We have been playing around for a while now, looking for the “best” way to rapidly identify isolates from positive blood cultures. 

First of all we had a look at FISH (Fluorescent In-Situ Hybridisation). This was accurate, and pretty quick, but for the volumes of positive blood cultures that we process, even in a fairly big lab, it was somewhat on the expensive side.

We then had a look at MALDI-ToF based “centrifugation” methods. We dabbled with the Bruker sepsityper, or at least “home brew” versions thereof… This was quickish, but quite labour intensive, and to be honest a bit tedious. Nevertheless pick-up rates were good, particularly for Gram negative organisms.

However now that we have the Kiestra TLA in place, I think we are going to settle for the “Hot Chocolate” method. This involves inoculating an aliquot from a positive blood culture on to a pre-warmed chocolate agar, incubating for a pre-programmed 6 hours on the Kiestra system, and then performing an immediate MALDI-ToF on the plate colonies.

OK, so it is not quite as quick as FISH or Sepsityper, but it is cost-effective, does not require a lot of manual input, and it is a service that we can provide 24 hours a day.

Realistic solutions always involve some degree of compromise…

Michael