Skip to main content

Serratia marcescens Colonization in a Newly Opened Neonatal Intensive Care Unit, Riyadh, Saudi Arabia.


A new neonatal intensive care unit (NICU) opened in Riyadh Medical Complex, Riyadh, Saudi Arabia, in December 1993. Initially, extensive environmental microbiologic monitoring was done. Thereafter, end tubes and catheters removed from patients were cultured routinely. Beginning one month after the NICU opened, Serratia marcescens was isolated frequently from these routine cultures.


We conducted a retrospective cohort study on all 95 neonates admitted to the NICU in the first three months. We compared colonized neonates with non-colonized neonates according to their exposure to different medical interventions in the NICU.


There was one nurse for every two patients. The nurses were using unsterile water for oxygen chambers, suction and ventilator humidifiers. Unit dosing was not used for albumin or intralipid. Twenty-one (22%) neonates colonized the pathogen and six (28.5%) of those colonized were infected. Sixty-four percent of isolates were from the endotracheal tubes (ETT), and 83% of the intubated neonates were colonized. Other sites from which the pathogen was isolated included post-operative drainage tubes and catheters, blood, urine and wounds. The infection was in the form of septicemia (two cases), pneumonia (two cases) and urinary tract infection (two cases). Statistical tests: In the NICU, the relative risks (RR) for endotracheal intubation=9.18 (95% confidence interval [CI] 4.38-19.2); ventilation=6.1 (CI 2.22-16.75); nasogastric tubing=7.57 (CI 2.39-23.99); umbilical catheterization=3.15 (CI=1.56-6.31); lumbar puncture=2.77 (CI 1.34-5.72); and intravenous total parenteral nutrition=3.4 (CI 1.69-6.81). Other intravenous fluids and blood products did not result in increased RR.


Although a few cases had clinical infection, this is mainly an outbreak of colonization. The increased rate of isolation of the pathogen from routine cultures led to the exaggeration of the outbreak situation. Water used for humidifying respiratory equipment was contaminated, and inadequate hand-washing led to transmission of the organism to other equipment and patients. Isolation of the organism from the NICU stopped after the appropriate control measures were applied. Routine culturing of endotracheal tubes was not recommended.