Neonatal Enterococcal Bacteremia: an Increasingly Frequent Event with Potentially Untreatable Pathogens

Background: Enterococci can cause serious infections in the newborn. The increased number of these infections since the late 1970s and the increased isolation of organisms resistant to many commonly used antimicrobials prompted review of our experience with enterococcal bacteremia in the neonatal intensive care unit. This review was aimed at defining the character of illness of newborns who had these infections during a 20-year period.

Methods: This was a retrospective review of the medical records of newborns with enterococci isolated from blood.

Results: Between January, 1974, and December, 1993, 138 episodes of enterococcal bacteremia occurred in newborns hospitalized in the neonatal intensive care unit. Thirty-four episodes occurred during the first decade and 104 episodes during the second decade. One hundred of the 138 episodes were reviewed. In 64% of these episodes other microorganisms were also isolated from blood. Comparison of clinical characteristics associated with these episodes in the first and second decade demonstrated that episodes occurring in the more recent decade occurred in older infants (mean age of onset, 44.7 vs. 16.1 days; episodes occurring after 14 days, 73% vs. 41%). Common characteristics associated with enterococcal bacteremia included the presence of a central vascular catheter (77%), necrotizing enterocolitis (33%) and abdominal distension (21%). Vancomycin-resistant enterococci caused bacteremia in 6 infants and caused illnesses indistinguishable from those caused by susceptible organisms.

Conclusions: In the more recent decade there were three times the number of episodes of enterococcal bacteremia in our neonatal intensive care unit than there were in the previous decade. The characteristics associated with these infections were similar to those occurring with other nosocomial bacterial infections in the neonate and did not change during the period reviewed. Most recent episodes occurred as part of polymicrobial infections in newborns hospitalized for more than 1 month. Infections caused by vancomycin-resistant enterococci occurred in older patients but were clinically indistinguishable from infections caused by sensitive organisms.