Impact of airborne algicidal bacteria on marine phytoplankton blooms

Ocean microbes are involved in global processes such as nutrient and carbon cycling. Recent studies indicated diverse modes of algal-bacterial interactions, including mutualism and pathogenicity, which have a substantial impact on ecology and oceanic carbon sequestration, and hence, on climate. However, the airborne dispersal and pathogenicity of bacteria in the marine ecosystem remained elusive. Here, we isolated an airborne algicidal bacterium, Roseovarius nubinhibens, emitted to the atmosphere as primary marine aerosol (referred also as sea spray aerosols) and collected above a coccolithophore bloom in the North Atlantic Ocean. The aerosolized bacteria retained infective properties and induced lysis of Gephyrocapsa huxleyi cultures.This suggests that the transport of marine bacteria through the atmosphere can effectively spread infection agents over vast oceanic regions, highlighting its significance in regulating the cell fate in algal blooms.

Quantitative Microbial Risk Assessment for Quantification of the Effects of Ultraviolet Germicidal Irradiation on COVID-19 Transmission

Quantitative microbial risk assessment (QMRA) is presented as a tool for evaluation of the effectiveness of ultraviolet germicidal irradiation (UVGI) systems for the disinfection of indoor air. The QMRA is developed in the context of UVGI system implementation for control of SARS-CoV-2 infection and comprises submodels to address problem formulation, exposure assessment, and health effects assessment, all of which provide input to a risk characterization submodel. The model simulations indicate that UVGI systems can effectively control the risk of infection associated with SARS-CoV-2 for low to moderate virus emission rates. The risk of disease transmission is strongly influenced by the rate of pathogen emission by an infected individual, the output power of UVGI fixtures and their configuration, the source of UV-C radiation implemented in the UVGI fixtures, and the characteristics of the heating, ventilation, and air conditioning (HVAC) system. The QMRA framework provides a quantitative link between UVGI/HVAC system characteristics and changes in the risk of disease transmission. The framework can be adapted to other airborne pathogens and provides a rational basis for the design, testing, and validation of UVGI systems.

The Environmental Spread of Aspergillus terreus in Tyrol, Austria

Fungal infections due to Aspergillus species have become a major cause of morbidity and mortality among immunocompromised patients. At the Medical University of Innsbruck, A. terreus and related species are the second most common causative agents of aspergillosis. In this one-year study we collected environmental samples to investigate (i) the environmental distribution, (ii) the ecological niche of A. terreus in Tyrol, (iii) the genetic relatedness of environmental and clinical isolates and the correlation between those two groups of isolates, and (iv) the antifungal susceptibility patterns. A. terreus was present in 5.4% of 3845 environmental samples, with a significantly higher frequency during winter (6.8%) than summer (3.9%). An increased A. terreus abundance in Tyrol’s Eastern part was detected which is in agreement with the proof of clinical cases. In total, 92% of environmental and 98% of clinical A. terreus isolates were amphotericin B resistant; 22.6% and 9.8% were resistant against posaconazole. Overall, 3.9% of clinical isolates were resistant against voriconazole. Short tandem repeat analysis identified three major genotypes persisting in Tyrol. Soil from agricultural cornfields seems to be an important source; the environmental frequency of A. terreus correlates with the high incidence of A. terreus infections in certain geographical areas.

Integrated Bioaerosol Sampling/Monitoring Platform: Field-Deployable and Rapid Detection of Airborne Viruses

Airborne pathogens causing infectious diseases are often highly transmittable between humans. Therefore, an airborne pathogen-monitoring system capable of on-site detection and identification would aid tremendously in preventing and controlling the early stages of pathogen spread. Here, we describe an integrated sampling/monitoring platform for on-site and real-time detection of airborne viruses. We used MS2 bacteriophage and avian influenza virus (AIV) H1N1 to evaluate bioaerosol sampling and detection performance of the platform. Our results show that, within 20 min, aerosolized viruses can be detected using the signal of near-infrared (NIR)-to-NIR nanoprobes. The pretreatment of the sampling pad improved the transfer efficiency of MS2 viruses to the detection zone, compared to an untreated pad. Our platform could detect concentrations as low as 10^4.294 50% egg infectious dose (EID₅₀)/m³ AIVs collected from a cloacal swab sample (10^4.838 EID₅₀/mL). These results indicate that our sampling/monitoring platform could be applied for the early detection of biological hazards in various fields.

Case Study of Airborne Pathogen Dispersion Patterns in Emergency Departments with Different Ventilation and Partition Conditions

The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate. Installing partitions between the beds and changing the ventilation system's inlet and outlet diffuser positions contributed only minimally to reducing the concentration of airborne pathogens.