Showing papers on "Bioaerosol published in 2018"

Bioaerosol concentrations generated from toilet flushing in a hospital-based patient care setting.

Abstract: In the United States, 1.7 million immunocompromised patients contract a healthcare-associated infection, annually. These infections increase morbidity, mortality and costs of care. A relatively unexplored route of transmission is the generation of bioaerosols during patient care. Transmission of pathogenic microorganisms may result from inhalation or surface contamination of bioaerosols. The toilet flushing of patient fecal waste may be a source of bioaerosols. To date, no study has investigated bioaerosol concentrations from flushing fecal wastes during patient care. Particle and bioaerosol concentrations were measured in hospital bathrooms across three sampling conditions; no waste no flush, no waste with flush, and fecal waste with flush. Particle and bioaerosol concentrations were measured with a particle counter bioaerosol sampler both before after a toilet flushing event at distances of 0.15, 0.5, and 1 m from the toilet for 5, 10, 15 min. Particle concentrations measured before and after the flush were found to be significantly different (0.3–10 μm). Bioaerosol concentrations when flushing fecal waste were found to be significantly greater than background concentrations (p-value = 0.005). However, the bioaerosol concentrations were not different across time (p-value = 0.977) or distance (p-value = 0.911) from the toilet, suggesting that aerosols generated may remain for longer than 30 min post flush. Toilets produce aerosol particles when flushed, with the majority of the particles being 0.3 μm in diameter. The particles aerosolized include microorganisms remaining from previous use or from fecal wastes. Differences in bioaerosol concentrations across conditions also suggest that toilet flushing is a source of bioaerosols that may result in transmission of pathogenic microorganisms. This study is the first to quantify particles and bioaerosols produced from flushing a hospital toilet during routine patient care. Future studies are needed targeting pathogens associated with gastrointestinal illness and evaluating aerosol exposure reduction interventions.

Influence of meteorological factors on the level and characteristics of culturable bacteria in the air in Gliwice, Upper Silesia (Poland).

Abstract: Numerous studies have focused on occupational and indoor environments because people spend more than 90% of their time in them. Nevertheless, air is the main source of bacteria in indoors, and outdoor exposure is also crucial. Worldwide studies have indicated that bacterial concentrations vary among different types of outdoor environments, with considerable seasonal variations as well. Conducting comprehensive monitoring of atmospheric aerosol concentrations is very important not only for environmental management but also for the assessment of the health impacts of air pollution. To our knowledge, this is the first study to present outdoor and seasonal changes of bioaerosol data regarding an urban area of Poland. This study aimed to characterize culturable bacteria populations present in outdoor air in Gliwice, Upper Silesia Region, Poland, over the course of four seasons (spring, summer, autumn and winter) through quantification and identification procedures. In this study, the samples of bioaerosol were collected using a six-stage Andersen cascade impactor (with aerodynamic cut-off diameters of 7.0, 4.7, 3.3, 2.1, 1.1 and 0.65 μm). Results showed that the concentration of airborne bacteria ranged from 4 CFU m−3, measured on one winter day, to a maximum equal to 669 CFU m−3 on a spring day. The average size of culturable bacterial aerosol over the study period was 199 CFU m−3. The maximal seasonally averaged concentration was found in the spring season and reached 306 CFU m−3, and the minimal seasonally averaged concentration was found in the winter 49 CFU m−3. The most prevalent bacteria found outdoors were gram-positive rods that form endospores. Statistically, the most important meteorological factors related to the viability of airborne bacteria were temperature and UV radiation. These results may contribute to the promotion and implementation of preventative public health programmes and the formulation of recommendations aimed at providing healthier outdoor environments.

Label-free bio-aerosol sensing using mobile microscopy and deep learning

Abstract: Conventional bioaerosol sensing requires the sampled aerosols in the field to be transferred to a laboratory for manual inspection, which can be rather costly and slow, also requiring a professional for labeling and microscopic examination of the samples. Here we demonstrate label-free bioaerosol sensing using a field-portable and cost-effective device based on holographic microscopy and deep-learning, which screens bioaerosols at a throughput of 13 L/min. Two different deep neural networks are designed to rapidly reconstruct the amplitude and phase images of the captured bioaerosols, and to classify the type of each bioaerosol that is imaged. As a proof-of-concept, we studied label-free sensing of common bioaerosol types, for example, Bermuda grass pollen, oak tree pollen, ragweed pollen, Aspergillus spore, and Alternaria spore and achieved >94% classification accuracy. The presented label-free bioaerosol measurement device, with its mobility and cost-effectiveness, will find several applications in indo...

