PLAT and syphilis: Nichols-like strains represent only a minority (about 6%) of contemporary strains circulating in the syphilis-infected population (Woznicová et al., 2007; Flasarová et al., 2012; Grillová et al., 2014, 2018c; Arora et al., 2016; Gallo Vaulet et al., 2017; Mikalová et al., 2017a; Pospíšilová et al., 2018), as revealed by molecular typing studies of TPA isolates.