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| Culturable Air Sampling |
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| Fungal Sampling Information |
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| Non Fungal Sampling Information |
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| Qualtest, Inc. 2458 Alton Parkway Irvine, CA 92606 Phone: (949) 838-0378 Contact Us |
Introduction
The purpose of this method is the identification of culturable (viable)
fungi and assessment of possible proliferation and dissemination of fungi
from building reservoirs. Air sampling for culturable fungi utilizes culture
media for the collection and analysis of viable fungal structures (spores
and hyphae). This method of air sampling involves drawing a measured
volume of air over culture media in petri dishes. The dishes are incubated
in the laboratory so the fungal structures impacted on the plate can grow
forming colonies. Fungal colonies are identified and enumerated to
determine the mixture of airborne fungi in an indoor environment. In
order for the fungus to grow , it must initiate from a viable spore or
hyphal fragment. Since it is impossible to determine if the colony grew
specifically from a spore or a hyphal fragment, it is reported as a colony
forming unit (CFU). Results of analysis includes identification of all fungi
present, quantification to CFUs/m3 and the % of each type of fungi.
This method commonly uses the Andersen N-6 Impactor (tm). The
sampler works by drawing measured volumes of air through the sampler.
Air is vacuumed through a sieve-like cover thereby forcing fungal
structures to adhere to the culture medium surface. Different culture
media are available from Qualtest free of charge. However, not all fungi
are able to grow on all culture media, so it is important to communicate
with one of our Mycologists who can recommend the most suitable media
for your project. Malt Extract Agar (MEA) is recommended as a general
isolating medium. Cornmeal Agar (CMA) or Cellulose Agar (CA) are
recommended to detect cellulolytic fungi such as Stachybotrys sp. and
Chaetomium sp. DG-18 medium is recommended to be used to recover
some xerophilic (dry tolerant) fungi such as certain Aspergillus sp.,
Eurotium sp., Penicillium sp., and Wallemia sp. After sampling, these petri
dishes are incubated for a period of time in the laboratory, typically 6-10
days, before being analyzed. If the aerosolized particles include viable
fungal spores or hyphal fragments, and the culture medium is suitable for
the particular fungi, then they will grow into colonies. If you utilize only
one type of media, you should realize that you are likely to underestimate
the total amount of culturable fungi in the air. It is recommended to
sample on several media in order to maximize the identification of all
possible culturable fungi.
Recommendations
Dusty, dirty, visible particles in the air 1 min.
Clean space (room/office) or outdoors with no visible dust 2-3 min.
Very Clean area 4-5 min.
Advantages
Disadvantages
Interpretation of culturable results
The purpose of this method is the identification of culturable (viable)
fungi and assessment of possible proliferation and dissemination of fungi
from building reservoirs. Air sampling for culturable fungi utilizes culture
media for the collection and analysis of viable fungal structures (spores
and hyphae). This method of air sampling involves drawing a measured
volume of air over culture media in petri dishes. The dishes are incubated
in the laboratory so the fungal structures impacted on the plate can grow
forming colonies. Fungal colonies are identified and enumerated to
determine the mixture of airborne fungi in an indoor environment. In
order for the fungus to grow , it must initiate from a viable spore or
hyphal fragment. Since it is impossible to determine if the colony grew
specifically from a spore or a hyphal fragment, it is reported as a colony
forming unit (CFU). Results of analysis includes identification of all fungi
present, quantification to CFUs/m3 and the % of each type of fungi.
This method commonly uses the Andersen N-6 Impactor (tm). The
sampler works by drawing measured volumes of air through the sampler.
Air is vacuumed through a sieve-like cover thereby forcing fungal
structures to adhere to the culture medium surface. Different culture
media are available from Qualtest free of charge. However, not all fungi
are able to grow on all culture media, so it is important to communicate
with one of our Mycologists who can recommend the most suitable media
for your project. Malt Extract Agar (MEA) is recommended as a general
isolating medium. Cornmeal Agar (CMA) or Cellulose Agar (CA) are
recommended to detect cellulolytic fungi such as Stachybotrys sp. and
Chaetomium sp. DG-18 medium is recommended to be used to recover
some xerophilic (dry tolerant) fungi such as certain Aspergillus sp.,
Eurotium sp., Penicillium sp., and Wallemia sp. After sampling, these petri
dishes are incubated for a period of time in the laboratory, typically 6-10
days, before being analyzed. If the aerosolized particles include viable
fungal spores or hyphal fragments, and the culture medium is suitable for
the particular fungi, then they will grow into colonies. If you utilize only
one type of media, you should realize that you are likely to underestimate
the total amount of culturable fungi in the air. It is recommended to
sample on several media in order to maximize the identification of all
possible culturable fungi.
