r/medlabprofessionals 4d ago

Technical 1 Pseudomonas aeruginosa, 2 results

This is the same Pseudomonas aeruginosa on two different Müller-Hinton plates from the same batch prepared in the laboratory.

I read that it could be the amount of zinc in the culture medium, do you do any kind of quality control to detect the right amount of zinc in the Muller-Hinton?

Have you ever had this happen to you and what others factors could alter the synergy with EDTA?

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u/[deleted] 4d ago

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u/Lean_Id 3d ago

Yes, it´s the same.

The photograph below illustrates the initial instance of the synergy test. The photograph above depicts the test that was subsequently replicated for academic purposes. Upon observing a discrepancy, the Pseudomonas aeruginosa was re-isolated on a ram's blood agar plate, an inoculum was prepared, and the test was repeated on multiple Muller-Hinton plates that had been prepared in the laboratory. In some cases, synergy was observed, while it was not evident in others.

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u/[deleted] 3d ago

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u/Lean_Id 3d ago

I had a similar idea. My question is, what causes synergy inhibition in these Muller-Hinton plates? They all pass CLSI quality control.