Molecular characterization of Treponema pallidum pallidum in children with acquired syphilis by nonsexual contact by multilocus sequencing

GARCIA LN; MORANDO N; OTERO A; MORONI S; MOSCATELLI G; GONZALEZ N; LASCANO F; BALLERING G; D AMICO I; PANDO MA; ALTCHEH J

Congreso; XIX Congreso Latinoamericano de Infectología Pediátrica, SLIPE 2021; 2021

INTRODUCTION: Syphilis is caused by the bacterium Treponema pallidumpallidum (TPA). A scare knowledge of the biology of the TPA during the complexclinical stages and the multiple routes of transmission allows syphilis to cause alarge proportion of morbidity in children in developing countries. Accordingly, thereare not data about molecular biology techniques (MBT) in the diagnosis of syphilisin Argentina or about the strains of TPA worldwide in the pediatric population. Werecently started a study evaluating the MBT for the diagnosis of syphilis in children.Among them, a multidisciplinary and strict evaluation detected 11 cases ofacquired secondary syphilis (AsS) suspected of had transmitted through nonsexualcontact with lesions of caretakers with untreated syphilis. OBJECTIVE: Evaluatethe use of PCR in swab lesions for the diagnostic of syphilis and examine theclusters of TPA by multilocus sequencing in child with AsS by nonsexual contact.METHODOLOGY:AND RESULTS: We conducted an exploratory study in 11pediatric cases (mean age±SD: 5±2 years old )of AsS attended at the Servicio deParasitología-Chagas, Hospital de Niños Ricardo Gutierrez from October 2018 toAugust 2021. Lesions in children were expressed mainly in oral and perianalzones. Lesion’ swabs (n=17) were processed for DNA extraction followed by PCRfor the genes of TPA: Tpp47 (conventional PCR) and dnaA (real time PCR byTaqman® probes). Frequency of Tpp47-positive samples was 47%, while dnaA-positive was 94%. Only 1 patient was negative for both PCRs. Additionally, nestedPCR for the TP0136, TP0548, TP0705 and 23s genes were performed. Thesequences were subsequently purified and sequenced by commercial kit(BigDye™) in a genetic analyzer (3500 analyzer).Then, edition and alignmentanalysis were performed compared to the reference sequences of cluster SS14(GenBank CP004011.1) and Nichols (GenBank CP004010.2) and Escherichia coli23S rRNA genes at the positions 2058 and 2059 (accession Number: V00331) formacrolide resistant mutation. As other studies in adults in Argentina, the Nicholsclade was greater than 10% and macrolide resistant mutation (A2058G mutation in1 patient) was nearly 10%, although in our pediatric population the prevalence ofNichols clade was higher (57%) that the reported (26,8%). CONCLUSION: Amongpatients, positive PCR corroborate active lesions while clade and macrolideresistant evaluation shares similarity with studies in adults in Argentina.