Tongue Coating and the Salivary Microbial Communities Vary in Children with Halitosis

Abstract

Halitosis is a common symptom mainly caused by microbial activities in the oral cavity. Here, we used 16S rRNA gene pyrosequencing and metagenomic sequencing to examine oral microbial compositions and their functional variations in children with halitosis. We found that the tongue coating of subjects with halitosis had greater bacterial richness than those of healthy subjects. The relative abundance and prevalence of Leptotrichia wadei and Peptostreptococcus stomatis were higher in tongue coating samples from children with halitosis than those from children without halitosis; Prevotella shahii had higher relative abundance and prevalence in saliva samples from children with halitosis. We present the first comprehensive evaluation of the co-occurrence networks of saliva and tongue coating communities under healthy and halitosis conditions, and investigated patterns of significant differences between these communities. Moreover, we observed that bacterial genes associated with responses to infectious diseases and terpenoid and polyketide metabolism were enriched in subjects with halitosis, but not in healthy subjects. Hydrogen sulphide (H2S)-related metabolic pathways suggested that there was higher microbial production and less usage of H2S in subjects with halitosis. Thus, the mechanism of halitosis was implied for the first time via metagenomic sequencing.

Leptotrichia species in human infections II

“…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].…”

“…L. hofstadii has been isolated from subgingival samples and gingival crevicular fluid of periodontitis patients [83], saliva, biofilm from caries [49,65], the mucosal surface of patients with removable partial dentures, and root canals of patients with or without disease [34,56,84], tumor tissue [40], and tongue coatings of halitosis patients (Table 2) [81,82]. …”

“…Saliva, plaque, and the oral mucosal surface of caries patients [34,37,56,67] and the oral cavity and biofilms from oral epithelial cells of a patient with new-onset rheumatoid arthritis [20,48] all contained L. wadei . Patient material from tongue plaque, saliva, and the tongue coating of malodor and halitosis patients [42,81] was isolated with L. wadei present. This bacterium was even isolated from the antral gastric biopsy of a dyspeptic patient [80], smokers’ plaque [90], and oropharyngeal samples (Table 2) [93].…”

“…Leptotrichia species were also isolated from bronchoalveolar lavage fluid, and patients with leukocytosis, hypoxemia, and dyspnea [24]. Further, Leptotrichia species were recovered from healthy patients with oral cancer, premalignant oral lesion [18,28,33,56,91], edentulous infants [29], human vaginal fluid of sexually active and inactive individuals [30,32], HIV-seropositive and -seronegative patients [46], pancreatic cancer patients [18,66], black pigmented stain caries patients [63], and patients with halitosis (Table 2) [42,65,81,82]. Besides, Leptotrichia species were isolated from the blood [4,5,22,74], the amniotic fluid of a patient with a wound and respiratory difficulties [4], breast milk of obese women with gestational diabetes and normal weight [36], oral samples of a patient with new-onset rheumatoid arthritis [20], oral lichen planus patients [88], and even from fermenting Lees liquor [39].…”

“…Leptotrichi a has also been associated with halitosis (oral malodor) [42,65,81,82]. Most of the species within the core microbiome of the tongue-coating biofilm are Gram-negative anaerobic bacteria that are adaptable to the tongue-coating environment (Table 2) [81].…”