Persistent bacteremia and outcome in late onset infection among infants in a neonatal intensive care unit

Background Persistent bacteremia despite antibiotic therapy has been correlated with adverse outcomes, including focal suppurative complications and death. Coagulase-negative staphylococci (CONS) are the most common cause of nosocomial infection in infants requiring neonatal intensive care and might yield more substantial pathology if infection were persistent. Methods. To compare the severity and features of persistent infection by CONS with those of other bacteria, we reviewed infants admitted to our neonatal intensive care unit from 1990 through 2001 who developed bacteremia at >5 days of age with recovery of the same bacterial species from blood for >24 h after initiation of antibiotic therapy to which the organism was susceptible. Cases were excluded if a focal complication was already present with the initial positive culture or if the medical record was unavailable. Outcomes of interest included focal suppurative complications, death attributable to infection and duration of hospitalization among survivors. Results. We identified 62 infants with sustained infection, caused by CONS in 30 and by other organisms in 32 [10 Gram-negative, 22 Gram-positive (16 Staphylococcus aureus)]. Infants with persistent CONS had significantly lower birth weight and gestational age, but no difference was found for multiple other clinical and demographic risk factors. Indwelling vascular catheters were present at diagnosis in 85% of the infants (CONS 26 of 30, non-CONS 27 of 32). Responses of bacteremia to catheter removal vs. in situ treatment did not differ between the groups. No differences were observed for death from all causes (27 vs 34%), death attributable to infection (6 vs. 12%) or duration of hospitalization among survivors [median (interquartile range): 102 (73 to 167) vs. 107.5 (89 to 130) days]. Focal suppurative complications were significantly more frequent in infants persistently infected with non-CONS (28 vs. 3%; P = 0.01). Duration of persistence correlated with focal complication in non-CONS infants (r = 0.988; P < 0.001). Conclusions. Although persistent infection with CONS occurs in significantly smaller and less mature infants than with non-CONS, death is no more frequent and focal complications are significantly less frequent. Infants with persistent infection should undergo aggressive evaluation for focal complications, with the yield expected to be higher in those with non-CONS.