Indoor Microorganisms Research Articles

A Study on Concentration, Identification, and Reduction of Airborne Microorganisms in the Military Working Dog Clinic.

BackgroundThe study was planned to show the status of indoor microorganisms and the status of the reduction device in the military dog clinic.MethodsAirborne microbes were analyzed according to the number of daily patient canines. For identification of bacteria, sampled bacteria was identified using VITEK®2 and molecular method. The status of indoor microorganisms according to the operation of the ventilation system was analyzed.ResultsAirborne bacteria and fungi concentrations were 1000.6 ± 800.7 CFU/m3 and 324.7 ± 245.8 CFU/m3. In the analysis using automated identification system, based on fluorescence biochemical test, VITEK®2, mainly human pathogenic bacteria were identified. The three most frequently isolated genera were Kocuria (26.6%), Staphylococcus (24.48%), and Granulicatella (12.7%). The results analyzed by molecular method were detected in the order of Kocuria (22.6%), followed by Macrococcus (18.1%), Glutamicibacter (11.1%), and so on. When the ventilation system was operated appropriately, the airborne bacteria and fungi level were significantly decreased.ConclusionAirborne bacteria in the clinic tend to increase with the number of canines. Human pathogenic bacteria were mainly detected in VITEK®2, and relatively various bacteria were detected in molecular analysis. A decrease in the level of bacteria and fungi was observed with proper operation of the ventilation system.

Associations between respiratory infections and bacterial microbiome in student dormitories in Northern China.

Recent studies reveal that the microbial diversity and composition in the respiratory tract are related to the susceptibility, development, and progression of respiratory infections. Indoor microorganisms can transmit into the respiratory tract through breathing, but their role in infections is unclear. Here, we present the first association study between the indoor microbiome and respiratory infections. In total, 357 students living in 86 dormitory rooms in Shanxi University were randomly selected to survey symptoms of infections. Settled air dust was collected to characterize bacterial compositions by 16S rRNA sequencing. The overall microbial richness was not associated with respiratory infections, but microorganisms from specific phylogenetic classes showed various associations. Taxa richness and abundance of Actinobacteria were protectively associated with infections (P<.05). The abundance of several genera in Gammaproteobacteria, including Haemophilus, Klebsiella, Buttiauxella, and Raoultella, was positively associated with infections (P<.005). The role of these microorganisms was consistent with previous human microbiota studies. Building age was associated with the overall microbial composition variation in dormitories and negatively associated with three potential risk genera in Proteobacteria (P<.05). The weight of vacuum dust was positively associated with a protective genus, Micrococcus in Actinobacteria (P<.05).

An overview about varieties and detection methods of pathogenic microorganisms in indoor air

