Pulmonary infection caused by Segniliparus rugosus in a patient without systemic immunodeficiency but with bronchiectasis: f irst identification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry with whole-genome confirmation

Segniliparus spp. are acid-fast, rapidly growing bacteria associated with pulmonary infections, particularly in patients with underlying lung disease. Two species, Segniliparus rugosus and Segniliparus rotundus, were f irst reported in 2005 from unidentifiable mycobacterial samples suspected of being involved in respiratory mycobacteriosis [1]. Segniliparus spp. infection in humans is exceedingly rare. To date, eight cases have been reported worldwide, with most having been caused by S. rugosus in patients with cystic fibrosis or bronchiectasis [2–7]. In previous reports, species identification relied primarily on 16S rRNA gene sequencing and less frequently on rpoB gene sequencing. Here, we present a case of pulmonary S. rugosus infection in a patient without evidence of systemic immunodeficiency but with bronchiectasis and prior nontuberculous mycobacterial pulmonary disease (NTM-PD), identified for the first time by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and confirmed by wholegenome sequencing (WGS). This case highlights that MALDI-TOF MS can identify rare acid-fast organisms within routine clinical workflows, with WGS providing species-level confirmation.