Background Chlamydia trachomatis (CT) is the most prevalent bacterial sexually transmitted infection (STI) reported worldwide. Accurate point-of-care diagnostic tests are urgently needed for the rapid treatment of patients. To address this need, we have previously developed a 16S rRNA-based Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF) assay for the detection of CT. Here we report the development of an additional CT cryptic plasmid-based MAMEF assay, the use of the assays on clinical samples and the implication of MAMEF as a point-of-care test.
Methods The cryptic plasmid-based assay was investigated with cultured, titered CT and vaginal specimens. Following the optimization of the assay, we tested a blinded cohort of dry-shipped vaginal swabs using both the 16S rRNA- and cryptic plasmid-based MAMEF assays, and compared the results to nucleic acid amplification tests (NAATs).
Results The MAMEF assays detected as few as 10 IFU/mL of CT in less than 10 minutes including DNA extraction and detection. A total of 257 vaginal swabs from 245 adolescent women (ages 14–22) were analysed by MAMEF. The overall prevalence of CT by NAAT was 17.5%. Of the 45 NAAT CT-positive samples and 212 CT-negative samples, 33/45 and 197/212 were correctly identified by both MAMEF assays (sens 73.3%, spec 92.9%). Using the plasmid-based assay alone, 37/45 CT+ and 197/212 CT- were detected (sens 82.2%; spec 92.9%). Using the 16S rRNA assay alone, 34/45 CT+ and 197/212 CT- (sens 75.5%; spec 92.9). For the overall % agreement with NAAT, the individual 16S rRNA and cryptic plasmid were 89.8% and 91%, respectively.
Conclusions Both CT MAMEF assays demonstrated moderate sensitivity and high specificity when using dry-shipped vaginal swabs. The cryptic plasmid assay was more sensitive than the 16S rRNA assay. MAMEF is an ultra-rapid platform with results in less than 10 minutes making it ideal as a point-of-care test.