DIVERSITY AND ABUNDANCE OF HOUSE DUST MITES IN IRISH HOMES, THEIR EXOSKELETON-ASSOCIATED BACTERIA AND SUSCEPTIBILITY TO CLINICALLY RELEVANT ANTIBIOTICS

Dust samples were collected from 56 homes (mainly student abodes) in Galway, Ireland, during the period 2020–22. Mites were recovered from 80% of homes and 3,585 mites were isolated from dust (256 samples) and identified. Dermatophagoides pteronyssinus was the most abundant species (71% of all mites identified). Storage mites represented 13% of the mites.Viable and cultivable bacteria were isolated from the exoskeletons of 110 mites (D. pteronyssinus).The average surface bacterial loading was 16 CFU/10 mites. Of 41 bacterial colonies sequenced, Staphylococci were predominant (83%) with Staphylococcus equorum was the dominant species overall (24%). Antibiogram analysis (using a panel of 18 antibiotics), was carried out for 23 bacterial strains isolated from the exoskeletons of house dust mites. Sixty-five percent (15 isolates) showed resistance to aztreonam. A further 30% (7 isolates) were resistant to ertapenem.These findings indicate that microorganisms on the surface of dust mites may act as a reservoir for antimicrobial resistance in the home.