A Guide to the selection
and use of analyses on the Prestige’s list.
Analyses by Microscopic Techniques
P001 Spore counting from air samples is an easy tool that can provide quick turnaround results in an environmental assessment for mold contamination. We recommend to stick with several well known and well documented sampling equipments, such as Burkard™ and Allergenco™ samplers, or devices, such as AllergencoD™ and Air-O-Cell™. These samplers and devices collect airborne particles, including mold spores, onto a sticky slide. The slide can be prepared and analyzed under an optical compound microscope. Users are strongly recommended to understand the pros and cons of using such sampling and analysis. The detected spores are presumptively identified at best and their viability is unknown. This means spores identified as Aspergillus/Penicillium may look like but not necessarily be Aspergillus and Penicillium at all. Most laboratories analyze and count approximately 25% of the sample trace. The reported concentrations have implied standard deviations (SDs), which are typically not reported. The SDs can vary between a few percentage points to over a few hundred percents, depending on the quality of the sample (dust and background loading), density of spores (low v. heavy loading), stop counting rules or estimation of a heavy spore load, and laboratory analyst. With such uncertainties, interpretation of results should be performed with great care. Negative results are often inclusive, particularly when a small sample number is collected. Please consult our technical document for information on such result interpretation. Spore counting is useful when Stachybotrys spores may be present and in mold remediation situations when biocides are applied. Dead, damaged or unculturable spores will not be recovered by culturable methods. Spore counting will detect dead, damaged or unculturable spores.
P003 Microscopic examination of bulk or tape lift samples for mold and fungi is a very good tool to confirm and document mold growth in an environment. However, the results are qualitative or semi-quantitative. Density of mold growth is often described using different terminology by different labs. The results also do not indicate viability of the fungi and their spores. Good laboratories with experienced and highly trained analysts can provide indications on whether the fungal growth may be old or dead. Please see Prestige’s technical document on how such information is observed. Another important piece of information provided in Prestige results is the presence of mites, insects, their fecal particles, or any combinations. The presence of such organisms is indicative of long-term water damage and mold growth. For those interested in such information, please consult the references (1-3) below.
P004 Wood decay evaluation is designed to determine whether wood samples from a wood-structured building may have wood decay due to long-term moisture issues and fungal growth. Wood decay evaluation is often overlooked by environmental professionals in their assessment of fungal growth and contamination in a wood-framed building. This analysis can help an environmental professional to determine whether the building has a recent or long-term moisture problem.
P005 Dust characterization is a useful tool to determine components of accumulated dust in a building and where they may be from. Our scientific & technical advisor is the first scientist to use such analysis and understand its importance in building diagnosis. A scientific paper based on the USEPA funded study was published in 1992 (4). Our knowledge has since further expanded.
Mycological (culture) analyses
Culturable fungi for air samples
P006 & P007 Culturable fungi recovered on MEA plates incubated at 25ºC (room temperature) can provide useful information on the conditions of the sampled indoor environment, particularly if the fungi are properly and accurate identified to species. For those interested in full speciation including Cladosporium and Penicillium, P007 is the code to use. Results of this analysis can complement well with P001 results. Andersen N6 single stage sampler is the most commonly used equipment. We strongly recommend MEA medium for such sampling. Other media, such as CMA and DG18, are used for special situation. CMA is suitable for recovery of Stachybotrys chartarum, while DG18 is for xerophilic fungi.
P008 Thermotolerant fungi, which can grow at 37ºC, can potentially grow in the human body and cause infection. A variety of thermotolerant fungi, including many Aspergillus species, can easily be recovered on MEA incubated at 37ºC. Samples must be stored and shipped on ice at approximately 4ºC to prevent germination of mesophilic spores, which may interfere with the germination and growth of thermotolerant fungi. This analysis should be considered when sampling in hospitals, health care facilities, or indoor environments where immune-deficient people may reside.
Culturable fungi for bulk, dust, swab, water
P009-P017 Culturable fungi can be recovered and grown on a variety of media. MEA is a general purpose fungal isolation and identification medium commonly used by mycologists. There are many formulations of MEA medium. We use the one most suitable for the recovery & identification of fungi based on our mycologist’s practical and academic experience. However, some fungi can grow better on other media. CMA has low nutrient but a slightly higher water activity and is used in the recovery and identification of Stachybotrys chartarum. DG18 contains 18% glycerol to reduce water activity. Therefore, it is routinely used in the recovery of xerophilic fungi. MEA plus 20 or 40% sugar is sometime used for xerophilic fungi. A combination of MEA, CMA and DG18 covers a broad spectrum of fungi that can be found in the indoor environment. Environmental consultants should consider their needs of each project by selecting appropriate analysis. If there is any uncertainty, contact our office. Please also reference discussions under P006, P007 and P008 for decision on reasons for full speciation and for incubation at 37ºC.
