Detection of C. trachomatis by LAMP-GE (A and C), LAMP-AuNP (B and D), and PCR-GE (E). (A, B) Specificity determination using C. trachomatis serovars D, E, F, G, H, and K (from left to right, lane numbers 1–6) and HPV, N. gonorrhoeae, S. epidermidis, and S. saprophyticus (lanes 7–10). Additional controls in B included AuNPs only and AuNPs with salt. (C, D, E) The positive results were observed from lanes 1 to 8, representing a detection limit of 180 genome copy numbers of ompA (equivalent to 0.085 fg of ompA), using C. trachomatis strain D. Lane 9 is 18 genome copy numbers of ompA (equivalent to 0.017 fg of ompA). M represents GeneRuler 100 bp plus DNA ladder (Invitrogen, New York). AuNP, gold nanoparticle probe; Ct, Chlamydia trachomatis; GE, gel-electrophoresis; HPV, human papillomavirus; LAMP, loop-mediated isothermal amplification; LOD, limit of detection; ompA, outer membrane protein A; PCR, polymerase chain reaction.