The analysis of the oral microbiome as a new technology for healthcare research

Naama Keshet, D.D.S., and Dr. Ronen Hazan, Ph.D.

The mouth is one of the most heavily colonized micro-organisms of our body. The large number of microbial and bacterial residents in the oral cavity is referred to as our microbiome or microflora. Abnormalities of the function and composition of the microbiome can have grave consequences for human health. The importance of oral fluids – mainly saliva in our everyday activities and the medicinal properties it possesses are often taken for granted. The oral cavity is also the major access to the gut (stomach and intestinal tract), and a correlation between the microflora in the digestive system in health and disease has been established. A large number of investigations have linked oral bacteria to a number of diseases affecting the body, and there is evidence suggesting that oral bacterial species are associated to a number of diseases such as cardiovascular disease, stroke, diabetes and pneumonia. However, meaningful and profound knowledge to identify and characterize the diversity of the major microbial and bacterial species, which is specific to each person, residing in the human microbiome, has not been largely investigated.

Although major research has been done on the microbiome of the gut, verifiable studies on the salivary microbiome at the population level and its role in general health has not been well characterized. The oral and gut microbiomes are co-dependent. Studies on the gut microbiota, for example, has produced a major effective treatment in 85% to 90% of the cases with the use of fecal microbiota transplantation for those patients in whom antibiotics had not worked or in whom the disease recurred following antibiotics. Dr. Naama Keshet, a senior clinician from the Department of Oral Medicine, Sedation and Maxillofacial Radiology; Prof Doron Aframinan, the chair of the departments and the Salivary Gland Diseases Laboratory in collaboration of Dr. Ronen Hazan from the Jerusalem Institute of Dental Sciences are undertaking a novel study to unravel the complexities of the parotid salivary gland microbiome. Their models consist of healthy individuals vs. those patients suffering from type 2 diabetes and other systemic diseases with oral manifestations. Saliva from the mouth and saliva from the parotid gland (which carry different species of microbes) are tested. Preliminary studies implicate that microbial DNA is present in the parotid saliva and in addition, exhibits major diversion compared to oral fluids. The salivary DNA represents the genomic information of a person and bacterial DNA can identify the kinds of bacteria in sick or healthy individuals. The researchers will be using the 16S metagenomics sequencing assay, a powerful tool in genomics to study the diversity of microbial communities that could lead to more diagnostic tests based on saliva samples.

This team of researchers benefit from having access to a large population of patients who are either healthy individuals suffering from dental problems or sick patients treated at the Hadassah Medical Center who are referred to the Dental Clinic. This investigation is very important not only to physicians, but also to patients since it will increase the knowledge and understanding of the oral microbiome and consequently, will allow physicians to use it as a tool to predict, diagnose and prevent many health problems and diseases. Moreover, the use of saliva for analysis is a noninvasive, more economical and painless alternative.