2460. Hospital-Wide Outbreak of Serratia marcescens of Unclear Source: When Extensive Infection Control Measures Are Needed

BACKGROUND: Nosocomial outbreaks of Serratia marcescens have been widely reported and the source is identified in most cases. We report a Serratia marcescens outbreak in a community hospital with no obvious source. METHODS: An epidemiologic investigation was started after an outbreak was suspected. Clinical data were collected from charts of patients with positive culture for Serratia marcescens. Molecular relatedness of available isolates was determined by pulsed-field gel electrophoresis. RESULTS: Between December 2016 and August 2017, 13 non-pigmented Serratia marcescens isolates were identified from 11 patients. Bacteria were isolated from blood, abdominal and respiratory cultures. Susceptibility profiles showed variable resistance to ceftriaxone, ceftazidime, imipenem, tobramycin and aztreonam. Infection control measures: Isolates were identified from adult patients who underwent various cardiothoracic/vascular surgeries. Patients were traced back to a single floor of the new hospital building. To control this outbreak, the infection prevention team started with hand hygiene initiatives and observations, environmental sampling, and reviewing management of ventilator, dialysis equipment, and ECMO machines. Ice machine carbonless filters were installed, UV disinfection systems were used, and new TEE cleaning rooms were designated. In conjunction with recommendations of department of health, hospital was contracted with a water cleaning company; laminar flow aerators were installed, water sampling plan was implemented and ultimately the whole building’s water system was hyper-chlorinated. CONCLUSION: While water contamination was the most likely source, a specific cause could not be identified. An important lesson learnt is the quick implementation of infection control measures after identifying infected patients is key in controlling an outbreak. DISCLOSURES: All authors: No reported disclosures.