Indoor Air Quality and Potential Health Risk Impacts of Exposure to Antibiotic Resistant Bacteria in an Office Rooms in Southern Poland.

Abstract: The aims of this article are to characterize: the quantity of culturable bacterial aerosol (QCBA) and the quality of culturable bacterial aerosol (QlCBA) in an office building in Southern Poland during the spring. The average concentration of culturable bacterial aerosol (CCBA) in this building ranged from 424 CFU m−3 to 821 CFU m−3, below Polish proposals for threshold limit values. Size distributions were unimodal, with a peak of particle bacterial aerodynamic diameters less than 3.3 μm, increasing potentially adverse health effects due to their inhalation. The spring office exposure dose (SPED) of bacterial aerosol was estimated. The highest value of SPED was in April (218 CFU kg−1), whereas the lowest was in June (113 CFU kg−1). Analysis was undertaken to determine the antibiotic resistance of isolated strains and their ability to form biofilms, which may facilitate the spread of antibiotic resistance genes. In the course of the study, it was found that Staphylococcus xylosus had the greatest ability to form biofilms, while the strains with the highest antibiotic resistance were Micrococcus luteus D and Macrococcus equipercicus. Given that mainly antibiotic-sensitive bacteria from bioaerosol were isolated, which transfers resistance genes to their plasmids, this shows the need for increased monitoring of indoor air quality in workplaces.

Do exposures to aerosols pose a risk to dental professionals

Abstract: Background Dental care professionals are exposed to aerosols from the oral cavity of patients containing several pathogenic microorganisms. Bioaerosols generated during dental treatment are a potential hazard to dental staff, and there have been growing concerns about their role in transmission of various airborne infections and about reducing the risk of contamination. Aims To investigate qualitatively and quantitatively the bacterial and fungal aerosols before and during clinical sessions in two dental offices compared with controls. Methods An extra-oral evacuator system was used to measure bacterial and fungal aerosols. Macroscopic and microscopic analysis of bacterial species and fungal strains was performed and strains of bacteria and fungi were identified based on their metabolic properties using biochemical tests. Results Thirty-three bioaerosol samples were obtained. Quantitative and qualitative evaluation showed that during treatment, there is a significant increase in airborne concentration of bacteria and fungi. The microflora included mainly gram-positive organisms (Staphylococcus epidermidis and Micrococcus spp.), gram-positive rod-shaped bacteria and those creating endospores as well as non-porous bacteria and mould fungi (Cladosporium and Penicillium). Conclusions Exposure to the microorganisms identified is not a significant occupational hazard for dental care professionals; however, evidence-based prevention measures are recommended.

Anaerobic bacteria in wastewater treatment plant

Abstract: The objective of this study was to assess exposure to anaerobic bacteria released into air from sewage and sludge at workplaces from a wastewater treatment plant (WWTP). Samples of both sewage and sludge were collected at six sampling points and bioaerosol samples were additionally collected (with the use of a 6-stage Andersen impactor) at ten workplaces covering different stages of the technological process. Qualitative identification of all isolated strains was performed using the biochemical API 20A test. Additionally, the determination of Clostridium pathogens was carried out using 16S rRNA gene sequence analysis. The average concentration of anaerobic bacteria in the sewage samples was 5.49 × 104 CFU/mL (GSD = 85.4) and in sludge—1.42 × 106 CFU/g (GSD = 5.1). In turn, the average airborne bacterial concentration was at the level of 50 CFU/m3 (GSD = 5.83) and the highest bacterial contamination (4.06 × 103 CFU/m3) was found in winter at the bar screens. In total, 16 bacterial species were determined, from which the predominant strains belonged to Actinomyces, Bifidobacterium, Clostridium, Propionibacterium and Peptostreptococcus genera. The analysis revealed that mechanical treatment processes were responsible for a substantial emission of anaerobic bacteria into the air. In both the sewage and air samples, Clostridium perfringens pathogen was identified. Anaerobic bacteria were widely present both in the sewage and in the air at workplaces from the WWTP, especially when the technological process was performed in closed spaces. Anaerobic bacteria formed small aggregates with both wastewater droplets and dust particles of sewage sludge origin and as such may be responsible for adverse health outcomes in exposed workers.

