Microorganisms In Aerosols Research Articles

Inactivation of airborne pathogenic microorganisms by plasma-activated nebulized mist

The airborne microorganisms in the aerosols are one main transmission way of pathogenic microorganisms and therefore inactivation of microorganisms in aerosols could effectively prevent the transmission of pathogenic microorganisms to control epidemics. The mist nebulized by plasma-activated air could effectively inactivate bacteria and could be developed for the sterilization of microorganisms in aerosols. In this study, the plasma-activated nebulized mist (PANM) was applied for the inactivation of microorganisms in aerosols and efficiently inactivated the bacteria, yeast, and viruses in aerosols after 2-min treatment. The PANM treatment caused morphologic changes and damage to the bacteria cells in aerosols. The PANM could also inactivate the microorganisms attached to the surface of the treatment chamber and the bacteria attached to the skin of mice within 6-min treatment. The biosafety assays demonstrated that the PANM treatment exhibited no effects on the behavior, hematological and serum biochemical parameters of blood, and organs from the mice. This study would supply an efficient, broad-spectrum, and safe aerosol sterilization strategy based on plasma technology to prevent the transmission of airborne microorganisms.

Composition and Concentration of the Biogenic Components of the Aerosols Collected over Vasyugan Marshes and Karakan Pine Forest at Altitudes from 500 to 7000 m

The purpose of this study was to compare the concentration of total protein, as well as the composition and abundance of culturable microorganisms in atmospheric aerosols collected over the Vasyugan marshes and the Karakan pine forest during a flight in September 2018 at altitudes from 500 to 7000 m. The determined concentrations of total protein in Karakan samples were on average much less than those for the same area in September of other years. The concentration and composition of microorganisms in aerosol samples were determined by cultural methods and isolate genotyping. Altitude dependences of concentrations of total protein and culturable microorganisms were revealed. A rather stable altitude profile of culturable microorganism concentration was found over the Vasyugan marshes. No microorganisms were found at altitudes 4000 and 5500 m over the Karakan pine forest. Non-spore-bearing and spore-forming bacteria, as well as molds and yeast-like fungi, were isolated from aerosol samples. A high concentration of cosmopolitan psychrotolerant yeast Aureobasidium, capable of causing severe mycoses, and opportunistic bacteria Acinetobacter were found. A great similarity of composition and an atypically high abundance of non-spore-bearing bacteria and psychrotolerant yeast-like fungi were revealed in samples taken at altitudes of 1000 and 500 m in both studied regions, which may be a consequence of large-scale horizontal transport of layers of atmospheric air contaminated with microorganisms.

Novel aerosol detection platform for SARS‑CoV‑2: Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection

The SARS‑CoV‑2 virus is released from an infectious source (such as a sick person) and adsorbed on aerosols, which can form pathogenic microorganism aerosols, which can affect human health through airborne transmission. Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard. In this study, we built a set of sub-micron aerosol detection platform, and carried out a simulation experiment on the SARS‑CoV‑2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR. The feasibility of the system in aerosol detection was verified, and the influencing factors in the detection process were experimentally tested. As a result, the sampling efficiency was 29.77%, and extraction efficiency was 98.57%. The minimum detection limit per unit volume of aerosols was 250 copies (102 copies/mL, concentration factor 2.5).

Oral Antiseptics against SARS-CoV-2: A Literature Review.

Dentists are health care workers with the highest risk of exposure to COVID-19, because the oral cavity is considered to be a reservoir for SARS-CoV-2 transmission. The identification of SARS-CoV-2 in saliva, the generation of aerosols, and the proximity to patients during dental procedures are conditions that have led to these health care workers implementing additional disinfection strategies for their protection. Oral antiseptics are widely used chemical substances due to their ability to reduce the number of microorganisms. Although there is still no evidence that they can prevent the transmission of SARS-CoV-2, some preoperative oral antiseptics have been recommended as control measures, by different health institutions worldwide, to reduce the number of microorganisms in aerosols and droplets during dental procedures. Therefore, this review presents the current recommendations for the use of oral antiseptics against SARS-CoV-2 and analyzes the different oral antiseptic options used in dentistry.

In Vitro Effect of Instrumentation Using Ultrasonication with and without Hydrogen Peroxide on the Removal of Biofilms and Spread of Viable Microorganisms in Aerosols.

