Gaik Chin Yap

Evaluation of stool microbiota signatures in two cohorts of Asian (Singapore and Indonesia) newborns at risk of atopy

BackgroundStudies have suggested that demographic and lifestyle factors could shape the composition of fecal microbiota in early life. This study evaluated infant stool microbiota signatures in two Asian populations, Singapore (n = 42) and Indonesia (n = 32) with contrasting socioeconomic development, and examined the putative influences of demographic factors on these human fecal associated bacterial signatures.ResultsLongitudinal analysis showed associations of geographical origin with Clostridium leptum, Atopobium and Bifidobacterium groups. Mode of delivery had the largest effect on stool microbiota signatures influencing the abundance of four bacterial groups. Significantly higher abundance of bacterial members belonging to the Bacteroides-Prevotella, Bifidobacterium and Atopobium groups, but lower abundance of Lactobacilli-Enterococci group members, were observed in vaginal delivered compared to caesarean delivered infants. Demographic factors influencing the structure of infants stool microbiota during the first year of life included breastfeeding, age of weaning, sibship size and exposure to antibiotics.ConclusionsDifferences in stool microbiota signatures were observed in relation to various demographic factors. These features may confound studies relating to the association of the structure of fecal microbiota and the predisposition to human modern disease.

Clinical and immunochemical profiles of food challenge proven or anaphylactic shrimp allergy in tropical Singapore

Shellfish allergy in Singapore is highly prevalent, and shrimp allergy is the most common.

Hierarchical Oligonucleotide Primer Extension as a Time- and Cost-Effective Approach for Quantitative Determination of Bifidobacterium spp. in Infant Feces

ABSTRACT The Bifidobacterium spp. present in 10 infant fecal samples (4 from infants with eczema and 6 from healthy infants) were quantified with both hierarchical oligonucleotide primer extension (HOPE) and fluorescence in situ hybridization-flow cytometry. The relative abundances of Bifidobacterium longum and B. catenulatum with respect to the total bifidobacteria had a poor correlation (ρ, <0.600; P value, >0.208), presumably due to differences in primer specificity and the level of hybridization stringency of both methods. In contrast, the relative abundances of organisms of the genus Bifidobacterium against the total amplified 16S rRNA genes and those of B. adolescentis, B. bifidum, and B. breve against the genus Bifidobacterium exhibited a good statistical correlation (ρ, >0.783; P value, <0.066). This good comparability supports HOPE as a method to achieve high-throughput quantitative determination of bacterial targets in a time- and cost-effective manner.

A novel LCMSMS method for quantitative measurement of short-chain fatty acids in human stool derivatized with 12C- and 13C-labelled aniline

&NA; A novel liquid chromatography tandem mass spectrometry (LCMSMS) method for the quantitative measurement of gut microbial‐derived short‐chain fatty acids (SCFAs) in human infant stool has been developed and validated. Baseline chromatographic resolution was achieved for 12 SCFAs (acetic, butyric, caproic, 2,2‐dimethylbutyric, 2‐ethylbutyric, isobutyric, isovaleric, 2‐methylbutyric, 4‐methylvaleric, propionic, pivalic and valeric acids) within an analysis time of 15 min. A novel sequential derivatization of endogenous and spiked SCFAs in stool via 12C‐ and 13C‐aniline respectively, facilitated the accurate quantitation of 12C‐aniline derivatized endogenous SCFAs based on calibration of exogenously 13C‐derivatized SCFAs. Optimized quenching of derivatization agents prior to LCMSMS analysis further reduced to negligible levels the confounding chromatographic peak due to in‐line derivatization of unquenched aniline with residual acetic acid present within the LCMS system. The effect of residual acetic acid, a common LCMS modifier, in analysis of SCFAs has not been addressed in previous SCFA assays. For the first time, a total of 9 SCFAs (acetic, butyric, caproic, isobutyric, isovaleric, 2‐methylbutyric, 4‐methylvaleric, propionic and valeric acids) were detected and quantitated in 107 healthy infant stool samples. The abundance and diversity of SCFAs in infant stool vary temporally from 3 weeks onwards and stabilize towards the end of 12 months. This in turn reflects the maturation of infant SCFA‐producing gut microbiota community. In summary, this novel method is applicable to future studies that investigate the biological roles of SCFAs in paediatric health and diseases. Graphical abstract Figure. No caption available. HighlightsNovel derivatization of endogenous and spiked SCFAs in stool via 12C‐ and 13C‐aniline.In‐line derivatization of residual acetic acid with aniline was identified and mitigated.Novel LCMSMS quantitation of 9 SCFAs in human infant stool.Establishment of temporal SCFA profiles in infant stool from 3 weeks to 12 months.

