I didn't use any positive controls for mcr6-9 in conventional PCR because they weren't available to me, and the findings for mcr6-9 were negative. Despite the fact that these genes are not common in Bangladesh according to the previous report, So, how can I say that all samples are true negative?
It is not appropriate to infer that all samples were true negatives based solely on negative results obtained without positive controls for mcr6-9 in conventional PCR. Positive controls are important to ensure that the PCR reaction is working properly and that there are no issues with the reagents or conditions that could lead to false negatives.
Without positive controls, it is not possible to rule out the possibility of false negatives. In addition, the absence of mcr6-9 in Bangladesh in previous reports does not necessarily guarantee that all samples in your study will be negative. Therefore, it is important to interpret the negative results with caution and consider the limitations of the study design. If possible, it is recommended to repeat the experiments with positive controls or consider alternative methods to confirm the absence of mcr6-9 in your samples.
These video playlists might be helpful to you:
https://www.youtube.com/playlist?list=PLzBiAPKi8vONSqjcweFWHMRy13y3484bE
https://www.youtube.com/playlist?list=PLzBiAPKi8vOMheKwb0mu1dcZRaeGUFSlw
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I completely agree with Nikolay Klyashtornyy that you can not infer anything from negative results without proper controls. You do not have any evidence that your primers, reagents, or PCR conditions are appropriate and are working properly.
No. We can not say that they are true negatives without a positive control.
@Nikolay Thank you for your insightful suggestions. One thing is that, all the samples carried mcr-1 gene and i had positive control of mcr-1 gene.
If you have a positive control for the mcr-1 gene and all of your samples test positive for this gene, it suggests that your PCR reaction and detection method are working properly. However, the absence of positive controls for the mcr6-9 gene makes it difficult to definitively say whether your negative results are accurate. While it is possible that none of the samples you tested contain the mcr6-9 gene, it is also possible that your PCR reaction was not sensitive enough to detect it or that there were other technical issues that prevented you from detecting the gene. In order to confirm your negative results for mcr6-9, you may want to consider using a different detection method or obtaining positive controls for the gene to rule out technical issues.
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