The application of high-throughput, next-generation sequencing technologies has greatly improved our understanding of the human oral microbiome. While deciphering this diverse microbial community using such approaches is more accurate than traditional culture-based methods, experimental bias introduced during critical steps such as DNA extraction may compromise the results obtained. Here, we systematically evaluate four commonly used microbial DNA extraction methods (MoBio PowerSoil® DNA Isolation Kit, QIAamp® DNA Mini Kit, Zymo Bacterial/Fungal DNA Mini PrepTM, phenol:chloroform-based DNA isolation) based on the following criteria: DNA quality and yield, and microbial community structure based on Illumina amplicon sequencing of the V3–V4 region of the 16S rRNA gene of bacteria and the internal transcribed spacer (ITS) 1 region of fungi. Our results indicate that DNA quality and yield varied significantly with DNA extraction method. Representation of bacterial genera in plaque and saliva samples did not significantly differ across DNA extraction methods and DNA extraction method showed no effect on the recovery of fungal genera from plaque. By contrast, fungal diversity from saliva was affected by DNA extraction method, suggesting that not all protocols are suitable to study the salivary mycobiome.
Head and neck squamous cell carcinoma (HNSCC) patients often present with poor oral health, making it difficult to assess the relationship between oral microbes, inflammation, and carcinoma. This study investigates salivary microbes and inflammatory cytokines as biomarkers for HNSCC, with consideration of oral health. Saliva was collected from 30 participants, including 14 HNSCC patients and 16 participants representing both dentally compromised and healthy individuals. Bacterial and fungal communities were analyzed based on 16S rRNA gene and ITS1 amplicon sequencing, respectively, and concentrations of inflammatory cytokines were quantified using a cytometric bead array, with flow cytometry. Diversity‐based analyses revealed that the bacterial communities of HNSCC patients were significantly different to those of the healthy control group but not the dentally compromised patients. Fungal communities were dominated by Candida, irrespective of cohort, with Candida albicans comprising ≥96% of fungal sequences in most HNSCC patients. Significantly higher concentrations of interleukin (IL)‐1β and IL‐8 were detected in HNSCC and dentally compromised patients, when independently compared with healthy controls. IL‐1β and IL‐8 concentrations were significantly positively correlated with the abundance of C. albicans. Our findings suggest that salivary microbial and inflammatory biomarkers of HNSCC are influenced by oral health.
The management of head and neck cancer (HNC) can lead to potentially severe physical, functional and psychological disturbances. As a result, many HNC patients develop symptoms of depression following diagnosis and treatment. Finding benefit in a disease and its treatment can reduce the symptoms of depression and enhance quality of life (QOL). 92 patients from the Head and Neck Cancer Clinic at Auckland Hospital completed measures of unmet needs and quality of life at diagnosis, and completed measures of benefit finding, coping, fear of recurrence and depression 12-18 months later. Patients reported at least moderate benefit finding in the majority of areas. More benefit finding was predicted by the presence of more advanced disease, Maori/Pacific Island ethnicity, lower baseline QOL, and the use of active coping strategies. These findings support the view that screening for QOL at diagnosis and facilitating the development of coping skills may lead to improved benefit finding and psychological adjustment in people with head and neck cancer. Identification of the factors that facilitate benefit finding may assist management of patients after treatment for HNC.
Xerostomia detrimentally affects the oral health of many head and neck cancer patients who undergo radiotherapy. Its sequelae become an ongoing burden for patients that often manifest as periodontal disease and dental decay. Bacteria play a major role in the pathogenesis of these conditions and here we explore the use of an oral probiotic to beneficially modulate the oral bacterial community postradiotherapy. In this pilot study, a four-week intervention with oral probiotic lozenges containing Streptococcus salivarius M18 was trialled in seven patients. Post-intervention changes in oral health and in the composition of the plaque and saliva bacterial communities were compared with six patients in a placebo group. An improvement in periodontal screening and plaque index scores was observed in both groups after the intervention period. The oral probiotic lozenges did not significantly impact bacterial community composition or diversity, nor did the probiotic lozenges increase the relative sequence abundance of ZOTU_1 (the probiotic-associated sequence assigned to S. salivarius) detected in the samples. Network analyses suggest negative interactions occurred between ZOTU_1 and species from the periopathogenic genera Campylobacter, Fretibacterium, Selenomonas and Treponema but further investigation is required to more fully understand the beneficial properties of this oral probiotic. Head and neck cancer describes a group of malignant tumours that often require radiotherapy as part of the treatment approach. Due to the close proximity of the salivary glands to the radiation portal, many head and neck cancer patients sustain permanent radiation-induced damage to the salivary glands during radiotherapy 1,2. Subsequently, salivary gland function is reduced, resulting in chronic hyposalivation and xerostomia (dry mouth) that causes considerable discomfort, compromises mastication and speech, increases the risk of oral health complications and decreases the quality of life for many patients 1,3,4. Hyposalivation and loss of salivary buffering capacity lead to a decrease in the pH of saliva and a shift to acidogenic and cariogenic bacteria, including an increase the in abundance of Streptococcus mutans and Lactobacillus spp. 5-7. These effects, combined with a decrease in the mechanical flushing mechanism of saliva to reduce plaque build-up, leave patients prone to post-radiotherapy gingivitis, periodontal disease and rampant dental decay 2,3,8. Oral probiotics, primarily those containing lactobacilli, have been successfully shown to decrease the abundance of periopathogens in sub-and supra-gingival plaque, significantly improve plaque index and periodontal
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