Fungi at the Scene of the Crime: Innocent Bystanders or Accomplices in Oral Infections?

Abstract

Purpose of Review Over the last decade, microbiome studies have enhanced our knowledge and understanding of the polymicrobial nature of oral infections. Recently, profiling of the fungal microbiome has expanded our conventional understanding of oral ecology, revealing the critical importance of yeasts within this complex microbiome. This review aims to explore our current appreciation of interkingdom interactions in oral disease. Recent Findings There is a growing evidence base of interactions and pathogenic synergy and antagonism with bacterial species within oral disease. Recent studies have helped to develop our knowledge of how Candida albicans, alongside bacteria such as Porphyromonas gingivalis, Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Lactobacillus species, influence overall pathogenicity. Summary Clinical and experimental evidence makes a compelling case for a role for C. albicans in a number of oral infections, though whether its role is an active accomplice or passive bystander remains to be determined.

A nanocarrier system that potentiates the effect of miconazole within different interkingdom biofilms

“…Therefore, the reduction in bacterial counts may be explained by the role of Candida in providing structural support for the bacterial community. The Candida yeast cell form has around 6.6 µm diameter, but its hyphae are much larger in size [43] and therefore serve as a scaffold for the smaller bacterial cells to attach [6]. Loss of this support structure may have resulted in the observed reductions in bacterial cell numbers.…”

“…For effective treatment and/or control of different oral biofilms, this requires a tacit understanding of the nature of the causative oral microbiome in order to recapitulate these interactions in vitro. Existing biofilm models often fail to account for polymicrobiality, a characteristic associated with the pathogenesis of gingivitis, caries and denture stomatitis [5,6]. Instead, commercial models for drug discovery rely on simplified mono-species biofilms that provide an inferior challenge to antimicrobial therapies.…”

Candida albicans Biofilm Heterogeneity and Tolerance of Clinical Isolates: Implications for Secondary Endodontic Infections

“…It is important to note that our studies did not explore the effect of irrigant activation, which is an integral part of endodontic disinfection protocols and could potentially, in combination with NaOCl and EDTA, eliminate C. albicans and prevent its regrowth. Furthermore, C. albicans coexist with multiple species and are known for their ability to form biofilms with and without other bacterial species (mono-microbial and poly-microbial biofilms), such as Enterococcus faecalis and Staphylococcus aureus [44]. As a result, future investigation should explore whether interkingdom interactions of C. albicans with bacteria could complicate root canal treatment and provide protection to one another ultimately leading to persistence.…”

Candida albicans Shields the Periodontal Killer Porphyromonas gingivalis from Recognition by the Host Immune System and Supports the Bacterial Infection of Gingival Tissue

“…In healthy individuals, the oral cavity is colonized mostly by Gram-positive facultative anaerobic bacteria that exist in a proper equilibrium with the host immune responses [4,5]. However, a microbiome imbalance resulting from improper oral hygiene, with the continuous formation of dental plaques in gingival tissues, contributes to oral diseases ranging from reversible gingivitis to irreversible periodontitis and results in the destruction of periodontal ligaments and alveolar bone [6]. Moreover, periodontitis may enhance the risk for developing systemic inflammatory diseases like atherosclerosis, infective endocarditis, diabetes, adverse pregnancy outcomes, respiratory diseases, and rheumatoid arthritis [7][8][9][10][11].…”