The most sensitive investigation for the diagnosis of asymptomatic Chlamydial infection is:

Ligase chain reaction (LCR) or polymerase chain reaction (PCR) are the most sensitive NAA methods. Isolation of C trachomatis has been the gold standard for diagnosis, but it is clear that it is less sensitive than specific nucleic acid amplification (NAA) assays. Culture is usually performed using idoxuridine or cycloheximide treated McCoy cells. C trachomatis inclusions contain glycogen and are stainable with iodine Serodiagnosis not helpful for most genital infections. Detection of IgM antibodies against C trachomatis is helpful in cases of infant pneumonitis. Ref: Ray C.G., Ryan K.J. (2010). Chapter 39. Chlamydia. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.