A Chamber Study on Performance Evaluation of Bioaerosol Samplers
Date Issued
2010
Date
2010
Author(s)
Chou, Fang-Chen
Abstract
It is expected that inhalation of culturable or viable L. pneumophila may result in Legionnaires’ disease. Thus, quantification of culturable or viable airborne L. pneumophila is an important environmental health issue. However, as the bacteria are aerosolized or sampled by bioaerosol samplers, the sampling stresses might decrease cellular culturability but not affect the viability. Previous studies evaluated the performance of samplers for airborne Legionella have presented the results by quantification of culturable or total cells, whereas the level of viable cells remains unknown. Moreover, no study has been conducted to determine the difference in performance among different agar-based samplers, liquid-based samplers or filter-based samplers for airborne L. pneumophila.
In this study, the performance of agar-based samplers (MAS-100 and Andersen one stage), liquid-based samplers (BioSampler, AGI-30 and MAS-100) and filter-based samplers (IOM with gelatin filter and cassette with polycarbonate filter) for collecting culturable, viable or total L.egionella pneumophila or E.scherichia coli determined by culture assay, real-time quantitative polymerase chain reaction (qPCR) and ethidium monoazide combined with qPCR (EMA-qPCR) were evaluated. According to the performance of samplers for L. pneumophila and E. coli determined by culture and EMA-qPCR, it was observed that a portion of L. pneumophila and E. coli was nonculturable but membrane-intact after being collected from the air. Evaluating and comparing the performance of samplers, the results showed that Andersen one stage performed better than MAS-100 for collecting both culturable L. pneumophila and E. coli. The performances of liquid-based BioSampler and AGI-30 for culturable L. pneumophila were greater than that of agar-based samplers in less than 4-min sampling time. In addition, for BioSampler and AGI-30, it was more efficient to use sterile and filtered de-ionized water (DW) to collect both culturable and viable L. pneumophila for 60 min and replenish the water every 15 min than to use Tween 80 mixture or DW without replenishment for collection. And the performance of BioSampler and AGI-30 with DW and replenishment for culturable and viable L. pneumophila were better than that of filter-based samplers. However, the performance for total L. pneumophila was better in filter-based samplers than in any liquid-based samplers for 30- and 60-min sampling time. Furthermore, IOM sampler with gelatin filter showed greater performance for collecting culturable and viable L. pneumophila than cassette with polycarbonate filter for 270-min sampling time. As for collecting total cells, the result was opposite. For sampling viable and total L. pneumophila and E. coli, the performance of BioSampler, AGI-30 and MAS-100 were consistently better for L. pneumophila than for E. coli.
In conclusion, EMA-qPCR could be applied to quantify the concentration of viable airborne L. pneumophila. The refilling process on BioSampler and AGI-30 may be effective to remain the culturability and viability of L. pneumophila, and it was further recommended monitoring and sampling for 60-min in field. As for quantification of total cells, filter-based samplers were suggested.
Subjects
airborne
Legionella pneumophila
Escherichia coli
culturable
viable
performance
bioaerosol samplers
replenishment
real-time qPCR
SDGs
Type
thesis
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