House dust mites in Irish homes: Their recovery, associated bacteria and antimicrobial resistance
Aljohani, Amal
Aljohani, Amal
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Publication Date
2024-07-26
Type
doctoral thesis
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Abstract
Dermatophagoides pteronyssinus (Acari: Pyroglyphidae) is amongst the most common house dust mite (HDM) species in Europe, and is associated with allergy and respiratory conditions in human beings. For Chapter 1, House Dust Mites (HDM) were sampled from fabrics by means of vacuuming. Dermatophagoides pteronyssinus specimens were added to cotton, denim and fleece and the efficiency of two vacuuming protocols were tested. Protocol 1 involved a single pass of the vacuum head across the fabrics for 60, 90 and 120 seconds and Protocol 2 encompassed multi-directional vacuuming for the same time periods, after which the recovery of HDM was determined for both protocols. Protocol 2 (120 seconds vacuuming) was the most efficient for the recovery of HDM, particularly for the recovery of entrapped HDM in denim and cotton weaves. Chapters 3 and 4 detail the bacterial microbiome/resistome of HDM. Dust samples were collected from 56 homes in Galway, Ireland, between 2020 and 2022. Mites were recovered from household dust in 80% of homes and D. pteronyssinus was the most abundant species. Viable and cultivable bacteria were isolated from the exoskeleton of HDM, and the exoskeleton was predominately populated by Staphylococci (Staphylococcus equorum was the most abundant species detected). Exoskeleton-associated bacteria showed resistance to monobactam and carbapenen among others. Staphylococcus epidermidis survived on the exoskeleton of D. pteronyssinus for eight days during laboratory studies. With a culture-independent approach, Staphylococci dominated the microbiome of household-sampled mites (whole-mite approach). The bacterial microbiomes of HDM and household dust were significantly correlated. Antimicrobial Resistance Genes (ARG) encoding for multi-drug resistance, macrolide- lincosamide-streptogramin B, mobile genetic elements, beta-lactam, tetracycline, and aminoglycosides were detected in both mites and household dust. The mite and household dust resistome were significantly correlated but a history of antibiotic use in the domestic setting did not influence the magnitude of ARGs detected.
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University of Galway
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Attribution-NonCommercial-NoDerivatives 4.0 International