Assessment of Bacterial Aerosol in a Preschool, Primary School and High School in Poland

Abstract: The issue of healthy educational buildings is a global concern because children are particularly at risk of lung damage and infection caused by poor indoor air quality (IAQ). This article presents the results of a preliminary study of the concentration and size distribution of bacterial aerosol in three educational buildings: a preschool, primary school, and high school. Sampling was undertaken in the classrooms with an Andersen six-stage impactor (with aerodynamic cut-off diameters of 7.0, 4.7, 3.3, 2.1, 1.1 and 0.65 μm) during spring 2016 and 2017, as well as the outside of the buildings. After incubation, bioaerosol particles captured on nutrient media on Petri dishes were quantitatively evaluated and qualitatively identified. The highest average concentration of bacterial aerosol was inside the primary school building (2205 CFU/m3), whereas the lowest average concentration of indoor culturable bacteria was observed in the high school building (391 CFU/m3). Using the obtained data, the exposure dose (ED) of the bacterial aerosol was estimated for children attending each educational level. The most frequently occurring species in the sampled bacterial aerosol were Gram-positive cocci in the indoor environment and Gram-positive rod-forming endospores in the outdoor environment.

Clothing as a transport vector for airborne particles: Chamber study.

Abstract: Strong evidence suggests that clothing serves as a reservoir of chemical pollutants and particles, including bioaerosols, which may have health significance. However, little is known about the role that clothing may play as a transport vector for inhaled airborne particles. Here, we contribute toward bridging the knowledge gap by conducting experiments to investigate clothing release fraction (CRF), determined as the size-dependent ratio of released to deposited particulate matter in the diameter range 0.5-10 μm. In a fully controlled chamber with low background particle levels, we deployed a programmable robot to reproducibly quantify the size-dependent CRF as a function of motion type and intensity, dust loadings, and activity duration. On average, 0.3%-3% of deposited particles were subsequently released with fabric motion, confirming that clothing can act as a vehicle for transporting airborne particles. The CRF increased with the vigor of movement and with dust loading. Rubbing and shaking the fabric were more effective than fabric stretching in resuspending particles. We also found that most of the release happened quickly after the onset of the resuspension activity. Particle size substantially influenced the CRF, with larger particles exhibiting higher values.

Quantification of multi-antibiotic resistant opportunistic pathogenic bacteria in bioaerosols in and around a pharmaceutical wastewater treatment plant

Abstract: Pharmaceutical wastewater treatment plants (WWTPs) are thought to be a “seedbed” and reservoirs for multi-antibiotic resistant pathogenic bacteria which can be transmitted to the air environment through aeration. We quantified airborne multi-antibiotic resistance in a full-scale plant to treat antibiotics-producing wastewater by collecting bioaerosol samples from December 2014 to July 2015. Gram-negative opportunistic pathogenic bacteria (GNOPB) were isolated, and antibiotic susceptibility tests against 18 commonly used antibiotics, including 11 β-lactam antibiotics, 3 aminoglycosides, 2 fluoroquinolones, 1 furan and 1 sulfonamide, were conducted. More than 45% of airborne bacteria isolated from the pharmaceutical WWTP were resistant to three or more antibiotics, and some opportunistic pathogenic strains were resistant to 16 antibiotics, whereas 45.3% and 50.3% of the strains isolated from residential community and municipal WWTP showed resistance to three or more antibiotics. The calculation of the multiple antibiotic resistance (MAR) index demonstrated that the air environment in the pharmaceutical WWTP was highly impacted by antibiotic resistance, while the residential community and municipal WWTP was less impacted by antibiotic resistance. In addition, we determined that the dominant genera of opportunistic pathogenic bacteria isolated from all bioaerosol samples were Acinetobacter , Alcaligenes , Citrobacter , Enterobacter , Escherichia , Klebsiella , Pantoea , Pseudomonas and Sphingomonas . Collectively, these results indicate the proliferations and spread of antibiotic resistance through bioaerosols in WWTP treating cephalosporin-producing wastewater, which imposed a potential health risk for the staff and residents in the neighborhood, calling for administrative measures to minimize the air-transmission hazard.

