Population growth and respiration in the dust mite Dermatophagoides farinae under different temperature and humidity regimes

The bacterial microbiome and resistome of house dust mites in Irish homes

Dust samples were collected from Irish homes. House Dust Mite and storage mites were separated from the dust. The microbiome and resistome of mites and originating dust were assessed using a culture-independent approach. The bacterial microbiome of mites and dust were predominantly populated by Staphylococci. There was a highly significant (P = 0.005; Spearman's rank test) correlation between the bacterial microbiome of mites and the dust. One-hundred and eighteen antimicrobial resistance genes (ARGs) were associated with mites and 176 with dust. Both contained ARGs encoding resistance for multi drug resistances, macrolide-lincosamide-streptogramin B, mobile genetic elements, Beta-lactam, Tetracycline and Aminoglycosides. By contrast, 15 ARGs were found for a laboratory-grown strain of Dermatophagoides pteronyssinus. A significant difference (P = 0.03; t test) was found in means between the resistome of mites and the household dust from which they emanated. No significant correlations (P = 0.23 and P = 0.22; Mantel test) were observed between the microbiome and resistome of mite and dust samples. There was not a significant difference (P = 0.54; t-test) between the means of ARGs for homes with and without a history of antibiotic use.

High Serum Allergen-Specific IgE of House Dust Mite in Predicting the Risk of Comorbidity in Children with Allergic Conjunctivitis

Purpose

To investigate the patterns of allergens in allergic conjunctivitis (AC) and the association with allergic comorbidity.

Methods

This retrospective cross-sectional study enrolled 2972 children with AC. Clinical data, including sex, age, allergic comorbidities (allergic asthma, allergic rhinitis, and atopic dermatitis), and serum allergen-specific immunoglobulin E (sIgE), were collected from the electronic medical record (EMR). The categorical variables were compared with the chi-square test. The characteristics of allergens in children of different ages and comorbidities were analyzed by trend chi-square. The sensitivity level of HDM associated with AC and comorbidities was assessed by odds ratios (ORs) with 95% confidence intervals of logistic regression analysis.

Results

A total of 2972 children (2015 boys and 957 girls) with AC were included in the study. The mean age was 3.78 (0.5~12) years. The most common allergen was house dust mite(HDM) (43.41%). With age, the positive rate for inhaled allergens gradually increased, and the positive rate for ingested allergens decreased. With the number of comorbidities increasing, the positive rates of sensitization were 38.33%, 74.51%, 80.72%, and 89.05%, and the incidence of polysensitization was 44.66%, 56.48%, 59.54%, and 74.59%, respectively. With the increase of HDM-sIgE level, the number of comorbidities and the risk increased gradually.

Conclusion

HDM is the most common allergen in AC children of different ages. High levels of HDM-sIgE may be a predictor for allergic comorbidities. Children with polysensitization and high levels of HDM sIgE will be an important target population for future intervention in other allergy-related disease prevention.

Genetic diversity and differentiation analysis reveals geographical structure characteristics of Dermatophagoides farinae (Acari: Pyroglyphidae)

Dermatophagoides farinae (Acari: Pyroglyphidae) has been reported as one of the major sources of indoor allergens that trigger allergic disease in humans. In this study, the genetic diversity and differentiation of nine geographic populations of D. farinae were investigated by analyzing mitochondrial and nuclear genes (COI, Cytb, COI+Cytb, and ITS). The results showed high genetic diversity across the D. farinae populations. The BX (Benxi) population showed the lowest genetic diversity, possibly due to climatic causes. Significant genetic differentiation was observed among D. farinae populations based on mitochondrial genes. The analysis of molecular variance (AMOVA) results elucidated that the contribution to the rate of variation was primarily from among populations. Phylogenetic analysis and haplotype network based on mitochondrial genes both indicated significant geographic structure among D. farinae populations. The nine geographic populations of D. farinae were divided into two groups with the Qinling Mountains-Huai River Line serving as the boundary for spatial analysis of molecular variance analysis (SAMOVA). However, the Mantel test analysis showed no association between genetic differentiation and geographic distance because of the high level of gene flow among some populations through the transportation of stored food. Overall, these results indicate both significant genetic differentiation among D. farinae populations, but also significant gene exchange between them. Results from the analysis of the nuclear gene ITS differed from the mitochondrial genes due to differences in molecular markers between mitochondrial genes and nuclear genes. These observations improve our understanding of the genetic diversity and structure of D. farinae populations.