Dear Renato,

In our laboratory we measure phagocytosis by a kit from molecular probe (now invitrogen) Catalogue number: A10025.

I also thought to do phagocytosis by E. coli particle but the problem was, there was no perfect solution for surface adherent bacteria. if you treat harshly the cells die.

Here comes the solution (thats the USP of kit) their buffer B (they dont disclose about its reagent) clears all the surface adherant bacteria and the fluorescence comes from internalized bacteria. You May try the kit.

Or you may indirectly measure it by NitroBlue tetrazolium test on slide after stimulation with bakers yeast. If the yeast is ingested, formazon crystals will be formed due to oxidative burst.

Dear Renato,

In our laboratory we measure phagocytosis by a kit from molecular probe (now invitrogen) Catalogue number: A10025.

I also thought to do phagocytosis by E. coli particle but the problem was, there was no perfect solution for surface adherent bacteria. if you treat harshly the cells die.

Here comes the solution (thats the USP of kit) their buffer B (they dont disclose about its reagent) clears all the surface adherant bacteria and the fluorescence comes from internalized bacteria. You May try the kit.

Or you may indirectly measure it by NitroBlue tetrazolium test on slide after stimulation with bakers yeast. If the yeast is ingested, formazon crystals will be formed due to oxidative burst.

If you stain or express fluorescent protein in the bacteria, it might be possible to use flow cytometry. The mean fluorescence intensity of macrophages would be expected to correlate with bacterial load. I guess the main caveat is that you'd need to make sure the instrument would be sensitive enough to detect invaded cells and the dynamic range of the instrument would allow you to resolve cells with differing numbers of intracellular bacteria.

I have also seen microscopy used with pretty great results, but it's obviously not nearly as high throughput as for would be.

Depending on what exactly you're looking to quantify, could you use a qPCR-based readout? Comparing signal from a bacterial gene to a host gene would allow you to quantitate bacterial load. You could also probe any phenotypic marker you want by measuring it's mRNA levels.