To evaluate the use of hydrogen peroxide as an adjunct to ultrasonication (US) in biofilm removal and whether it can limit the spread of viable microorganisms in the aerosol. Multi-species biofilms were formed on dentin disks and titanium disks fixed on a plastic surface. After placing the specimens in a periodontal pocket model, an ultrasonic scaler was applied for 30 s, in part combined with 0.25% or 0.5% H2O2. After treatment, the remaining biofilm was analysed for bacterial counts (colony forming units [CFU]), biofilm quantity and metabolic activity. Further, the cytotoxic effect of hydrogen peroxide on periodontal ligament fibroblasts was assessed and the spread of bacteria in aerosol was quantified. Ultrasonication reduced bacterial counts in biofilm, biofilm mass and metabolic activity on both dentin and titanium disks. Adjunctive use of 0.25% and 0.5% H2O2 more effectively reduced the viable bacteria in biofilm than ultrasonication alone; this was also found on both dentin and titanium. The different concentrations of H2O2 did not lead to corresponding differences in bacterial mass and metabolic activity. The spread of bacteria through aerosols was statistically significantly reduced when adjunctive H2O2 was used. However, a certain cytotoxic effect on periodontal ligament fibroblasts by H2O2 could not be ruled out. Irrigating with H2O2 during periodontal instrumentation with an ultrasonic scaler increases the reduction of viable bacteria within biofilms. It might limit bacterial spreading via aerosols.

Coronavirus Disease 2019 and Mouthwashes - A Review Article

The coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) belongs to the coronavirus family. It is linked to transmission from person to person. Coronavirus disease 2019 (COVID-19) was recently discovered in contaminated patients saliva. Because of the close closeness to the patient during dental care, the significant production of aerosols, and the discovery of SARS-CoV-2 in saliva, the oral cavity has been identified as a potential reservoir for COVID-19 transmission. Mouthwashes are popular because they help to reduce the amount of bacteria in the mouth. Despite the lack of clinical evidence, to minimize the amount of microorganisms in aerosols and drops during oral procedures, antimicrobial mouth rinses with chlorhexidine, cetylpyridinium chloride, povidone-iodine, Listerine, and hydrogen peroxide have been prescribed before surgery. As a result, the aim of this paper is to analyze the benefits and drawbacks of most antiseptic mouthwashes used in dentistry, as well as to provide a detailed review of current guidelines for the use of mouthwashes in the battle against the COVID-19 pandemic.

Use of mouthwashes against COVID-19 in dentistry.

The proximity to the patient during dental care, high generation of aerosols, and the identification of SARS-CoV-2 in saliva have suggested the oral cavity as a potential reservoir for COVID-19 transmission. Mouthwashes are widely-used solutions due to their ability to reduce the number of microorganisms in the oral cavity. Although there is still no clinical evidence that they can prevent the transmission of SARS-CoV-2, preoperative antimicrobial mouth rinses with chlorhexidine gluconate (CHX), cetylpyridinium chloride (CPC), povidone-iodine (PVP-I), and hydrogen peroxide (H2O2) have been recommended to reduce the number of microorganisms in aerosols and drops during oral procedures. This paper therefore aims to provide a comprehensive review of the current recommendations on the use of mouthwashes against the COVID-19 pandemic and to analyse the advantages and disadvantages of most conventional antiseptic mouthwashes used in dentistry.

Demystifying the mist: Sources of microbial bioload in dental aerosols.

