Microbiological air analysis in dental surgeries: A comparison between two methods

The microbiological quality of indoor air is creating an increasing interest especially as far as places at risk such as hospitals, clinics, medical and odontological surgeries are concerned. Working with the odontologists of our province we have been carrying out a research aimed at preventing cross-infection in odontology. Data obtained from the microbiological analysis of the air in 36 surgeries using S.A.S were discussed during the V National Congress of Aerobiology. During that congress the need of setting a standardized technique of air sampling in indoor environments emerged and two routes have been identified: (1) the gravimetric technique on open plate exposed for an hour close to the dental unit and (2) the use of the volumetric sampler which gives qualitative data expressed as colonies forming units per cubic metre of air. However, both of these techniques present some problems: using the first a loss of micro-organisms has been noticed due to the variability of the air fluxes and the different weight of the biological particles; using the second one the bacterial charge is also undervalued, because of the stress suffered by the bacteria with the use of the volumetric sampler. In the light of these statements we decided to use both in dental surgeries to be able to compare the results obtained. Our project is expected to carry out at least one inspection and the relative sampling (indoor air, water of the dental unit, air of the syringe, disinfectant solution, surface tampons, biological test of sterility) in each dental surgery in the territory of our health Unit, located in Ferrara, Northern Italy.     

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins in the indoor environment

The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m3 of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.     

Airborne bacteria, fungi, and endotoxin levels in residential microenvironments: a case study

Limited data are currently available on the concentrations of airborne bacteria, fungi, and endotoxins in indoor environments. The levels of aerial bacteria and fungi were measured at several microenvironments within a well-ventilated residential apartment in Singapore including the living room, kitchen, bedroom, toilet, and at a workplace environment by sampling indoor air onto culture medium plates using the 6-stage Andersen sampler. Total microbial counts were determined by collecting the air samples in water with the Andersen sampler, staining the resultant extracts with a fluorescent dye, acridine orange, and counting the microbes using a fluorescent microscope. The levels of airborne endotoxins were also determined by sampling the airborne microorganisms onto 0.4?μm polycarbonate membrane filter using the MiniVol sampler at 5?l/min for 20?h with a PM_2.5 cut-off device. The aerial bacterial and fungal concentrations were found to be in the ranges of 117–2,873?CFU/m³ and 160–1,897?CFU/m³, respectively. The total microbial levels ranged from 49,000 to 218,000?microbes/m³. The predominant fungi occurring in the apartment were Aspergillus and Penicillium while the predominant bacterial strains appeared to be Staphylococcus and Micrococcus. The average indoor endotoxin level was detectable in the range of 6–39?EU/m³. The amount of ventilation and the types of human activities carried out in the indoor environment appeared to be important factors affecting the level of these airborne biological contaminants.     

Quantitative analysis of bacterial aerosols in two different dental clinic environments.

Microbial aerosols are generated during dental treatments and may represent an important source of infection. This study was designed to quantify bacterial air contamination during dental treatments in both a closed dental operatory and a multichair dental clinic. Air was sampled by using a slit type of biological air sampler. Following air sampling, blood-supplemented Trypticase soy agar plates were incubated at 37 degrees C under anaerobic conditions for 7 days. The maximum levels of air contamination in the closed dental operatory were observed while dental treatments were being performed (four trials; 216 +/- 75 CFU/m3 for ultrasonic scaling treatments and 75 +/- 22 CFU/m3 for operative treatments). At 2 h after completion of the treatments, the bacterial counts were about the same as the pretreatment levels (12 to 14 CFU/m3). In the second part of the study, a multichair dental clinic was divided into four areas, and air contamination was monitored at each site. Three sites were located in active dental treatment areas, whereas no dental treatments were performed within an 11-m radius of the fourth site. At 3 h after the beginning of dental treatments, the highest bacterial counts were obtained in the three active dental treatment areas (76 to 114 CFU/m3). However, there was noticeable contamination in the inactive dental treatment area (42 CFU/m3). Thus, bacterial aerosols were able to spread into areas where there was no dental activity. My data show that dental treatments significantly increased the levels of bacterial air contamination in both a closed dental operatory and a multichair dental clinic.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enumeration of airborne molds in some indoor environments of Madras city (India) by cultural and non-cultural volumetric samplers