Mycological Forensic Analyses
Combination of Microscopic and Culture analyses
P018 Dust samples can be processed and analyzed for both spore counting and culturable fungi. This analysis is designed to complement the advantages of both P002 and P010. Spore counting provides a better quantitation of spores in the sample and a better detection of spores which may have lower recovery efficiency due to death, declined viability, low number, or other factors. Culturable results provides information on the viability of fungal spores detected and identified as well as better identification of fungal spores in the sample. These combined results can be useful in a forensic investigation.
P019 Bulk samples with visible mold growth can be analyzed by direct examination and culturing. Direct examination provides detection, confirmation and partial identification of “fungal growth” or other organisms (such as mites and insects) on samples. Culturing provides concentrations of viable fungi, proper and accurate identification of detected fungi, and confirms viability of fungi. The combined results can be a useful tool in a forensic investigation.
P020 Wood decay evaluation by microscopy (as in P004) provides useful information on the presence of wood decay fungi, confirmation of wood decay and degree of wood decay. In decayed wood, many other fungi may inhabit the wood with wood decay fungi. By including culturing, other fungi in the sample can be recovered and identified. Wood decay fungi may also be recovered for identification, if necessary. The combined results provide more useful information in a forensic investigation.
Culturable bacteria for air samples
P022 Culturable bacteria analysis can provide additional information when the bacterial population is broken into species, genera or groups. Elevated human-associated bacteria levels, such as Micrococcus and Staphylococcus, are signals of crowded conditions, human activities, poor ventilation, poor hygiene and maintenance, or any combinations. Elevated gram negative bacteria may indicate moisture issues or soiled conditions. The presence of E. coli is a sign of sewage or fecal contamination from humans or animals.
P023 Culturable thermophilic bacteria and actinomycetes are indicators of composting or long-term moisture conditions. They have been associated with diagnosis of hypersensitivity pneumonitis of building occupants. They may be found indoors in poorly maintained air-conditioner, wood products (particularly OSB wood) subject to long-term water problems, or soiled carpets. Naturally, they are from soils rich in organic matter or composted mulch.
Culturable bacteria for bulk, dust, swab, water
P025 Culturable bacteria analysis can provide additional information when the bacterial population is broken into species, genera or groups. Elevated human-associated bacteria levels, such as Micrococcus and Staphylococcus, are signals of crowded conditions, human activities, poor ventilation, poor hygiene and maintenance, or any combinations. Elevated gram negative bacteria may indicate moisture issues or soiled conditions. The presence of E. coli is a sign of sewage or fecal contamination from humans or animals.
P026 Culturable airborne thermophilic bacteria and actinomycetes are indicators of composting or long-term moisture conditions. They have been associated with diagnosis of hypersensitivity pneumonitis of building occupants. They may be found indoors in poorly maintained air-conditioner, wood products (particularly OSB wood) subject to long-term water problems, or soiled carpets. Naturally, they are from soils rich in organic matter or composted mulch. Sample plates must be shipped on ice at approximately 4ºC.
Combination of Mycological and Bacteriological Analyses
P027 This analysis combines P006 and P021.The results give a broader picture of microbiological status of the sampled environment.
P028 This analysis combines P007 and P022. The results give a broader picture of microbiological status of the sampled environment. Additional breakdown of fungal and bacterial taxa offers more useful information as discussed in P007 and P022.
Specialty Bacteriological Analyses
P029 & P030 In an investigation for sewage and fecal contamination, this analysis provides a useful indication to assist an investigator to determine the presence of sewage and fecal microbes. Fecal coliform bacteria are more likely associated with sewage or fecal matter of warm-blood animals. Total coliform bacteria may include bacteria from other sources. In 2004, Enterococcus spp. took the place of fecal coliform as the new federal standard for water quality at public beaches. It is believed to provide a higher correlation than fecal coliform, with many of the human pathogens often found in city sewage.
P031 Legionella bacteria are well documented to cause legionellosis (Legionnaire disease and Pontiac fever). Water samples are the primary choice of sample collection, followed by swab samples. For potable water, a 500-ml sample or more is recommended. For non-potable water, a 250-ml sample is recommended. Samples are processed according to the CDC or ISO method. Positive colonies are identified to species or groups using the direct fluorescence assay (DFA). DFA is the gold standard for Legionella identification. This analysis is recommended for general, proactive (non-outbreak situation) sampling in hospital, health care facilities, office & commercial buildings with cooling towers and large plumbing systems, or residential buildings.
P032 In an outbreak investigation of Legionnaire disease, further breakdown of recovered Legionella species into serotypes provides useful information to determine or link environmental strains to clinical strains.
Pseudomonas aeruginosa is a gram-negative, environmental bacterium
commonly found in stagnant water, biofilm (or slime) or wet, damp areas. It
is known to cause human infections. Sampling and testing for this microbe is
recommended when stagnant water is common in an environment. Stagnant water
sources can include a drain pan of a HVAC, humidifier reservoir,
fire-suppression system, or a dead leg of a plumbing system.
No part of this work may be reproduced or used in any corm or by any means-graphic, electronic, or mechanical, including photocopying, recording, taping, or information storage and retrieval systems-without written consent of Prestige EnviroMicrobiology, Inc. Version 2009