lawsonia intracellularis lawsonia intracellularis lawsonia intracellularis is a species of bacterium. it is obligately intracellular and was isolated from intestines of pigs with proliferative enteropathy disease. lawsonia intracellularis scientific classification domain: bacteria phylum: thermodesulfobacteriota class: desulfovibrionia order: desulfovibrionales family: desulfovibrionaceae genus: lawsonia species: l. intracellularis binomial name lawsonia intracellularismcorist et al. 1995 pathogenicity lawsonia intracellularis is highly pathogenic. the species has been associated with outbreaks of bacterial infection-associated protein losing enteropathy in horses.