Oral Microbiome: Contributions to Local and Systemic Infections

Abstract

The recent revolution of diagnostic methods emphasizing non-culture techniques has redefined the oral microbiota, its “Dual Citizenship”, recognizing oral flora inhabitants of eight dispersed locations are colonized by over 700 species, equal in bacteria (16S) and fungi (18S). Either prefers the attached biofilm phenotype, biotic or abiotic surfaces, its extra polymeric substance (EPS) protected environment promoting horizontal gene transfer (HGT), and gene amplified resistance. The biofilm growth pattern mimics that of solid tumors and a four-stage lifestyle (I–IV) catalyzing the term biotumor, emphasizing dispersal via metastasis. The molecular methods are now multitiered system platforms employing: PCR, mass spectrometry, fluorescent in situ hybridization (FISH), highlighted by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), and IBIS or microarray gene sequencing providing inexpensive rapid results complementing the Human Genome Project unmasking a rich, diverse oral microbiota and mycobiota. The emerging head-neck oral diseases now emphasize medical devices [endotracheal tube (ETT) and voice boxes], dentures, and links with cognition [Alzheimer’s disease (AD)] and NOMA, while systemic manifestations highlight extra oral communications via inflammation, microbial presence (metastasis), or both, recently consolidated by the new Yin Yang hypothesis. These migrating oral microbiota-associated diseases include rheumatoid arthritis (RA), perio-arthritis, child-mother birth issues [adverse pregnancy outcomes (APO)], gestational diabetes (GDM), and liver consequences [non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH)], all inter-related using a four-quadrant microbial clock. New interventions employ the disarm/replace hypothesis, avoiding “kill” focusing on therapeutic bacteria (probiotics), recognizing untoured consequences of antibiotics, and a need for a balanced oral microbiota. Most importantly is the recognition that the disconnect between dentistry and medicine is no longer tenable, and oral health and systemic health are integrated by the human oral microbiota, which is part of the host Dual Citizenship.