As you know, antibiogram resulted as susceptible (S), intermediate (I) or resistant(R). i also want to detect gene expression between resistant and susceptibel strains. Can i think intermediates as a resistant?
I think it depends on the value of "I". If it was closer to the breakpoint of "Sensitive" , it should considered Sensitive, otherwise If it was closer to the breakpoint of "resistant" , it should considered Resistance. However, you have first to re-test your organism three times by DDt before you determine it was "I" or not.
Well, this may depends on your research objectives and goals, in addition to ISO and or other standardization or regulatory organizations. See this articles for better guidance. I will advice that you also do more literature search on the organisms that you are working on, to see if there are any such reports, particularly it clinical outcomes of the antibiotics. Since, there are many factors to be considered, even if an antibiotics appears "intermidiate" in vitro
http://jcm.asm.org/content/49/9_Supplement/S15.full#ref-5
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2701059/
http://jac.oxfordjournals.org/content/48/suppl_1/87.abstract?ijkey=d81e4ae16245a43ebe05fe378eabbee77a563938&keytype2=tf_ipsecsha
Dear Ibrahim Türkel,
you can consider intermediate (I) value of antimicrobial susceptibility as resistant.
Because intermediate susceptibility is also comes under resistant range.
Best Regards,
Dr Anand
Yes as Dr Anand also mentions if you get intermediate when testing clinical strains this indicates that the microbe is resistant to the recomended and mostly used concentration of this antimicrobium. Intermediate antimicrobium/antibioticum can be used if you use a higher concentration when treating the patient. But if you define your cut-off to be the recomended concentration you can say that intermediate is considered to be resistant.
On the other hand if you deal with bacteria with more unknown resistance pattern use the EUCAST guidelines; Non-species related breakpoints as a guide to find your cut-off. See added file.
If you want to find a relationship between your expression data and suceptibility - use E-test for your sucseptibility testing- then you will always hav a MIC "number" to relate to wether or not you have more or less expression. this way if you have a difference at a certain MIC you can say something regardless of what was prederemined as S I or R.
Hope you find this helpful. Good luck.
Jane
Thanks for your valuable informations.
i used disc diffusion technic unfortunately. i have no idea how confirm my cut off value for each antibiotic. You are true if have MİC values, it is easy for me to analyze expression data with the help ANOVA.
You may find the following speech (given at the last ECCMID congress last week) helpful in guiding you through the interpretation of your results and future planning.
http://eccmidlive.org/#resources/what-does-intermediate-really-mean
Luca
Sometimes it could be referred as resistant because intermediate means the organism is at the way to resistant if its limit is at higher range.
If you have intermediate susceptible strain to certain antimicrobial and are intended to check for genes encoding resistance then you can do PCR for the detection of the genes and will see do the intermediate susceptible strains have this gene or not. That would be more clear view as among S and I and R and I the line is very narrow and often depends on many factors when you testing for susceptibility using agar plates. Thus if you intended to find genes you would better test all intermediate isolates as well together with resistant ones. If to talk about treatment we need to talk about concrete antibiotics then.
I think it depends on the value of "I". If it was closer to the breakpoint of "Sensitive" , it should considered Sensitive, otherwise If it was closer to the breakpoint of "resistant" , it should considered Resistance. However, you have first to re-test your organism three times by DDt before you determine it was "I" or not.
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