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Abstract Purpose This study aimed to verify that aerosolization ocular surface microorganisms (AOSMs) accumulated during non-contact tonometry (NCT) measurements. Methods A total of 508 participants (740 eyes) were enrolled in the study. In Experiment 1, before NCT was performed on each eye, the air was disinfected, and environment air control samples were collected via Air ideal® 3P (Bio Merieux). During NCT measurements, microbial aerosol samples were collected once from each eye. In Experiment 2, we collected initial blank control samples and then repeated Experiment 1. Finally, in Experiment 3, after the background microbial aerosol investigation, we cumulatively sampled AOSMs from each 10 participants then culture once, without any interventions to interrupt the accumulation. The collected samples were incubated and identified using matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Results Pathogenic Aerococcus viridans and other microorganisms from human eyes can spread and accumulate in the air during NCT measurements. The species and quantity of AOSMs produced by NCT measurements can demonstrate an accumulation effect. Conclusion AOSMs generated during NCT measurements are highly likely to spread and accumulate in the air, thereby may increase the risk of exposure to and transmission of bio-aerosols.

Purpose: This study aimed to verify that aerosolization ocular surface microorganisms (AOSMs) accumulated during non-contact tonometry (NCT) measurements. Methods: A total of 508 participants (740 eyes) were enrolled in the study. In Experiment 1, before NCT was performed on each eye, the air was disinfected, and environment air control samples were collected via Air ideal® 3P (Bio Merieux). During NCT measurements, microbial aerosol samples were collected once from each eye. In Experiment 2, we collected initial blank control samples and then repeated Experiment 1. Finally, in Experiment 3, after the background microbial aerosol investigation, we cumulatively sampled AOSMs from each 10 participants then culture once, without any interventions to interrupt the accumulation. The collected samples were incubated and identified using matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Results: Pathogenic Aerococcus viridans and other microorganisms from human eyes can spread and accumulate in the air during NCT measurements. The species and quantity of AOSMs produced by NCT measurements can demonstrate an accumulation effect. Conclusion: AOSMs generated during NCT measurements are highly likely to spread and accumulate in the air, thereby may increase the risk of exposure to and transmission of bio-aerosols. Precis: Pathogenic Aerococcus viridans and other species of aerosolization ocular surface microorganisms (AOSMs) can spread and accumulate with the increase of NCT measurement person times, demonstrating an accumulation effect. [ABSTRACT FROM AUTHOR]

Abstract Purpose To compare the effect of traditional conjunctival sac swab sampling (A) with aerosolization ocular surface microorganism sampling (B),a novel microbial sampling method, in detecting ocular microbial infection. Methods The study included 61 participants (122 eyes) enrolled at the Eye Hospital, Wenzhou Medical University from December, 2021 to March, 2023. Each eye of the participants underwent sampling first with method A then B.Before aerosolization sampling, the air environment was disinfected and sampled as blank air control sample. Subsequently, the air pulses impinging the ocular surface causes dehiscence of the tear film covering the ocular surface and aerosols are formed.The microorganisms from the ocular surface attach to the aerosols generated as aerosolization ocular surface microorganism and be sampled as subject sample by bio-aerosol sampler.The samples were collected and incubated at 25℃ for 3–5 days and 37℃ for 24–48 h.The colonies were counted and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Results The accuracy in Group B was higher than that in Group A (45.8% vs. 38.3%, P = 0.289). There was a slight level of agreement between the results from both the sampling methods (k = 0.031, P = 0.730). The sensitivity in Group B was higher than that in Group A (57.1% vs. 35.7%, P = 0.453). The specificity results in Group B was higher than that in Group A (44.3% vs. 38.7%, P = 0.480). There were 12 and 37 types of microbes detected in Groups A and B, respectively. Conclusions Compared with traditional swab sampling, the novel aerosolization sampling method shows higher accuracy and more comprehensive detection of microbes; however, it cannot completely replace swab sampling. The novel method can be a novel conducive strategy and supplement swab sampling to auxiliary diagnose ocular surface infection.

