Microbiological Air Research Articles

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators

The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m³ and 54.6 CFU/m³, respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.

Microbiological Environmental Monitoring After the Use of Air Purifier Ozone Generator

The work aimed to evaluate the indoor microbiological air quality after using the purifier ozone generator (Brizzamar®), by counting the total viable microorganisms. The plates containing the culture media were exposed on pre-defined locations for 10 min at the times 0 h (without purifier), 1, 2 and 3 h (with purifier). The results showed significant decreases in the microorganisms after using the purifier, reaching a reduction up to 80% of the fungi and bacteria in the environment after two hours. The amount of ozone in the atmosphere was kept at 0,01 ppm, which is considered non-toxic to human exposure. The purifier significantly improved the air quality in indoors.

Particle counting and microbiological air sampling: Results of the simultaneous use of both procedures in different types of hospital rooms

IntroductionIn order to assess the relationship between the concentrations of airborne fungi and particles, particle counting was combined with fungal air sampling in several rooms of a hospital. MethodsConcentrations of ≥0.5μm particles (P05) and ≥1μm particles (P1) were measured using a particle counter; fungal air sampling was performed with volumetric air samplers, which impacted air on Rodac plates with Sabouraud chloramphenicol agar. Particle counts were categorised according to ISO 14644-1 standard cut-off points; their association with fungal detection was assessed with Fisher's exact test. ResultsForty-two simultaneous samplings were carried out: 24 in operating rooms, 13 in rooms for burns or haematology patients, 3 in pharmacy clean rooms, and two in other procedure rooms. Filamentous fungi were recovered in 5 samples, which also had higher particle counts. No fungi were detected in 12 samplings with both P05 and P1 concentrations below the maximum for class 6 clean rooms; 4 of 7 samplings with both concentrations within the range for class 8 clean rooms were positive for fungi. The association between fungal detection and higher particle counts was statistically significant, both for P05 (p=.004) and P1 (p=.003). There was a partial overlap between the concentrations of particles of samplings which were positive or negative for fungi. ConclusionsThere is a relationship between the concentrations of P05 and P1 and airborne fungi in hospital rooms. When both P05 and P1 concentrations are below the maximum for class 6 clean rooms, a negative fungal detection can be predicted.

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators.

The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m3 and 54.6 CFU/m3, respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.

Microbial Air Contamination on the Marketplaces in Krakow

Microbiological air research was conducted on five different marketplaces in Krakow and on the Blonia meadows in different seasons. The air was sampled by using the collision method with a microbiological air-sampler MAS-100 (Merck). Abundance of bacteria ranged from 42 to 2300 CFU/m. Fungi were seldom present and ranged from 30 to 3460 CFU/m. Actinomycetes were most uncommon and their quantities ranged from 0 to 140 CFU/m, but quantities that ranged over 100 CFU/m also caused heavy atmospheric air pollution. Research proved a tight correlation between microorganisms’ occurrence and seasons. During summer bacteria appeared in larger numbers whereas fungi and actinomycetes had larger quantities during springtime.

Microbiological air quality in tie-stall dairy barns and some factors that influence it

The aim of this study was to assess the microbiological quality of the air in tie-stall dairy cattle barns and to investigate some factors that influence it. We evaluated 52 dairy cattle barns with tie-stalls, during two years, in the winter period. The number of bacteria and fungi was slightly higher in the evening in comparison to the one in the morning and significantly higher in large barns (P<0.01), with bedding (P<0.01) and dirty (P<0.05). Both in the morning and in the evening positive correlations were observed between temperature and airborne bacteria, relative humidity and fungi. The prevalent species of bacteria were Staphylococcus epidermidis, Staphylococcus xilosus, Aerococcus viridans, Enterococcus faecalis, Enterobacter agglomerans andEscherichia coli. Among fungi, Aspergillus, Penicillium and yeasts predominated. This study’s results showed that the number of bacteria and fungi is variable and high in many cases in the indoors air of dairy cattle tie-stall barns, with the predominance of gram positive bacteria. Many of the identified bacterial and fungal species have pathogenic potential, posing risks for the health of animals and humans. Based on the obtained results, we consider the improvement of barn hygiene to be the most practical recommendation for decreasing concentrations of bacteria. Key words: Airborne bacteria, airborne fungi, indoor air quality, barn hygiene.

