Standard regimens for endocarditis caused by the HACEK group
Susceptibility testing is difficult in the majority of HACEK group strains because they are fastidious, and many also produce beta-lactamase enzymes.
Treat native and prosthetic valve endocarditis caused by HACEK group strains that produce beta-lactamase enzymes, or strains for which susceptibility testing is difficult, as if they are penicillin-resistant. For these patients, broad-spectrum cephalosporins are the treatment of choice. In adults and children, use:
1ceftriaxone 2 g (child 1 month or older: 50 mg/kg up to 2 g) intravenously, daily for 4 to 6 weeks. For patients with septic shock or requiring intensive care support, use 1 g (child 1 month or older: 50 mg/kg up to 1 g) intravenously, 12-hourly ceftriaxone ceftriaxone ceftriaxone
OR
1cefotaxime 2 g (child: 50 mg/kg up to 2 g) intravenously, 8-hourly for 4 to 6 weeks. For patients with septic shock or requiring intensive care support, use 2 g (child: 50 mg/kg up to 2 g) intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see cefotaxime dosage adjustment. cefotaxime cefotaxime cefotaxime
Pharmacokinetics may be altered in patients who are critically ill (eg because of enhanced kidney clearance or changes in volume of distribution). To ensure adequate drug exposure in patients with endocarditis caused by the HACEK group who have septic shock or require intensive care support, modified dosages of ceftriaxone and cefotaxime are recommended. Once the critical illness has resolved, consider switching to the standard dosage. If the isolate is not reported to have dose-dependent susceptibility to ceftriaxone or cefotaxime (ie susceptible dose dependent [SDD] or susceptible increased exposure [I or SIE]), it may also be appropriate to switch to the standard dose – seek expert advice.
Treat adults and children with endocarditis caused by HACEK group strains that are clearly susceptible to penicillin and are beta-lactamase negative with:
benzylpenicillin 2.4 g (child: 60 mg/kg up to 2.4 g) intravenously, 4-hourly for 4 to 6 weeks. For dosage adjustment in adults with kidney impairment, see benzylpenicillin dosage adjustment. benzylpenicillin benzylpenicillin benzylpenicillin
Duration of therapy for native valve endocarditis is usually 4 weeks. Prosthetic valve endocarditis requires 6 weeks of therapy, and surgery is often required.
For complicated cases of native valve or prosthetic valve endocarditis, the addition of gentamicin is sometimes required for synergy in the first 2 weeks – seek expert advice.