The risk of transmitting airborne pathogens is an important consideration in dentistry and has acquired special significance in the context of recent respiratory disease epidemics. The purpose of this review, therefore, is to examine (1) what is currently known regarding the physics of aerosol creation, (2) the types of environmental contaminants generated by dental procedures, (3) the nature, quantity, and sources of microbiota in these contaminants and (4) the risk of disease transmission from patients to dental healthcare workers. Most dental procedures that use ultrasonics, handpieces, air‐water syringes, and lasers generate sprays, a fraction of which are aerosolized. The vast heterogeneity in the types of airborne samples collected (spatter, settled aerosol, or harvested air), the presence and type of at‐source aerosol reduction methods (high‐volume evacuators, low volume suction, or none), the methods of microbial sampling (petri dishes with solid media, filter paper discs, air harvesters, and liquid transport media) and assessment of microbial bioload (growth conditions, time of growth, specificity of microbial characterization) are barriers to drawing robust conclusions. For example, although several studies have reported the presence of microorganisms in aerosols generated by ultrasonic scalers and high‐speed turbines, the specific types of organisms or their source is not as well studied. This paucity of data does not allow for definitive conclusions to be drawn regarding saliva as a major source of airborne microorganisms during aerosol generating dental procedures. Well‐controlled, large‐scale, multi center studies using atraumatic air harvesters, open‐ended methods for microbial characterization and integrated data modeling are urgently needed to characterize the microbial constituents of aerosols created during dental procedures and to estimate time and extent of spread of these infectious agents.

The Influence of Simulated Sunlight on the Inactivation of Influenza Virus in Aerosols.

Environmental parameters, including sunlight levels, are known to affect the survival of many microorganisms in aerosols. However, the impact of sunlight on the survival of influenza virus in aerosols has not been previously quantified. The present study examined the influence of simulated sunlight on the survival of influenza virus in aerosols at both 20% and 70% relative humidity using an environmentally controlled rotating drum aerosol chamber. Measured decay rates were dependent on the level of simulated sunlight, but they were not significantly different between the 2 relative humidity levels tested. In darkness, the average decay constant was 0.02 ± 0.06 min-1, equivalent to a half-life of 31.6 minutes. However, at full intensity simulated sunlight, the mean decay constant was 0.29 ± 0.09 min-1, equivalent to a half-life of approximately 2.4 minutes. These results are consistent with epidemiological findings that sunlight levels are inversely correlated with influenza transmission, and they can be used to better understand the potential for the virus to spread under varied environmental conditions.

Reagentless Microsensor Based on Conducting Poly(3‐aminophenylboronic Acid) for Rapid Detection of Microorganisms in Aerosol

AbstractWe report on microsensor for direct detection of microorganisms in aerosol. Microsensor is based on interdigitated ultramicroelectrodes modified with electropolymerized 3‐aminophenylboronic acid (3‐APBA). Appearance of Penicillium chrysogenum in aerosol as well as further increase of its concentration lead to poly(3‐APBA) conductivity increase found by impedance spectroscopy. According to Raman spectroscopy data, the presence of microorganism affects polymer conductivity similarly to binding of glucose to polymer which results in self‐doping phenomenon. The elaborated detection technique is 100 times faster comparing to agar plate cultivation: it requires less than 20 minutes for analysis. Dynamic range of microsensor includes the upper limit for non‐contaminated air in Russian hygienic standard (500 colony‐forming units per cubic meter). The first reported reagentless detection of Penicillium chrysogenum in aerosol by conductivity increase reveals a prospect for creation of a promising alternative to conventional techniques for detection of microorganisms.

Microbial structure and chemical components of aerosols caused by rotating brushes in a wastewater treatment plant

Bacterial community structure and the chemical components in aerosols caused by rotating brushes in an Orbal oxidation ditch were assessed in a Beijing municipal wastewater treatment plant. Air samples were collected at different distances from the aerosol-generating rotating brushes. Molecular culture-independent methods were used to characterize the community structure of the airborne bacteria in each sample regardless of cell culturability. A clone library of 16S rDNA directly amplified from air DNA of each sample was constructed and sequenced to analyze the community composition and diversity. Insoluble particles and water-soluble ions emitted with microorganisms in aerosols were analysis by a scanning electron microscope together with energy dispersive X-ray spectroscopy and ion chromatogram analyzer. In total, most of the identified bacteria were Proteobacteria. The majority of sequences near the rotating brushes (the main source of the bioaerosols) were Proteobacteria (62.97 %) with β-(18.52 %) and γ-(44.45%) subgroups and Bacteroidetes (29.63 %). Complex patterns were observed for each sampling location, suggesting a highly diverse community structure, comparable to that found in water in the Orbal oxidation ditch. Accompany with microorganisms, 46.36μg/m(3) of SO (4) (2-) , 29.35μg/m(3) of Cl(-), 21.51μg/m(3) of NO (3) (-) , 19.76μg/m(3) of NH (4) (+) , 11.42μg/m(3) of PO (4) (3-) , 6.18μg/m(3) of NO (2) (-) , and elements of Mg, Cl, K, Na, Fe, S, and P were detected from the air near the aerosols source. Differences in the structure of the bacterial communities and chemical components in the aerosols observed between sampling sites indicated important site-related variability. The composition of microorganisms in water was one of the most important sources of bacterial communities in bioaerosols. Chemical components in bioaerosols may provide a media for airborne microorganism attachment, as well as a suitable microenvironment for their growth and survival in the air. This study will be benefit for the formulation of pollution standards, especially for aerosols, that take into account plant workers' health.

