Microbial Consulting Services
 

Microbial Consulting Services

 



MICROBIAL CONSULTING SERVICES (COMMERCIAL & RESIDENTIAL) 
 
TBE uses only microbial analytical laboratories which have certification in the American Industrial Hygiene Association’s (AIHA) Environmental Microbiology Proficiency Analytical Testing (EMPAT) program.

TBE uses the US EPA, “Mold Remediation in Schools & Commercial Buildings”, 2001, and the New York City Department of Health, April 2000, “Guidelines on Assessment & Remediation of Fungi in Indoor Environments” as a template for preforming microbial work, with some adaptions for the specific conditions in the building. TBE typically addresses microbial projects systematically in several phases as follows:
 
Phase A:
 
TBE performs a thorough visual survey, which may include sampling, and also utilizing moisture meters to assess the extent, if any, of fungi (mold) contamination at a property. The analog moisture meter measures the relative amount of moisture in a material. Since the meter does not provide absolute values of moisture in a material, it is necessary to compare readings for similar types of materials in different areas. In this manner, TBE will be able to compare moisture contents of materials in areas which have visual microbial growth (or may have microbial growth which is not visual) with those materials that are not supporting growth.

If necessary, several types of microbial air and surface sampling techniques can be employed. The sampling can determine if microbial contamination is present, and if so to what extent. The testing is often necessary to better define the scope of microbial remediation required. Reference Appendix A for a description of sampling protocols.

For air sampling, TBE uses spore traps, bioaerosol and/or polymerase chain reaction (PCR) techniques. Spore trap air samples can identify viable and non-viable molds (i.e., living and dead) down to genus level and concentration levels are reported in fungal structures/m3. The samples are analyzed microscopically and results are typically available in 7 days. These samples can be expedited for 24 hour results. Bioaerosol samples are analyzed for culturable mold (living only) and require 10 to 14 days for laboratory results. DNA-based realtime quantitative polymerase chain reaction (PCR) air sampling is a rapid and reliable detection and identification of fungi. PCR technology not only overcomes the time-consuming process using conventional culture analysis, but also provides a sensitive, accurate and reliable analysis.

Surface sampling techniques include: (1) tapelifts; (2) swabs; (3) micro-vac dust; and (4) bulk sampling. Tapelift samples are analyzed microscopically and can identify viable and non-viable molds. The tapelift samples can be expedited for 24 hour results. The remaining surface sampling techniques are analyzed for culturable mold (requiring 10 to 14 days for laboratory results).
 
Phase B:
 
Remediation specifications can be developed for the eradication of microbiological contamination based on risk assessment. The specifications address methods for protecting unaffected areas of the building during abatement. An assessment is made of the various sample findings by TBE to determine suitable action for mold abatement. The specifications address whether mycocide treatment of affected materials is appropriate or if removal of affected materials is required. Environmental monitoring criteria must be developed for during and after abatement to certify that the site will be safe for re-occupancy. Reference Appendix B for an overview of microbial abatement procedures.
 
Phase C: Environmental Monitoring During Abatement
 
Environmental monitoring should be performed during a remediation project to insure that the remediation contractor is performing the remediation work correctly. At the end of the remediation project, outdoor ambient bioaerosol and spore trap air sampling should be performed to establish criteria for determining levels of microbials during indoor final clearance testing. Inspections and testing must be performed after remediation to certify that the building area will be safe for re-occupancy.
 
Phase D: Final Clearance Testing
 
The decision to declare a work area has passed the clearance testing is based on three parameters: visual inspections, results of air sampling, and results of surface sampling. A visual inspection is performed prior to any clearance sampling, and sampling would only proceed after the work zone has passed a visual inspection(s). A visual inspection will only be acceptable based on the following: no sign of any fungal growth and/or water damage on all surfaces and no visible dust on surfaces.

Both viable (culturable) samples as well as non-viable (spore trap air samples) are collected. There are instances where time does not allow for culturable analysis and spore traps and tapelifts alone are used for final clearance. If the spore trap samples and/or the tapelift samples show that the work area(s) are still not sufficiently cleaned, these work area(s) must be re-cleaned and re-sampled.