Various microorganisms of different size ranges present in air are called bioaerosol which mainly includes fungi and bacteria, their metabolites, virus, pollens, etc. Bioaerosols can travel hundreds of meters or even kilometers through air, so that bioaerosols can be transmitted to all corners of public places, greatly increasing the scope of their hazards. Tiny biological particles can directly reach to human lungs through human respiration, resulting in lung diseases and increasing the risk of suffering from lung related disease. Diseases caused by pathogenic species are classified as bacterial diseases, fungal diseases, viral diseases and diseases caused by other pathogenic microorganisms. Everyone spends about 90% of their time indoors. Indoor environments with poor air quality are more likely to cause harm to vulnerable groups such as children, adolescents, the elderly, patients with chronic respiratory diseases and patients with cardiovascular diseases than outdoor pollutions. Bioaerosols may cause human health problems, severely resulting in death. In addition, Candida , Aspergillus fumigatus , Staphylococcus aureus and some other pathogenic microorganisms may cause nosocomial infections. The medical equipment and hospital environment are the main sources of these microorganisms. There are many studies on the types of microorganisms in different indoor environments. However, there are few studies on the sources of microorganisms, especially pathogenic microorganisms, in indoor air. Source-sink analysis shows that the outdoor air is the main source of most indoor microorganisms. In addition, indoor factors (such as occupants, pets, moldy substances, ventilation, etc.) also affect the distribution of indoor microorganisms. Bioaerosol sampling methods are diverse and many methods are still in development. So far, neither a sampling method nor a sampling standard is suitable for collecting various types of airborne microorganisms. Impaction, impingement and filtration are the most common methods for collecting bioaerosols. In addition, the natural sedimentation method, electrostatic precipitation and cyclone are also used to collect bioaerosols. The detection of microorganisms is the second step in bioaerosol monitoring process. Detection methods of microorganisms can be divided into two major categories called culturable approach and nonculturable approach. Culturable approach is a traditional microbiological detection method, which is simple and low cost. The main drawback of the culturable approach is that the proportion of microorganisms that can be cultured and identified in the environment is small (about 10%), so the culturable approach cannot provide information on the total number of microorganisms in the air. With the development of fluorescent dyes, it is possible to quantitate all the microorganisms (including culturable and nonculturable microorganisms) collected in the liquid medium. Advances in genomics and sequencing technologies, as well as advances in nonculturable molecular technologies (such as Genetic Fingerprinting, Metagenomics and Next Generation Sequencing) not only help identify and quantify microbial loads, but also help understand the possible microbial populations changes. In addition, advances in methods such as Chromatography, Immunoassay and PCR are also useful for microorganism identification. Bioaerosol sampling techniques and detection techniques are crucial for assessing bioaerosol levels. Different sampling and detection methods have different advantages and disadvantages, so multiple technologies can be combined to overcome the limitations of each technology. Through comprehensive and systematic understanding of the types and sources of these pathogenic microorganisms, as well as sampling and detection methods, it will help people to understand the influencing factors of indoor microbial communities, reduce the risk of indoor biological aerosols.

Galvanic microcells as control agent of indoor microorganisms.

Today, fungicides are part of the basic tool kit for indoor surface maintenance. However, fungi develop resistance to fungicides, which consequently accelerates the evolution of virulence. Fungicides also carry the risk of adverse effects in humans. Galvanic microcells are a new tool for fungal control on indoor surfaces. We used two types of electrodes, Zn and Cu, with two potential anti-fungal mechanisms: the oligodynamic action of the metal ions themselves and the electricidal effect of the current between the electrodes. The size of the inhibition zone is related to the distance between the electrodes. We hypothesized that the unique geometric properties of the observed inhibition zone could be modelled using multi foci curve Cassini ovals. Moreover, the size of the inhibition zone possessed two maximum values, while the shape of the observed inhibition zones correlated with the shape of the electric field strength. The control activity of the galvanic microcells correlated with decreasing water content in building materials. Thus, this acute antifungal system works the best in damp building environments where the risk of fungal contamination is highest.

Are pets important in spreading dermatophytes in indoor environment?

Introduction: Poor hygiene and indoor microorganisms affect men and animals` health. Dermatophytes have been reported in different species of pets and they cause zoonoses. However, researches about their presence in homes are still scarce. The aim of this study was to investigate the presence of dermatophytes in indoor environment. Methods: There were visited 26 homes of pets that had dermatophytosis confirmed by mycological culture. There were collected 188 samples in indoor environment: 78 (41.5%) samples from sites were of predominant use by the owners (sofas, chairs, beds, sheets); 66 (35.1%) from sites of predominant use by the animals (animals’ houses, cribs, toys, feeders); and 44 (23.4%) from general flooring (carpet, wood). There were collected 24 samples from other animals, which were in contact with the infected animals (contactants). Samples from the animals and the environment were collected by rubbing the fur/objects with sterile carpets (5x5cm). Samples were seeded on Mycosel agar and incubated at 25° C. Colonies were submitted to microculture and identified by their macro-and-microscopic characteristics. Results: Dermatophytes were found in 69.2% (18/26) of the surveyed homes. The same species of dermatophytes previously detected in animals with lesions were isolated indoors (Microsporum canis, M. gypseum, Trichophyton mentagrophytes and T. quinckeanum). Among the samples taken from indoor environments, 34.6% (65/188) were positive, with dermatophytes isolated in 29.5% (23/78) of the sites/objects of predominant use by owners, 42.4% (28/66) of prevalent animal use, 31.8% (14/44) from floors, and 50.0% (12/24) from contactants. Conclusions: Nowadays the contact between humans and pets is becoming more intimate, with greater sharing of the same space in a home. We conclude that pets are helping to spread these fungi in the indoor environment making dermatophytosis important in medical/veterinary clinics and in public health as a whole.

