for example they know now serology for Bartonella often false negative
but optimised culture with PCR has high sensitivity and extremely high specificity, and can caputre almost any type of bartonella...most labs only test for 1 or 2 types using test procedure wit low sensitivity, and it is at least 8 or more bartonella types that can affect humans accroding to the big books on infection medicine as well as a series of published scientific papers