From the Research
For a patient with Neisseria elongata bacteremia who has a mechanical aortic valve, even with negative TTE and TEE findings, I recommend treating for at least 6 weeks with intravenous antibiotics as presumed prosthetic valve endocarditis. The preferred regimen would be ceftriaxone 2g IV daily, or penicillin G 3-4 million units IV every 4 hours if the organism is highly susceptible, as seen in a case report where a patient recovered after six weeks of treatment with intravenous ceftriaxone and oral ciprofloxacin 1. N. elongata has a strong association with endocarditis, particularly in patients with prosthetic valves, and negative echocardiographic findings do not rule out endocarditis in this setting. Some key points to consider in the management of this condition include:
- The sensitivity of echocardiography for prosthetic valve endocarditis is limited, with false negatives occurring in up to 30% of cases.
- Given the high mortality risk of undertreating prosthetic valve endocarditis (20-40%) versus the relatively lower risk of extended antibiotic therapy, a full endocarditis treatment course is warranted.
- Blood cultures should be repeated to document clearance, and clinical monitoring for complications should continue throughout treatment.
- Infectious disease consultation is strongly advised to guide therapy and determine exact duration based on clinical response. Other studies have also reported successful treatment of N. elongata endocarditis with prolonged antibiotic therapy, ranging from 6 to 8 weeks 2, 3, 4. However, the most recent and highest quality study, which reported a case of infective endocarditis due to Neisseria elongata, supports the recommendation of at least 6 weeks of treatment 1. It's also worth noting that another study reported a case of mechanical aortic valve infective endocarditis caused by Neisseria sicca, which was successfully treated with 8 weeks of therapy 5, but this is not directly relevant to N. elongata. Overall, the recommendation for at least 6 weeks of treatment is based on the most recent and highest quality evidence available.