Tag Archives: smart incubators

“Getting Rid of Unwanted Guests”


Week 4 of the Kiestra TLA at the lab I work in. Things are starting to settle, routines are being adopted, and life is becoming boring again!

One thing I have been thinking about though, is whether contamination rates will be lower for sterile site samples, and in particular for orthopaedic samples, which often get prolonged incubation periods in the laboratory. It is not something that is talked about much when one listens to the company reps about the pros and cons of smart incubators, but there are good theoretical reasons why this might be the case.

Think about the traditional way of plate inspection. The plates are handled by human hands day after day, the plate lids removed for anything up to a couple of minutes, breathed on and occasionally coughed or sneezed on… It is actually quite an achievement to incubate a plate for 10 days without getting a contaminant somewhere along the line!

Then think about how these plates are handled by Kiestra. The plates rarely, if ever come into human contact. The lids are only removed for a few seconds in a Hepa-filtered environment for imaging.

It would be difficult, but not impossible to perform a trial to prove this hypothesis. The main difficulty is in deciding what is regarded as a contaminant and what is not. Hopefully someone will do it however.

Obviously not much can be done (in the lab) about contamination of the sample at time of sampling (in theatre etc.) but I would like to think that the (laboratory) contamination rates will be less.

And when I think about how many orthopaedic patients worldwide that are likely to have been overtreated because of plate contaminants, that cannot be a bad thing…


“The dogma of day 1 and day 2”

Readers who work in a clinical microbiology lab will be familiar with day 1 and day 2 reading. That is the way it has always been. Regardless of when the specimen was put up, the plates are incubated overnight and then read on day 1, re-incubated and then read again the next day, on day 2. This old-fashioned system is so non-standardised, it is actually a wonder that we still get away with it with regards to accreditation.

However not to worry. Smart incubators are becoming increasingly prevalent (e.g. WASP, Kiestra).These systems know when each plate enters the incubator, and thus allows plates to be incubated for a specific pre-programmed time, before automatic imaging occurs, and the scientist is notified that they are ready to be read.

As these automated systems become increasingly common, we need to move away from the day 1, day 2 dogma. Most plates will only need incubated for somewhere between 12 and 18 hrs before bacterial growth is visible.

Instead we should be talking about 1st reading and 2nd reading, or something similar. We should simply stop referring to plate reads as day 1 and day 2…..

The other area that Day 1, day 2 dogma is seen is with regards to enrichment broths. Enrichment broths such as MRSA/Gp B broths tend to get incubated for a day before being subbed onto plates. Of course 1 day/24 hrs is a completely arbitrary figure. With smart incubators and 24 hr rosters we need to start validating shorter enrichment periods, in order to decrease turnaround times.

Continuous put-up, continuous reading, continuous reporting. That should be the vision of all clinical microbiology laboratories.