Characteristics of Staphylococcus lugdunensis isolated from humans and animals

Staphylococcus lugdunensis is an opportunistic coagulase-negative Staphylococcus increasingly reported in both humans and companion animals. In this study, we performed a comprehensive characterization of S. lugdunensis isolates obtained from different hosts and clinical backgrounds. Species identification was conducted using MALDI-TOF MS and confirmed by PCR targeting the species-specific fbl gene, complemented by partial rpoB sequencing. The isolates were analysed using multilocus sequence typing (MLST), PCR-based detection of antimicrobial resistance genes, and phenotypic antimicrobial susceptibility testing. Biofilm formation was assessed using a crystal violet microtiter plate assay under different incubation temperatures, and the virulence of selected strains was evaluated using the Galleria mellonella larvae infection model. The isolates exhibited genetic diversity and variable antimicrobial resistance and biofilm phenotypes. Among the analysed isolates, biofilm production was significantly influenced by incubation temperature and host origin, and selected strains caused differential larval survival in the G. mellonella model. Collectively, these findings highlight the heterogeneity of the analysed S. lugdunensis collection comprising human- and animal-derived isolates and support the need for further studies within the One Health framework.