Comparison of patients with enterococcal bacteremia due to strains with and without high-level resistance to gentamicin.

Patients with enterococcal bacteremia due to strains with and without high-level gentamicin resistance (HLGR; MIC, > 2,000 mg/L) were compared. Between 1986 and 1991, there were 178 episodes of enterococcal bacteremia: 47 and 131 episodes, respectively, due to enterococcal strains with and without HLGR. Sixty-two, 57, and 59 episodes, respectively, were in patients with transient bacteremia (a single positive blood culture), bacteremia (two or more positive blood cultures), and polymicrobial bacteremia. Nosocomial bacteremia accounted for 61.7% and 51.1% of episodes due to strains with and without HLGR, respectively. All isolates were strains of Enterococcus faecalis except for 13 strains of Enterococcus faecium, 4 of Enterococcus avium, and 3 of Enterococcus durans. Although the mortality was slightly higher among patients infected with strains with HLGR than among those infected with strains without HLGR (38.3% vs. 30.5%, respectively), there was no statistical difference. The mortality rate was adversely affected by old age (P < .01) and rapidly and ultimately fatal underlying conditions (P < .001). The addition of gentamicin to the treatment regimens had no effect on mortality.