Sometimes, we have DNA bacterial in specimen, but PCR is false negative. Therefore, materials used for specimen collection, transport, and processing, as well as DNA extraction procedures, need to be carefully considered and optimized for PCR.
high Maryam, firstly you shouldfirstly work on fresh samples which were collected aseptically as possible. The extracted DNA should have good quality.ands finally optimize PCR with positive control.
I have PCR inhibitors for throat swab specimens at transport media (PPLO Broth). For resolve that, I wash specimens with PBS to deletion inhibitors. I so glad if everyone has experience in this subject say to others.
I assume that when you collect your sample, the swap has the bacteria. So, you can culture the bacteria on agar plate then from a colony (a light touch by the end of a small tip) you can run very successful PCR. If you have difficulties to grow the bacteria or that could affect your experiment goal, you could try a different DNA polymerase that tolerates the inhibitor in your media.