The effect of chlorhexidine on reduction of viable organisms in aerosol produced by ultrasonic scaler

Purpose: The aerosol generated by ultrasonic scaler can contain bacteria or virus which can penetrate into body through respiratory systems of dentists, dental hygienist or patients. The aim of this study is to evaluate the effect of chlorhexidine digluconate as preoperative mouthrinse or lavage for ultrasonic scaler on the reduction of viable organisms in aerosol produced during periodontal treatment using ultrasonic scaler. Methods: 30 patients with moderate chronic periodontitis were included and divided into 3 groups: Control (no preoperative mouthrinse and tap water as lavage), CHG (preoperative mouthrinse with 0.1% chlorhexidine digluconate and tap water as lavage), CHL (no preoperative mouthrinse and 0.1% chlorhexidine digluconate as lavage). Each patient received scaling or subgingival curettage for 30 min. In CHG group, mouthrinse with chlorhexidine digluconate was performed for 1 min. before treatment. Before, during and after scaling or subgingival curettage, air sampling was performed for 7 min. each (1000 L/7 min.) with trypticase-soy agar plate. Agar plates were incubated in 37℃ aerobically. The numbers of colony-forming units (CFU) were counted and compared. Results: The numbers of CFUs of the samples obtained during treatment were 97±14.0 in control, 73.1±14.9 in CHG group and 44.5±9.0 in CHL group. The difference among the 3 groups was determined to be statistically significant (one-way ANOVA with Bonferroni’s correction, p-value: 0.0003). In contrast, the numbers of CFU of samples obtained before and after treatment were not significantly different among the groups. Conclusions: Chlorhexidine digluconate used as preoperative mouthrinse or lavage for ultrasonic scaler can reduce the microorganisms in aerosol produced during periodontal treatment using ultrasonic scaler. Less number of microorganisms were detected when chlorhexidine was used as lavage for ultrasonic scaler. (J Korean Acad Periodontol 2009;39:303-310)

Microbiological quality of reclaimed water used for golf courses' irrigation

Microbial quality of reclaimed water used for irrigation in two golf courses located in the southern Iberian Peninsula (Spain and Portugal) was evaluated. Bacterial indicators for faecal pollution (total and faecal coliforms, Escherichia coli and enterococci) were tested by membrane filtration using appropriate selective media. In addition, somatic E. coli bacteriophages, enteric viruses (entero-, hepatitis A and rota-) and Legionella pneumophila were also analysed. The results obtained showed that all wastewater treatment processes reduced adequately the number of indicator microorganisms although a significant correlation between pathogenic and indicator microorganisms tested was not found. L. pneumophila was detected by PCR but not confirmed by culture. Survival experiments of pathogenic microorganisms in aerosols and irrigated turf are conducted to determine the health hazards for the golf practice and to propose a microbial standard for wastewater used for irrigation of golf courses.

The sea surface microlayer as a source of viral and bacterial enrichment in marine aerosols

Marine aerosols are formed primarily by the eruption of rising bubbles through the sea-surface microlayer (SML), and aerosol formation is the main vector for transport of bacteria and viruses across the air–sea interface. The processes by which materials are transported to and through the SML to the atmosphere results in an enrichment in the SML of microbial and other organisms. We evaluated concentrations of marine bacteria and viruses in natural aerosols and in those simulated by bubbling sea sprays and compared them to the concentrations in SML (200– 400 μ m thick) and in subsurface water. Association of microorganisms with transparent gel-like organic particles and physiological status of bacteria were also assessed. We found a 15–25-fold enrichment in bacteria and viruses during transport from subsurface waters to the SML, and then into the atmosphere. The majority of microorganisms in aerosols were found embedded in the organic particles. Large portions of microorganisms in the SML were also associated with the particles, while in subsurface waters most of them were free-living. A larger percentage of damaged and less active bacterial cells occur in the microlayer than in subsurface waters, and preliminary data suggest that an even greater percentage occurs in aerosols. Our data support the idea that the SML in a major source of microorganisms entering the atmosphere from water bodies. Aerosolization is potentially an important long-distance dispersal mechanism and may account for observed cosmopolitan distributions of some bacteria.

