Detection of antimicrobial-treated Chlamydia trachomatis with Amplicor PCR test kit

A polymerase chain reaction (PCR) method for the detection of Chlamydia trachomatis has been developed and is now available in the clinical setting. However, one of the major problems with this method is possible false-positive detection posttreatment. Nonviable C. trachomatis was established by in-vitro exposure to an antimicrobial agent, and we tried to detect the nonviable cells (NVCs) of C. trachomatis by PCR with variant primer sets. C. trachomatis strains (D/UW-3/Cx) were cultured in a medium containing the antimicrobial agent, at 8 x MIC (minimal inhibitory concentration) 15 to 20 h postinfection. Amplicor and two sets of PCR primers were used to detect the DNA of NVCs. Serial passages of NVCs were done five times. All samples were positive on Amplicor, and all except the fourth passage were positive for the two sets of primers. Although the PCR test appears to be valuable, NVCs may possibly be detected by this method, and this may be clinically responsible for the false detection of C. trachomatis after appropriate antimicrobial chemotherapy.