Mold Contamination Due to Construction Dust in Ventilation System Detected During Routine Pre-commissioning Air Sampling

BACKGROUND: Outbreaks of invasive mold infection associated with active construction sites are well documented in the literature. We routinely perform air sampling for mold prior to opening all new inpatient and high-risk outpatient units. Historically this practice led to early identification of an outbreak linked to a contaminated ventilation system. Based on our experience, we clean areas 3 times, wait at least 8h then sample. We describe the results of air sampling during the commissioning of our new Labor and Delivery unit and the identification of the source of fungal contamination. METHODS: Fungal cultures were obtained throughout the unit using a two stage viable Andersen Cascade Impactor loaded with Sabouraud dextrose with chloramphenicol and gentamicin agar (BBL, BD, Sparks MD). Additional surface cultures were obtained using a 3M Sponge stick with neutralizing buffer (3M Healthcare, St Paul MN) and inoculated onto the same media. Plates were incubated for 10 days and mold colonies were counted and identified by standard methods. RESULTS: Initial samples in several rooms were positive for mold, suggesting more detailed cleaning was needed. Continued positives, including in previously negative rooms, prompted further investigation. No leaks or moisture were found. Construction dust was found in the supply plenum and ducts. We discovered that during construction the ventilation system was on allowing air from the unit to recirculate. The contractor assumed the filters would remove any dust, but the filters were not gasketed and a failed duct seam was found above the rooms with highest contamination. After replacement of filters and cleaning of all ductwork, one OR remained positive. Swabs of the laminar flow diffuser grew mold. After cleaning, final samples were all negative for mold. CONCLUSION: A complete understanding of air flow and filtration capability during construction is critical to maintaining a healthy environment. Routine air sampling before opening new units identifies mold contamination and allows for remediation prior to occupancy by patients. DISCLOSURES: All authors: No reported disclosures.