Evaluation of microbiological air quality and of microclimate in university classrooms

The proliferation of air-diffused microorganisms inside public buildings such as schools, hospitals, and universities, is often indicated as a possible health risk. In this research, we have illustrated the results of an investigation realized to determine the health of the air in some university classrooms, both from a microbiological and a microclimatic viewpoint, during the normal didactic activity of direct lessons. The results obtained have been expressed by means of contamination indices, already used in previous works. Very little contamination was recorded in the different phases of air treatment, which underlines the efficiency of the system and of the maintenance protocols. The Global Index of Microbial Contamination (GIMC per cubic meter) showed a value greater than the mean during the heating period (290), while the highest values (95th percentile 1,138.45) were recorded in the period using air conditioning. The index of mesophilic bacterial contamination, though it did not show any significant differences in the various modes of air treatment, showed a mean value (1.34) and the 95th percentile value (4.14), which was greater in the air-conditioning phase. Finally, the mean value of the amplification index underlined a decrease in the microbial contamination in comparison to the outside, while showing situations of increased microbial amplification during the period of simple ventilation (95th percentile 4.27). The 95th percentile values found for GICM in the three sampling periods, however, permitted us to identify the value of GIMC per cubic meter equal to 1,000 as a guide to provide a means of self-monitoring the quality of the air inside the classrooms. From a microclimatic viewpoint, two periods of the year manifested discomfort situations: during the heating phase (winter) and during the simple ventilation phase (spring). The results obtained indicate, therefore, a need to intervene on the environmental parameters, not being able, in this particular case, to intervene on other aspects that influence the microclimate.

Differences in the correlation between microbiological air sampling and particle counting in operating theatres and hospital cleanrooms

The process of environmental monitoring in cleanrooms of clinical pharmacy and operating theatres is difficult, the measurement of bio burden is time consuming and the result is available several days after the operation. This study examines the correlation between the number of airborne bacteria and particles in operating theatres and cytostatic compounding cleanrooms in order to evaluate if applying solely particle monitoring is sufficient for hygienic-microbiological risk assessment.

Incorporation of microbiological and molecular methods in HACCP monitoring scheme of molds and yeasts in a Greek dairy plant: A case study

Yogurt and yogurt based products are widely consumed globally within European countries. The main microbiological spoilage problems occur from acid tolerant yeasts and molds. The prevention and /or reduction of such contamination is a major objective of HACCP. One of the prerequisite control points is the microbiological air quality of the facility. A one year prospective study of fungal air contamination was conducted in one outdoor and two indoor areas, in a Greek dairy plant. Air was sampled with a portable air system impactor and identified mainly through classical microbiological methods and molecular typing techniques. During the period of survey, the mean viable fungal load was 362.3 CFU/m3 in outdoor air samples and 69.8 CFU/m3 and 266.2 CFU/m3 in samples from the two indoor locations. The three dominant fungal genus recovered were Cladosporium spp., Penicillium spp. and yeasts. Seasonal variations observed in all locations were examined and corrective actions were applied to reduce the fungal load, in one of the interior areas. HEPA air filters were installed and a twenty time reduction (from 69.8 to 3.5 CFU/m3) was achieved concerning the total fungal load. Implementation of a constant monitoring of the air quality and the recognition, as a critical control point (CCP) led to lower fungal air load, furthermore enhancing the microbiological quality and safety of the products.

Analysis of children and #8217;s rooms in terms of microbiological air quality

Objective: The aim of this study was to determine the total count of organisms in air specimens of children’s rooms and to investigate the factors thought to be effective on the microbiological quality of the air in children’s rooms. Method: The research was carried out in households containing children under the age of 10. Air samples, including morning and afternoon, were taken twice a day, 100 litres of air were filtered and microbiological seeding performed directly onto slides containing general-purpose medium. Results: In measurements, the total count of organisms from the morning samples were lower compared to the samples which were taken in the afternoon (64.9±65.4 and 41.4±63.7 CFU respectively for every 100 liters). As a result of adequate ventilation, afternoon data showed significant declines (from 57.5±62.0 to 23.0±26.8 CFU per 100 l). The attributable effectiveness to ventilation was 27.7% and the effectiveness ratio was 34.0%. Conclusion: This study has shown that adequate ventilation is an effective method in reducing microorganisms in indoor environments. With one hour of ventilation in every six-hour period, microbiological air quality in the rooms can be improved by approximately one-third.

P11.22 Time trend of Legionella colonization in the waterline of a hospital of Rome, Italy

P11.22 Time trend of Legionella colonization in the waterline of a hospital of Rome, Italy

P11.08 The effect of a mobile air purification unit on the air quality of a room contaminated with Aspergillus sp.

P11.08 The effect of a mobile air purification unit on the air quality of a room contaminated with Aspergillus sp.

P11.09 Water microfiltration at the point of use – a procedure to prevent infection/colonization with water borne pathogens in ICU patients?

P11.09 Water microfiltration at the point of use – a procedure to prevent infection/colonization with water borne pathogens in ICU patients?