Bioaerosol Sampler Choice Should Consider Efficiency and Ability of Samplers To Cover Microbial Diversity.

Abstract: Bioaerosol studies aim to describe the microbial content and increase understanding of the aerosolization processes linked to diseases. Air samplers are used to collect, identify, and quantify bioaerosols. Studies comparing the performances of air samplers have typically used a culture approach or have targeted a specific microorganism in laboratory settings. The objective of this study was to use environmental field samples to compare the efficiencies of 3 high-airflow-rate samplers for describing bioaerosol diversity using a next-generation sequencing approach. Two liquid cyclonic impactors and one electrostatic filter dry sampler were used in four wastewater treatment plants to target bacterial diversity and in five dairy farms to target fungal diversity. The dry electrostatic sampler was consistently more powerful in collecting more fungal and bacterial operational taxonomic units (OTUs). Substantial differences in OTU abundances between liquid and dry sampling were revealed. The majority of the diversity revealed by dry electrostatic sampling was not identified using the cyclonic liquid impactors. The findings from this work suggest that the choice of a bioaerosol sampler should include information about the efficiency and ability of samplers to cover microbial diversity. Although these results suggest that electrostatic filters result in better coverage of the microbial diversity among the tested air samplers, further studies are needed to confirm this hypothesis. While it is difficult to determine a single universally optimal air sampler, this work provides an in-depth look at some of the considerations that are essential when choosing an air sampler for studying the microbial ecology of bioaerosols.IMPORTANCE Associating bioaerosol exposure and health problems is challenging, and adequate exposure monitoring is a priority for scientists in the field. Conclusions that can be drawn from bioaerosol exposure studies are highly dependent on the design of the study and the methodologies used. The air sampling strategy is the first methodological step leading to an accurate interpretation of what is present in the air. Applying new molecular approaches to evaluate the efficiencies of the different types of samplers used in the field is necessary in order to circumvent traditional approaches and the biases they introduce to such studies. The results and conclusions provided in this paper should be taken in consideration when conducting a bioaerosol study.

Iron oxide nanowire-based filter for inactivation of airborne bacteria

Abstract: Heating, ventilation, and air conditioning (HVAC) systems are among the most common methods to improve indoor air quality. However, after long-term operation, the HVAC filter can result in a proliferation of bacteria, which may release into the filtered air subsequently. This issue can be addressed by designing antibacterial filters. In this study, we report an iron oxide nanowires-based filter fabricated from commercially available iron mesh through a thermal treatment. At optimal conditions, the filter demonstrated a log inactivation efficiency of > 7 within 10 seconds towards S. epidermidis (Gram-positive), a common bacterial species of indoor bioaerosol. 52 % of bioaerosol cells can be captured by a single filter, which can be further improved to 98.7 % by connecting five filters in-tandem. The capture and inactivation capacity of the reported filter did not degrade over long-term use. The inactivation of bacteria is attributed to the synergic effects of the hydroxyl radicals, electroporation, and Joule heating, which disrupted the cell wall and nucleoid of S. epidermidis, as verified by the model simulations, fluorescence microscopy, electron microscopy, and infrared spectroscopy. The relative humidity plays an important role in the inactivation process. The filter also exhibited a satisfactory inactivation efficiency towards E. coli (Gram-negative). The robust synthesis, low cost, and satisfactory inactivation performance towards both Gram-positive and Gram-negative bacteria make the filter demonstrated here suitable to be assembled into HVAC filters as an antibacterial layer for efficient control of indoor bioaerosols.

