16S rRNA gene sequencing is a useful tool for identification of non-cultured or hard-to-identify bacteria. This technique can be used to detect and identify bacteria in clinical materials, such as cerebrospinal fluid and heart valves, if conventional methods do not reveal pathogens. A major advantage compared with other techniques is that it is not necessary to know in advance what pathogen is the likely cause of the disease. An important drawback is the background noise generated by traces of bacterial DNA in reagents.