Outbreak Of Serratia Marcescens Research Articles

Serratia marcescens outbreak in a neonatal intensive care unit associated with contaminated handwashing sinks

This article describes the origin of a S. marcescens outbreak in a neonatal intensive care unit (NICU). A retrospective case-control study including 12 S. marcescens-positive and 22 S. marcescens-negative neonates in the NICU was performed to identify the source of the outbreak. S. marcescens isolates were collected during the outbreak and analyzed using whole-genome sequencing (WGS). IQ-Tree software, BEAST2 software package and SCOTTI software were used to construct a phylogenetic tree and a propagation path map. The index case occurred on February 21st and outbreak ended on March 9th, 2021, affecting a total of 12 neonates (2 with S. marcescens infection and 10 with S. marcescens colonization). Multivariate logistic regression identified that the distance of <0.8 m between the bed unit and the sink (odds ratio [OR], 20.50; 95% confidence interval [CI], 1.09-384.86), a large number of rotating nurses within a week (OR 2.58, 95% CI, 1.09-6.11) and use of humidification water in the incubator (OR 189.70, 95% CI, 2.76-13027.31) were significantly increased risk factors for S. marcescens infection or colonization in the outbreak. WGS sifted out a predominant clone between contaminated handwashing sinks and patients, suggesting that cross-transmission was involved in the dissemination of S. marcescens. Contaminated handwashing sinks can be a communication intermediary of S. marcescens infection of colonization of neonates in the NICU. A distance of <0.8 m between the bed unit and the sink, and a large number of rotating nurses might play important roles in this outbreak. Attention should be paid to sinks contamination and contact transmission to prevent outbreaks.

Within-host transition to GES-55 during a GES-6-producing Serratia marcescens outbreak: Emergence of ceftazidime-avibactam resistance and increased susceptibility to carbapenems

To describe the in vivo emergence of ceftazidime-avibactam resistance in GES-type carbapenemases and to characterize an unusual outbreak of GES-6-producing Serratia marcescens during the COVID-19 pandemic in Spain. Retrospective study to describe a GES-CPSM outbreak based on whole genome sequencing and antimicrobial susceptibility testing (AST). Transferability of blaGES-carrying plasmid was assessed by conjugation experiments. In December 2020, we identified a cluster of S. marcescens harbouring blaGES-6 involving 9 patients. Whole-genome sequence analysis revealed a clonal relationship (≤3 SNPs) between the first isolates identified in each of the evolved patients and environmental samples with GES-CPSM detection. Plasmid analysis showed that the blaGES-6 gene was located in an IncQ3-type plasmid. Triparental mating experiments using a helper plasmid demonstrated mobilization of the blaGES-6-carrying plasmid. Our results also demonstrate within-host evolution in S. marcescens isolates, leading to a transition from blaGES-6 to the new blaGES-55, caused by the P162S mutation, in a subsequent infection in one of the affected patients. In blaGES-55 we identified emergence of ceftazidime-avibactam resistance along with an increase of carbapenems susceptibility. This patient had been treated with a 14-day course of ceftazidime-avibactam. AST of the transformants bearing blaGES-6 and blaGES-55 plasmids, confirmed susceptibility variation affecting ceftazidime-avibactam and carbapenems. We report an unusual outbreak of GES-6 whose incidence is becoming increasing. Transition from GES-6 to GES-55 may readily occur in vivo leading to ceftazidime-avibactam resistance, which brings to the fore the critical need for developing more accurate diagnosis tools for detection of GES β-lactamases and optimise the use of antimicrobials.

Implications of ad-hoc molecular typing for infection control measures in a multi-cluster, multi-phenotypic Serratia marcescens outbreak in a neonatal intensive care unit

Serratia marcescens is known to cause outbreaks in Neonatal Intensive Care Units (NICU). Traditionally epidemiological data, antimicrobial resistance patterns and epidemiological typing are being used to guide infection prevention methods. Whole genome sequencing (WGS) applications such as core-genome multi-locus sequence typing (cgMLST) applied during an outbreak would potentially give more detailed information on the source and spread of bacteria enabling more efficient control measures. CgMLST was used during an S. marcescens outbreak at a NICU. Neonates admitted to the NICU of the Leiden University Medical Center (LUMC) during an outbreak between September 2023-January 2024, with S. marcescens being cultured were included. Environmental samples were taken to search for a common source, antibiotic susceptibility testing was performed, and antimicrobial resistances genes were analysed. S. marcescens strains from 17 of the 20 positive patients were available for molecular typing. The cgMLST scheme revealed five different complex types consisting of four separate clusters. Multiple clusters made an unidentified persistent environmental source as cause of the outbreak less likely, leading to a quick downscaling of infection prevention measures. Differences were shown in aminoglycoside resistance patterns of isolates within the same complex types and patients. The use of ad-hoc cgMLST provided timely data for rational decision making during an S. marcescens outbreak at the NICU. Antibiotic phenotyping alone was found not to be suitable for studying clonal spread during this outbreak with S. marcescens.