Establishment of the nasal microbiota in the first 18 months of life: Correlation with early-onset rhinitis and wheezing

Background: Dynamic establishment of the nasal microbiota in early life influences local mucosal immune responses and susceptibility to childhood respiratory disorders. Objective: The aim of this case‐control study was to monitor, evaluate, and compare development of the nasal microbiota of infants with rhinitis and wheeze in the first 18 months of life with those of healthy control subjects. Methods: Anterior nasal swabs of 122 subjects belonging to the Growing Up in Singapore Towards Healthy Outcomes (GUSTO) birth cohort were collected longitudinally over 7 time points in the first 18 months of life. Nasal microbiota signatures were analyzed by using 16S rRNA multiplexed pair‐end sequencing from 3 clinical groups: (1) patients with rhinitis alone (n = 28), (2) patients with rhinitis with concomitant wheeze (n = 34), and (3) healthy control subjects (n = 60). Results: Maturation of the nasal microbiome followed distinctive patterns in infants from both rhinitis groups compared with control subjects. Bacterial diversity increased over the period of 18 months of life in control infants, whereas infants with rhinitis showed a decreasing trend (P < .05). An increase in abundance of the Oxalobacteraceae family (Proteobacteria phylum) and Aerococcaceae family (Firmicutes phylum) was associated with rhinitis and concomitant wheeze (adjusted P < .01), whereas the Corynebacteriaceae family (Actinobacteria phylum) and early colonization with the Staphylococcaceae family (Firmicutes phylum; 3 weeks until 9 months) were associated with control subjects (adjusted P < .05). The only difference between the rhinitis and control groups was a reduced abundance of the Corynebacteriaceae family (adjusted P < .05). Determinants of nasal microbiota succession included sex, mode of delivery, presence of siblings, and infant care attendance. Conclusion: Our results support the hypothesis that the nasal microbiome is involved in development of early‐onset rhinitis and wheeze in infants.

Immune-modulatory genomic properties differentiate gut microbiota of infants with and without eczema

Gut microbiota play an important role in human immunological processes, potentially affecting allergic diseases such as eczema. The diversity and structure of gut microbiota in infants with eczema have been previously documented. This study aims to evaluate by comparative metagenomics differences in genetic content in gut microbiota of infants with eczema and their matched controls. Stools were collected at the age of one month old from twelve infants from an at risk birth cohort in a case control manner. Clinical follow up for atopic outcomes were carried out at the age of 12 and 24 months. Microbial genomic DNA were extracted from stool samples and used for shotgun sequencing. Comparative metagenomic analysis showed that immune-regulatory TCAAGCTTGA motifs were significantly enriched in the six healthy controls (C) communities compared to the six eczema subjects (E), with many encoded by Bifidobacterium (38% of the total motifs in the C communities). Draft genomes of five Bifidobacterium species populations (B. longum, B. bifidum, B. breve, B. dentium, and B. pseudocatenulatum) were recovered from metagenomic datasets. The B. longum BFN-121-2 genome encoded more TCAAGCTTGA motifs (4.2 copies per one million genome sequence) than other Bifidobacterium genomes. Additionally, the communities in the stool of controls (C) were also significantly enriched in functions associated with tetrapyrrole biosynthesis compared to those of eczema (E). Our results show distinct immune-modulatory genomic properties of gut microbiota in infants associated with eczema and provide new insights into potential role of gut microbiota in affecting human immune homeostasis.