The air mycoflora of six indoor environments in Madras city (India) has been investigated by sampling air with an Andersen sampler and a Burkard personal sampler. Forty-eight species assignable to 24 genera were recorded by Andersen sampler. Spores belonging to 14 genera in addition toPenicillium andAspergillus were identified from Burkard trap slides. Species ofAspergillus, Penicillium, Mucor andRhizopus were most frequently isolated in considerable numbers. As a single genusAspergillus ranked first followed byPenicillium at some sites, andCladosporium at some other sites. The predominance ofPenicillium andAspergillus was also confirmed by Burkard trap data. Spores belonging toGanoderma, Nigrospora, Epicoccum, andTetraploa were recorded only by Burkard sampler, thereby suggesting the necessity of using two complimentary spore traps, cultural and non-cultural, in any aerobiological investigation.     

Determination of the collection efficiency of a microbial air sampler

The Biotest RCS Plus air sampler was compared with the well-established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub-micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre-select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro-organisms in a variety of locations.     

Immunoblotting of mite aeroallergens collected with an indoor Burkard air sampler

We examined the kinetics of airborne levels of mite allergen particles in a house by combined use of an indoor Burkard air sampler and immunoblotting. Airborne mite allergens collected on the Burkard sampling tape were transferred onto a nitrocellulose membrane, reacted with mouse monoclonal anti-mite allergen (Der pI) antibody, then treated with alkaline phosphatase conjugated anti-mouse IgG. Finally, the blotted allergen on the membrane was reacted with BCIP/NBT phosphatase, and purple spots visible by the naked eye were produced. The shape of the spots was observed under a microscope, and the spot area was measured by an image processor. This technique might be useful for analyzing the behavior of airborne allergen particles in indoor environments.     

Detection and identification of moulds in dutch houses and non-industrial working environments

The mycoflora of indoor non-industrial environments is reported from “case” studies in The Netherlands. Both air sampling by a RCS-Reutcr centrifugal air sampler and surface sampling by swabs and cellotape preparations were carried out in homes, archives and libraries, musea, offices and schools. Common species encountered in these indoor environments are Aspergillus versicolor, Penicillium brevicompactum, P. chrysogenum, Cladosporium spp. and the xerophilic fungi Eurotium spp. and Wallemia sebi. Aspergillus fumigatus, Scopulariopsis spp. and Stachybotrys chartarum were occasionally isolated. It is not always possible to detect the mycoflora growing on surfaces by air sampling. Therefore direct microscopical examination and sampling from surfaces in addition to air sampling is strongly recommended for the detection of viable moulds in indoor environments. Selection of the most suitable media for isolation of fungi is discussed.     

Detection of Airborne Stachybotrys chartarum Macrocyclic Trichothecene Mycotoxins in the Indoor Environment

The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m³ of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.     

Fast Monitoring of Indoor Bioaerosol Concentrations with ATP Bioluminescence Assay Using an Electrostatic Rod-Type Sampler

A culture-based colony counting method is the most widely used analytical technique for monitoring bioaerosols in both indoor and outdoor environments. However, this method requires several days for colony formation. In this study, our goal was fast monitoring (Sampling: 3 min, Detection: < 1 min) of indoor bioaerosol concentrations with ATP bioluminescence assay using a bioaerosol sampler. For this purpose, a novel hand-held electrostatic rod-type sampler (110 mm wide, 115 mm long, and 200 mm tall) was developed and used with a commercial luminometer, which employs the Adenosine triphosphate (ATP) bioluminescence method. The sampler consisted of a wire-rod type charger and a cylindrical collector, and was operated with an applied voltage of 4.5 kV and a sampling flow rate of 150.7 lpm. Its performance was tested using Staphylococcus epidermidis which was aerosolized with an atomizer. Bioaerosol concentrations were measured using ATP bioluminescence method with our sampler and compared with the culture-based method using Andersen cascade impactor under controlled laboratory conditions. Indoor bioaerosol concentrations were also measured using both methods in various indoor environments. A linear correlation was obtained between both methods in lab-tests and field-tests. Our proposed sampler with ATP bioluminescence method may be effective for fast monitoring of indoor bioaerosol concentrations.     

