Incidence and microbiological characteristics of neonatal late onset sepsis in a neonatal intensive care unit in Peru

•Neonatal late onset sepsis (LOS) in a neonatal intensive care unit in Peru.•Neonatal sepsis contributes significantly to neonatal morbidity and mortality.•Coagulase-negative Staphylococcus is the most common pathogen in LOS in our series.•Pseudomonas aeruginosa and Candida spp. have very high fatality in neonatal LOS. Our study aimed to determine the incidence of late onset sepsis and the most frequent microorganisms causing it in the neonatal unit at Hospital Cayetano Heredia in Lima, Peru. Descriptive and retrospective study. We reviewed all positive blood cultures and cultures of cerebrospinal fluid drawn from inborn patients beyond 72 h of life, admitted to the neonatal unit from January 2015 to December 2019. The incidence of late onset sepsis was 7.4% of admitted patients and 10.04 per 1000 live births. During our study period, 234 episodes of late onset sepsis occurred in 204 patients. The incidence was higher in very low birth weight infants, reaching 36.2% and even higher in extremely low birth weight infants (40.7%). Coagulase-negative Staphylococcus and then Klebsiella spp. were the most frequent causative microorganisms. The most frequent cause of late onset sepsis in very low birth weight infants was gram-negative bacteria (Klebsiella spp., was the most frequent causative microorganism). Late onset neonatal sepsis is prevalent in our neonatal unit. It is important to know which are the most prevalent causative microorganisms to be able to choose adequate antibiotic coverage and to design strategies to prevent infection.