Microbiota of the indoor environment: a meta-analysis.

BackgroundAs modern humans, we spend the majority of our time in indoor environments. Consequently, environmental exposure to microorganisms has important implications for human health, and a better understanding of the ecological drivers and processes that impact indoor microbial assemblages will be key for expanding our knowledge of the built environment. In the present investigation, we combined recent studies examining the microbiota of the built environment in order to identify unifying community patterns and the relative importance of indoor environmental factors. Ultimately, the present meta-analysis focused on studies of bacteria and archaea due to the limited number of high-throughput fungal studies from the indoor environment. We combined 16S ribosomal RNA (rRNA) gene datasets from 16 surveys of indoor environments conducted worldwide, additionally including 7 other studies representing putative environmental sources of microbial taxa (outdoor air, soil, and the human body).ResultsCombined analysis of subsets of studies that shared specific experimental protocols or indoor habitats revealed community patterns indicative of consistent source environments and environmental filtering. Additionally, we were able to identify several consistent sources for indoor microorganisms, particularly outdoor air and skin, mirroring what has been shown in individual studies. Technical variation across studies had a strong effect on comparisons of microbial community assemblages, with differences in experimental protocols limiting our ability to extensively explore the importance of, for example, sampling locality, building function and use, or environmental substrate in structuring indoor microbial communities.ConclusionsWe present a snapshot of an important scientific field in its early stages, where studies have tended to focus on heavy sampling in a few geographic areas. From the practical perspective, this endeavor reinforces the importance of negative “kit” controls in microbiome studies. From the perspective of understanding mechanistic processes in the built environment, this meta-analysis confirms that broad factors, such as geography and building type, structure indoor microbes. However, this exercise suggests that individual studies with common sampling techniques may be more appropriate to explore the relative importance of subtle indoor environmental factors on the indoor microbiome.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-015-0108-3) contains supplementary material, which is available to authorized users.

Engineering control of respiratory infection and low-energy design of healthcare facilities

Indoor microorganisms and infection have become an emerging direction in indoor air quality research science. Airborne droplet nuclei can serve as carriers of respiratory infectious diseases. The study of expiratory droplets and their exposure control has received particular attention since the 2003 severe acute respiratory syndrome epidemics and the 2009 influenza pandemics. Little is known about how effective the commonly used indoor environment control strategies are for infection control. Significant questions also exist on the ventilation requirements for airborne infection control. There is a broad range of relevant important issues, including the exposure risk, and effective control methods in various indoor settings, such as hospitals, homes, schools, and offices. What is known is that the minimum required ventilation rate for infection control in hospitals can be much higher than the general health and comfort requirement in homes and offices. This has resulted in significant energy-efficiency issues in healthcare facilities. This review considers the current knowledge on airborne transmission of infection and the potential implications of a move to low-energy design, particularly in hospitals, on the risk of infection. The review outlines active research and development on reducing hospital energy use while improving infection control and discusses the potential for conducting “clinical trials” to gain the necessary evidence to support changes in hospital ventilation design.

Efficacy of the Precise Climate Controller on the reduction of indoor microorganisms.

