Meningitis in a French pig farmer caused by a serotype 2 Streptococcus suis isolate from the uncommon ST25 lineage.

Abstract

Background: Human Streptococcus suis infections occur worldwide but are most common in East and Southeast Asia. In Europe, most cases are linked to occupational contact with pigs and are usually caused by serotype 2 sequence type 1 (ST1) and ST20 strains, whereas other serotype 2 genotypes seldom cause human disease on the continent.

Case summary: A 55-year-old male pig farmer from Brittany, France, presented with acute confusion, fever, and nuchal rigidity consistent with meningitis. Cerebrospinal fluid cultures were negative, but blood cultures grew S. suis. Empirical treatment with cefotaxime and dexamethasone was initiated, followed by high-dose amoxicillin once antimicrobial susceptibility results confirmed β-lactam sensitivity. The patient required 5 days of intensive care and 7 additional days in a general ward and then completed 8 days of home intravenous ceftriaxone, fully recovering without hearing loss, a frequent sequela of S. suis meningitis. The isolate was typed as serotype 2. It belonged to the ST25 lineage and was genetically closely related to North American strains.

Conclusion: This case serves as a reminder that S. suis should be considered in meningitis among swine-exposed individuals and expands the known range of ST25 human infections to Western Europe, providing useful insights for regional surveillance efforts.