JMM Editor’s Choice: rapid identification of Treponema pallidum 

Posted on January 20, 2021   by Microbiology Society

This month Professor Roberto La Ragione discusses “A novel peptide nucleic acid- and loop-mediated isothermal amplification assay for the detection of mutations in the 23S rRNA gene of Treponema pallidum” which was chosen as Editor’s Choice for the December issue of theJournal of Medical Microbiology.

Syphilis is an important sexually transmitted disease (STD) caused by the Treponema pallidum. Resistance to antibiotics in T. pallidum  is increasing worldwide, but determining resistance and susceptibility levels is challenging as T. pallidum  cannot be culture in vitro. Although penicillin is still effective as a first-line antibiotic for syphilis, macrolides are now also sometimes recommended as alternatives. However, due to widespread use, macrolide-resistance is already on the rise in T. pallidum  and this is a significant concern. Therefore, the establishment of culture-independent methods for detecting macrolide resistance in T. pallidum  are urgently required. In this study, a sensitive and specific PNA-mediated LAMP-based assay for the identification of T. pallidum  and macrolide resistance was developed for point-of-care testing (POCT). 

A novel peptide nucleic acid- and loop-mediated isothermal amplification assay for the detection of mutations in the 23S rRNA gene of Treponema pallidum 

Macrolides could be a potential alternative treatment for Treponema pallidum, the bacterial cause of syphilis. However, macrolide-resistant T. pallidum is spreading rapidly worldwide. 

Because T. pallidium can’t be cultured in vitro, determining antimicrobial susceptibility can only be done using serological tests. To address this, we constructed a method for rapidly identifying T. pallidum and confirming macrolide resistance by using loop-mediated isothermal amplification (LAMP) with peptide nucleic acids (PNAs). 

This PNA-mediated LAMP method that enabled us to rapidly identify T. pallidum and determine its macrolide susceptibility via a culture-independent protocol.