BackgroundNowadays, there are many methods to reduce microorganisms in the air, such as dehumidifier, air purifier or humidity and temperature controller. The Precise Climate Controller is an instrument for controlling humidity and temperature, a concept that is demonstrated.ObjectiveTo determine the efficacy of this device, in order to reduce the quantity of the fungi and bacteria in the closed system.MethodsThis study is a perspective experimental study and is conducted as follows - the air sample in the closed system, a 42-cubic-meter room, is collected before the installation of the Precise Climate Controller. Next, the room is fumed with Aspergillus flavus and closed for 2 days. Then the instrument is in use in order to keep the relative humidity (RH) and the temperature constant at 55% RH and 25 degrees Celsius (℃). The air samples are collected every 3 days for 5 times during the period of 15 days to identify the type and calculate the quantity of the microorganisms.ResultsBefore the Precise Climate Controller has been installed. Three species of bacteria are found in the air samples, but none of the fungus exists in the testing room. Once the room has been fumed with a large amount of A. flavus and the instrument is in use for 3 days, nine colonies of A. flavus are identified, but later on when the instrument is in use for 6, 9, 12, and 15 days, the air samples contain neither fungus nor bacteria.ConclusionAfter keeping the RH and temperature of the closed system constant at 55% RH and 25℃ by using the Precise Climate Controller, it is found that the efficaciousness in controlling the quantity and species of fungi and bacteria is clinically significant.

Evaluation of Microbial Contaminations from Emergency Eyewash and Shower Fluid in Southern Taiwan

Background. Emergency eyewash and shower stations were usually unused for months or years, which may represent a reservoir for many waterborne and indoor microorganisms. Aims. This study therefore aims to sample the flush water or fluid from selective emergency eyewash and shower stations in industries, senior high school and colleges and assess the microbial contamination and other water quality indicators. Methods. Heterotrophic bacteria, free chlorine, water temperature, pH, conductivity, turbidity, and suspended solids will be measured in all water/fluid samples. A checklist will used to evaluate the characteristics of stations such as type of stations, way and frequency of maintenance, age and other functional indicators comply with guidance of emergency eyewash and shower stations in Taiwan. Results. Our study established the checklist for the performance and maintenance of emergency eyewash and shower stations for field survey and conducted 48 stations from industrial and universities. One hundred and eighty-two water samples were collected for the analysis of various water quality indicators. The results showed that 94 % flushing water with insufficient free residual chlorine, 25 % flushing water with higher turbidity and 60 % flushing water with heterotrophic bacteria higher than drinking water standard. Among the characteristics of facilities and water indicators, the insufficient free residual chlorine in flushing water have been found to be the key factor in heterotrophic bacteria contamination with statistical signigicance in logistic regression model. Conclusions. Emergency eyewash and shower stations were usually unused for months and the water quality will deteriorate. People might expose to bad quality water in the emergent need and increase the potential risk of waterborne infection. Guidance of maintenance including flushing frequencies and decontamination system should be recommended in the near future in Taiwan.

Microbiomes of built environments: 2011 symposium highlights and workgroup recommendations

The air we breathe inside buildings dominates overall inhalation exposure to most air pollutants, whether of indoor or outdoor origin. The same is true for our exposure to microorganisms. Over the past three decades much has been learned about chemicals (in gas and particle phases) in building air, including typical levels, sources, fate, and control. Far less has been learned about the types, sources, and fate of microorganisms in buildings, and about how building design, and operation and maintenance affect microorganisms in buildings. Knowledge creation has been constrained by historical reliance on culture-based methods that can yield only partial or biased assessments of microbial community structure, sometimes dramatically underestimating uncultivable organisms, and failing to detect fragments of organisms that may themselves influence human health. However, in the past several years, advances in culture-independent analytical methods have significantly increased knowledge related to microbial communities and diversity in buildings. We are positioned to make even stronger gains in the coming years.

Workplace exposure to bioaerosols in pet shops, pet clinics, and flower gardens

The present study evaluated exposure to bioaerosols at three different types of facilities (pet shops, pet clinics, and flower gardens) by measuring the bacterial, fungal and/or PM 10 concentrations in indoor and outdoor air. Regardless of the season, the total bacteria and total fungi were detected for all samples, whereas the fungal genera were not. The bioaerosol concentrations measured in the flower gardens were significantly higher than those of the pet shops and pet clinics. The mean microbial concentrations at the three types of facilities were close to or exceeded the Korean indoor bioaerosol guidelines (800 CFU m −3), thus suggesting the need for remedial action regarding indoor microorganisms, in order to reduce the exposure at the surveyed facilities. Another suggestion was that contrary to the airborne microbes, flower gardens are not an important microenvironment for PM 10 (particulate matter ⩽10 μm in aerodynamic diameter) exposure. Two temporal characteristics (seasonal variation and the summer survey period) were important regarding exposure to airborne microbes, depending upon the type of facility surveyed, microbial or sample types, whereas the sampling time of the day was not. The microbial concentration ratio of indoor air to outdoor air depended upon the facility and season.

