Water quality - ? test for bacteria in deionised water

From:Richard Pitman <Richard.Pitman@wri-tr.wmids.nhs.uk>

Hi All,

We had some problems with a Warthin Starry last week. (Is this an appropriate stain for suspected Cat Scratch disease?) Finished slides were covered witha background of bacteria. Usual places for these to get in are either via a dirty section floating bath, or contaminated staining solutions and/or buffer stocks.

So, we set out to make up fresh solutions, change baths etc. Which lead to any interesting debate. I had always 'assumed' that water from our deionisation plant would be bug free. Water passes through a coarse filter on the supply side, passes a UV lamp, then a reverse osmosis filter, finally through an ion exchange column. Vendor claimed water  quality better than double distilled. System should be sanitised with hypochlorite every so often, not done this recently, was done on installation 12 months back.

Other suggestion was that we obtain 'sterile' water from Micro. This has been through process above, then autoclaved. Any bugs would still be there, but dead. They'd still stain up, though ?

Is there a quick test I can do to see if bugs are present in the holding tank ? Suggestions range from sending sample to Micro to see if they can grow anything, or evaporating some water onto a slide, then doing a Gram on the deposit.

Any thoughts please,


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