Optimization of bacterial diagnosis yield after needle aspiration in immunocompetent adults with brain abscesses

Abstract

Objective: Brain abscesses (BA) are life threatening, even in immunocompetent patients, in part because microbiological diagnosis is often lacking and management is empirical. Recent epidemiological changes make it all the more important to have a precise microbiological diagnosis. Our purpose was to evaluate the efficacy of a strategy aimed at obtaining a microbiological diagnosis in immunocompetent patients presenting with suspected BAs.

Methods: We conducted a cohort study including all consecutive patients suspected of having BAs according to clinical, biological, and radiological findings. Severely immunocompromised patients were excluded. Aspiration was performed free-hand in patients with superficial abscesses (<1 cm depth from the cortical surface) and under stereotactic guidance in patients with deep-seated abscesses. Microbiological diagnosis was optimized, using the best aerobic and anaerobic growth conditions, blood culture bottles inoculated in the operating room, and molecular biology techniques if necessary. Antibiotic treatment was adapted according to the findings.

Results: Twenty-six patients were suspected of having BAs during the study period. Twenty-four patients benefited from aspiration (stereotactic puncture in 3 cases), which was safe, confirmed the diagnosis of BAs, and yielded microbiological diagnosis in all cases, even in those patients who had previously received antibiotics (n = 8; 33%). In 10 patients (42%), microbiological results led to a different choice in antibiotic therapy than the recommended empirical regimen.

Conclusion: Microbiological diagnosis can be obtained in all cases of BA. This is achieved by the conjunction of rapid needle aspiration and the optimization of microbiological diagnosis resulting from fast management of the surgical specimen, good anaerobic culture conditions, and the use of blood culture bottles and molecular biology techniques when appropriate. Moreover, it is of clinical and therapeutic interest when BAs are suspected in immunocompetent patients.