Exposure to Bioaerosols, and Symptoms Associated with Infections, in the Paper Industry

Operators of paper machines may be exposed to bioaerosols containing both cultivable and non-cultivable microorganisms. A study was conducted in 11 paper mills to retrospectively examine the presence of symptoms related to infections in operators. The atmospheric concentrations of cultivable microorganisms in aerosols in the wet area of paper machines were determined by sampling on agar medium and typical microorganisms in the process waters from four of the largest mills were classified based on sequencing of 16S rDNA. Workers were assigned to groups based on the measurements and job tasks. Under the supervision of health care personnel a cohort of 781 exposed and 285 unexposed workers completed a questionnaire that provided data pertaining to the diagnosis of infectious diseases and the presence of associated symptoms. Operators of paper machines exposed to cultivable bioaerosols reported higher cumulative incidences of episodes with fever [odds ratio (OR) = 5.9, P 10 5 c.f.u./m 3 .

The Relationship between the Characteristics of some Cations and Anions and Sulfur-Oxidizing Activity by Microorganisms in Aerosol and Rainwater

The Relationship between the Characteristics of some Cations and Anions and Sulfur-Oxidizing Activity by Microorganisms in Aerosol and Rainwater

Applications of flow cytometry for the detection and characterization of biological aerosols

Flow cytometry (FCM), unlike conventional forms of spectroscopy, allows one to interrogate individual members of a sample population for size, shape, biological, and/or chemical properties. Over the past several years, we have investigated the use of flow cytometry to detect and identify microorganisms in aerosols. The effort to date has shown that changes in scatter patterns or DNA composition suggest that changes in the ambient air are evident. The use of macromolecular dyes and antibodies tagged by fluorescence can be used to identify specific components in the aerosol. Moreover, it is possible to combine several of these modes into one step. The assays presented here take 5 min or less to perform. Strategies for the use of flow cytometry to characterize biological aerosols will be discussed. Both laboratory and field studies that demonstrate the potential use of FCM as a means to detect and characterize microbiological materials in aerosols are discussed. © 1999 John Wiley & Sons, Inc.* Field Analyt Chem Technol 3: 291–306, 1999

Survival of Micro-Organisms in Aerosols Produced in Cleaning and Disinfecting

Survival of Micro-Organisms in Aerosols Produced in Cleaning and Disinfecting

Studies of the loss of viability of bacterial aerosols. III. Factors affecting death rates of certain non-pathogens

1. Additional quantitative studies of the survival of micro-organisms in aerosols are reported.2. Substitution of nitrogen for oxygen in the ambient medium decreases k′2, the rate of secondary loss of viability ofM. candidus, Esch. coliandS. marcescens, by 30–50%.3. The rate of primary decay (k′1) ofEsch. colidoes not appear to be affected by a similar change of atmosphere.4. The rate of secondary decay, k′2, ofM. candidusappears to increase two-to three-fold for 10°C. increments in temperature.5. Treatment of suspensions ofEsch. coliwith petroleum ether alone or containing lipid material increases k′1in aerosols generated from such suspensions.6. Treatment ofMyco. phleiwith petroleum ether appears to lower resistance to subsequent sonic irradiation.These observations are consistent with the hypothesis that differences in the physical and chemical structure of micro-organisms are reflected in constants k′1, k′2and b.We gratefully acknowledge the effective interest of two former assistants, T. Grant Maple and Eugene Mills, as well as the careful, effective, and conscientious work of our technical assistants, Ann Barr, Nora Galins, Cynthia Hartwig, Grace C. Leigh, Elizabeth Neidhardt, Paulette Slaney and Martha Szerslip, who have at different times helped secure the data presented here. Mrs Joseph J. Ecker deserves special thanks for care in the preparation of the manuscript.