Breakthrough bacteremia in the neonatal intensive care unit: Incidence, risk factors, and attributable mortality

Background: An episode of breakthrough bacteremia, which was defined as positive blood cultures despite appropriate antibiotic therapy, imposes a treatment challenge in the neonatal intensive care unit (NICU). Methods: All episodes of breakthrough bacteremia from a tertiary level NICU in Taiwan between 2004 and 2011 were analyzed and compared with nonbreakthrough bacteremia. Results: Breakthrough bacteremia was identified in 7.6% (72/942) of neonatal bacteremia, and 43 (59.7%) occurred as recurrent episodes. Gram-negative organisms (41.7%) and fungi (15.3%) accounted for more than half of all microorganisms in breakthrough bacteremia. Compared with nonbreakthrough bacteremia, breakthrough bacteremia was significantly associated with more severe disease, was more likely to require aggressive therapies, and had a higher rate of infectious complications. Previous use of broadspectrum antibiotics (odds ratio [OR], 7.54; P < .001) and particular microbial etiologies (Pseudomonas aeruginosa: OR, 4.40; P = .025; fungi: OR, 2.70; P = .013) were independent risk factors for developing breakthrough bacteremia. The crude sepsis-attributable mortality rate was greater in breakthrough bacteremia episodes (16.7% vs 6.4%; P = .004), and this condition was independently associated with an increased risk of death (OR, 2.14; 95% confidence interval, 1.04-4.40; P = .040). Conclusion: Breakthrough bacteremia is not uncommon (7.6% of all bacteremia) in NICUs and represents a more severe form of neonatal bacteremia that is independently associated with an increased risk of death.