Infective Endocarditis (IE)

Clinical Considerations

Empiric treatment of IE is not recommended. A microbiologic diagnosis should be aggressively sought before therapy is started. Please consult with Infectious Diseases service if empiric therapy is being considered.

Choice of Antimicrobials

Indication for Therapy	Usual Causative Organisms	Antimicrobial Regimens
Streptococcal endocarditis (penicillin-susceptible strains)	Viridans group streptococci (S. sanguis, S. mitis, S. salivarius, S. mutans), Streptococcus bovis	Native Valve
		penicillin G sodium 12-18 MU IV divided q4-6h x 4-6 weeks
		cefTRIAXone 2 g IV/IM q24h x 4-6 weeks
		Shorter treatment duration (only with ID consultation): penicillin G sodium 12-18 MU IV divided q4-6h x 2 weeks OR cefTRIAXone 2 g IV/IM q24h x 2 weeks + gentamicin^* 1 mg/kg IV q8h x 2 weeks
		β-lactam allergy (anaphylaxis): vancomycin^† IV x 4 weeks
		Prosthetic Valve
		penicillin G sodium 24 MU IV divided q4-6h x 6 weeks +/- gentamicin^* 1 mg/kg IV q8h x 2 weeks
		cefTRIAXone 2 g IV/IM q24h x 6 weeks +/- gentamicin^* 1 mg/kg IV q8h x 2 weeks
		β-lactam allergy (anaphylaxis): vancomycin^† IV x 6 weeks
Staphylococcal endocarditis	Staphylococcus aureus (MSSA)	Native Valve
		cloxacillin 2 g IV q4h x 6 weeks
		ceFAZolin 2 g IV q8h x 6 weeks
		β-lactam allergy (anaphylaxis): vancomycin^† IV x 6 weeks
		Prosthetic Valve
		cloxacillin 2 g IV q4h x 6 weeks OR ceFAZolin 2 g IV q8h x 6 weeks + rifAMPin 300 mg PO q8h x 6 weeks + gentamicin^* 1 mg/kg IV q8h x 2 weeks
		β-lactam allergy (anaphylaxis): vancomycin^† IV x 6 weeks + rifAMPin 300 mg PO q8h x 6 weeks + gentamicin^* 1 mg/kg IV q8h x 2 weeks
Enterococcal endocarditis (penicillin, gentamicin and vancomycin susceptible strains)	Enterococcus spp.	Native Valve
		ampicillin 2 g IV q4h x 6 weeks + cefTRIAXone 2g IV q12h x 6 weeks
		ampicillin 2 g IV q4h x 4-6 weeks^‡ + gentamicin^* 1 mg/kg IV q8h x 4-6 weeks
		β-lactam anaphylaxis or resistant organism: vancomycin^† IV x 6 weeks + gentamicin^* 1 mg/kg IV q8h x 6 weeks
		Prosthetic Valve
		ampicillin 2 g IV q4h x 6 weeks + cefTRIAXone 2g iv q12h x 6 weeks
		ampicillin 2 g IV q4h x 6 weeks + gentamicin* 1 mg/kg IV q8h x 6 weeks
		β-lactam anaphylaxis or resistant organism: vancomycin^† IV x 6 weeks + gentamicin^* 1 mg/kg IV q8h x 6 weeks
Endocarditis caused by other pathogens	Coagulase-negative staphylococci, MRSA, Enterococcus (drug-resistant), HACEK species, fungi, culture-negative	Consult Infectious Diseases.

^* There is insufficient data for the use of high dose (once-daily) aminoglycosides in the treatment of IE. Target peak 3-4 mg/L, trough < 1 mg/L. Addition of gentamicin in IE caused by staphylococci in absence of prosthetic material is optional as clinical benefit of this practice has not been established.

^† Vancomycin - dose as per hospital guidelines. Target trough 13-20 mg/L.

^‡ Treat x 6 weeks if patient has had symptoms of illness for greater than 3 months.

References

AHA Scientific Statement. Infective Endocarditis: Diagnosis, Antimicrobial Therapy and Management of Complications. Circulation. 2005:11:e394-e433.
Ribera E, Gomez-Jimenez J, Cortes E et al. Effectiveness of cloxacillin with and without gentamicin in short-term therapy for right-sided Staphylococcus aureus endocarditis: a randomized, controlled trial. Ann Intern Med. 1996:125:969-74.
Fernandez-Hidalgo N, Almirante B, Gavalda J et al. Ampicillin plus ceftriaxone is as effective as ampicillin plus gentamicin for treating enterococcus faecalis infective endocarditis. Clin Infect Dis. 2013;56(9):1261-8.