Purpose: To compare the effect of traditional conjunctival sac swab sampling (A) with aerosolization ocular surface microorganism sampling (B),a novel microbial sampling method, in detecting ocular microbial infection. Methods: The study included 61 participants (122 eyes) enrolled at the Eye Hospital, Wenzhou Medical University from December, 2021 to March, 2023. Each eye of the participants underwent sampling first with method A then B.Before aerosolization sampling, the air environment was disinfected and sampled as blank air control sample. Subsequently, the air pulses impinging the ocular surface causes dehiscence of the tear film covering the ocular surface and aerosols are formed.The microorganisms from the ocular surface attach to the aerosols generated as aerosolization ocular surface microorganism and be sampled as subject sample by bio-aerosol sampler.The samples were collected and incubated at 25℃ for 3–5 days and 37℃ for 24–48 h.The colonies were counted and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Results: The accuracy in Group B was higher than that in Group A (45.8% vs. 38.3%, P = 0.289). There was a slight level of agreement between the results from both the sampling methods (k = 0.031, P = 0.730). The sensitivity in Group B was higher than that in Group A (57.1% vs. 35.7%, P = 0.453). The specificity results in Group B was higher than that in Group A (44.3% vs. 38.7%, P = 0.480). There were 12 and 37 types of microbes detected in Groups A and B, respectively. Conclusions: Compared with traditional swab sampling, the novel aerosolization sampling method shows higher accuracy and more comprehensive detection of microbes; however, it cannot completely replace swab sampling. The novel method can be a novel conducive strategy and supplement swab sampling to auxiliary diagnose ocular surface infection. [ABSTRACT FROM AUTHOR]

Environmental aerosols in animal houses are closely related to the productive performance and health level of animals living in the houses. Preferable housing environments can improve animal welfare and production efficiency, so it is necessary to monitor and study these environments. In recent years, there have been many large-scale outbreaks of respiratory diseases related to biological aerosols, especially the novel coronavirus that has been sweeping the world. This has attracted much attention to the mode of aerosol transmission. With the rapid development of large-scale and intensive breeding, microbial aerosols have gradually become the main factor of environmental pollution in animal houses. They not only lead to a large-scale outbreak of infectious diseases, but they also have a certain impact on the health of animals and employees in the houses and increase the difficulty of prevention and control of animal-borne diseases. This paper reviews the distribution, harm, and control measures of microbial aerosols in animal house environments in order to improve people's understanding of them.

The odor and microbial aerosol gas produced in the pretreatment area, biochemical treatment area and sludge treatment area of the municipal wastewater treatment plant were treated by high-efficiency atomizing spray technology, integrated high-efficiency deodorization technology, high-efficiency atomizing spray technology and integrated high-efficiency deodorization technology. The results showed that odor and microbial aerosol gas in different functional areas of the municipal wastewater treatment plant were effectively removed. [ABSTRACT FROM AUTHOR]

Microbes are fundamental to Earth’s ecosystems, thus understanding ecosystem connectivity through microbial dispersal is key to predicting future ecosystem changes in a warming world. However, aerial microbial dispersal remains poorly understood. Few studies have been performed on bioaerosols (microorganisms and biological fragments suspended in the atmosphere), despite them harboring pathogens and allergens. Most environmental microbes grow poorly in culture, therefore molecular approaches are required to characterize aerial diversity. Bioinformatic tools are needed for processing the next generation sequencing (NGS) data generated from these molecular approaches; however, there are numerous options and choices in the process. These choices can markedly affect key aspects of the data output including relative abundances, diversity, and taxonomy. Bioaerosol samples have relatively little DNA, and often contain novel and proportionally high levels of contaminant organisms, that are difficult to identify. Therefore, bioinformatics choices are of crucial importance. A bioaerosol dataset for bacteria and fungi based on the 16S rRNA gene (16S) and internal transcribed spacer (ITS) DNA sequencing from parks in the metropolitan area of Auckland, Aotearoa New Zealand was used to develop a process for determining the bioinformatics pipeline that would maximize the data amount and quality generated. Two popular tools (Dada2 and USEARCH) were compared for amplicon sequence variant (ASV) inference and generation of an ASV table. A scorecard was created and used to assess multiple outputs and make systematic choices about the most suitable option. The read number and ASVs were assessed, alpha diversity was calculated (Hill numbers), beta diversity (Bray–Curtis distances), differential abundance by site and consistency of ASVs were considered. USEARCH was selected, due to higher consistency in ASVs identified and greater read counts. Taxonomic assignment is highly dependent on the taxonomic database used. Two popular taxonomy databases were compared in terms of number and confidence of assignments, and a combined approach developed that uses information in both databases to maximize the number and confidence of taxonomic assignments. This approach increased the assignment rate by 12–15%, depending on amplicon and the overall assignment was 77% for bacteria and 47% for fungi. Assessment of decontamination using “decontam” and “microDecon” was performed, based on review of ASVs identified as contaminants by each and consideration of the probability of them being legitimate members of the bioaerosol community. For this example, “microDecon’s” subtraction approach for removing background contamination was selected This study demonstrates a systematic approach to determining the optimal bioinformatics pipeline using a multi-criteria scorecard for microbial bioaerosol data. Example code in the R environment for this data processing pipeline is provided. [ABSTRACT FROM AUTHOR]

