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Endocarditis caused by Lactobacillus casei subspecies rhamnosus. A case report
W D Naudé1, A Swanepoel, R H Böhmer
1Department of Medical Microbiology, University of Cape Town.
Summary
Subacute endocarditis caused by Lactobacillus casei subspecies rhamnosus, a common oral bacterium, is rare. This case highlights the need to consider Lactobacillus in endocarditis with negative blood cultures.
Area of Science:
- Infectious Diseases
- Microbiology
- Cardiology
Background:
- Subacute bacterial endocarditis (SBE) is a serious infection affecting heart valves.
- Mitral incompetence is a known risk factor for endocarditis.
- Lactobacillus species are common oral commensals but rarely cause systemic infections.
Observation:
- A 66-year-old male presented with subacute endocarditis and mitral incompetence.
- Blood cultures were initially negative, including subcultures from a positive Bactec system.
- The causative organism was identified as Lactobacillus casei subspecies rhamnosus.
Findings:
- Lactobacillus casei subspecies rhamnosus, an oral commensal, was identified as the etiological agent.
- This specific type of endocarditis is notably rare despite the organism's prevalence.
- Diagnosis requires specific culture media and prolonged incubation (≥48 hours) for positive identification.
Implications:
- Lactobacillus species should be considered in the differential diagnosis of endocarditis, especially with negative blood cultures.
- Enhanced diagnostic protocols, including specialized media and extended incubation, are crucial for identifying rare pathogens.
- Understanding the factors contributing to the rarity of Lactobacillus endocarditis may inform future prevention and treatment strategies.