Chemicals and microbes in bioaerosols from reaction tanks of six wastewater treatment plants: survival factors, generation sources, and mechanisms

Abstract: Sampling was conducted from biochemical reaction tanks of six municipal wastewater treatment plants in the Yangtze River and Zhujiang deltas and the Jing-Jin-Ji region to assess their morphology, level, and composition. Morphological observations suggested that particles were scattered amorphously with C, O, and Si as the major elements. Bioaerosols are composed of spatially varying levels of microorganisms and chemicals. As the sampling height increased, the level of the components in the bioaerosols decreased. Wastewater in the biochemical reaction tanks was identified as an important source of bioaerosols using SourceTracker analysis. The aerosolization of film drops produced by bursting of bubbles was the main reason for the generation of bioaerosols. Increasing the aeration rate of water may promote bioaerosol generation. Relative humidity, temperature, wind speed, and solar illumination influenced the survival of bioaerosols. Large particle sedimentation and wind diffusion significantly decreased the atmospheric aerosol concentration. When the sampling point height increased from 0.1 m to 3.0 m, the concentrations of the microorganisms and total suspended particles decreased by 23.71% and 38.74%, respectively. Considerable attention should be paid to the control of total suspended particles and microorganisms in bioaerosols.

Fluorescent biological aerosol particles: Concentrations, emissions, and exposures in a northern California residence.

Abstract: Residences represent an important site for bioaerosol exposure. We studied bioaerosol concentrations, emissions, and exposures in a single-family residence in northern California with 2 occupants using real-time instrumentation during 2 monitoring campaigns (8 weeks during August-October 2016 and 5 weeks during January-March 2017). Time- and size-resolved fluorescent biological aerosol particles (FBAP) and total airborne particles were measured in real time in the kitchen using an ultraviolet aerodynamic particle sizer (UVAPS). Time-resolved occupancy status, household activity data, air-change rates, and spatial distribution of size-resolved particles were also determined throughout the house. Occupant activities strongly influenced indoor FBAP levels. Indoor FBAP concentrations were an order of magnitude higher when the house was occupied than when the house was vacant. Applying an integral material-balance approach, geometric mean of total FBAP emissions from human activities observed to perturb indoor levels were in the range of 10-50 million particles per event. During the summer and winter campaigns, occupants spent an average of 10 and 8.5 hours per day, respectively, awake and at home. During these hours, the geometric mean daily-averaged FBAP exposure concentration (1-10 μm diameter) was similar for each subject at 40 particles/L for summer and 29 particles/L for winter.

Dissimilar Emission Characteristics between Bioaerosol and suspended Particles from Gaseous Biofilters and Bioaerosol Health Risk Evaluation

Abstract: Biofiltration is a common technology for treating volatile organic compounds (VOCs); however, bioaerosols may be emitted in the gas flow, indicating a potential risk to human health. In this study, we analyzed the emission characteristics of bioaerosol and suspended particles (mainly nonbiological particles) emitted from biofilters and their health risk at different gas velocities and temperatures and with different amounts of moisture in the packing bed. Results showed that a high gas velocity enabled easy transport of microbes from the carriers. The maximum bacterial aerosol outlet concentration was 223 CFU m−3 at 50°C, although the fungal aerosol concentration decreased at temperatures above 25°C. The peak bacterial concentration was 349 CFU m−3, with a moisture content of 70%, whereas the highest fungi concentration was nearly 267 CFU m−3, with a moisture content of 40%. The bioaerosol concentrations also changed with the experimental conditions: A high gas velocity, low temperature, and high moisture content favored the emission of fine particles; however, changes in the concentration and size distribution of coarse particles were not obvious. The relationship between bioaerosols and suspended particle emissions demonstrates that biofilters are a source of bioaerosol emissions despite the removal of nonbiological suspended particles due to filtration. The health risk evaluation indicates that bioaerosol emissions from biofilters pose the highest risk of infection via inhalation to adult males.