Two polypropylene HVAC electret filters: a regular filter and an antimicrobial filter containing zinc pyrithione (ZPT), were compared for filtration performance. The study was conducted over 7 months in realistic conditions with semi-urban outdoor air. Several parameters were monitored over the study period: the average temperature was about 20 °C and relative humidity about 60%, the average inlet concentration of cultivable microorganisms was 50 CFU m−3, the average inlet concentration of particles was 10 μg m−3, the filter pressure drop increased moderately by about 30 Pa, and the particle collection efficiency of soda fluorescein (median diameter 0.35 μm) decreased in the first half of the study period by about 30% and then stabilized. The microbial concentration on the filters was quantified every 2 months using an innovative methodology based on media coupons in conjunction with microorganism quantification by CFU counting, with 5 culture media favorable to bacteria and/or fungi growth. The microbial concentrations on the filters were between 100 and 2000 CFU cm−2. The antimicrobial effect of zinc pyrithione was confirmed by the fungi cultivated with DRBC agar: no effects in the level of filter clogging were revealed in the range studied. The high statistical deviation in the results regarding the inhibiting effect of zinc pyrithione on bacteria prevents any conclusion. [ABSTRACT FROM AUTHOR]

Bioaerosol, particulate matter concentration and antibiotic resistance of airborne Staphylococcus was assessed in animal and public premises (classroom, sports hall, horse stable, cowshed, newborn calf shed and outdoor background control site) of Poland’s oldest agricultural school. The concentration and size distribution of bacteria, fungi, actinomycetes and staphylococci were assessed with a six stage Andersen impactor. Particulate matter (PM10, PM4, PM2.5 and PM1) was determined using the DustTrak aerosol monitor. The Staphylococcus species were determined with MALDI-TOF mass spectrometry and antimicrobial resistance was assessed using disk diffusion. Bioaerosol concentrations differed significantly between sampling points, with the highest levels of all microorganisms occurring in the newborn calf shed. The proportion of respirable fraction exceeded 60% in all sites, indicating potential harmfulness to exposed people. Mean concentrations of particulate matter were the smallest in school rooms and the highest in the newborn calf shed. Neither particulate matter nor microbial aerosol exceeded threshold values for workplaces. Among thirty-four isolated staphylococcal strains, S. equorum (35%), S. succinus (26%) and S. xylosus (15%) were the most prevalent. Resistance to macrolides (erythromycin) and lincosamides (clindamycin) was the most frequent. One strain was methicillin-resistant. Farm animals are significant sources of bioaerosol and therefore attention should be paid with respect to maintaining appropriate sanitary conditions and hygiene of premises and animals.

