1.
A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.
Proctor, DM, Fukuyama, JA, Loomer, PM, Armitage, GC, Lee, SA, Davis, NM, Ryder, MI, Holmes, SP, Relman, DA
Nature communications. 2018;9(1):681
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Identifying spatial patterns in the human microbiota is necessary to provide insight into mechanisms that either maintain or disrupt its healthy state. The aim of this study was to identify the type and extent of oral spatial patterns formed by bacterial communities, as well as observe the impact of low salivary flow on the spatial patterns. Dental exams were performed on 31 participants to evaluate the oral health status and follow-up was dependent on group allocation. This study found bacterial communities were distinguishable depending on types of teeth and tissue. Further, bacteria on soft and hard tissues varied across the front and back of the oral cavity in a gradient-manner, implying that salivary flow plays a role in establishing the bacterial community gradient in the oral cavity. Based on these results, the authors recommend spatial patterns and processes be explored in other body parts to better understand health and disease.
Abstract
Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.
2.
Emollient use alters skin barrier and microbes in infants at risk for developing atopic dermatitis.
Glatz, M, Jo, JH, Kennedy, EA, Polley, EC, Segre, JA, Simpson, EL, Kong, HH
PloS one. 2018;13(2):e0192443
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Atopic dermatitis (AD) is a type of eczema common in babies and young children. Poor function of the skin barrier is thought to lead to changes in the composition of bacteria found on the skin. This small study investigated the effects of daily use of an emollient, Cetaphil Moisturising Cream, on the barrier function and bacterial communities on the skin of infants at risk of developing AD. After 6 months, the emollient group had a lower skin pH than the control group. The group using the emollient had more diverse skin bacterial communities than the control group. The proportion of Streptococcus salivarius was higher in the emollient versus control groups. The authors concluded that lower skin pH and increased skin bacterial diversity after long-term emollient use may reduce inflammation and lower the risk of infants developing AD.
Abstract
BACKGROUND Emollients are a mainstay of treatment in atopic dermatitis (AD), a disease distinguished by skin bacterial dysbiosis. However, changes in skin microbiota when emollients are used as a potential AD preventative measure in infants remain incompletely characterized. RESULTS We compared skin barrier parameters, AD development, and bacterial 16S ribosomal RNA gene sequences of cheek, dorsal and volar forearm samples from 6-month-old infants with a family history of atopy randomized to receive emollients (n = 11) or no emollients (controls, n = 12). The emollient group had a lower skin pH than the control group. The number of bacterial taxa in the emollient group was higher than in the control group at all sites. The Streptococcus salivarius proportion was higher in the emollient versus control groups at all sites. S. salivarius proportion appeared higher in infants without AD compared to infants with AD. A decrease in S. salivarius abundance was further identified in a separate larger population of older children demonstrating an inverse correlation between AD severity at sampling sites and S. salivarius proportions. CONCLUSIONS The decreased skin pH and the increased proportion of S. salivarius after long-term emollient use in infants at risk for developing AD may contribute to the preventative effects of emollients in high-risk infants.
3.
Effects of fasting and preoperative feeding in children.
Yurtcu, M, Gunel, E, Sahin, TK, Sivrikaya, A
World journal of gastroenterology. 2009;15(39):4919-22
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Preoperative fasting is usually carried out to prevent the risk of vomiting during anaesthesia. The study investigated whether children should have a long period of fasting before surgery. Eight groups of 10 children (aged 1-10 years) with disorders of groin and scrotum were orally fed normal liquid food (NLF) or a high calorie diet (HCD) in 2 divided doses at 6 hour intervals, then fasted for 2, 3, 4 or 5 hours prior to surgery. Four groups had NLF and 4 groups had HCD. All children had their glucose, prealbumin and cortisol levels measured twice, just after the oral feeding and just before surgery. Once anaesthesia was sufficient and stable, gastric liquid was collected and measured. Patients with disease that could delay gastric emptying, had high acid production or were on medication were excluded from the trial. The researchers found that there was no significant difference in blood prealbumin levels in all groups. There was significant increase in blood cortisol in 4 groups when fasted (NLF-2h fasted, HCD-2h fasted, NLF-3h fasted and HCD-5h fasted). Stomach aid residue liquids were at tolerable levels of 1-2ml in all children. Anaesthesia was uneventful, with no coughing, laryngospasm or vomiting reported, and outcomes of surgery and wound healing were not affected. The authors noted that drinking clear liquids up to 2 hours before surgery was unlikely to substantially affect the volume of gastric fluids, and did not appear to increase the risk of vomiting in normal, healthy children. Glucose and insulin infusions appeared to minimise endocrine stress response and normalised post-op insulin sensitivity. Additionally, there may be a psychological benefit for children as irritability appeared to decrease prior to surgery. The study concluded that there was no need for fasting longer than 2 hours prior to inguinoscrotal region surgery.
Abstract
AIM: To investigate whether children should undergo surgery without a long period of fasting after feeding. METHODS Eighty children with inguinoscrotal disorders (aged 1-10 years) were studied prospectively. They were divided into eight groups that each contained 10 children who were fed normal liquid food (NLF) and a high-calorie diet (HCD) 2, 3, 4 and 5 h before surgery, in two doses at 6-h intervals. NLF was given to four groups and HCD to the other four. In all groups, glucose, prealbumin and cortisol levels in the blood were measured twice: just after oral feeding and just before the operation. After the establishment of adequate anesthesia, gastric residue liquid was measured with a syringe. RESULTS Blood glucose levels in all patients fed NLF and HCD were high, except in patients in the HCD-4 group. There was no significant difference in the blood prealbumin levels. There was a significant increase in the blood cortisol levels in the NLF-2 (14.4 +/- 5.7), HCD-2 (13.2 +/- 6.0), NLF-3 (10.9 +/- 6.4), and HCD-5 (6.8 +/- 5.7) groups (P < 0.05). CONCLUSION The stress of surgery may be tolerated by children when they are fed up to 2 h before elective surgery.