Analysis of Home Dust for Allergens Related to Staphylococcus Aureus
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Shanna Ludwig, PhD, Isabel Jimenez-Bush, Emily Brigham, MD, Sonali Bose, Gregory B. Diette, MD MHS, Meredith C. McCormack, MD, Elizabeth Matsui, MD MHS, Meghan F. Davis, DVM, MPH, PhD
Rationale: The bacterium Staphylococcus aureus (SA) is known to induce allergic inflammatory responses, including through secreted staphylococcal enterotoxin (SE) A-D superantigens. SA is known to exacerbate eczema; a growing body of evidence suggests SA exposure may exacerbate a related disease, atopic asthma. While methods are established to quantify home environmental allergen exposure, corresponding methods for SA/SE assessment have not yet been validated. We adapted a method for home dust SA/SE detection and applied it in INHALE study homes of inner-city adults with asthma.

Methods: We conducted laboratory experiments to optimize sample processing and real-time PCR methods for genetic assessment of SA (femB) and SEA-D, based on published primers. We applied this method to dust and dust extract from 21 homes. We compared results from bacterial gene assessment to culture-based results from the same homes.

Results: The Biostic® Bacteremia DNA Isolation Kit (MoBio Laboratories) with 50mg raw dust and using 9µl isolated DNA for qPCR assessment performed equally or better than alternative methods. Application to INHALE homes demonstrated that while 10 (48%) of 21 homes were culture-positive for SA, all had detectable SA genes. Prevalence of SE detection in cultured SA isolates was 0% but in raw dust was: SEA 33%; SEB 76%; SEC 62%; SED 24%. Dust extract and raw dust demonstrated strong SA gene correlation (femB, Pearson’s coefficient 0.80), but weaker correlations for SE genes.

Conclusions: Compared to culture-based assessment, bacterial gene-based testing of home dust was more sensitive for staphylococcal (SA/SE) exposures. Staphylococcal exposures may be common among inner-city adults with asthma.