Evaluation of bioaerosol sampling techniques for Legionella pneumophila coupled with culture assay and quantitative PCR

Efficient bioaerosol sampling methods are required for characterization of exposure risk to airborne pathogenic Legionella pneumophila, which may cause severe pneumonia and death in humans. By using culture assay and quantitative PCR, the effects of sampler type, sampling time (1–60 min), collection fluid (deionized water (DW) and Tween mixture), and DW replenishment during sampling on the recovery of culturable and total L. pneumophila were assessed. Escherichia coli was also tested as a comparison. The collection efficiency was consistently greater for culturable L. pneumophila than E. coli by a factor of 2.7–12.2 ( P=0.005). Besides, total and culturable bioaerosols were both recovered less in microbiological air sampler (MAS-100) by 1–2 orders of magnitude than in Andersen one-stage sampler (Andersen 1-STG), all-glass impinger (AGI-30), and BioSampler regardless of sampling time, bacterial species ( L. pneumophila and E. coli), and collection principle (agar impaction and liquid impingement) ( P<0.05). BioSampler was more efficient than AGI-30 to capture total L. pneumophila ( P=0.003), whereas a comparable bioefficiency was found for culturable cells ( P=0.74). DW obtained more culturable L. pneumophila than Tween mixture by a factor of 4.1–12.5 in BioSampler and 2.2–6.8 in AGI-30 during 3–60 min sampling ( P<0.0001). Increasing sampling time deteriorated the accuracy of L. pneumophila quantification, particularly for culturable cells ( P<0.0001). However, DW replenishment every 15 min during sampling significantly improved the recovery of culturable L. pneumophila in both AGI-30 and BioSampler by a factor of 3.3 and 7.1, respectively ( P=0.001). Considering a longer sampling is preferred to quantifying airborne L. pneumophila usually at a low level of concentration, this study recommends to collecting this pathogen by BioSampler with periodical refilling of DW.

Microbiological air quality in an urban solid waste selection plant

Background: Exposure to bioaerosols may pose health risks to workers operating in the processing of UrbanSolid Waste (USW). The aim of this study is to evaluate microbiological air quality within an USW selectionfacility.Methods: Nine sampling points in an USW selection plant situated in central-southern Italy were selected.One outdoor sampling point provided the background data. Sampling was performed on a yearly basis (2005– 2009) upon request by the management of the selection plant. Total Mesophilic Counts (TMC), as well asfungal and Gram-negative concentrations were determined.Results: The highest viable fungal particles concentrations (medians) were found in waste delivery areas(about 20000 CFU/m3), while the lowest were found in the control rooms (485 – 967 CFU/m3). TMC (median)was highest (6116 CFU/m3) at the delivery pit, followed by the machine shop (3147 CFU/m3), where no wasteprocessing takes place. Medians of Gram-negative bacteria are below the suggested Occupational ExposureLimit of 1000 CFU/m3, although this limit was exceeded at several single time-points in the waste deliveryareas, and also in a personnel resting room. The lowest Gram-negative contamination was found in the controlrooms (medians &lt;1 CFU/m3).Conclusions: Some areas within a USW selection plant act as internal sources of contamination towards thoseareas where partially processed waste, or no waste at all, is present. Well-designed air flows, or carefully-thought positioning of areas that are not directly involved in waste processing are necessary and effective inobtaining satisfactory microbiological air quality, provided that personal protection practices are strictlyenforced.

Characterization of microbial community during Asian dust events in Korea

An Asian dust event, also sometimes known as a Yellow Sand event, is a seasonal meteorological phenomenon affecting East Asia, typically in the early spring. Because of the significant ecological and health effects of these events on East Asia, and the large amount of dust that is transported from the desert in China to Korea and Japan, these events have been receiving increased attention. It is likely that these storms often provide long-range transport to various microorganisms. However, despite a certain level of attention to the chemical analysis of these storms, microbiological studies of Yellow Sand dust have been scarce. We collected a total of 30 microbiological air samples using a PM 2.5 cyclone sampler in Seoul, Korea from April 2007 to March 2008. Six of these samples were collected during Yellow Sand events, while 24 were from non-Yellow Sand events. Chemical analysis was performed on the samples using a thermal–optical transmittance (TOT) method. Total nucleic acids were also extracted, and the 16S rDNA was amplified by PCR and analyzed by denaturing gradient gel electrophoresis (DGGE). Dendrogram analysis, based on DGGE, indicated that the microbial profiles from the Yellow Sand were distinctive from those of the non-Yellow Sand samples. Microorganisms identified in Yellow Sand samples included Aquabacterium sp., Flavobacteriales bacterium sp., Prevotellaceae bacterium sp., and others, whereas microorganisms in non-Yellow Sand samples included Propionibacterium sp., Bacillus sp., Acinetobacter sp., and others . These results suggest that, as a result of Yellow Sand events, humans in the affected regions are exposed to communities of microorganisms that might cause various adverse health effects.