Objectives: This study was aimed to assess the concentration of microbial aerosol and species composition of airborne staphylococci in 10 healthcare facilities in southern Poland including primary healthcare units and hospital wards; and to assess whether the selected components of microbial aerosol pose a threat of severe infections to either patients or the personnel.Methods: The study was conducted at monthly intervals over a period of one year. Air samples were collected by MAS-100 sampler. The number of mesophilic bacteria, mould fungi, actinomycetes and staphylococci was determined on general and selective media. The species identification of staphylococci was conducted using API tests for strains that were pre-selected based on macroscopic and microscopic observations.Results: A total number of 1,584 samples were collected during the sampling period. The numbers of airborne microorganisms varied between the examined premises and between the seasons of the year. The observed differences were statistically significant with one exception for actinomycetes and their differences between the examined premises. The concentrations of mesophilic bacteria varied from 5 to 297 CFU/m3 of air, for Staphylococcus the values ranged from 1 to 96 CFU/m3, for fungi - from 1 to 100 CFU/m3, and the number of actinomycetes ranged from 7 to 321 CFU/m3. Ten species of coagulase-negative staphylococci (CoNS) were identified among 55 isolates with S. saprophyticus and S. warneri being the most frequently detected (n = 14 and 13, respectively). S. haemolyticus, which is one of the most common causal agents of nosocomial infections was observed in four facilities (n = 5).Conclusions: The microbial concentrations varied both between the seasons of the year and between the examined facilities. The highest bioaerosol concentrations were observed in most crowded premises. The identified species of staphylococci, although not typically associated with human infections, are common causal agents of nosocomial infections and infections in immunocompromised people. [ABSTRACT FROM AUTHOR]

The aim of the present study was to analyze the aerosol concentrations and microbial community structures in closed cage broiler houses at different broiler growth stages to assess the dynamic pattern of microbial aerosols in closed cage systems. Our results revealed that the total concentration of bacterial aerosols gradually increased during the growth cycle of broilers. Highthroughput sequencing of 16S rDNA revealed that microbial compositions differed tremendously during different growth stages, although Firmicutes and Proteobacteria were the dominant taxa in samples from all broiler growth stages. At the genus level, dominant phylotypes displayed great variation during different growth stages. Escherichia and Shigella were the most dominant taxa throughout the growth cycle, increasing from 4.3 to 12.4% as the broilers grew. The alpha index revealed that the microbial diversity displayed significant differences between the different growth stages and that the bacterial community had the highest diversity when broilers were 22 days old. High-throughput sequencing analyses revealed that environmental microbes and opportunistic pathogens had relatively high abundances during the winter growth period. The data revealed the composition and aerodynamic diameters of microbial aerosols in closed cage broiler houses at different broiler growth stages in winter. The results also enabled us to elucidate the dynamic pattern of microbial aerosols in broiler houses in response to bacterial communities. Our results may provide a basis for developing technologies for air quality control in caged poultry houses. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate effects of microbial aerosols on immune function of ducks and shed light on the establishment of microbial aerosol concentration standards for poultry. A total of 1800 1-d-old Cherry Valley ducks were randomly divided into 5 groups (A, B, C, D and E) with 360 ducks in each. To obtain objective data, each group had three replications. Concentrations of airborne bacteria, fungi, endotoxin in different groups were created by controlling ventilation and bedding cleaning frequency. Group A was the control group and hygienic conditions deteriorated progressively from group B to E. A 6-stage Andersen impactor was used to detect the aerosol concentration of aerobes, gram-negative bacteria, fungi and AGI-30 microbial air sampler detect the endotoxin, and Composite Gas Detector detect the noxious gas. In order to assess the immune function of meat ducks, immune indicators including H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme and immune organ indexes were evaluated. Correlation coefficients were also calculated to evaluate the relationships among airborne bacteria, fungi, endotoxin and immune indicators. The results showed that the concentration of airborne aerobe, gram-negative bacteria, fungi, endotoxin have a strong correlation to H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme and immune organ indexes, respectively. In addition, when the concentration of microbial aerosol reach the level of group D, serum IgG (6 - 8 weeks), lysozyme (4 week) were significantly higher than in group A (P < 0.05); serum IL-2 (7 and 8 weeks) , T-lymphocyte transformation rate, lysozyme (7 and 8 weeks), spleen index (6 and 8 weeks) and bursa index (8 week) were significantly lower than in group A(P < 0.05 or P < 0.01). The results indicated that a high level of microbial aerosol adversely affected the immune level of meat ducks. The microbial aerosol values in group D provide a basis for recommending upper limit concentrations of microbial aerosols for healthy meat ducks.

