What is the time-to-positivity of blood cultures in infective endocarditis?

Subculturing and Gram staining of blood cultures flagged negative by the BACTEC™ FX system: Optimizing the workflow for detection of Cryptococcus neoformans in clinical specimens

Objective

To investigate whether an incubation time of 5 days (Aerobic/F, Anaerobic/F) and 14 days (Myco/F) blood culture bottles is sufficient to prevent false-negative results.

Methods

We evaluated 1,244 blood bottles (344 patients) defined as negative by the BACTEC™ FX system. We also reviewed published cases and our own cases of bloodstream infection caused by Cryptococcus neoformans and simulated different scenarios, including different inoculation concentrations, bottle types, and clinical isolates.

Results

Two bottles (0.16%) were found to contain C. neoformans when subcultured and Gram stained. A 5-day protocol with Aerobic/F bottles was insufficient for the growth of C. neoformans in some cases, and C. neoformans grew better in Myco/F bottles than in Aerobic/F bottles.

Conclusion

Subculturing and Gram staining after a 5-day protocol were important for the detection of C. neoformans, and Myco/F bottles should be collected for the blood culture of C. neoformans.

[Better Late than Never - Fever of Unknown Origin in a Patient with a Prosthetic Valve]

Better Late than Never - Fever of Unknown Origin in a Patient with a Prosthetic Valve Abstract. A patient presents with worsening of his general condition, chills and dyspnoea on exertion. With a history of aortic valve replacement, infective endocarditis is suspected, but due to negative imaging by transesophageal echocardiography and negative blood cultures cannot be confirmed. Finally, Cutibacterium acnes prosthetic valve endocarditis is diagnosed after culture of C. acnes during an extended incubation period of blood cultures, the presence of embolic complications and a characteristic finding on PET-CT scan.

HACEK Infective Endocarditis at a Tertiary Children's Hospital

HACEK organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella species) are rare causes of endocarditis. HACEK organisms are fastidious and may escape detection by culture techniques, but the use of molecular studies may aid diagnosis. A 10-year review of pediatric HACEK endocarditis cases at Texas Children's Hospital identified 10 patients, with 2 cases recognized by next-generation sequencing, highlighting potential benefits of these assays.

WITHDRAWN: Application of Echocardiographic Information Technology in the Research of Infective Endocarditis and Its Neurological Complications

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