Salivary Microbiome Diversity in Caries-Free and Caries-Affected Children

Abstract

Dental caries (tooth decay) is an infectious disease. Its etiology is not fully understood from the microbiological perspective. This study characterizes the diversity of microbial flora in the saliva of children with and without dental caries. Children (3–4 years old) with caries (n = 20) and without caries (n = 20) were recruited. Unstimulated saliva (2 mL) was collected from each child and the total microbial genomic DNA was extracted. DNA amplicons of the V3-V4 hypervariable region of the bacterial 16S rRNA gene were generated and subjected to Illumina Miseq sequencing. A total of 17 phyla, 26 classes, 40 orders, 80 families, 151 genera, and 310 bacterial species were represented in the saliva samples. There was no significant difference in the microbiome diversity between caries-affected and caries-free children (p > 0.05). The relative abundance of several species (Rothia dentocariosa, Actinomyces graevenitzii, Veillonella sp. oral taxon 780, Prevotella salivae, and Streptococcus mutans) was higher in the caries-affected group than in the caries-free group (p < 0.05). Fusobacterium periodonticum and Leptotrichia sp. oral clone FP036 were more abundant in caries-free children than in caries-affected children (p < 0.05). The salivary microbiome profiles of caries-free and caries-affected children were similar. Salivary counts of certain bacteria such as R. dentocariosa and F. periodonticum may be useful for screening/assessing children’s risk of developing caries.

Leptotrichia species in human infections II

“…oral clone FP036Dental cariesSaliva P. melaninogenica , P. histicola , P. salivae , R. dentocariosa , Haemophilus, S. mutans , S. sanguinis , Neisseria, Gemella , Veillonella, Veillonella sp. oral taxon 780, A. odontolyticus , A. graevenitzii , Scardovia, F. periodonticum , Lactobacillus , MiSeq sequencing[69]M/F 3–4 Leptotrichia sp. oral clone FP036HealthySaliva P. melaninogenica , P. histicola , P. salivae , R. dentocariosa , Veillonella, A. odontolyticus , A. graevenitzii , Veillonella sp.…”

“…Since previous reviews [2,3], Leptotrichia species have been reported in >124 cases [4,7,16,18–69,87–93], whereby 30 cases involved L. buccalis [4,8,15,21,34,52,56,70–79,87], 24 cases L. wadei [4,20,24,34,37,42,48,56,67,80,81,90,93], 16 cases L. trevisanii [4,5,9,10,13,14,17,37,87], 14 cases L. hofstadii [34,40,49,56,81–84,93], 10 cases L. goodfellowii [4,11,12,21,56,74,85,87], eight cases L. hongkongensis [4,6,18,45,47,56], and five L. shahii [34,56,86]. L. trevisanii and L. wadei bacteremia are extremely rare; clinicians should consider these species in cases involving immunocompromised patients with oral lesions [4,5,13,17,87].…”

“…They were also recovered from oral plaque of guinea pigs [21] and feces of piglets [54], dental plaque from healthy individuals, plaque and saliva from patients with various types of caries, gingivitis, chronic periodontitis, and peri-implantitis [23,25–27,34,35,37,38,44,45,47,49,52,59,60,62,66–69,91,94], decayed tooth surfaces and discordant caries from intact enamel surfaces [53]. Leptotrichia species were also isolated from bronchoalveolar lavage fluid, and patients with leukocytosis, hypoxemia, and dyspnea [24].…”

“…Inappropriate clinical situations can affect the protective function of the indigenous bacterial flora, which can lead to disruption by broad-spectrum antibiotic therapy [2–4,12,69,103], resulting in infection. Likewise, enhanced Leptotrichia proliferation and tissue invasion can culminate in bloodstream invasion and dissemination [2,3].…”

“…Herbivorous fish harbored abundant cellulose-degrading bacteria, including Clostridium , Citrobacter , and Leptotrichia (Table 2) [58]. L. hofstadii was considered and reported as a potential biomarker for dental caries in association with Campylobacter showae and Parvimonas micra [69,84]. Leptotrichia species were found together with Fusobacterium and Campylobacter species in patients with colorectal carcinoma.…”