Early and Late Onset Neonatal Sepsis: Epidemiology and Effectiveness of Empirical Antibacterial Therapy in a III Level Neonatal Intensive Care Unit

Bloodstream infections play an important role in neonatal morbidity and mortality. In this study, we retrospectively analyzed etiology and antibiotic resistance profiles of bacteria isolated from blood or Cerebro Spinal Fluid (CSF) cultures to evaluate the appropriateness of initial empirical therapy of neonatal sepsis. Methods: microbiological data from patients admitted to Neonatal Intensive Care Unit (NICU), from January 2005 to October 2018, were anonymously extracted from the Laboratory of Microbiology database. According to the neonatal sepsis definition for patients admitted to NICU, positive cultures obtained within the first 72 h of life were labeled as Early Onset Sepsis (EOS); and Late Onset Sepsis (LOS) for those obtained later. Results: 859 bacterial strains, 846 from blood and 13 from CSF, were detected in 611 neonates. In EOS, 75 blood cultures were found: 61 yielded Gram-positives and 14 Gram-negatives. Coagulase Negative Staphylococci (CoNS) represented the majority (52% n = 39). Streptococcus agalactiae and Escherichia coli were both isolated in 8% (n = 6) of cases. 784 strains were isolated in LOS: 686 (87%) Gram-positives and 98 (13%) Gram-negatives. CoNS represented most pathogens (n = 560, 71.4%) followed by Staphylococcus aureus (n = 57, 7.3%) and Enterococcus faecalis (n = 33, 4.2%). Ampicillin/gentamicin therapy resulted effective in 15/20 (75%) of EOS isolates. Internal protocol for LOS initial empirical therapy, calling for piperacillin/tazobactam and vancomycin resulted effective in 98.5% (734/745) of LOS strains. Conclusions: knowledge of local epidemiology of resistant pathogens, both in EOS and LOS, is fundamental to set up an effective empirical therapy in NICU. Aminoglycosides were fundamental in EOS. On the other side, LOS empirical therapy with vancomycin is sustained by the observation of 38% of methicillin resistance among S. aureus and about 95% in CoNS.