Recommendations
- Recommended flow rate is 28.3 lpm.
- The sampling time is dependant on the density of the particulates
in the environment.
Dusty, dirty, visible particles in the air 1 min.
Clean space (room/office) or outdoors with no visible dust 2-3 min.
Very Clean area 4-5 min.
- Sampling location should include complaint areas, a non-complaint
area if available, and one or more outdoor samples for results
interpretation.
Advantages
- The primary advantage of the culturable sampling method is that
species identifications are possible. Species identification is crucial
with Penicillium sp. and Aspergillus sp. - This method of sampling is important for the recovery and
recognition of a wide variety of potentially toxigenic fungi such as
Paecilomyces, Fusarium, Trichoderma, Acremonium and Wallemia. - It is important for the detection of a wide variety of potentially
pathogenic fungi such a Microsporum gypseum, Penicillium marneffei,
Trichophyton mentagrophytes and Trichosporon cutaneum. - Fungal cultures can determine whether spores are viable (alive).
- Provides fungal identifications not possible with non-culturable air
sampling techniques such as "Aspergillus sp. and Penicillium sp."
group and "Dreschlera sp. and Bipolaris sp." group. - Culturable air sampling provides counts indicative of how many
fungal structures are viable and present in the air. This is important
especially for immunocompromised individuals who would be
more susceptible to the infections that viable spores may cause.
Disadvantages
- Culturing takes 6-10 days for the fungal structures to grow and be
analyzed. - Non-viable spores contain a large number of microorganisms
(including fungi) which have to compete with each other to grow
on the culture media. As a result, fungi present in the air may not
be well represented. - Some fungi are unable to be identified, as they fail to produce
spores, or have not yet been scientifically characterized. - Fungal structures require specific nutrients and environmental
conditions to grow under laboratory conditions. This means that
different types of culture media will support the growth of different
types of fungi. Therefore, some fungal spores will not grow on the
standard culture medium. For example, if you are testing for
Stachybotrys sp. or Chaetomium sp., specific culture media types
should be requested.
Interpretation of culturable results
- There are currently no guidelines or regulations to indicate safe
acceptable levels for fungi in an indoor environment. - The general guideline to follow is that the concentration and types
of fungal colonies found in the indoor sample should be similar to
or lower than the concentration and types of colonies found in the
outdoor samples. - Rank order of fungal species found in indoor and outdoor samples
should be the same. - If different fungal species were found in indoor samples, look for a
possible indoor source. - Remember that Stachybotrys sp. does not grow well on most
culture media and an absence of Stachybotrys sp. on a culturable
sample report should not rule out this type of mold. - Identify indicator fungi species. The presence of some fungi is an
indication of wet, damp or water related conditions. - Acremonium sp., Apergillus sp., Chaetomium sp., Fusarium sp.,
Memnoniella sp., Stachybotrys sp. and Ulocladium sp. are moisture
loving fungi. Their detection suggests wet conditions. - Aspergillus sp., Eurotium sp., Penicillium sp., and Wallemia sp. are
xerophilic fungi that prefer growing in high humidity conditions.
The consistent detection of these fungi is usually indicative of
persistent high relative humidity with poor air circulation. - Some fungi such as Cladosporium sp. are common outdoors,
however, it can grow well indoors in fiberglass insulation and on
other surfaces in water-damaged building materials. - Keep in mind the seasonal effects on airborne fungi. Indoor fungal
growth may become dormant during the cold winter season unless
there are water sources to support growth. Therefore, low airborne
fungal levels in winter do not indicate a clean or healthy
environment. - Identify medically important fungi, as some fungi can cause serious
medical problems, particularly to immune deficient people. - Apergillus fumigatus, A. flavus, A. niger, and Fusarium moniliforme
are some major fungi that you should look for. Their presence is a
major problem in hospitals and health care facilities. - Some fungi produce clusters of slimy spores such as Acremonium
sp., Fusarium sp., Trichoderma sp., and Stachybotrys sp. Slimy spores
are not airborne but are mostly disseminated by running water,
insects and small animals. When these fungi are detected in indoor
samples at low counts, even only one colony, it should be
considered significant to look for possible indoor reservoirs.
| Qualtest, Inc. |
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