From Pig Bite to Endocarditis: An Invasive LA-MRSA Infection

We describe a case of severe invasive infection caused by livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA, ST398 lineage) in a patient with occupational exposure to pigs. The patient presented with confusion and clinical findings suggestive of bacterial meningitis. Initial cerebrospinal fluid multiplex PCR testing was negative, and empirical antimicrobial therapy was adjusted to intravenous vancomycin to broaden empirical coverage to include staphylococci, including methicillin-resistant strains. Subsequently, both blood and cerebrospinal fluid cultures yielded MRSA. Persistent bacteremia prompted further diagnostic evaluation, revealing native aortic valve infective endocarditis complicated by a perivalvular abscess. Molecular typing confirmed the isolate as LA-MRSA ST398. The patient reported sustaining a pig bite one week before symptom onset, which was considered a plausible portal of entry. Because bacteremia persisted despite treatment with vancomycin and linezolid, antimicrobial therapy was escalated to daptomycin, ceftaroline, and rifampicin, followed by surgical aortic valve replacement. This case highlights the invasive potential of LA-MRSA ST398 and emphasizes the importance of early recognition of persistent bacteremia and metastatic infectious foci. It also underlines that, even in low-endemic countries such as the Netherlands, where MRSA accounts for approximately 2% of all S. aureus isolates, LA-MRSA should be considered in patients with relevant livestock exposure and severe invasive disease.