A Study of Air Microbe Levels in Different Areas of a Hospital

Airborne transmission is an important route for many microbial pathogens in outdoor and indoor environments, including hospitals. A 2-year-long survey of bioaerosol quality in operating theatres (OT), hospital rooms (HR) and maternity wards (MW) at a hospital in Murcia, Spain, was performed. Total aerobic counts (TAC) and fungal load (FL) were assessed using a microbiological air sampler (MAS-100 single-stage impactor). While fungal levels were below 1 cfu/m(3) (0-7.33 cfu/m(3)) in OT, they were higher in MW (mean, 6.9 cfu/m(3); range 0.44-44.67 cfu/m(3)) and in HR (mean, 10.6 cfu/m(3); range, 0-266 cfu/m(3)). In OT the aerobic counts were considerably higher, with a mean of 25.6 cfu/m(3) (range, 1.67-157 cfu/m(3)). MW and HR also showed higher means for total aerobic counts compared to OT. Seasonal changes were not detected in mould and bacteria levels in OT. Hospital renovation occurred during this study and OT adjacent to renovated areas were closed. A survey of TAC and FL in OT resumed when renovation was completed. We observed an outstanding increase in FL (more than 100 cfu/m(3)), particularly Aspergillus spp., during this period, but no significant changes in TAC were observed after renovation.

Airborne enteric coliphages and bacteria in sewage treatment plants

The concentrations of airborne culturable microorganisms were determined in wastewater and sludge treatment processes of seven sewage treatment plants. Two types of coliphages, Salmonella and total viable bacteria were sampled by the BioSampler and the numbers of faecal coliforms and enterococci were obtained from the Andersen 6-stage impactor. The BioSampler recovered higher numbers of airborne coliphage viruses than has been measured with other liquid samplers in previous studies, suggesting that this sampler has improved efficiency for sampling airborne coliphages. Airborne coliphages were detected in many stages of the wastewater or sludge treatment process. The highest microbiological air contaminations were found in pre-treatment and aerated grit separation stages of the operation. This was attributed to aerosolisation of microorganisms by mechanical handling or forced aeration. Aeration and settling processes located outdoors caused low microbial concentrations, but the brush aerator released more microorganisms into the air. Our results emphasize the necessity for controlling the exposure of sewage workers to airborne microorganisms, especially in process areas that involve mechanical agitation or forced aeration of wastewater.

Risk factors for particulate and microbial contamination of air in operating theatres

This study was designed to standardize dust collection in recently built operating theatres equipped with a continuous monitoring system. The objectives were to establish the relationship between microbiological and dust contamination, and then to compare those parameters with the main indicators of surgical activity in order to better define risk factors affecting air quality. The air quality during 23 surgical operations was studied in three conventionally ventilated operating theatres. Microbiological air counts were taken using both passive and active sampling methods. Air dust particles, > or =0.5 and > or =5 microm in size, were measured using a light-scattering particle analyser. The overall dust load was mainly (98%) composed of fine particulate matter, most probably due to its longer suspension time before settlement. These particles positively correlated with operation length, but not with surgical technique, suggesting that fine particles may be a good tracer of operation complexity. In contrast, the surgical technique was the main predictor for the concentration of particles > or =5 microm, with a higher risk from general conventional surgery compared with scope surgery. The frequency of door-opening, taken as an index of staff and visitor movement, was the main negative predictor of over-threshold values of both fine and larger dust particles but, conversely, was a positive predictor of raised bacterial counts.

Analysis of Portable Impactor Performance for Enumeration of Viable Bioaerosols

Portable impactors are increasingly being used to estimate concentration of bioaerosols in residential and occupational environments; however, little data are available about their performance. This study investigated the overall performances of the SMA MicroPortable, BioCulture, Microflow, Microbiological Air Sampler (MAS-100), Millipore Air Tester, SAS Super 180, and RCS High Flow portable microbial samplers when collecting bacteria and fungi both indoors and outdoors. The performance of these samplers was compared with that of the BioStage impactor. The Button Aerosol Sampler equipped with gelatin filter was also included in the study. Results showed that the sampling environment can have a statistically significant effect on sampler performance, most likely due to the differences in airborne microorganism composition and/or their size distribution. Data analysis using analysis of variance showed that the relative performance of all samplers (except the RCS High Flow and MAS-100) was statistically different (lower) compared with the BioStage. The MAS-100 also had statistically higher performance compared with other portable samplers except the RCS High Flow. The Millipore Air Tester and the SMA had the lowest performances. The relative performance of the impactors was described using a multiple linear regression model (R 2 = 0.83); the effects of the samplers' cutoff sizes and jet-to-plate distances as predictor variables were statistically significant. The data presented in this study will help field professionals in selecting bioaerosol samplers. The developed empirical formula describing the overall performance of bioaerosol impactors can assist in sampler design.