Genomic and metagenomic analyses of the domestic mite Tyrophagus putrescentiae identify it as a widespread environmental contaminant and a host of a basal, mite-specific Wolbachia lineage (supergroup Q).

Tyrophagus putrescentiae (mould mite) is a global, microscopic trophic generalist that commonly occurs in various human-created habitats, causing allergies and damaging stored food. Its ubiquity and extraordinary ability to penetrate research samples or cultures through air currents or by active walking through tights spaces (such as treads of screw caps) may lead to sample contamination and introduction of its DNA to research materials in the laboratory. This prompts a thorough investigation into potential sequence contamination in public genomic databases. The trophic success of T. putrescentiae is primarily attributed to the symbiotic bacteria housed in specialized internal mite structures, facilitating adaptation to varied nutritional niches. However, recent work suggests that horizontal transfer of bacterial/fungal genes related to nutritional functionality may also contribute to the mite's trophic versatility. This aspect requires independent confirmation. Additionally, T. putrescentiae harbors an uncharacterized and genetically divergent bacterium, Wolbachia, displaying blocking and microbiome-modifying effects. The phylogenomic position and supergroup assignment of this bacterium are unknown. Here, we sequenced and assembled the T. putrescentiae genome, analyzed its microbiome, and performed detailed phylogenomic analyses of the mite-specific Wolbachia. We show that T. putrescentiae DNA is a substantial source of contamination of research samples. Its DNA may inadvertently be co-extracted with the DNA of the target organism, eventually leading to sequence contamination in public databases. We identified a diversity of bacterial species associated with T. putrescentiae, including those capable of rapidly developing antibiotic resistance, such as Escherichia coli. Despite the presence of diverse bacterial communities in T. putrescentiae, we did not detect any recent horizontal gene transfers in this mite species and/or in astigmatid (domestic) mites in general. Our phylogenomic analysis of Wolbachia recovered a basal, mite-specific lineage (supergroup Q) represented by two Wolbachia spp. from the mould mite and a gall-inducing plant mite. Fluorescence in situ hybridization confirmed the presence of Wolbachia inside the mould mite. The discovery of an early derivative Wolbachia lineage (supergroup Q) in two phylogenetically unrelated and ecologically dissimilar mites suggests that this endosymbiotic bacterial lineage formed a long-term association with mites. This finding provides a unique insight into the early evolution and host associations of Wolbachia. Further discoveries of Wolbachia diversity in acariform mites are anticipated.

[Oral anaphylaxis by ingestion of mites contaminated oats in Panama City]. / Anafilaxia oral por ingestión de avena contaminada por ácaros en la ciudad de Panamá.

BACKGROUND: Oral anaphylaxis due to food intake contaminated with mites (OMA, oral mite anaphylaxis) is an allergic reaction that can represent life risk for patients. There are reports of cases from different parts of the world and they involve mainly processed foods based on wheat flour contaminated with mites of several families of the Astigmatina cohort. However, it remains as a little known and difficult to diagnose syndrome. The objective of this study was to describe the first clinical case of OMA due to the consumption of oat flakes in Panama City, Panama. CLINICAL CASE: Female patient of 39-years-old was entered an emergency room with allergic cutaneous and respiratory symptoms one hour after ingesting granola and oatmeal with milk at breakfast. After antiallergic treatment, the cause of allergy was determined by applying skin prick tests for ingested food and house mites. Results indicated a negative reaction for food and positive for mites. The mite analysis of the food samples directed in the identification of the species Blattisocius keegani and Suidasia pontifica, with a high density of the latter in flaked oats. CONCLUSION: This work is the first worldwide report of anaphylaxis due to consumption of oats contaminated with mites.

Antecedentes: La anafilaxia oral por ingesta de alimentos contaminados con ácaros (OMA) es una reacción alérgica que puede representar riesgo de vida para los pacientes. Aun cuando se tienen reportes de casos de diversas partes del mundo que involucran principalmente alimentos elaborados con harina de trigo contaminada con ácaros de varias familias de la cohorte Astigmatina, OMA permanece como un síndrome poco conocido y de difícil diagnóstico. El objetivo del estudio fue describir el primer caso de OMA por consumo de avena en hojuelas ocurrido en la ciudad de Panamá, Panamá. Caso clínico: Mujer de 39 años que ingresó a urgencias de un hospital con cuadro alérgico cutáneo y respiratorio una hora después de ingerir granola y avena con leche en el desayuno. Después del tratamiento antialérgico se procedió a determinar la causa de la alergia mediante aplicación de pruebas de punción cutánea para los alimentos ingeridos y ácaros domésticos. Los resultados indicaron reacción negativa para alimentos y positiva para ácaros. El análisis acarológico de las muestras de alimentos resultaron en la identificación de las especies Blattisocius keegani y Suidasia pontifica, con alta densidad de la última en la muestra de avena. Conclusiones: El presente reporte constituye el primero en el mundo de anafilaxia por consumo de avena contaminada con ácaros.

