Gentamicin for the treatment of infective endocarditis
Gentamicin given once daily is recommended as part of the empirical therapy regimen for the following conditions to treat the possibility of gram-negative sepsis:
- native valve infective endocarditis
- prosthetic valve infective endocarditis
- cardiac implantable electronic device–associated endocarditis.
The empirical therapy regimen is used initially pending the results of blood culture. Gentamicin is the preferred aminoglycoside for empirical therapy of infective endocarditis because of its proven efficacy. Other aminoglycosides have less evidence in the treatment of infective endocarditis and clinical experience is lacking. If gentamicin is not available, amikacin or tobramycin may be initial alternatives for empirical therapy, to treat the possibility of gram-negative sepsis.
For confirmed streptococcal or enterococcal endocarditis, gentamicin is often continued for several weeks for synergistic therapy. For these types of endocarditis, these guidelines continue to recommend multiple-daily dosing of gentamicin.
Some international consensus-based guidelines recommend once-daily dosing of gentamicin for streptococcal and enterococcal endocarditis because of ease of administration and lower rates of nephrotoxicity compared with multiple-daily dosing. This recommendation is based on animal studies and small observational studies. It is the consensus view of the Antibiotic Expert Group that there is insufficient evidence to support routine once-daily dosing of gentamicin for the treatment of streptococcal or enterococcal endocarditis. However, once-daily gentamicin dosing (3 mg/kg) may have a role for patients receiving ambulatory antimicrobial therapy, particularly for patients with streptococcal endocarditis.
Monitor the gentamicin plasma concentration and regularly assess for nephrotoxicity, as well as vestibular and auditory toxicity, if gentamicin therapy is planned for longer than 48 hours – see Principles of aminoglycoside use.
The combination of gentamicin with vancomycin is recommended for synergistic therapy for various types of infective endocarditis. Combining gentamicin with vancomycin increases the risk of nephrotoxicity compared with using either drug alone; this risk must be considered on a case-by-case basis. For patients who have had a severe immediate1 hypersensitivity reaction to a penicillin, using a cephalosporin or performing desensitisation is preferred to using a prolonged course of vancomycin – seek expert advice.