Bactericidal effects of plasma-generated cluster ions

Air purification by plasma-generated cluster ions (PCIs) relies on a novel technology producing hydrated positive and negative ions. Phenomenological tests have shown strong evidence of lethal effects of the PCIs on various micro-organisms. However, the mechanisms of PCI action are still widely unknown. The aim was thus to test the bactericidal efficacy of PCI technology on common indoor micro-organisms and to explore possible PCI mechanisms of action. According to time/dose-dependent experiments with Staphylococcus, Enterococcus, Micrococcus and Bacillus, the inhibiting effects became apparent within the first few minutes of PCI exposure and led to an irreversible 99.9% destruction within the following 2-8 h of exposure. The destructive effect of the PCIs corresponded to membrane damage of the bacteria. Use of the techniques of both SDS PAGE and 2D PAGE revealed changes in the bacterial surface protein composition induced by the PCIs. In contrast, neither DNA nor cytoplasm protein damage was detected electrophoretically. The antimicrobial action of the PCIs seems to occur because of chemical modification of the surface proteins of bacteria. In situ hydroxyl radical formation on the surface of bacteria was proposed as the leading mechanism of the protein damage caused by the PCIs. At the same time, DNA damage seems not to be involved in the antibacterial action of the PCIs. The data obtained would broaden the knowledge concerning the antibacterial effects of air-born plasma-generated cluster ions and help to produce more efficient air-cleaning devices.

Indoor and outdoor bioaerosol levels at recreation facilities, elementary schools, and homes

One major deficiency in linking environmental exposure to health effects is the current lack of data on environmental exposure. Therefore, to address this issue, the present study measured the bacterial and fungal concentrations in the indoor and outdoor air from two types of recreation facility (42 bars and 41 Internet cafes), 44 classrooms at 11 elementary schools, and 20 homes under uncontrolled environmental conditions during both summer and winter. No major environmental problems were reported at the four microenvironments being investigated during the entire study period. Bacteria and fungi were found in all the air samples, and the environmental occurrence of individual fungi was in the order of Cladosprium, Penicillium, Aspergillus, and Alternaria. The six parameters surveyed in the present study were all found to influence the indoor and outdoor bioaerosol levels: microenvironment type, sampling time in elementary school classrooms, agar type for measuring the fungal species, seasonal variation, facility location, and summer survey periods. The indoor and outdoor air concentrations of bacteria and fungi found in this study were comparable to those in other reports, with GM values for the total bacteria and total fungi between 10 and 10 3 colony-forming units per cubic meter of air (CFU m −3). The fungal concentrations found at most of the indoor environments fell within the specified guidelines of the American Conference of Government Industrial Hygienists (ACGIH), between 100 and 1000 CFU m −3 for the total fungi. However, the indoor bioaerosol concentrations at most of the surveyed environments exceeded the Korean indoor bioaerosol guideline (800 CFU m −3). Consequently, the current findings suggest the need for reducing strategy for indoor microorganisms at the surveyed microenvironments.

Assessment of an Ultraviolet Air Sterilizer on the Incidence of Childhood Upper Respiratory Tract Infections and Day Care Centre Indoor Air Quality

A double-blind trial was conducted to evaluate the effect of an ultraviolet air sterilizer in reducing the incidence of upper respiratory infections in children and the concentration of micro-organisms in 3 day-care centres located in Montreal. A population of 122 children (12-36 months of age) was under daily surveillance for respiratory illness during an average period of 12 weeks. Four ultraviolet and four control units were placed in the children's rooms. Indoor parameters were measured in four rooms, before and after installation of the devices. Even when a reduction in concentration of indoor micro-organisms was observed, the effect of the devices on the respiratory illness was negligible. The results suggest that the other routes of infection transmission are predom inant in the day-care centre.