Hospital water environment and antibiotic use: key factors in a nosocomial outbreak of carbapenemase-producing Serratia marcescens

BackgroundThe healthcare water environment is a potential reservoir of carbapenem-resistant organisms (CROs). Here, we report the role of the water environment as a reservoir and the infection control measures applied to suppress a prolonged outbreak of Klebsiella pneumoniae carbapenemase-producing Serratia marcescens (KPC-SM) in two intensive care units (ICUs). MethodsThe outbreak occurred in the ICUs of a tertiary hospital from October 2020 to July 2021. Comprehensive patient contact tracing and environmental assessments were conducted, and a case–control study was performed to identify factors associated with the acquisition of KPC-SM. Associations among isolates were assessed via pulsed-field gel electrophoresis (PFGE). Antibiotic usage was analyzed. . ResultsThe outbreak consisted of two waves involving a total of 30 patients with KPC-SM. Multiple environmental cultures identified KPC-SM in a sink, a dirty utility room, and a communal bathroom shared by the ICUs, together with the waste bucket of a continuous renal replacement therapy (CRRT) system. The genetic similarity of the KPC-SM isolates from patients and the environment was confirmed by PFGE. A retrospective review of 30 cases identified that the use of CRRT and antibiotics were associated with acquisition of KPC-SM (p < 0.05). There was a continuous increase in the use of carbapenems; notably, the use of colistin has increased since 2019. ConclusionOur study demonstrates that CRRT systems, along with other hospital water environments, are significant potential sources of resistant microorganisms, underscoring the necessity of enhancing infection control practices in these areas.

Rapid management of Serratia marcescens outbreak in neonatology unit in Singapore: Risk factors and infection control measures

We describe the investigations for control of two consecutiveSerratia marcescensoutbreaks inneonatology unit of Singapore General Hospital. Epidemiological investigations, environmental sampling and risk-factors analysis were performed to guide infection control measures. Active surveillance sampling of nasopharyngeal aspirate and/or stool from neonates was conducted during both outbreaks. Whole-genome-sequencing was done to determine clonal links. Retrospective case-control study was conducted for second outbreak to identify risk factors for S marcescens acquisition. In 2022, two genetically unrelated S marcescens outbreaks were managed involving five neonates in March 2022 (outbreak 1) and eight neonates in November 2022 (outbreak 2). A link to positive isolates from sinks in intensive care units and milk preparation room was identified during outbreak 1. Neonatal jaundice (aOR, 16.46; p-value= 0.023) and non-formula milk feeding (aOR, 13.88; p-value= 0.02) were identified as risk factors during second outbreak. Multiple interventions adopted were cohorting of positive cases, carriage-screening, enhanced environmental cleaning, and emphasis on alcohol-based handrubs for hand-hygiene. The two outbreaks were likely due to infection prevention practices lapses and favourable environmental conditions. Nosocomial S marcescens outbreaks in neonatology units are difficult to control and require multidisciplinary approach with strict infection prevention measures to mitigate risk factors.

Outbreak of Invasive Serratia marcescens among Persons Incarcerated in a State Prison, California, USA, March 2020-December 2022.

Serratia marcescens is an environmental gram-negative bacterium that causes invasive disease in rare cases. During 2020-2022, an outbreak of 21 invasive Serratia infections occurred in a prison in California, USA. Most (95%) patients had a history of recent injection drug use (IDU). We performed whole-genome sequencing and found isolates from 8 patients and 2 pieces of IDU equipment were closely related. We also identified social interactions among patients. We recovered S. marcescens from multiple environmental samples throughout the prison, including personal containers storing Cell Block 64 (CB64), a quaternary ammonium disinfectant solution. CB64 preparation and storage conditions were suboptimal for S. marcescens disinfection. The outbreak was likely caused by contaminated CB64 and propagated by shared IDU equipment and social connections. Ensuring appropriate preparation, storage, and availability of disinfectants and enacting interventions to counteract disease spread through IDU can reduce risks for invasive Serratia infections in California prisons.