With dense population, the Beijing-Tianjin-Hebei region of China is one of the regions most severely stricken by atmospheric pollution in the world. Research shows that the annual average concentration of airborne bacteria in this region is 1,380-3,020 CFU/m3. The concentration of gram-positive (G+) bacteria (80%-85%) is significantly higher than that of G- bacteria (15%-20%) and a total of 47 genera of bacteria are found. The number of airborne fungi in Beijing is 89-2,270 CFU/m3 and a total of nine genera of fungi are detected. Bacterial aerosols in the air are mostly distributed in particles bigger than 2 μm (82.2%). Fungal aerosols are mainly found in 1-6 μm particles, accounting for 71.6%, and are the most densely distributed in 2-3.5 μm particles. The regular changes in distribution region, time, and particle size of microbial aerosol in the air may provide an important research basis for the further study on the correlation between the quantity and genera of microorganisms in haze and human infectious disease. [ABSTRACT FROM AUTHOR]

Abstract: Quantitative (CFU counting, ergosterol rate) and qualitative (SEM observations) analyses and a dedicated experimental set-up were combined in this study to examine the growth and release of a bacteria–fungi consortium collected by fibrous filters used in HVAC systems. The influence of three parameters was examined: air relative humidity (60%, 80% or close to 100%), the presence of airflow after microbial contamination of filters, and the nature of the fibrous media (glass or polypropylene fibers). First, the initial filtration efficiency of the microbial consortium, composed of bacterial cells of Staphylococcus epidermidis and fungal spores of Penicillium oxalicum, was analyzed and compared to the initial filtration with a polyvinyl-acetate aerosol. Then, microbial behavior was evaluated in terms of microbial growth onto filters (in the situation of a simulated airflow stop) and particles released from filters (after a simulated restart of the ventilation). The results demonstrated that, whatever the operating conditions, S. epidermidis did not grow onto filters. On the contrary, P. oxalicum demonstrated significant growth multiplying by more than 100 times its number of colonies (CFU) and by more than 10 times its ergosterol rate in saturated moist air conditions. SEM images provided information about microbial behavior. A significant mycelia development was observed after 48h of filters conditioning at 100% RH, while after a longer period of conditioning (168h), P. oxalicum spores were mostly observed. Regarding particle release, spores were detected downstream of the filters conditioned during 168h when ventilation was restarted. [Copyright &y& Elsevier]

The aim of this study was to develop an experimental set-up and a methodology to uniformly contaminate several filter samples with high concentrations of cultivable bacteria and fungi. An experimental set-up allows contaminating simultaneously up to four filters for range of velocities representative of heating, ventilating and air-conditioning systems. The test aerosol was composed of a microbial consortium of one bacterium (Staphylococcus epidermidis) and one fungus (Penicillium oxalicum) and aerosol generation was performed in wet conditions. Firstly, the experimental set-up was validated in regards to homogeneity of the air flows. The bioaerosol was also characterized in terms of number and particle size distribution using two particle counters: optical particle counter Grimm® 1.109 (optical diameters) and TSI APS 3321 (aerodynamic diameters). Moreover, stabilities of the number of particles generated were measured. Finally, concentrations of cultivable microorganisms were measured with BioSamplers (SKC) downstream of the four filters. [ABSTRACT FROM PUBLISHER]

Biological aerosols from air constitute a significant source of exposure to microorganisms in public places. Airborne microorganisms are involved in the development of certain respiratory symptoms, allergies, or infections among users and occupants. Various sampling instruments have commonly been used in aerobiology to collect bacteria and fungi suspended in the air. The objective of this study was to develop a reliable procedure for sampling in indoor public environments presenting different levels of occupancy, airborne bacteria and fungi to be subjected to molecular analysis (bacteria and fungi quantitative PCR, capillary electrophoresis single strand conformation polymorphism fingerprinting). Four different sampling devices were tested in situ in an office building (open-plan type) and the sampling strategy chosen was tested in two museum contexts. In accordance with the drawbacks involved to our study (quantitative and qualitative aspects, cost, and overcrowding), cyclone device appeared to be most suitable. The results underline the effectiveness of this high-volume aerosol sampling device for both qualitative and quantitative molecular analysis. Four in situ sampling collections were carried out in 1 day in the Louvre Museum to study quantitative and qualitative variations of airborne bacterial and fungal diversity. The quantitative results revealed a similar order of magnitude for the numbers of both bacteria and fungi. In the Louvre Museum, the samples yielded between 3.7 × 104 and 4.1 × 104 genome equivalent (GE) bacteria/m3 air and between 5.0 × 104 and 5.9 × 104 GE fungi/m3 air and in the Decorative Arts Museum between, 2.1 × 104 and 2.5 × 104 GE bacteria/m3 air and between 1.4 × 104 and 1.7 × 104 GE fungi/m3 air. The results also indicate that the dominant bacterial community displayed a stable structure over a short period of time whereas dominant eukaryotic airborne community appeared more variable. [ABSTRACT FROM AUTHOR]

