Treatment of Infective Endocarditis Due to HACEK Gram-Negative Bacilli

Infective endocarditis caused by HACEK organisms is a clinically distinct scenario. Blood culture identification of the causative organism is central to guiding appropriate antibiotic selection.

Clinical scenario: Endocarditis attributed to one of the HACEK Gram-negative bacilli:

Haemophilus spp.
Aggregatibacter spp.
Cardiobacterium spp.
Eikenella corrodens
Kingella spp.

Treatment approach

The standard approach centres on a specific beta-lactam antibiotic as first-line therapy. Whether an alternative combination regimen is appropriate depends on beta-lactamase production by the causative organism. A fluoroquinolone is recognised as a less well-validated option in select cases. The complete structured regimen — including agent selection, duration, and native versus prosthetic valve considerations — is available in the full protocol.

Instant Access to Structured Evidence-Based Regimens

References

DOI: 10.1093/eurheartj/ehad193

The standard treatment is ceftriaxone 2 g/day for 4 weeks in NVE and for 6 weeks in PVE.

If they do not produce beta-lactamase, ampicillin (12 g/day i.v. in 4 or 6 doses) for 4–6 weeks plus gentamicin (3 mg/kg/day divided into 2 or 3 doses) for 2 weeks is an option.

Ciprofloxacin (400 mg every 8–12 h i.v. or 750 mg every 12 h orally) is a less well-validated alternative.

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