Serratia marcescens Septicemia: An Outbreak in the Neonatal Unit of Al Yarmouk Teaching Hospital

Abstract

Serratia marcescens is a nosocomial pathogen, rod shaped gram negative bacteria in the family Enterobacteriaceae, involved in many outbreaks and endemic infections, especially in neonatal units, with significant mortality and morbidity. We had an outbreak of neonatal sepsis with this organism in our unit that took us three months to eradicate.Objective: To identify the source of infection, potential risk factors and the outcome associated with S. marcescens septicemia outbreak in our neonatal unit.Patients and methods: A case control study conducted during the outbreak period between December 2010 till the end of February 2011 at the Neonatal Unit of Al Yarmouk Teaching Hospital. S. marcescens was isolated from blood cultures of fifty neonates, controls were hundred and fifty neonates during the same period of the outbreak who showed no sign of sepsis and with negative blood cultures and were matched for gender, gestational age and birth weight. Hospital environmental investigation was also investigated. Data was analyzed using medical statistical software (MedCalc®v9.3.90,2008).Potential risk factors were assessed by calculating the Odds ratio (OR) with P value <0.5 was considered significant.Results: In the group suffering septicemia, male neonates were more prone to infection (P=0,003), timing of onset of symptoms of sepsis ranged from twenty four hours to forty eight hours (mean: 36.9±8.4),with a hospital stay duration of four to nineteen days (mean:12±3.5);while controls one to seventeen days (mean: 8±3.36). Risk factors significantly associated with S. marcescens sepsis were the infants weighing less than 1500 grams (Odds ratio(OR):1.92;95% CI:1.0-3.68),gestational age less than 33 weeks (OR:1.9;95% CI:0.94-3.51).Mortality rate was 15% in infected group compared to 5% in controls. Underlying maternal diseases showed 30% of the mothers had premature rupture of membranes, 11%had hypertension, 9% had twin pregnancy, and 4% suffered from diabetes mellitus. Hospital environmental cultures revealed the source of infection one delivery suite bathroom and a delivery couch as well as a soap dispenser in the operating rooms.Conclusion: Serratia marcescens infection causes a highly fatal septicemia in the low birth weight and the very preterm neonates, and as it was found to be a nosocomial pathogen it is preventable with proper and strict adherence to the universal precautions and hand hygiene measures as well as to control outbreaks.