Outbreak of Serratia marcescens in the Neonatal Intensive Care Unit of a Tertiary Care Hospital in Mexico.

We describe an outbreak of Serratia marcescens (S. marcescens) infection in the neonatal intensive care unit at Women's Hospital in Sinaloa, Mexico. In April 2021, an outbreak of S. marcescens infection was identified. A case was identified as any patient who tested positive for S. marcescens and showed signs of an infectious process. S. marcescens was isolated from the blood cultures of 15 neonates with clinical signs of neonatal sepsis. Statistical analysis showed that all neonates had an invasive medical device. The problem was controlled after hospital hygiene and sanitation measures were strengthened. The study provides evidence of an outbreak of nosocomial bacteremia due to the cross-transmission of S. marcescens. The findings highlight the need for hospitals to implement strict hygiene measures, especially regarding hand washing, to prevent future outbreaks.

Serratia marcescens Outbreak at a Correctional Facility: Environmental Sampling, Laboratory Analyses and Genomic Characterization to Assess Sources and Persistence.

Serratia marcescens is an environmental bacterium and clinical pathogen that can cause an array of infections. We describe an environmental sampling and comparative genomics approach used to investigate a multi-year outbreak of S. marcescens at a correctional facility. Whole genome sequencing analysis revealed a predominant cluster of clonally related S. marcescens from nine patient cases and items associated with illicit drug use. Closely related strains found among items associated with case-patient cells and diluted Cell Block 64 (CB64), a quaternary ammonium disinfectant, and Break Out (BO), a multipurpose cleaner, highlighted their role as environmental reservoirs for S. marcescens in this outbreak. Comparative genomic analysis suggested outbreak strains were both persistent (identical strains found over long periods and in multiple locations of the correctional facility) and diverse (strains clustered with multiple global samples from NCBI database). No correlation was found between antimicrobial resistance (AMR) genes of outbreak strains; NCBI strains have more AMR genes. Principal component analysis (PCA) of virulence factors associated with persistence and infectivity indicated variation based on phylogroups, including the predominant cluster; identifiable variations among environmental versus clinical strains were not observed. Identification of multiple distinct genetic groups highlights the importance of putting epidemiological genomic studies in a proper genetic context.

Brote nosocomial causado por Serratia marcescens en una unidad de cuidados intensivos neonatal de un hospital regional. Análisis y propuestas de mejora

ObjectivesSerratia marcescens may cause nosocomial outbreaks in neonatal intensive care units. We describe an outbreak of Serratia marcescens in a neonatal intensive care unit and propose additional prevention and control recommendations. MethodsBetween March 2019 and January 2020, samples were taken from patients in the neonatal intensive care unit (rectal, pharyngeal, axillary and other locations) and from 15 taps and their sinks. Control measures were implemented including thorough cleaning of incubators, health education to staff and neonates’ relatives, and use of single-dose containers. PFGE was performed in 19 isolates from patients and in 5 environmental samples. ResultsFrom the first case in March 2019 to the detection of the outbreak, a month elapsed. Finally, 20 patients were infected and 5 colonized. Eighty percent of infected neonates had conjunctivitis, 25% bacteremia, 15% pneumonia, 5% wound infection, and 5% urinary tract infection. Six neonates had 2 foci of infection. Among the 19 isolates studied, 18 presented the same pulsotype and only one of the isolates from the sinkhole showed a clonal relationship with those of the outbreak. Initial measures established were ineffective to control the outbreak and were implemented with exhaustive cleaning, use of individual eye drops, environmental sampling and changing sinks. ConclusionThis outbreak presented a high number of neonates affected due to its late detection and torpid evolution. The microorganisms isolated from the neonates were related to an environmental isolate. Additional prevention and control measures are proposed, including routine weekly microbiological sampling.

Outbreak of extensively drug-resistant Serratia marcescens in an intensive care unit.

We present the investigation and control of an extensively drug-resistant Serratia marcescens outbreak in a 30-bed intensive care unit (ICU). Within 6 weeks, 4 critically ill trauma patients were infected by the same strain. Intensive containment measures limited the spread of this strain while sustaining the capacity of the trauma ICU.

Serratia marcescens outbreak in a neonatal intensive care unit associated with contaminated donor milk.