Indoor exposure to bioaerosol particles: levels and implications for inhalation dose rates in schoolchildren

Abstract: Children spend most of their time inside schools and bioaerosol particles are part of their everyday environment. Although bioaerosol particles are considered to be a potential risk factor for various health concerns, information concerning the indoor exposures and inhalation doses is still limited. This study aimed (i) to quantify bacterial and fungal particles levels in indoor and outdoor air of public primary schools, (ii) to assess the influence of ambient air on bacteria and fungi presence indoors, and (iii) to estimate the inhalation dose rates for respective children (8–10 years old) in comparison with adult staff. Air samples were collected in 20 primary schools in a total of 71 classrooms during heating season with a microbiological air sampler. The results showed that indoor bacterial and fungal concentrations were higher than outdoor levels (p < 0.05), which could be explained by differences in density of occupation, occupant’s activities, and inadequate ventilation. CO2 levels were significantly correlated with indoor bacteria concentrations. Moreover, mean indoor bacteria concentrations were above national limit values in all the evaluated Porto primary schools, from two to nine times higher. Regarding fungi concentrations, indoor levels were above the reference value in 75% of the schools and overall indoor levels registered a 3-fold increase compared with outdoor values. Children had two times higher inhalation dose rates to bioaerosol particles when compared to adult individuals. Thus, due to their susceptibility, special attention should be given to educational settings in order to guarantee the children healthy development.

Concentrations and Size Distributions of Fungal Bioaerosols in a Municipal Landfill

Abstract: The object of this research was to study the behavior of fungal bioaerosols during a sampling period of 12 months (April 2015–April 2016), in each treatment stages of a landfill located in Atlantico Department, Colombia. The fungi bioaerosol samples were collected using a Six-Stage Viable Andersen Cascade Impactor - Thermo Fisher Scientific, a vacuum pump with a flow rate of 28.3 L /min–1, and ammeter KESTREL 4500 for the weather conditions. With the large amount of data obtained, a database was made in excel and analyzed using Statgraphics Centurion XVI software. The processing of data mining was carried out applying to a generalized linear regression model and Multifactorial ANOVA. Golden Surfer 11 program was used to stablish the distribution of temporal and spational mold airborne. The Variables: sampling campaign, stage, taxa, temperature and relative humidity presented a statistically significant correlation with the concentration P-value = 0. The concentrations of fungal bioaerosols varied considerably over the whole sampling period with average concentrations from 73.02 ± 26, 75 CFUs/m3 to 1830.38 ± 971.28 CFUs/m3. The fungal bioaerosols presented in both the coarse and fine fraction; but the fraction of 2.1–3.3 μm (stage 4) was the fraction of the dominant size in terms of higher concentration. According to the taxa identification, there was a higher prevalence of Aspergillus: the highest concentration corresponds to A. fumigatus, associated to toxins that may be cytotoxic [1, 2].

Comparison of wastewater treatment plants based on the emissions of microbiological contaminants.

Abstract: This article presents the current and important results of bioaerosol studies which allow for the comparison of microbial contamination of air in 11 wastewater treatment plants (WWTPs), which differed in terms of capacity from 350 to 200,000 m3/day. The abundance of mesophilic bacteria, M+ and M− Staphylococcus, Pseudomonas fluorescens, Actinobacteria, coliform and psychrophilic bacteria, and microscopic fungi was determined. Additionally, the air temperature, relative humidity, wind velocity, and direction were also analyzed at each research station. The obtained very numerous results of bioaerosol and climate parameter studies were subjected to statistical analysis. The results regarding the minimum, maximum, and median abundance of the studied bacteria and microscopic fungi at 11 WWTPs and in background studies at control stations were presented in tables. Additionally, basic descriptive statistics for all studied microorganisms at specific seasons were presented. It was established that at the areas of WWTPs, the microscopic fungi were present that the highest concentrations (ranging from 0 to 1,148,530 CFU m−3), followed by psychrophilic bacteria (ranging from 40 to 225,000 CFU m−3) and mesophilic bacteria (ranging from 0 to 195,000 CFU m−3). The novel elaboration of bioaerosol study results based on cluster analysis and determination of a dendrogram allowed to compare the studied WWTPs. The similarity was decided based on the type of studied microorganisms and their dominance and abundance, while no similarities were observed in terms of capacity. In order to investigate the relation between the abundance of bacterial groups as well as microscopic fungi and microclimatic parameters (air temperature and humidity), a calculation of Spearman’s range correlation coefficients was conducted.