A preliminary survey of cycloheximide-resistant airborne fungi in Turin,Italy

Numbers and type of the cycloheximide-resistant part of the aerially transmitted mycoflora of Turin were studied. Samples from three areas characterized by differing human usage were taken in the first week of March. During each sampling, 12 m³ of air were aspirated, using an one-stage volumetric sieve sampler. Fifty-two mesophilic species and eight thermotolerant were isolated. Propagule load varied from 2.92 to 120.31 cfu m^–3. The following species appear not to have been reported previously from air samples:Ascotricha bosei, Blastobotrys navarrensis, Cryptendoxyla hypophloia, Chrysosporium an.gymnoascus demonbreunii, Ophiostoma piceae, Penicillium vulpinum, Phialophora mustea, Rhinocladiella pedrosoi, Scopulariopsis croci, S. komngii andSesquiallium candelabrum. A significant number of potential opportunistic pathogens was isolated.Abbreviations CH Cycloheximide - RH relative humidity     

A report on Penicillium in the intramural and extramural air of residential areas of Nagpur city (India)

Prevalence of different species of Penicillium and their concentrations per cubic meter of air were evaluated with the use of Hi-Air sampler system Mark II (Hi-Media Laboratories Ltd., India) in the air of homes (bed-rooms) at four different sites in Nagpur. At each of these sites, air sampling was done fortnightly in triplicate for 2 years duration from June 2000 to May 2002. The sampling was also done in triplicate for the outdoor air in the vicinity of each home on the same day immediately after the indoor sampling was over. The mean concentration of Penicillium colony forming units at four different sites in the indoor air was 32, 46.9, 35 and 35.4 CFU/m³, respectively, whereas in the outdoor air at these same four sites, the mean concentration was 24, 28, 25 and 25.8 CFU/m³ respectively. The Penicillium concentration in the indoor air was found to be higher in winter than in other seasons (ANOVA, p < 0.05). Concentration of Penicillium spp. in intramural environment was always higher than that in extramural environment. Statistically significant difference existed between intramural and extramural environments at all the sites, with maximum difference at a site, which is old crowded area of the city. During the 2-years investigations, 11 species of Penicillium were isolated from the indoor air while nine species were isolated from the air outside the homes. The dominant species of Penicillium in indoor as well as outdoor air were P. citrinum (33.78 and 32.81), P. oxalicum (19.70 and 22.60), and P. chrysogenum (17.64 and 14.50). The percentage of the Penicillium in the indoor air was 10.70 while it was 8.36 in outdoor air. Indoor air showed the presence of P. glaber and P. sclerotiorum, which were absent in the outdoor air.     

Using a bioaerosol personal sampler in combination with real-time PCR analysis for rapid detection of airborne viruses

We have recently developed a new personal sampler and demonstrated its feasibility for detection of viable airborne microorganisms including bacteria, fungi and viruses. To accelerate the time-consuming analytical procedure involving 2-5 days of biological testing, we employed a real-time PCR protocol in conjunction with the personal sampler for collection of airborne viruses. The advantage of this approach is that if the presence of a particular pathogen in the air is detected by the PCR, the remaining collecting liquid can be further analysed by more time-consuming biological methods to estimate the number of airborne infectious/live microorganisms. As sampling of bioaerosols in natural environments is likely to be associated with substantial contamination by a range of microorganisms commonly existing in an ambient air, an investigation of the specificity of detection by targeted PCR analysis is required. Here we present the results of the study on the detection of Influenza virus in the ambient air contaminated with high concentrations of bacteria and fungi using real-time PCR protocol. The combined sampling PCR detection method was found to be fully feasible for the rapid ( approximately 2.5 h) and highly specific (no cross-reactivity) identification of the labile airborne virus in the air containing elevated concentrations of other microorganisms.     

Monitoring airborne fungal spores in an experimental indoor environment to evaluate sampling methods and the effects of human activity on air sampling.

