One fof the post-docs tested the media bottles for toxic detergent residues by making one big batch of our standard BHI medium and pouring it into 20 different bottles of all the types we use for media. E. coli grew in the media from all these bottles.
I don't know whether she tested growth of H. influenzae over the weekend. If they all grew too then we have the unfortunate resolution that the problem has gone away without our ever discovering what causes it. In any case I think we're going to have our lab assistant thoroughly rinse all our bottles.
A Magnolia experiment
20 hours ago in The Phytophactor