Liver abscess and empyema due to Lactococcus lactis cremoris

Area of Science:

• Medical Microbiology
• Infectious Diseases

Background:

• Lactococcus lactis cremoris is a lactic acid bacterium typically used in dairy fermentation.
• Human infections with L. lactis cremoris are exceptionally rare, with limited documented cases.

Observation:

• A 42-year-old immunocompetent male presented with fever and abdominal pain.
• Computed tomography revealed a liver abscess and empyema (loculated pleural effusion).
• Lactococcus lactis cremoris was identified as the causative agent from abscess and blood cultures.

Findings:

• The patient underwent surgical drainage of the liver abscess and video-assisted thoracoscopic decortication for empyema.
• Antibiotic therapy included cefotaxime and levofloxacin.
• Complete recovery was achieved following the comprehensive treatment regimen.

Implications:

• This case highlights the potential for L. lactis cremoris to cause severe invasive infections even in immunocompetent hosts.
• It underscores the importance of considering unusual pathogens in the differential diagnosis of abscesses and empyema.
• This report represents the first documented instance of L. lactis cremoris infection in Korea, expanding the known geographical distribution of such rare events.