Enterococcal endocarditis complicated with ruptured infected-intracranial aneurysm: With pharmacokinetic-pharmacodynamic documentation in proof of the successful antimicrobial treatment

A 74-year-old man presented with sudden onset of aphasia and apraxia. Magnetic resonance image (MRI) of the brain disclosed a left frontal hemorrhage. The concomitant low grade fever suggestive of infection was unresponsive to cefazolin 1 g q12h, and refractory to piperacillin (PIPC) 2 g q8h. Blood culture grew enterococci, establishing together with echocardiography the diagnosis of infective endocarditis. The angiography revealed cerebral hemorrhage to have resulted from the rupture of the infected intracranial aneurysm. The antimicrobial therapy was switched to ampicillin (ABPC) 2 g q4h plus gentamicin (GM) 60 mg q8h. The positive blood culture was subsequently identified Enterococcus faecium to which the minimum inhibitory concentration (MIC) of PIPC, and ABPC was 16 mcg/mL, and 4 mcg/mL, respectively. The peak concentration of serum ABPC was 83.1, median 50.8, and trough 25.8 mcg/mL. Thus, the percent time > MIC for ABPC was 100%, and the time > minimum bactericidal concentration (MBC) as well. On the other hand, time > MIC for PIPC, was found nearly 30% in retrospective analysis using population pharmacokinetics. The neurological deficit of the patient was completely restored to the normal status after 4-weeks' antimicrobial therapy with ABPC plus GM, then he underwent cardiac surgery for valvular replacement, where microbiological culture of the resected valve was negative. The constellation of the clinical, pharmacological and microbiological outcome in our case provides scientific evidence that the antibiotic therapy given to our case is the best available strategy as an antimicrobial treatment of severe enterococcal endocarditis complicated by disseminated lesion as infected intracranial aneurysm.