Mold spores and bacteria are everywhere. Add water to organic building materials and they will grow. How about wet swabs? Do things start to grow on wet swabs after you introduce water to your samples?

When you mop floor, wet mop will pick up much more dirt than dry mop. That's why wet swabs are usually used for surface microbial sampling. However, adding additional water to the samples may cause spore germination and multiplication of yeasts and bacteria because some nutrients (organic dust) in the environment will be picked up by the swabs. The common clinical swabs are designed for presence/absence test of pathogens. Some of them even have nutrients in the liquid to enhance the detection or "preserve" the pathogens from dying. Adding water also dilutes the waste produce by microorganisms, which will signal them to start growing again because environment is cleaner now.

If quantitative results are crucial, it's recommended to:
(1) Collect bulk samples whenever possible.
(2) Use quantitative swabs without nutrients, not those clinical presence/absence swabs. Follow the link below to read the last newsletter to see the differences.
(3) Pour off any remaining excess liquid. Some swabs come with 1 ml of liquid. Pour off excess (clean) liquid after wetting the swabs. Shaking mold spores, yeast, bacteria, and some nutrients (organic dust) in 1 ml of liquid on a delivery truck for 24 hours will cause significant growth.
(4) Add biocide (e.g. Sporicidin) to "preserved" (kill) them if only microscopic direct exam is needed.
(5) Put swab samples at low temperature (in an insulated container) right after collection. If ice packs are used, put ice packs (or samples) inside of bubble warp to avoid freezing the samples.
(6) Send swab samples to lab as soon as possible.

Using dry swabs is an alternative. Just bear in mind that you will stir up and aerosolize more spores when you sample and the collection efficiency of dry swab is lower than that of wet swab.

We have been helping companies that were frustrated with unsatisfying services from their microbiology labs on issues such as:
(1) poor technical support
(2) no personal attention
(3) questionable results
(4) project delay; slow turnaround time
(5) reports not making sense
(6) lack of ethics

Call us today, and understand how we can help you with that!

Host: Joe Hughes/Cliff Zlotnik

Episode Notes: Today at 12:00 noon eastern time, Indoor Air Quality Radio best known as IAQ Radio will celebrate our 100th show with a turn the tables interview. Glenn Fellman will interview show hosts "Radio Joe" Hughes and "The Z-Man" Cliff Zlotnik. It's hard to believe it has been over two years since the show started. Two years of interviewing the top people in the IAQ, disaster restoration and building science industries has been an honor we will always cherish. Join us for the celebration!

Scheduled Time:
Date: Fri, October 24, 2008
Time: 12:00 PM EDT