These sponges go to 14

Friend of barfblog, and frequent contributor (and modeler extraordinaire), Don Schaffner writes,

I’m always interested in the way microbiology is perceived in the popular culture. When peer reviewed research articles get wide pick up, I’m especially interested. This happened recently with an article on kitchen sponges. Rob Mancini has already blogged about this right here on barfblog, but I’d like to share my thoughts and perspectives.

The fact the kitchen sponges can be massively contaminated by high levels of microorganisms is not news. This has been shown repeatedly in the peer reviewed literature.

What was apparently new in this latest article was the application of “454–pyrosequencing of 16S rRNA genes and fluorescence in situ hybridization coupled with confocal laser scanning microscopy (FISH–CLSM)”. And I get it. Molecular-based methods are all the rage, and the ability to visualize the presence of microorganisms is very important.

But we shouldn’t lose sight of the fact that experimental design, and proper experimental controls are important no matter what sort of science you’re doing. When I dug a little deeper into the above article I was shocked to learn that all of their conclusions were based on a sample of 14 sponges. That’s right, 14 sponges. Furthermore, the authors make claims that “sponge sanitation methods appear not sufficient to efectively reduce the bacterial load in kitchen sponges”. How did they know this? Well when they were collecting those 14 sponges they asked the sponge owners “to specify whether they regularly apply special measures to clean their sponge. The procedures mentioned were: heating in a microwave and rinsing with hot, soapy water”. Of the 14 sponges collected, in five cases the sponge owners reported applying special measures, although the authors do not which of the five used microwaving and which used rinsing with hot, soapy water.

What’s my take away message from this? By all means, go out there and use the hot new technology. But please don’t forget that sample size is very important, and while surveying people for their opinion about what they do might be convenient, it’s no substitute for actually investigating. And if I had to predict the effect of washing sponges with hot soapy water? Probably no different than washing in cold soapy water.

And if anybody out there has access to “454–pyrosequencing of 16S rRNA genes and fluorescence in situ hybridization coupled with confocal laser scanning microscopy (FISH–CLSM)“ and wants to collaborate, I am available.