3.3. Cross-Contamination Assessed Using KRAS Analysis by Pyrosequencing
Since the detection of mycobacterium in the negative samples may be influenced by the level of infection, we carried out the analysis of KRAS mutational status on colorectal cancers. Using only a manual punching device without cleaning step and alternating between tissue samples, no cross‑contamination could be seen. When analysis of KRAS gene mutation was performed using the automated device with cleaning step, again no cross-contamination of tissue samples was found. All mutated samples carried the same mutations, while all WT samples were clearly WT (Figure 4).