Indoor allergen levels in settled airborne dust are higher in day-care centers than at home.

BACKGROUND: Early-life sensitization to indoor allergens predicts asthma development. The aim of this study was to compare allergen concentrations in day-care centers (DCC) with those in private homes. METHODS: Settled airborne dust was collected 4 times a year from 20 German DCC (620 samples) and from the homes of children and day-care workers (602 samples) using electrostatic dust collectors (EDC). The samples were analyzed with fluorescence enzyme immunoassays recognizing domestic mite allergens (DM), Fel d 1, Can f 1, and Mus m 1. Pet allergen thresholds that discriminate samples from homes with cats or dogs from those without were calculated using receiver-operating characteristics. Influences on allergen levels were analyzed using multilevel models. RESULTS: Allergen loads were on average higher in DCC than in homes. In DCC, 96% of the samples were positive for DM, 95% for Can f 1, 90% for Fel d 1, and 83% for Mus m 1. In homes, 84% contained DM, 48.5% Can f 1, 33% Fel d 1, and 43% Mus m 1. The threshold level for homes with dogs was 75 ng/m² Can f 1 (96.8% sensitivity, 96% specificity), and the threshold level for homes with cats was 46 ng/m² Fel d 1 (92% sensitivity, 94.9% specificity). In DCC, Can f 1 and Fel d 1 loads were higher than these thresholds in 37% and 54% of the samples, respectively. Allergen levels were significantly influenced by the season and room type; however, carpets on floors had no influence. CONCLUSIONS: Mite, mouse, cat, and dog allergens were mostly higher in DCC than in homes. Exposure to dog and cat allergens in DCC often reached levels of households with pets.

Mite and booklouse fauna from vacuumed dust samples from beijing.

A significant-source of allergens come from house dust that contain particles derived from arthropods, molds, and pet dander. This study evaluated mite and booklouse fauna from vacuumed dust samples in Beijing China (a temperate zone). Our survey was carried out in Beijing in the homes of mite allergic patients who visited our Allergy Department. In total, 38 homes were selected for the collection of dust samples by vacuuming, from December 2008 to January 2010. The flotation method was used to isolate mites from house dust. Permanent slides were prepared for mite specimens and mites were identified and counted under a microscope. In total, 1,798 separate mite and insect specimens were found in 345 dust samples taken from 38 homes. A total of 95 individual Dermatophagoides (D) siboney were detected in 35 dust samples from 19 homes (representing 5.3% of all mite and insect species found in house dust); in addition, this mite was found to co-exist with D. farinae (Hughes, 1961) in 33 dust samples. Our results demonstrated the presence D. siboney that co-existed with D. farinae in house dust in Beijing China (a temperate zone).

Mite and Booklouse Fauna From Vacuumed Dust Samples From Beijing

A significant-source of allergens come from house dust that contain particles derived from arthropods, molds, and pet dander. This study evaluated mite and booklouse fauna from vacuumed dust samples in Beijing China (a temperate zone). Our survey was carried out in Beijing in the homes of mite allergic patients who visited our Allergy Department. In total, 38 homes were selected for the collection of dust samples by vacuuming, from December 2008 to January 2010. The flotation method was used to isolate mites from house dust. Permanent slides were prepared for mite specimens and mites were identified and counted under a microscope. In total, 1,798 separate mite and insect specimens were found in 345 dust samples taken from 38 homes. A total of 95 individual Dermatophagoides (D) siboney were detected in 35 dust samples from 19 homes (representing 5.3% of all mite and insect species found in house dust); in addition, this mite was found to co-exist with D. farinae (Hughes, 1961) in 33 dust samples. Our results demonstrated the presence D. siboney that co-existed with D. farinae in house dust in Beijing China (a temperate zone).