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Assessing allergenic fungi in house dust by floor wipe sampling and quantitative PCR
N Yamamoto1, D G Shendell, J Peccia
1Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA.
Unlabelled:
In the present study, we modified an existing surface wipe sampling method for lead and other heavy metals to create a protocol to collect fungi in floor dust followed by real-time quantitative PCR (qPCR)-based detection. We desired minimal inconvenience for participants in residential indoor environmental quality and health studies. Accuracy, precision, and method detection limits (MDLs) were investigated. Overall, MDLs ranged from 0.6 to 25 cell/cm² on sampled floors. Overall measurement precisions expressed as the coefficient of variation because of sample processing and qPCR ranged 6-63%. Median and maximum fungal concentrations in house dust in study homes in Visalia, Tulare County, California, were 110 and 2500 cell/cm², respectively, with universal fungal primers (allergenic and nonallergenic species). The field study indicated samplings in multiple seasons were necessary to characterize representative whole-year fungal concentrations in residential microenvironments. This was because significant temporal variations were observed within study homes. Combined field and laboratory results suggested this modified new wipe sampling method, in conjunction with growth-independent qPCR, shows potential to improve human exposure and health studies for fungal pathogens and allergens in dust in homes of susceptible, vulnerable population subgroups.
Practical Implications:
Fungi are ubiquitous in indoor and outdoor environments, and many fungi are known to cause allergic reactions and exacerbate asthma attacks. This study established--by modifying an existing--a wipe sampling method to collect fungi in floor dust followed by real-time quantitative PCR (qPCR)-based detection methodologies. Results from this combined laboratory and field assessment suggested the methodology's potential to inform larger human exposure studies for fungal pathogens and allergens in house dust as well as epidemiologic studies of children with asthma and older adults with chronic respiratory diseases.
Insights
A new wipe sampling method effectively collects fungi from floor dust for accurate detection using quantitative PCR (qPCR). This approach minimizes participant burden in health studies assessing fungal allergens and pathogens in homes.
Area of Science:
- Environmental Science
- Microbiology
- Public Health
Background:
- Fungi are common in indoor environments and can trigger allergic reactions and asthma.
- Accurate assessment of fungal exposure in homes is crucial for public health research.
- Existing sampling methods may be inconvenient for participants in long-term studies.
Purpose of the Study:
- To modify an existing surface wipe sampling method for collecting fungi in floor dust.
- To develop a protocol for real-time quantitative PCR (qPCR)-based detection of collected fungi.
- To evaluate the accuracy, precision, and detection limits of the modified method for use in residential studies.
Main Methods:
- Modified a lead and heavy metal surface wipe sampling protocol to collect fungal spores from floor dust.
- Utilized real-time quantitative PCR (qPCR) for sensitive and specific fungal detection.
- Assessed method accuracy, precision, and method detection limits (MDLs) in laboratory settings.
- Conducted a field study in California homes to determine fungal concentrations and temporal variations.
Main Results:
- Method detection limits (MDLs) ranged from 0.6 to 25 cells/cm².
- Measurement precision (coefficient of variation) ranged from 6% to 63% due to sample processing and qPCR.
- Median and maximum fungal concentrations in Visalia, CA homes were 110 and 2500 cells/cm², respectively.
- Field studies revealed significant seasonal variations in fungal concentrations, necessitating multi-season sampling.
Conclusions:
- The modified wipe sampling method combined with qPCR offers a convenient and accurate approach for assessing fungal presence in floor dust.
- This methodology has the potential to enhance human exposure and health studies, particularly for vulnerable populations.
- Results support the use of this method in epidemiological studies of asthma and chronic respiratory diseases.