Accompanying rapid social and economic development, increasing numbers of industrial activities have resulted in the release of a variety of pathogenic microorganisms into the air, and the detection of these microbial aerosols has become a research topic of great interest. Presently, microbial aerosols can be detected by the plate count method, direct microscopic examination, spectrographic method, biosensor method, and by molecular biological methods. Among the latter group, real-time polymerase chain reaction (PCR) not only has high specificity, simplicity, and convenience in operation, but also provides quantitative DNA or RNA data. Thus, it should be readily applicable to the detection of microbial aerosols. In this article, the use of real-time PCR in the domain of microbial aerosols was reviewed. Problems with real-time PCR that require resolution, and its suitability for detecting microbial aerosols, were analyzed. [ABSTRACT FROM PUBLISHER]

The aim of this study was to develop an experimental set-up and a methodology to uniformly contaminate several filter samples with high concentrations of cultivable bacteria and fungi. An experimental set-up allows contaminating simultaneously up to four filters for range of velocities representative of heating, ventilating and air-conditioning systems. The test aerosol was composed of a microbial consortium of one bacterium (Staphylococcus epidermidis) and one fungus (Penicillium oxalicum) and aerosol generation was performed in wet conditions. Firstly, the experimental set-up was validated in regards to homogeneity of the air flows. The bioaerosol was also characterized in terms of the number and particle size distribution using two particle counters: optical particle counter Grimm® 1.109 (optical diameters) and TSI APS 3321 (aerodynamic diameters). Moreover, stabilities of the number of particles generated were measured. Finally, concentrations of cultivable microorganisms were measured with BioSamplers SKC downstream of the four filters. [ABSTRACT FROM AUTHOR]

Laminar flow cabinets (LFCs) ensure a safe working space within which product manipulation can be carried out safely excluding contaminations of the product with the environmental microorganisms. However, for environmental monitoring applications mobile laboratories are required and these prefer the lighter gloveboxes (GB; restricted arm movement) or still air boxes (SAB; free arm movement) over the heavier, more expensive LFCs, which need to be regularly maintained. Nevertheless, the efficiency of simple GBs/SABs (no HEPA filter), in providing semi-sterile working conditions has yet to be clearly defined. Consequently, our aim was to assess the suitability of GBs/SABs for semi-sterile applications by using passive and active bioaerosol sample collection procedures within the interior spaces of these boxes. Prior to sample collection the boxes were pre-treated with different spraying preparations (70% ethanol, 2% detergent or sterile water). For a greater restriction of bioaerosol entry, SABs were constructed with covered arm ports and these were classified as partially covered (SAB PC) and completely covered SABs (SAB CC). Results showed that ethanol sprayed GB and SAB CC exhibited microbial aerosol colony counts of zero after one hour of passive sample collection, and active sample collection revealed counts ranging between 1.9 (for GB) - 2.3 Log 10 CFU/m3 (for SAB CC). However, ethanol sprayed SAB and SAB PC were ineffective having colony counts of 6.9 and 6.5 Log 10 CFU/m3, respectively. Other spraying regimes resulted in even higher colony counts (up to 7.3 Log 10 CFU/m3). Therefore, the ethanol sprayed GB and SAB CC could effectively be used for semi-sterile applications, with the SAB CC allowing for an unrestricted arm movement within it. • GB and SAB CC sprayed with ethanol exhibited microbial colony counts of zero after 1 h of passive sampling. • SAB CC allows for the full freedom of hand movement. • SAB PC and SAB UN showed unsatisfactory results in any of the spraying treatments. [ABSTRACT FROM AUTHOR]

