May I know whether MIC values "move" when the E-test is performed on a fresh sample vs stocked isolates.
This has been described and may account for vancomycin MIC creep in the case of MRSA. However does this phenomena happen across the different organisms (i.e. Enterobacteriacea )?
Dear Helmi,
The agar diffusion methods are strongly influenced by factors, such as agar depth, diffusion rate of the antimicrobial agent and growth rate of the specific bacteria. However, no report on the effect of the age of the sample has been recorded, yet.
For more information, you may see the following link:
http://www.antimicrobialresistance.dk/data/images/anti2_pdf.pdf
Hoping this will be helpful,
Rafik
Hi,
I have also come across similar phenomenon but with cefotaxime MIC with Klebsiella and E.coli where MIC decreased with prolonged storage. There could be multiple reasons behind this, like changes( deletion or reverting to wild type structure) in the outer membrane protein which plays an entry in drug entry or down regulation of RND efflux pump, or loss of plasmids carrying the resistance gene. I have also not come across any documented evidence of this phenomenon.
Hope this helps..
Priya
Thanks Both
Thanks Priya, the paper on MIC creep for vancomycin against MRSA has been reported though I have troubled looking for the paper now.. Buried in my laptop and I forgot under which title.. Will upload here if I have it..
BTW that really helps to know that this is possible
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