore, the study using Galleria mellonella as an alternative model of mixed bacterial-fungal infection did not show any significant changes in fungal abundance and morphological changes during 12 h of co-infections of larvae by C. albicans strain ATCC 18804, S. mitis, and S. sanguinis (do Rosaŕio Palma et al, 2019). However, for other bacterium from the group of early colonizers-S. gordonii-a promotion of C. albicans strain ATCC SC5314 biofilm formation was demonstrated (Bamford et al, 2009).…”

“…Prior exposure of C. albicans oral isolates to S. sanguinis isolated from healthy and HIV-infected individuals resulted in an inhibition or promotion of candidal germ tube formation, respectively (Nair et al, 2001). Further in vitro analyses showed that the addition of S. sanguinis and S. mitis cells to C. albicans ATCC 18804 cells pre-incubated to promote initial fungal adhesion considerably reduced fungal CFU in mixed biofilm compared with single-species fungal biofilm, while also the presence of S. mitis, but not S. sanguinis, reduced C. albicans filamentation (do Rosaŕio Palma et al, 2019). These data contrast with a study of biofilm formation on the salivary flow which showed that C. albicans strain ATCC SC5314 exhibits an enhanced biofilm-formation capacity in the presence of S. sanguinis and S. gordonii (Diaz et al, 2012).…”

“…In the group of oral streptococci, the problem of co-adhesion of bacteria and fungi during biofilm development has been quite decently studied and attempts have been made to indicate the mechanisms of these interactions. It was demonstrated that when C. albicans strain ATCC 18804 creates biofilm together with S. mitis, the expression levels of genes encoding major adhesins, agglutinin-like sequence proteins ALS1 and ALS3, and hyphal cell wall protein HWP1 were significantly upregulated, whereas in the coexistence in biofilm with S. sanguinis, only the gene expression for HWP1 was upregulated, for ALS3 the expression did not change, and for ALS1 downregulation was observed (do Rosaŕio Palma et al, 2019). On the other hand, the increase in ALS1 gene expression was noticed during the formation of mature biofilm by C. albicans strain SC5314 and S. oralis at a ratio of 1:10 and the als1D/D deletion mutant strain was deficient in co-aggregation with this bacterial species (Xu et al, 2017).…”

“…The studies of do Rosaŕio Palma et al (2019) showed that interactions of C. albicans standard strain ATCC 18804 with S. mitis during the formation of mixed biofilm in 24-well microtiter plates for 48 h, when streptococci were added to the fungal biofilm preformed for 2 h after initial adhesion of 10 7 /ml of C. albicans cells, resulted in the upregulation of genes involved in the biofilm formation and filamentation, like BCR1 required for the formation of biofilm and regulation of genes encoding cell surface-associated proteins and CPH1 involved in the filamentation (Nobile and Mitchell, 2005;Nobile et al, 2006;Maiti et al, 2015). Additionally, an increase with uncertain statistical significance was also detected for EFG1, the major transcriptional regulator involved in fungal morphogenesis and a key transcriptional activator of hypha-specific genes (HSGs) (Stoldt et al, 1997;do Rosaŕio Palma et al, 2019). In contrary, in the same work, the downregulation of BCR1 and EFG1 was noticed under the same conditions for C. albicans ATCC 18804 interaction with S. sanguinis (do Rosaŕio Palma et al, 2019).…”

Microbial Etiology and Prevention of Dental Caries: Exploiting Natural Products to Inhibit Cariogenic Biofilms

“…In addition to S. mutans, Lactobacillus [48], Bifidobacterium [60], and Scardovia species [47] are also considered as caries-associated colonizers. Data from previous studies have suggested that the susceptibility of biofilms to antibiotics, preservatives, or anti-adhesion compounds is closely related to microbial diversity [61][62][63]. Due to the strong competitiveness of cariogenic microorganisms, microbial abundance decreases during the maturation of cariogenic biofilms [50].…”