Microbial growth onto HVAC filters was observed in real conditions with possible degradation of the indoor air quality. The filtration performance of marketed antimicrobial filters containing zinc pyrithione was tested under laboratory conditions and compared to that of similar filters with the same classification, F7 (EN779:2002). The filtration performance of the two tested filters during loading with PM10 particles was quantified in an experimental setup with filter pressure drop measurement and particle counting upstream and downstream of the filters. The microbial growth on the new and loaded filters, both contaminated with a microbial airborne consortium composed of two bacteria (Gram-positive and -negative) and fungi, was quantified by colony-forming units after conditioning the filters for a few days under controlled temperature (25 °C) and humidity (50% or 90% relative humidity). The results reveal that there was no degradation of the filtration performance of the filters treated with the antimicrobial agent. The efficiency of the antimicrobial treatment, i.e., the ability to inhibit the growth of microorganisms during the incubation period, was significant with the new filters regarding the fungal growth, but the results demonstrate that the antimicrobial treatment became inefficient with the loaded filters. [ABSTRACT FROM AUTHOR]

Bioaerosol, particulate matter concentration and antibiotic resistance of airborne Staphylococcus was assessed in animal and public premises (classroom, sports hall, horse stable, cowshed, newborn calf shed and outdoor background control site) of Poland's oldest agricultural school. The concentration and size distribution of bacteria, fungi, actinomycetes and staphylococci were assessed with a six stage Andersen impactor. Particulate matter (PM10, PM4, PM2.5 and PM1) was determined using the DustTrak aerosol monitor. The Staphylococcus species were determined with MALDI-TOF mass spectrometry and antimicrobial resistance was assessed using disk diffusion. Bioaerosol concentrations differed significantly between sampling points, with the highest levels of all microorganisms occurring in the newborn calf shed. The proportion of respirable fraction exceeded 60% in all sites, indicating potential harmfulness to exposed people. Mean concentrations of particulate matter were the smallest in school rooms and the highest in the newborn calf shed. Neither particulate matter nor microbial aerosol exceeded threshold values for workplaces. Among thirty-four isolated staphylococcal strains, S. equorum (35%), S. succinus (26%) and S. xylosus (15%) were the most prevalent. Resistance to macrolides (erythromycin) and lincosamides (clindamycin) was the most frequent. One strain was methicillin-resistant. Farm animals are significant sources of bioaerosol and therefore attention should be paid with respect to maintaining appropriate sanitary conditions and hygiene of premises and animals. [ABSTRACT FROM AUTHOR]

• Three wards have an average aerobic bacterial concentration of 132 CFU∙m−3. • All E. coli isolated from wards show multi-drug resistance. • The wards' ESBL-positive strains mainly have the TEM gene, and the detection rate is 66.67% (8/12). • PFGE results show that airborne E. coli in the ward environment can be spread through the air into the corridor. Antibiotic-resistant bacteria (ARB) present a global public health problem. Microorganisms are the main cause of hospital-acquired infections, and the biological contamination of hospital environments can cause the outbreak of a series of infectious diseases. Therefore, it is very important to understand the spread of antibiotic-resistant bacteria in hospital environments. This study examines the concentrations of aerobic bacteria and E. coli in ward environments and the airborne transmission of bacterial drug resistance. The results show that the three wards examined have an average aerobic bacterial concentration of 132 CFU∙m−3 and an average inhalable aerobic bacterial concentration of 73 CFU∙m−3, with no significant difference (P > 0.05) among the three wards. All isolated E. coli showed multi-drug resistance to not only third-generation cephalosporin antibiotics, but also quinolones, aminoglycosides, and sulfonamides. Furthermore, 51 airborne E. coli strains isolated from the air in the three wards and the corridor were screened for ESBLs, and 12 (23.53%) were ESBL-positive. The drug-resistance gene of the 12 ESBL-positive strains was mainly TEM gene, and the detection rate was 66.67% (8/12). According to a homology analysis with PFGE, 100% homologous E. coli from the ward at 5 m and 10 m outside the ward in the corridor shared the same drug-resistance spectrum, which further proves that airborne E. coli carrying a drug-resistance gene spreads out of the ward through gas exchange. This leads to biological pollution inside, outside, and around the ward, which poses a direct threat to the health of patients, healthcare workers, and surrounding residents. It is also the main reason for the antibiotic resistance in the hospital environment. More attention should be paid to comprehensive hygiene management in the surrounding environment of hospitals. [ABSTRACT FROM AUTHOR]