I’ve suffered through some nagging issues that don’t have a good answer. I'm making a few short posts to vent. Do these problems happen in every lab? Problem 1 – Fallgar In a Micro lab, it’s common practice to invert plates when incubating them. But why? Incubators are pretty humid. Condensation inside the petri dish pools on the media surface. Water causes colonies to spread out, making them impossible to count! If bacteria show up, you’ll never really know if it’s mass contamination or just one CFU that spread. For about six months straight, 1-2 times a month, the agar in one of our incubating plates fell into the lid. This would’ve been great if our agar was a Jell-o shot and we wanted to easily eat/drink it. Instead, we got non-hangover related headaches. Some pictures for context: This is what normal plates look like, before they're inverted, with media on the bottom of the plate: Prior to incubation, we invert the plates: During incubation- the agar fell, as depicted by those beautiful arrows and red line. When we read results, the surface of the media where colonies grow was flat against the lid of the plate. Since the plate was inverted, the condensation droplets collected in the lid. Basically the agar fell into a mini pool of water.
There were so many questions from such a silly issue. They boiled down to these 2: 1. If microbes were on the media, would they have grown in this condition? What if there was a mass contamination event in a filling room that occurred right where this sample was collected, but due to the falling agar, we couldn’t recover any organisms? Organisms could have gotten into our sterile product and we never would have seen it. We did a quick study to look into this: Inoculate a bunch of plates with different organisms, cut around the edge of the agar, force the agar to fall into the lid, incubate, then see if final count matched our inoculation count. Luckily, the study supported we could recover organisms when this happened. Luckier yet, all the original plates with fallen agar had no growth, so we didn’t have to answer any awkward questions about whether the condensation messed with our counts (although we don’t know if water could have “drowned” anything there). 2. Why the hell was this happening? This occurred for multiple media lots over 6 months. We’d gotten our media from the same supplier for years. They made no changes to their formulation or plates. Our incubators remained the same, including all measurements like humidity and temperature. It happened to such a small percentage of total plates (about 1 in every few thousand) that the supplier didn’t consider it a major issue. Yet every time it happened, we had to open a quality record to investigate the root cause and impact. We never found a root cause, so we had no corrective action. This whole thing made me look like an idiot when it popped up as our most frequent type of event in our trend reports. How did we make it stop? We shut down the entire plant! There were other quality issues and remediation costs at the site, so the decision was made to close the plant. This media issue was nowhere close in severity to the other quality concerns. But had the plant not shut down, I have no idea how much longer this issue would have lasted. Have you ever seen something like this?
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