Investigation of the origin of a Serratia marcescens outbreak in a neonatal intensive care unit. Retrospective case-control study. Regional level 3 perinatal center in Germany. This study included 4 S. marcescens-positive and 19 S. marcescens-negative neonates treated between February 1 and February 26, 2019, in the neonatal intensive care unit. A case-control study was performed to identify the source of the outbreak. The molecular investigation of S. marcescens isolates collected during the outbreak was performed using pulsed-field gel electrophoresis and next-generation sequencing. The retrospective case-control study showed a significant correlation (P < .0001) between S. marcensens infection or colonization and consumption of donor milk that had tested negative for pathogenic bacteria from a single breast milk donor. Pulsed-field gel electrophoresis and next-generation sequencing retrospectively confirmed an S. marcescens strain isolated from the breast milk of this donor as the possible origin of the initial outbreak. The outbreak was controlled by the implementation of an infection control bundle including a multidisciplinary infection control team, temporary nutrition of infants with formula only and/or their mother's own milk, repeated screening of all inpatients, strict coat and glove care, process observation, retraining of hand hygiene and continuous monitoring of environmental cleaning procedures. Low-level contaminated raw donor milk can be a source of infection and colonization of preterm infants with S. marcescens even if it tests negative for bacteria.

Successful control of Serratia marcescens outbreak in a neonatal unit of a tertiary-care hospital in Spain

ObjectiveSerratia marcescens is a Gram-negative bacterium that is found in hospital environments and commonly associated with outbreaks in neonatal units. One S. marcescens isolate was detected from a bloodstream culture from a neonate in our hospital that was followed by an outbreak. The aim of this study was to describe the molecular epidemiology of a S. marcescens outbreak in the neonatal unit. MethodsIn order to investigate the outbreak, weekly surveillance rectal swabs were submitted for culture from all patients admitted in this unit from August to September 2018. Environmental samples were obtained from potential sources in September 2018. Typing of isolates was performed by pulsed field gel electrophoresis (PFGE). In addition, we studied the in vitro activity of chlorhexidine against S. marcescens. ResultsDuring this period, 146 infants were hospitalised in our neonatal unit, of which 16 patients had a S. marcescens-positive sample. A total of 36 environmental surveillance samples were collected, and one sample from a stethoscope from an incubator of a colonized baby was positive for S. marcescens. All the 18 isolates, including the isolate from the stethoscope, belonged to a single PFGE cluster. We found that very low concentrations of chlorhexidine, even with application times close to 0 achieved significant reductions in the amount of S. marcescens. ConclusionA unique clone of S. marcescens caused this outbreak, including isolates from patients and from one stethoscope. The outbreak was controlled with the early implementation of specific control measures.

Prompt control of a Serratia marcescens outbreak in a neonatal intensive care unit informed by whole-genome sequencing and comprehensive infection control intervention package.

This report describes a cluster of patients infected by Serratia marcescens in a metropolitan neonatal intensive care unit (NICU) and a package of infection control interventions that enabled rapid, effective termination of the outbreak. Cross-sectional analytical study using whole-genome sequencing (WGS) for phylogenetic cluster analysis and identification of virulence and resistance genes. NICU in a metropolitan tertiary-care hospital in Sydney, Australia. All neonates admitted to the level 2 and level 3 neonatal unit. Active inpatient and environmental screening for Serratia marcescens isolates with WGS analysis for identification of resistance genes as well as cluster relatedness between isolates. Planning and implementation of a targeted, multifaceted infection control intervention. The cluster of 10 neonates colonized or infected with Serratia marcescens was identified in a metropolitan NICU. Two initial cases involved devastating intracranial infections with brain abscesses, highlighting the virulence of this organism. A targeted and comprehensive infection control intervention guided by WGS findings enabled termination of this outbreak within 15 days of onset. WGS examination demonstrated phylogenetic linkage across the cluster, and genomic unrelatedness of later strains identified in the neonatal unit and elsewhere. A comprehensive, multipronged, infection control package incorporating close stakeholder engagement, frequent microbiological patient screening, environmental screening, enhanced cleaning, optimization of hand hygiene and healthcare worker education was paramount to the prompt control of Serratia marcescens transmission in this neonatal outbreak. WGS was instrumental in establishing relatedness between isolates and identification of possible transmission pathways in an outbreak setting.

