Extraintestinal Pathogenic Escherichia coli (ExPEC)-like Infection Associated with Septicemia and Neurological Signs in Suckling Piglets: A Case Report.

Extraintestinal pathogenic Escherichia coli (ExPEC) are opportunistic pathogens in pigs and can cause systemic infections with neurological signs. Cases in suckling piglets have rarely been reported. In November 2024, suckling piglets aged 1-3 weeks on a commercial pig farm developed neurological signs, including altered consciousness, vertical nystagmus, ataxic gait, and recumbency. Within two affected batches comprising 1150 and 1200 piglets, 17 and 26 animals, respectively, developed clinical signs (morbidity 1.48% and 2.17%). Initial treatment with amoxicillin and dexamethasone was ineffective. Early administration of intramuscular enrofloxacin combined with dexamethasone was associated with clinical improvement in approximately 50% of affected piglets. Pathological examination revealed atelectatic lung regions, dilated small intestines with yellowish content, and moderate mesenteric vessel congestion. Histologically, the central nervous system of both piglets exhibited hyperemia, edema, disseminated diapedesis hemorrhages, thrombi, and intravascular rod-shaped bacteria. E. coli was isolated from the CNS, lungs, pericardium, and joints. Molecular analysis confirmed the presence of virulence-associated genes fimA, fimH, and iucD. Differential diagnostic PCRs for Streptococcus suis, Glaesserella parasuis, and Mycoplasma hyorhinis were negative. This case report documents the first occurrence of an ExPEC-like E. coli infection in this herd. The documented clinical, pathological, and molecular findings support the importance of considering ExPEC-like E. coli as a differential diagnosis in therapy-resistant neurological diseases in piglets.