What if a microbe is detected by one testing modality but not the other?

Cultures and molecular diagnostics provide similar information, such as organisms detected in a sample. However, the technology behind each method is different. Sometimes a specimen may have microbes detected via PCR but that same sample may not have those microbes detected via cultures. The opposite can occur as well, where cultures may have microbes detected, but the PCR test on the sample may be negative. There are many reasons for these discordant results. In any case, negative results from one method, do not disqualify a positive result from another method. Therefore, a positive result from any modality, even when discordant, should be considered when determining the cause of an infection.