Food allergy and anaphylaxis – 2044. Component resolved allergen sensitzation profiles in shrimp allergy in the tropics

pared to Group1B (Der p 10 [33.3%vs9.7%], and Pen m 1 [33.3%vs9.7%], p<0.037); and to Group2 (Blo t 10 [19.4% vs0%], Pen m 1 [33.3%vs5.3%], Pen I 1 [27.8%vs5.3%], Lit v 1 [22.2%vs5.3%], p<0.05). Sensitization to Lit v 2 were higher in Group1A (22.2%) compared to Group1B (6.5%) and Group2 (5.2%) (p<0.093). The sensitization rates to Lit v 3, 4 were low (<10%). A positive test for a combination of shrimp (ImmunoCAP f24)+any tropomyosin+any shrimp allergens gave the highest sensitivity(81.8%) to distinguish FC positive from negative subjects but had a low specificity of 24.1%. The specificity was highest (93.1%) when using a positive test for Der p 10 or any shrimp tropomyosin, but sensitivity was low (31.8%). Conclusions

MICROFLORA OF THE INTESTINE | The Natural Microflora of Humans

This article is a revision of the previous edition article by Caroline L. Willis, Glenn R. Gibson, volume 2, pp 1351–1355,

Allergic diseases of the skin and drug allergies – 2013. Longitudinal analysis of fecal microbiota of infants followed-up for eczema till 2 years of age

Methods Children with eczema at 2 years old (n=26) and their matched (for gender, mode of delivery and feeding in first 6 months) healthy controls (n=26) were selected from the placebo group of a cohort of at-risk infants participating in an randomized double-blind placebo controlled trial on the protective effects of supplemental probiotics (first 6 months) on eczema and allergies. Children with eczema were subclassified into atopic eczema (n=12) and non-atopic eczema (n=14). Molecular evaluation of fecal microbiota were conducted using Fluorescence In Situ Hybridization-Flow Cytometry (FISH-FC) for fecal samples collected at 3 days, 1, 3, and 12 months. Probes were selected to target Eubacterium rectale-Clostridium coccoides group (Erec482), Clostridium leptum subgroup (Clep866 and the corresponding competitor probes), Bacteroides-Prevotella group (Bac303), Bifidobacterium genus (Bif164), Atopobium group (Ato291), LactobacilliEnterococci group (Lab158), Enterobacteriaceae family (Enter1432) and Clostridium perfringens (Cperf191). Linear mixed model was used to evaluate the longitudinal differences (i.e. 4 time points) of bacterial targets while adjusting for gender, mode of delivery, feeding up to 6 months, and allergic rhinitis and wheezing within the eczema group at 2 years of age. Results Longitudinal analyses over four time points showed that higher relative abundance of Enterobacteriaceae [coefficient (B): 1.104, 95% confidence interval (CI):0.175-2.033, adj p=0.022] in children with eczema by 2 years of age. Similar observations were made when eczema group was subanalyzed into non-atopic and atopic eczema, where higher relative abundance of Enterobacteriaceae [B:1.357, 95%CI; 0.382-2.332, adj p=0.008] and [B:1.165, 95%CI; 0.221-2.109, adj p=0.019] were observed respectively as compared to healthy controls. Relative abundance of Clostridium perfringens were also higher when subanalyzed for non-atopic [B:0.572, 95%CI; 0.0009-1.144, adj p=0.050] and atopic eczema [B:0.000451, 95%CI: 0.0001-0.0007, adj p=0.012] compared to healthy controls.