Phenotypic and genotypic characteristics of a carbapenem-resistant Serratia marcescens cohort and outbreak: describing an opportunistic pathogen

Serratia marcescens is an emerging opportunistic pathogen with high genetic diversity. This article describes the microbiological characteristics of isolates and the risk factors for infections caused by carbapenem-resistant S. marcescens. A retrospective study of patients colonized (n=43) and infected (n=20) with carbapenem-resistant S. marcescens over a 3-year period was conducted. Polymerase chain reaction for carbapenemase genes and molecular typing of all available strains was performed. Forty-two isolates were analysed, including three environmental samples identified during an outbreak. Thirty-five carbapenem-resistant S. marcescens carried blaKPC-2, one isolate was blaNDM-positive and four isolates carried blaOXA-101. The genomes were grouped into three clusters with 100% bootstrap; three patterns of mutations on ompC and ompF were found. The strains carried virulence genes related to invasion and haemolysis, and the environmental strains presented fewer mutations on the virulence genes than the clinical strains. Multi-variate analysis showed that previous use of polymyxin (P=0.008) was an independent risk factor for carbapenem-resistant S. marcescens infection. This study highlighted that blaKPC-2 in association with ompC or ompF mutation was the most common mechanism of resistance in the study hospital, and that previous use of polymyxin was an independent risk factor for carbapenem-resistant S. marcescens. There was a predominant clone, including the environmental isolates, suggesting that cross-transmission was involved in the dissemination of this pathogen.

Serratia marcescens outbreak in a COVID-19 intensive care unit – Are there any factors specific to COVID-19 units that facilitate bacterial cross-contamination between COVID-19 patients?

COVID-19 dedicated units were created early in the pandemic. Despite their need, factors specific to these units can possibly increase the risk of bacterial cross-contamination between COVID-19 patients. We report a Serratia marcescens outbreak in a COVID-19 intensive care unit, later discussing factors specific to COVID-19 units that may facilitate bacterial cross-contamination in such units, and raising awareness for such an issue.

Successful control of Serratia marcescens outbreak in a neonatal unit of a tertiary-care hospital in Spain

ObjectiveSerratia marcescens is a Gram-negative bacterium that is found in hospital environments and commonly associated with outbreaks in neonatal units. One S. marcescens isolate was detected from a bloodstream culture from a neonate in our hospital that was followed by an outbreak. The aim of this study was to describe the molecular epidemiology of a S. marcescens outbreak in the neonatal unit. MethodsIn order to investigate the outbreak, weekly surveillance rectal swabs were submitted for culture from all patients admitted in this unit from August to September 2018. Environmental samples were obtained from potential sources in September 2018. Typing of isolates was performed by pulsed field gel electrophoresis (PFGE). In addition, we studied the in vitro activity of chlorhexidine against S. marcescens. ResultsDuring this period, 146 infants were hospitalised in our neonatal unit, of which 16 patients had a S. marcescens-positive sample. A total of 36 environmental surveillance samples were collected, and one sample from a stethoscope from an incubator of a colonized baby was positive for S. marcescens. All the 18 isolates, including the isolate from the stethoscope, belonged to a single PFGE cluster. We found that very low concentrations of chlorhexidine, even with application times close to 0 achieved significant reductions in the amount of S. marcescens. ConclusionA unique clone of S. marcescens caused this outbreak, including isolates from patients and from one stethoscope. The outbreak was controlled with the early implementation of specific control measures.

Serratia marcescens outbreak in a neonatal intensive care unit and the potential of whole-genome sequencing

Serratia marcescens is notorious for its increasing antimicrobial resistance and potential to cause outbreaks in neonatal intensive care units (NICUs). A promising tool in outbreak investigations is whole-genome sequencing (WGS). To describe a S.marcescens outbreak (2018-2019) in an NICU and discuss which infection control measures contributed to containment, addressing the potential of WGS. S.marcescens isolates from patients and the environment isolated during the 2018-2019 NICU outbreak were analysed. In comparison, isolates from previous presumed NICU outbreaks and adult blood cultures were included. WGS and whole-genome multi-locus sequence typing analysis were performed. Sixty-three S.marcescens isolates were analysed. The 2018-2019 outbreak was divided into three clusters, including four environmental strains (drains, N=3; baby scale, N=1). The strains differed significantly from those of an NICU outbreak in 2014 and adult blood cultures. Besides standard infection control measures, the siphons were replaced and weekly decontamination was performed with acetic acid 10%. Seven acquired-resistance genes and 29 virulence-associated genes were detected. It was assumed that both neonates and drains were reservoirs of S.marcescens cross-contamination via the hands of healthcare workers and parents. Initially, standard measures, including hand hygiene, were reinforced. However, definitive containment was achieved only after replacement of the siphons and weekly decontamination with acetic acid. WGS enables faster recognition of an outbreak with accurate mapping of the spread, facilitating the implementation of infection control measures. WGS also provides interesting information about the spread of antibiotic resistance and virulence genes.

