Intractable　functional　constipation　(IFC),　a　severe　form　of　chronic　constipation　characterized　by　slow　transit　and　resistance　to　conventional　treatments,　posed　a　significant　clinical　challenge.　Here,　we　identified　Lactococcus　formosensis　(Lf),　a　Gram-positive　bacterium　prevalent　in　IFC　patients,　as　a　novel　contributor　to　intestinal　motility　impairment.　Clinically,　IFC　patients　exhibited　increased　colonic　mucosal　colonization　of　Lf　and　significant　myenteric　neuronal　loss　and　pyroptosis,　particularly　in　excitatory　choline　acetyltransferase　(ChAT)+　neurons,　but　not　inhibitory　neuronal　nitric　oxide　synthase　(nNOS)+　neurons.　In　mice,　Lf　and　its　supernatant　impaired　intestinal　motility,　reducing　fecal　water　content,　prolonging　transit　times,　and　inhibiting　spontaneous　contractions　and　maximum　contractile　force　in　isolated　intestinal　segments.　RNA　sequencing　revealed　that　Lf　disrupted　neurochemical　signaling,　implicating　neuronal　damage　in　its　pathogenic　effects.　Mechanistically,　Lf　and　its　supernatant　selectively　induced　pyroptosis　in　ChAT+　neurons　via　caspase-1　activation.　Metabolomic　profiling　identified　4-acetamidobutanoic　acid　(4-ABA)　as　a　key　metabolite　shared　between　Lf　supernatant　and　IFC　patient　feces.　4-ABA　induced　ChAT+　neuronal　pyroptosis　through　a　caspase-11-dependent　pathway,　further　impairing　intestinal　motility,　which　was　confirmed　in　Casp11⁻/⁻　mice.　This　study　uncovered　a　previously　unrecognized　pathway　of　single　microbiota-induced　neuronal　damage　in　IFC　and　provided　a　foundation　for　novel　diagnostic　and　therapeutic　strategies　targeting　gut　microbiota-ENS　interactions　©　2025　Elsevier　GmbH