Final clearance will only be approved for passing after all samples have been analyzed. Depending on the results, it may be necessary to perform re-cleaning in one or more areas. If any re-cleaning is done by the abatement contractor, TBE re-samples those areas.


APPENDIX A: Microbials Sampling Protocol
 
 
TBE will perform sampling for microbials using protocols established by the American Conference of Governmental Industrial Hygienists (Bioaerosols: Assessment & Control, ACGIH, 1999) and the American Industrial Hygiene Association (Field Guide for the Determination of Biological Contaminants in Environmental Samples, AIHA, 1996). TBE uses only microbial analytical laboratories which have certification in the American Industrial Hygiene Association’s (AIHA) Environmental Microbiology Proficiency Analytical Testing (EMPAT) program.

TBE will conduct microbial testing concentrating on specific selected areas. The samples can be collected utilizing air, swab surface, bulk (material), and micro-vac dust sampling methods, using cultural media plates. Microscopy spore trap air and tapelift surface sampling can provide for quicker turn-around results. Surface samples will be collected from areas with both visible & suspect (non-visible) microbial growth.

For air samples, besides any specific complaint area(s), at least two additional sample sites in an outdoor area is needed (required to establish background ambient conditions) and, if possible, a non-problematic room within the building to provide a control sample for purposes of comparison with the complaint area samples.

For bioaerosol air samples, each area will be sampled by collecting airborne matter (using a sieve impactor instrument with a high flow pump) onto a plate of nutrient media, which is typically MEA (Malt Extract Agar) for fungi. In some cases, more than one culture media may be used. TBE will have the plates incubated (to allow microbials to proliferate) then analyzed for microbial species.

For each of the samples analyzed, the number of colony forming units (CFU) of fungi present per sample will be reported, and the predominant genera and species of each will be identified and rank-ordered. The microbial sampling data described above will be evaluated to determine whether fungi are present in the building area samples, within the limits of detection of the protocol. The data obtained under this multiple sampling protocol provides greater understanding of microbial activity in an area. The sampling would also include blank field test samples for quality control purposes.
 
Following are air and surface testing methods and the advantages and limitations for each:
 
Spore Trap Air Sampling
 
Spore trap air sampling will show both viable (living) and non-viable microbials. The spore trap samples offer a quicker turn-around time than culturable air and swab samples (7 days versus 12 days). Samples are analyzed by microscopy methods. The results will only identify molds down to the genus level. Spore trap air samples can't show specific species of molds, as opposed to culturable sampling.
 
Bioaerosol Air Samples
 
Bioaerosol air samples can only identify viable (living) microbials (molds); however, the results show specific species. These samples identify airborne mold spores to which occupants may be exposed; however, molds such as Stachybotrys chartarum which do not readily become airborne will not be as easily identified in bioaerosol samples. Samples are collected and cultured on agar plates (petri dishes) using a high flow air pump and an Andersen N-6 viable impactor sampler. Bioaerosols have a turn-around time of 12 days from the laboratory.
 
PCR Air Samples
 

Conventional fungal identification carried out by culture analysis takes 14 days. A rapid and reliable detection and identification of fungi is important for facilitating better assessment of contamination and eventually the remediation process. Researchers at the U.S. EPA have recently developed a new DNA-based realtime quantitative polymerase chain reaction (PCR) technique, a nucleic acid-based technology. The laboratory that TBE uses for microbial analysis has licensed this patented cutting-edge technology from the U.S. EPA.

Every fungal species has its own unique, characteristic genetic signature, which varies among species and can serve as a genetic fingerprint for their identification. The power of PCR is to amplify the selected sequence of genetic fingerprint to the level that it can be easily detected and quantitated.

