Serratia Marcescens Bacteremia Characteristics in a Tertiary Children’s Medical Center

Background: Serratia marcescens is the leading human pathogenic species amongst the Serratia genus. It may lead to healthcare-associated infections amongst children, causing 3.3% of bloodstream infections in intensive care units according to the 2016 European Surveillance System. Despite its rising frequency, data regarding risk factors and clinical characteristics is lacking.

Methods: A retrospective study was conducted: The microbiology database of a tertiary children`s hospital was queried for Serratia marcescens positive blood cultures between January 2007 to May 2020. The patients’ demographic, clinical and microbial characteristics were collected and analyzed.

Results: Eighty-five patients were identified of which 81 patient files were accessible. Ages ranged from 4 days to 16.5 years, median age was 78 days. In-hospitalisation mortality rate was 25.9%. Sixty five (80%) were hospitalized in intensive care units. Ninety-five percent of all cases had underlying conditions including prematurity, congenital cardiac defects, chronic illnesses or malignancies. Prior to bloodstream infection, 61.7% of patients underwent interventional procedures. Thrombocytopenia and elevated C-reactive protein levels were found in the majority of children. The most common empiric treatment regimen included piperacillin/tazobactam (62.3%). Twenty-eight children received either piperacillin/tazobactam or cephalosporin in monotherapy as final treatment. Results showed similar survival rates in both groups (84.6%).

Conclusion: Risk factors for bloodstream infections include prematurity, congenital heart disease, chronic disease, central lines, respiratory support and surgical interventions. Mortality is associated with hospitalization in intensive care units and thrombocytopenia (p<0.05). Survival rates are similar following treatment with a third generation cephalosporin as with piperacillin-tazobactam.