Pentoxifylline, a Non-Antibiotic Drug, Promotes Adaptation of Clinical Isolates of Staphylococcus aureus via Modulating c-di-AMP Signaling

This study investigated how Staphylococcus aureus adapts under pentoxifylline (PTX) therapy through analyzing three phylogenetically related isolates (L1, L2, L3) from a bacteremia patient. Whole genome sequencing revealed L1 contained a 2400-bp insertion disrupting nupC, while L3 harbored mutations in the anti-Shine-Dalgarno sequences of 16S rRNA. Each isolate evolved distinct mechanisms to reduce c-di-AMP levels, accompanied by changes in survival ability and virulence. Molecular analysis demonstrated PTX noncompetitively inhibits GdpP phosphodiesterase, directly modulating cyclic diadenosine monophosphate (c-di-AMP) signaling. Our findings provide novel insights into how non-antibiotic medications shape bacterial adaptation through second messenger modulation, highlighting the complex trade-offs between stress resistance and fitness in clinical settings. ImportanceThis study reveals how pentoxifylline, a non-antibiotic drug, drives Staphylococcus aureus adaptation by modulating c-di-AMP signaling. Our findings highlight the unintended consequences of non-antibiotic medications on bacterial evolution, offering new insights for clinical treatment strategies to mitigate resistance development. HighlightsO_LIPTX noncompetitively inhibits GdpP, modulating bacterial c-di-AMP signaling C_LIO_LIS. aureus evolves distinct mechanisms to reduce c-di-AMP under PTX pressure C_LIO_LINon-antibiotic medications significantly shape bacterial adaptive trajectories C_LI