To understand how SARS-CoV-2 spreads indoors, in this study bovine coronavirus was aerosolized as simulant into a plexiglass chamber with coupons of metal, wood and plastic surfaces. After aerosolization, chamber and coupon surfaces were swiped to quantify the virus concentrations using quantitative polymerase chain reaction (qPCR). Bio-layer interferometry showed stronger virus association on plastic and metal surfaces, however, higher dissociation from wood in 80% relative humidity. Virus aerosols were collected with the 100 L/min wetted wall cyclone and the 50 L/min MD8 air sampler and quantitated by qPCR. To monitor the effect of the ventilation on the virus movement, PRD1 bacteriophages as virus simulants were disseminated in a ¾ scale air-conditioned hospital test room with twelve PM2.5 samplers at 15 L/min. Higher virus concentrations were detected above the patient’s head and near the foot of the bed with the air inlet on the ceiling above, exhaust bottom left on the wall. Based on room layout, air measurements and bioaerosol collections computational flow models were created to visualize the movement of the virus in the room airflow. The addition of air curtain at the door minimized virus concentration while having the inlet and exhaust on the ceiling decreased overall aerosol concentration. Controlled laboratory experiments were conducted in a plexiglass chamber to gain more insight into the fundamental behavior of aerosolized SARS-CoV-2 and understand its fate and transport in the ambient environment of the hospital room.

Wastewater-based surveillance (WBS) on SARS-CoV-2 has been proved to be an effective approach to estimate the prevalence of COVID-19 in communities and cities. However, its application was overlooked at smaller scale, such as a single facility. Meat processing plants are hotspots for COVID-19 outbreaks due to their unique environment that are favorable for the survival and persistence of SARS-CoV-2. This is the first known WBS study in meat processing plants. The goal was to understand the temporal variation of the SARS-CoV-2 levels in wastewater from a meat processing plant in Canada during a three-month campaign and to find any correlation with clinically confirmed cases in the surrounding city area. Higher SARS-CoV-2 concentrations and detection frequencies were observed in the solid fraction compared to the liquid fraction of the wastewater. The viruses can be preserved in the solid fraction of wastewater for up to 12 days. The wastewater virus level did not correlate to the city-wide COVID-19 cases due to the unmatching scales. WBS on SARS-CoV-2 in meat processing plants can be useful for identifying COVID-19 outbreaks in the facility and serve as an effective alternative when resources for routine individual testing are not available.

Nontuberculous mycobacteria (NTM) are opportunistic pathogens widely distributed in natural and human-built environments. Despite their environmental frequency, the airborne presence and distribution of NTM in clinical settings remain poorly understood. In this study, we assessed NTM in air and floor surface samples within a clinical care center using both culture-based and qPCR methods. Air and floor samples were collected across three days from patient rooms, a dictation room, and a hallway using a wetted wall cyclone (WWC), a gelatin filter-based air sampler, and foam swabs. Using the culture-based method, viable NTM were recovered from three floor surface swabs, while all other samples were culture-negative. qPCR analysis revealed frequent NTM detection in air samples, with a higher positivity rate from WWC samples compared to gelatin filters, despite total bacterial count (TBC) being two orders of magnitude higher in gelatin filter samples. The highest frequency of qPCR-tested NTM-positive samples was observed in the clinic hallway, suggesting that airflow dynamics and patient movement influence bacterial redistribution. Floor swabs showed transient NTM detection patterns, likely influenced by environmental deposition and routine cleaning. Despite confirmed Mycobacterium avium complex (MAC) infections among patients, M. avium was not detected in any environmental samples, suggesting species-specific aerosolization differences. Although viable NTM were not recovered from air samples, the high qPCR positivity suggests the potential presence of airborne NTM that may not have been captured by culture due to viability loss or sampling limitations. These findings emphasize the role of air sampling methodologies in capturing NTM and highlight the need to better understand the factors influencing the persistence and distribution of airborne NTM in clinical environments.

Antimicrobial resistance (AMR) in bacteria is a critical global health threat, yet the impact of environmental stressors such as aerosolization on resistance remains unclear. We previously showed that aerosolization can induce antibiotic resistance in Escherichia coli MG1655, a gram-negative pathogen simulant. Here, we investigated Bacillus globigii, a surrogate for the gram-positive pathogen Bacillus anthracis, to assess how aerosolization affects bacterial survival and antibiotic resistance. B. globigii vegetative cells and spores were aerosolized under varying conditions and durations (5, 10, 15, 30, and 45 min) into a sterile, airtight chamber and collected using the wetted wall cyclone (WWC) system. Samples were analyzed via antibiotic susceptibility testing, culture-based assay, and quantitative polymerase chain reaction (qPCR). Vegetative cells exhibited the lowest culturability after 5 and 30 min aerosolization, while spores showed reduced culturability at 15–45 min. Both vegetative cells and spores displayed lowest antibiotic susceptibility profiles after 15 min of aerosolization. Our findings suggest that aerosolization duration and bacterial state (vegetative vs. spores) can influence bacterial survival and development of antibiotic resistance. Understanding these dynamics is essential for designing strategies to mitigate the airborne spread of antibiotic-resistant bacteria.

Foodborne illnesses caused by Shiga toxin-producing Escherichia coli (STEC) and Salmonella represent a major public health concern, particularly in meat processing facilities where bioaerosols generated during processes like carcass spraying and dehiding can lead to contamination. In this study, we assessed airborne concentrations of STEC and Salmonella at multiple locations within a full-scale meat processing facility using quantitative polymerase chain reaction (qPCR) and Illumina MiSeq sequencing. Additionally, we utilized computational fluid dynamics (CFD) simulations to model airflow within the facility and evaluated the effectiveness of air curtains in mitigating the transfer of bioaerosols between high-risk (dehiding and tripe) and low-risk (chiller and fabrication) areas. qPCR results showed that pathogen concentrations in the dehiding rooms were 126 GCN/m³ for STEC and 105 GCN/m³ for Salmonella during spring, with levels rising significantly in summer (2198 GCN/m³ for STEC and 1799 GCN/m³ for Salmonella). Simulated airflow patterns revealed that entrained bioaerosols could be transported from unclean to clean areas, increasing the risk of cross-contamination. The use of air curtains effectively reduced this spread by creating barriers between high- and low-risk areas. Our findings suggest that bacterial survivability and aerosolization was enhanced in summer, highlighting the critical role of environmental factors and airflow management in controlling contamination risks. This study demonstrates the value of integrating experimental data with CFD simulations to assess pathogen spread and identify effective mitigation strategies in meat processing facilities.