Trick or Treating in Forensics—The Challenge of the Saliva Microbiome: A Narrative Review

Abstract

The oral microbiome harbours microbial community signatures that differ among individuals, highlighting that it could be highly individualizing and potentially unique to each individual. Therefore, the oral microbial traces collected in crime scenes could produce investigative leads. This narrative review will describe the current state-of-the-art of how the salivary microbiome could be exploited as a genetic signature to make inferences in the forensic field. This review has been performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines. Even if further studies are needed to relate the variation in the oral microbiome to specific factors, in order to understand how the salivary microbiome is influenced by an individual’s lifestyle, by reviewing the studies published so far, it is clear that the oral microbial analysis could become a useful forensic tool. Even if promising, caution is required in interpreting the results and an effort to direct research towards studies that fill the current knowledge gaps is certainly useful.

Salivary Microbiome Diversity in Kuwaiti Adolescents with Varied Body Mass Index—A Pilot Study

“…Similarly, Liu et al (2012) recorded the following taxa, Actinomyces, Prevotella, Streptococcus, Fusobacterium, Leptotrichia, Corynebacterium, Veillonella, Rothia, Capnocytophaga, Selenomonas, Treponema, and TM7 as core microbiome [49]. The reason for observing slightly different core microbiome taxa in our study than earlier studies could be due to the population level differences [50]. Earlier studies have shown a strong association between ethnicity and microbiome composition [51][52][53][54][55][56][57].…”

Acute Radiation Syndrome and the Microbiome: Impact and Review

“…Microbiota not only refers to bacteria, but encompasses all the microorganisms of the body, including archaea, fungi, protozoans, bacteria, and viruses ( Lederberg and McCray, 2001 ; Zhu et al, 2010 ; Jandhyala et al, 2015 ). The human microbiome is incredibly diverse with an individual’s microbiome so distinct that it has been proposed to be used as a differentiating biomarker in forensics ( D’Angiolella et al, 2020 ; García et al, 2020 ). Not only is the microbiome diverse among individuals but also across the body and even within body areas ( Roth and James, 1988 ; Hakansson and Molin, 2011 ; Seidel et al, 2020 ).…”

“…In the oral cavity, there may be from 10 8 to 10 10 CFU per gram of saliva ( Lazarevic et al, 2009 ). It should be noted that the oral microbiota even in healthy people varies drastically across location in the oral cavity, time of day, hydration, what and when the person ate, oral hygiene, age, smoking status, and so on ( Aas et al, 2005 ; Bik et al, 2010 ; Cameron et al, 2015 ; Leake et al, 2016 ; Hall et al, 2017 ; Belstrøm, 2020 ; D’Angiolella et al, 2020 ). In radiation exposures, oral side effects such as xerostomia (dry mouth) are seen in patients receiving external beam radiotherapy to the head and neck ( Wijers et al, 2002 ; Dirix et al, 2006 ) and radioiodine therapy ( Alexander et al, 1998 ; Solans et al, 2001 ; Jeong et al, 2013 ; Hollingsworth et al, 2016 ).…”

Microbiome Forensic Biobanking: A Step toward Microbial Profiling for Forensic Human Identification

“…In the past few years, several studies have focused on stability in the human microbiome over time [36]. The literature published in this field over the past few years has ascertained clearly enough that microbial communities, although personalized, vary systematically across body sites and time, with intrapersonal differences over time being smaller than interpersonal ones, showing such a high degree of spatial and temporal variability that the degree and nature of this variability can constitute in and of itself an important parameter that is useful in distinguishing individuals from one another [37][38][39][40][41]. It is paramount to make the effort to organically synthesize all results achieved until now and to implement the number of participants to this type of study.…”