PCR technology not only overcomes the time-consuming process using conventional culture analysis, but also provides a sensitive, accurate and reliable analysis. The advantages of using PCR analysis are:

  • Rapid turnaround time
  • Accurate fungal identification
  • Reproducible results
  • Detection of fungal spores whether they are viable or not
  • Quantitative and qualitative results
  • Excellent detection sensitivity
  • Long term air sampling [3 hours] versus 2 to 8 minutes by other methods
  • The laboratory offers a broad coverage of 23 fungal species that may be found in a water-damaged environment.
The fungi detected by the PCR analysis includes: Acremonium strictum, Alternaria alternata, Stachybotrys chartarum, Memnoniella echinata, 8 species of Aspergillus, 5 species of Penicillium, and 2 species of Cladosporium.
 
Dust Tapelift Surface Samples
 
Another testing method is microscopic dust tapelift surface samples. These samples offer quicker turn-around time from the laboratory (3 days), and are analyzed by microscopic analysis similar to the spore trap samples. As with the spore trap samples, the tapelifts will identify all fungal structures (viable and non-viable). However, most fungal species can’t be identified, due to the limitations of the microscopy methods.
 
Swab Surface Samples
 
Microbial swab surface samples can only identify viable microbials, and they have a longer turn-around time from the laboratory (14 days). Samples are swabbed and cultured onto agar plates at the laboratory. Swab surface samples identify microbials present on various building surfaces. For molds such as Stachybotrys chartarum which are not readily airborne it will be easier to identify these molds in the swab surface samples. Identifying surface molds will help the testing company to determine what is actually present in the remediation area(s).
 
The more samples that are collected in a remediation space, the more confidence the environmental testing company can have in the sampling results. If the testing company were only to collect a few samples in a few locations, then they may miss what is actually present in the remediation space.
 
The quantity of samples required are site specific. It is dependent on the degree of contamination being remediated and the size of the work area. In many instances sampling should be performed in adjacent areas to demonstrate that contamination has not been spread. In addition, control samples in uncontaminated areas away from the work areas may be necessary to establish background levels. Spore trap, PCR and bioaerosol air sampling should also include outdoor air samples in order to compare outdoor ambient levels to the levels inside the remediation area.

APPENDIX B: An Overview of Microbial Abatement Procedures
 
Building-related exposure to molds is becoming recognized as a major indoor air quality (IAQ) problem. In some cases, when mold growth is extensive, it becomes necessary to perform a microbial abatement. After a microbial (mold) abatement is completed, the building area should not be re-occupied until the project area has passed post remediation sampling. Performing only a visual inspection after an abatement project (without collecting samples) is not enough to ensure that the molds have been successfully abated.

The presence of molds in settled dust is an important source of airborne spores. When the dust is disturbed, spores in settled dust can become airborne. It is important to note that even non-viable (non-living) cell parts from bacteria and mold can cause allergic reactions in some individuals. Primarily using biocides to kill the molds is not sufficient. Instead, the main effort should be to physically remove the mold contaminated materials and dust.

After wet and porous materials and visible molds are removed, it is possible that microbial contamination is still present. Mold spores can survive in any dust that may be present in the space. If moisture or high relative humidity is re-introduced into the remediated area(s), then mold growth can quickly reoccur. If abatement was not done carefully, mold may not only still be in the original area but it may have also contaminated other areas in the building. The new mold problems may be more severe and wide spread than the original problem the contractor was hired to remediate.

The risk to the building owner is that health problems may occur or re-occur after re-occupancy. If this occurs, then the remediation contractor may be held responsible for leaving microbial contamination in the work space or actually spreading it elsewhere in the building. The legal consequences can be severe for either or both parties. In order to minimize these potential problems, post remediation testing should be performed to demonstrate that microbial levels have returned to normal background.

An experienced environmental consulting company should be contracted by the building owner. The environmental consultant should be independent of the remediation contractor and building owner. The environmental testing company should be experienced in handling microbial contamination problems and microbial remediation projects.

Post remediation testing consists of air and surface sampling. Prior to any testing, the contractor should ensure that the work area has no sign of any fungal growth on all surfaces and no visible dust on surfaces.


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