Aerobiological monitoring was conducted in an experimental room to aid in the development of standardized sampling protocols for airborne microorganisms in the indoor environment. The objectives of this research were to evaluate the relative efficiencies of selected sampling methods for the retrieval of airborne fungal spores and to determine the effect of human activity on air sampling. Dry aerosols containing known concentrations of Penicillium chrysogenum spores were generated, and air samples were taken by using Andersen six-stage, Surface Air System, Burkard, and depositional samplers. The Andersen and Burkard samplers retrieved the highest numbers of spores compared with the measurement standard, an aerodynamic particle sizer located inside the room. Data from paired samplers demonstrated that the Andersen sampler had the highest levels of sensitivity and repeatability. With a carpet as the source of P. chrysogenum spores, the effects of human activity (walking or vacuuming near the sampling site) on air sampling were also examined. Air samples were taken under undisturbed conditions and after human activity in the room. Human activity resulted in retrieval of significantly higher concentrations of airborne spores. Surface sampling of the carpet revealed moderate to heavy contamination despite relatively low airborne counts. Therefore, in certain situations, air sampling without concomitant surface sampling may not adequately reflect the level of microbial contamination in indoor environments.     

A report on <Emphasis Type="Italic">Penicillium</Emphasis> in the intramural and extramural air of residential areas of Nagpur city (India)

Prevalence of different species of Penicillium and their concentrations per cubic meter of air were evaluated with the use of Hi-Air sampler system Mark II (Hi-Media Laboratories Ltd., India) in the air of homes (bed-rooms) at four different sites in Nagpur. At each of these sites, air sampling was done fortnightly in triplicate for 2 years duration from June 2000 to May 2002. The sampling was also done in triplicate for the outdoor air in the vicinity of each home on the same day immediately after the indoor sampling was over. The mean concentration of Penicillium colony forming units at four different sites in the indoor air was 32, 46.9, 35 and 35.4 CFU/m³, respectively, whereas in the outdoor air at these same four sites, the mean concentration was 24, 28, 25 and 25.8 CFU/m³ respectively. The Penicillium concentration in the indoor air was found to be higher in winter than in other seasons (ANOVA, p < 0.05). Concentration of Penicillium spp. in intramural environment was always higher than that in extramural environment. Statistically significant difference existed between intramural and extramural environments at all the sites, with maximum difference at a site, which is old crowded area of the city. During the 2-years investigations, 11 species of Penicillium were isolated from the indoor air while nine species were isolated from the air outside the homes. The dominant species of Penicillium in indoor as well as outdoor air were P. citrinum (33.78 and 32.81), P. oxalicum (19.70 and 22.60), and P. chrysogenum (17.64 and 14.50). The percentage of the Penicillium in the indoor air was 10.70 while it was 8.36 in outdoor air. Indoor air showed the presence of P. glaber and P. sclerotiorum, which were absent in the outdoor air.     

A Monitor for Airborne Bacteria

A unique agar drum sampler is described which indicates, continuously, the number of viable, bacterial particles per unit volume of air at the time and point of sampling. By selection of the timer and the sampling rate the sampler is suitable for quite a wide range of concentration and time. An impaction line of 484 in. greatly increases the capacity of this device over slit samplers and other instruments designed to give time-concentration data for viable airborne particles. This sampler should prove useful for: (i) monitoring airborne bacteria in hospitals, public places, and food and industrial plants; (ii) decay rate studies of bacterial aerosols; (iii) evaluation of aerial germicides; (iv) determination of effectiveness of air conditioning systems in removing airborne bacteria; and (v) many other studies in aerobiology.     

An automated, pressure-driven sampling device for harvesting from liquid cultures for genomic and biochemical analyses

Here we describe an automated, pressure-driven, sampling device for harvesting 10 to 30 ml samples, in replicate, with intervals as short as 10 s. Correlation between biological replicate time courses measured by microarrays was extremely high. The sampler enables sampling at intervals within the range of many important biological processes.     

An in-situ mobile interstitial water and sediment sampler (MISS)

An inexpensive, easily constructed sampler for collecting interstitial water and sediment, seperately or combined is presented. The instrument has been developed for use in wetlands and shallow water as a tool for taxonomical and ecological investigations. Different to other samplers, our sampling depth is down to more than one meter at defined depths. Sampling showed highly reproducable sampling results for both, hydrophysical-chemical and biological analysis, which will be shown in the article.