Epidemiology of Serratia Marcescens in the Neonatal ICU of A Tertiary Hospital in Oman over a 10 Years Period

Abstract

Background: Serratia marcescens has been described as a significant nosocomial organism. Several S. marcescens outbreaks in Neonatal Intensive Care Units (NICUs) were described as causing fatal meningitis, sepsis or pneumonitis in premature or low birth weight neonates with a mortality rate of 44%. The primary objective of this study is to describe the outcome (mortality and length of hospital stay) of S. marcescen s infection in NICU at a tertiary care hospital over ten years (2009 -2018). Secondary objectives are to describe the incidence of S. marcescens infection/colonization in NICU, study the risk factors associated with S. marcescens infection/colonization, and the microbiology of this organism. Method: A retrospective, unmatched case-control study was conducted between January 2009 to December 2018. Data were analyzed using IBM SPSS Statistics 28.0. A multivariate binary logistic regression analysis was performed to determine the independent predictors of Serratia marcescens and mortality among Serratia marcescens infected patients. The Odds Ratio (OR) was reported with its 95% CI. A P-value less than 0.05 was considered statistically significant. Result: A total of 93 cases had a positive culture of S. marcescens in neonates hospitalized in the NICU during the study period and 201 controls were included. 50.5% (n=47) of cases were male and 49.5% (n=46) were females. The clinical features of infection by S. marcescens range from asymptomatic colonization (16.1%) to potentially fatal sepsis (38.7%) and meningitis (1.1%). 13 cases (17.3 %) had colonization before infection. Mortality rate among infected neonates was 17%. Multivariate analysis showed that female gender (OR= 1.969, 95% CI= 1.020-3.801, P= 0.044), premature birth ((OR= 2.670, 95% CI= 1.156-6.167, P= 0.021). C-section (OR= 3.238, 95% CI= 1.591-6.591, P= 0.001), type of feeding and surgery (OR= 3.719, 95% CI= 1.546-8.946, P= 0.003) were independent predictors for acquiring S. marcescens . Female gender was an independent factor for mortality from Serratia infection (OR= 6.741, 95% CI= 1.307-34.767, P= 0.023). Conclusion: S. marcescens is an important pathogen that has a propensity to cause difficult-to-control outbreaks in NICUs. Healthcare workers' awareness of this organism and enhancement of infection prevention and control measures is a vital requirement to prevent HAIs among susceptible neonates.