SSBB researchers have tested the ability of the synthetic antimicrobial peptide SET-M33 to target porcine respiratory pathogens and a collection of porcine commensal nasal microbiota members in vitro. The experiments revealed three key results. First, there were large differences in SET-M33 sensitivity across the tested strains. In particular, pathogenic Glaesserella parasuis was highly sensitive to SET-M33 at concentrations that did not affect the growth of most commensal strains. Second, some of the tested commensal strains (Rothia nasimurium and Staphylococcus aureus) were able to inactivate SET-M33 during in vitro cultivation. Third, despite this potential for SET-M33 inactivation by commensal strains, SET-M33 was still able to selectively eliminate pathogenic G. parasuis from in vitro co-cultures that also contained R. nasimurium. Overall, this study highlights the substantial complexity that emerges from the interplay between antimicrobials, pathogens, and commensals, even within a comparatively simple in vitro system, and provides a template for identifying suitable use cases for newly developed antimicrobials.
SET-M33 peptide as a selective in vitro antimicrobial agent against the porcine respiratory pathogen Glaesserella parasuis. Pereira Lourenço A.L., Rouam el Khatab O., Falciani C., Pini A., Aragon V., Cerdà-Cuéllar M., Kochanowski K. Microbiol Spectr. 2026 Feb 18:e0391825. DOI: 10.1128/spectrum.03918-25. Full publication.