A Simple Cleaning Intervention to Prevent Transmission of Carbapenemase-Producing Enterobacterales from Hospital Sinks

Background: A prolonged outbreak of carbapenemase-producing Serratia marcescens (CPSM) was identified in our quaternary healthcare center over a 2-year period from 2015 through 2017. A reservoir of IMP-4–producing S. marcescens in sink drains of clinical hand basins (CHB) was implicated in propagating transmission, supported by evidence from whole-genome sequencing (WGS). We assessed the impact of manual bioburden reduction intervention on further transmission of CPSM. Methods: Environmental sampling of frequently touched wet and dry areas around CPSM clinical cases was undertaken to identify potential reservoirs and transmission pathways. After identifying CHB as a source of CPSM, a widespread annual CHB cleaning intervention involving manual scrubbing of sink drains and the proximal pipes was implemented. Pre- and postintervention point prevalence surveys (PPS) of CHB drains performed to assess for CPSM colonization. Surveillance for subsequent transmission was conducted through weekly screening of patients and annual screening of CHB in transmission areas, and 6-monthly whole-hospital PPS of patients. All CPSM isolates were assessed by WGS. Results: In total, 6 patients were newly identified with CPSM from 2015 to 2017 (4.3 transmission events per 100,000 surveillance bed days [SBD]; 95% CI, 1.6–9.4). All clinical CPSM isolates were linked to CHB isolates by WGS. The CHB cleaning intervention resulted in a reduction in CHB colonization with CPSM in transmission areas from 72% colonization to 28% (ARR, 0.44; 95% CI, 0.25–0.63). A single further clinical case of CPSM linked to the CHB isolates was detected over 2 years of surveillance from 2017 to 2019 following the implementation of the annual CHB cleaning program (0.7 transmissions per 100,000 SBD; 95% CI, 0.0–3.9). No transmissions were linked to undertaking the cleaning intervention. Conclusions: A simple intervention targeted at reducing the biological burden of CPSM in CHB drains at regular intervals was effective in preventing transmission of carbapenemase-producing Enterobacterales from the hospital environment to patients over a prolonged period of intensive surveillance. These findings highlight the importance of detailed cleaning for controlling the spread of multidrug-resistant organisms from healthcare environments.Funding: NoneDisclosures: Jason Kwong, Austin Health

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

BackgroundNosocomial 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.MethodsAn 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.ResultsBetween 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.ConclusionWhile 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.

Serratia marcescens outbreak in a neonatology unit of a Spanish tertiary hospital: Risk factors and control measures

BackgroundWe describe the investigation undertaken and the measures adopted to control a Serratia marcescens outbreak in the neonatology unit of La Paz University Hospital in Madrid, Spain. MethodsWeekly rectal and pharyngeal screenings for S marcescens were performed in the neonates starting after detection of the outbreak. Environmental samples and samples from health care workers (HCWs) were obtained for microbiological analysis. An unmatched case-control study was carried out to investigate risk factors for infection/colonization. ResultsThe outbreak began in June 2016 and ended in March 2017, affecting a total of 59 neonates. Twenty-five (42.37%) neonates sustained an infection, most frequently conjunctivitis and sepsis. Multivariate logistic regression identified the following risk factors: parenteral nutrition (odds ratio [OR], 103.4; 95% confidence interval [CI], 11.9-894.8), history of previous radiography (OR, 15.3; 95% CI, 2.4-95.6), and prematurity (OR, 5.65; 95% CI, 1.5-21.8). Various measures were adopted to control the outbreak, such as strict contact precautions, daily multidisciplinary team meetings, cohorting, allocation of dedicated staff, unit disinfection, and partial closure. Hands of HCWs were the main suspected mechanism of transmission, based on the inconclusive results of the environmental investigation and the high number of HCWs and procedures performed in the unit. ConclusionsS marcescens spreads easily in neonatology units, mainly in neonatal intensive care units, and is often difficult to control, requiring a multidisciplinary approach. Strict measures, including cohorting and medical attention by exclusive staff, are often needed to get these outbreaks under control.