Methodological and Analytical Pitfalls in Appraising Treponema pallidum Beta-Lactam Susceptibility In Vitro

The effect of Tp0705 penicillin-binding protein polymorphisms on Treponema pallidum susceptibility to ceftriaxone and penicillin G was assessed in a recent study by Tantalo et al. While the study provides valuable phenotypic data from challenging in vitro cultures, its small sample size (N=3) and reliance on historical strains isolated over two decades ago may limit its immediate evolutionary generalizability to currently circulating lineages. Additionally, exploring the role of alternative penicillin-binding proteins and integrating in vivo pharmacokinetic parameters, such as serum protein binding, could provide a more comprehensive overview of susceptibility. Furthermore, the statistically significant variations observed at sub-inhibitory concentrations represent interesting physiological phenomena that warrant further exploration rather than being dismissed as experimental variations. To robustly delineate therapeutic efficacy, incorporating dynamic pharmacokinetic models alongside expanded prospective multi-locus genomic surveillance will be essential for future research.