The impact of ventilation rate on reducing the microorganisms load in the air and on surfaces in a room-sized chamber

Hospital-acquired infections (HAIs) are a global challenge incurring mortalities and high treatment costs. The environment plays an important role in transmission due to contaminated air and surfaces. This includes microorganisms' deposition from the air onto surfaces. Quantifying the deposition rate of microorganisms enables understanding surface contamination and can inform strategies to mitigate the infection risk. We developed and validated a novel Automated Multiplate Passive Air Sampling (AMPAS) device. This enables sequences of passive deposition samples to be collected over a controlled time period without human intervention. AMPAS was used with air sampling to measure the effect of ventilation rate and spatial location on the deposition rate of aerosolized Staphylococcus aureus in a 32 m3 chamber. Increasing the ventilation rate from 3 to 6 ACH results in a reduction of microbial load in the air and on surfaces by 45% ± 10% and 44% ± 32%, respectively. The deposition rate onto internal surfaces λd was calculated as 1.38 ± 0.48 h−1. Samples of airborne and surface microorganisms taken closer to the ventilation supply showed a lower concentration than close to the extract. The findings support the importance of controlling the ventilation and the environmental parameters to mitigate both air and surface infection risks in the hospital environment

Multiplate air passive sampler to measure deposition rate of airborne microorganisms over time

A novel Automated Multiplate Passive Air Sampler (AMPAS) is introduced to study the spatiotemporal deposition rate of airborne microbes and to autonomously achieve fine-tuned, timely and precise sampling over time with regards to other environmental factors. AMPAS consists of an Arduino kit (Elegoo mega 2560 microcontroller) that controls a stepper motor which in turn rotates allowing a specific plate to be exposed to air for a given period. This invention makes it possible to efficiently collect reliable data from a controlled (biological test chamber) and non-controlled (hospital and office) environment in a flexible and scalable fashion. It also ensures that all collected samples are taken under precisely the same conditions. Results show that AMPAS provides reliable data and makes it possible to perform large-scale passive sampling in various locations at the same time