Transmission Of Clostridium Difficile Research Articles

Prevalence of Clostridium difficile in Hospital Environment within Yola Adamawa State Nigeria

Introduction: Clostridium difficile infection (CDI) is an emerging health problem in hospital setting. The ability of the spores to persist in the environment is a key factor in rates of infection. Clostridium difficile has also been described as one of the leading cause of nosocomial diarrhea. It is responsible for an increase in hospital stay with high healthcare and economic repercussions. Objectives: This study was aimed at determining the prevalence and antimicrobial susceptibility profile of Clostridium difficile isolated from surfaces within hospital environment in Yola Adamawa State Nigeria. Materials and Methods: A total of 150 surface samples were collected from different wards of two hospitals (Specialist Hospital Yola (SHY) and Federal Medical Centre Yola (FMCY)) using moistened swabs. Clostridium difficile isolates were obtained by enriching and culturing samples in cycloserine-cefoxitin fructose broth (CCFB) and cycloserine-cefoxitin fructose agar (CCFA) respectively. Susceptibility test (MIC determination) was done by well diffusion technique on Mueller Hinton agar supplemented with 5% sodium taurocholate. Results: A total of 18 (12%) Clostridium difficile were recovered from the two hospitals sampled. FMC had a prevalence rate of 13.3% with table top, toilet, window and bed sheets as sites implicated while SHY had a prevalence rate of 10.7% with bed sheet, bed railing and window as implicated sites. The antibiotic susceptibility test reveals that Clostridium difficile isolates obtained were resistant to the antibiotics tested which includes Ciprofloxacin (MIC >64 µg/ml), Erythromycin (MIC >64 µg/ml), Metronidazole (MIC 64 µg/ml), Tetracycline (MIC > 128 µg/ml) and Clindamycin (MIC > 64 µg/ml). Conclusions: The study depicts that multidrug resistant Clostridium difficile is prevalent in hospital environments within Yola Adamawa State Nigeria. The need for the sensitization of healthcare workers to improve understanding of Clostridium difficile transmission, treatment, management and prevention is of paramount importance.

191 Decreasing Hospital Clostridium difficile Infections: Impact of an Educational Module

INTRODUCTION: Clostridium difficile is a leading cause of healthcare associated infections in the United States accounting for approximately 12% of infections acquired in healthcare settings. Currently there is no primary prevention through immunization to prevent Clostridium difficile infections. Therefore hospital staff should be knowledgeable about evidence-based infection-control guidelines to decrease transmission of Clostridium difficile and decrease risk of infection in the hospital. We created an educational module that focused on Clostridium difficile education. METHODS: We developed an educational module that focuses on general information about Clostridium difficile including the pathogenesis of infection and ways to decrease or prevent transmission. A module was created which consisted of a pre-test to determine the level of knowledge prior to our intervention as well as an educational module which consisted of PowerPoint slides going over information about Clostridium difficile as well as strategies to decrease and prevent transmission and answering frequently asked questions. This is followed up with a post-test which was meant to test retained information provided during the module. Our initial study was conducted with physicians, nurses and nursing assistants. Our second cycle was conducted from January to June 2018 and expanded to include hospital staff that may not be involved with medical management but also would interact with patients, which included case managers, social workers, patient transportation staff, janitorial staff, food services and other staff. RESULTS: Our PDSA cycle revealed a pre-test score of 70.63% with an increase to 96.93% post-test (P < 0.001). The Standardized Infection Ratio in the months prior to the intervention was 1.967 (P = 0.0139) and post-intervention it was 0.746 (P = 0.4187). CONCLUSION: Our study shows that an educational module is an effective way to help combat Clostridium difficile infection rates. We had a statistically significant improvement in test scores which correlated with a decrease in Clostridium difficile infections. While the post-intervention SIR was not statistically significant, it was clinically significant and there was a statistically significant improvement from pre to post-intervention. Some concerns include the possibility of a decay effect from a passive intervention such as a module.

Biocide Resistance and Transmission of Clostridium difficile Spores Spiked onto Clinical Surfaces from an American Health Care Facility.

Clostridium difficile is the primary cause of antibiotic-associated diarrhea globally. In unfavorable environments, the organism produces highly resistant spores which can survive microbicidal insult. Our previous research determined the ability of C. difficile spores to adhere to clinical surfaces, finding that spores had markedly different hydrophobic properties and adherence abilities. Investigation into the effect of the microbicide sodium dichloroisocyanurate on C. difficile spore transmission revealed that sublethal concentrations increased spore adherence without reducing viability. The present study examined the ability of spores to transmit across clinical surfaces and their response to an in-use disinfection concentration of 1,000 ppm of chlorine-releasing agent sodium dichloroisocyanurate. In an effort to understand if these surfaces contribute to nosocomial spore transmission, surgical isolation gowns, hospital-grade stainless steel, and floor vinyl were spiked with 1 × 106 spores/ml of two types of C. difficile spore preparations: crude spores and purified spores. The hydrophobicity of each spore type versus clinical surface was examined via plate transfer assay and scanning electron microscopy. The experiment was repeated, and spiked clinical surfaces were exposed to 1,000 ppm sodium dichloroisocyanurate at the recommended 10-min contact time. Results revealed that the hydrophobicity and structure of clinical surfaces can influence spore transmission and that outer spore surface structures may play a part in spore adhesion. Spores remained viable on clinical surfaces after microbicide exposure at the recommended disinfection concentration, demonstrating ineffectual sporicidal action. This study showed that C. difficile spores can transmit and survive between various clinical surfaces despite appropriate use of microbicides.IMPORTANCEClostridium difficile is a health care-acquired organism and the causative agent of antibiotic-associated diarrhea. Its spores are implicated in fecal to oral transmission from contaminated surfaces in the health care environment due to their adherent nature. Contaminated surfaces are cleaned using high-strength chemicals to remove and kill the spores; however, despite appropriate infection control measures, there is still high incidence of C. difficile infection in patients in the United States. Our research examined the effect of a high-strength biocide on spores of C. difficile which had been spiked onto a range of clinically relevant surfaces, including isolation gowns, stainless steel, and floor vinyl. This study found that C. difficile spores were able to survive exposure to appropriate concentrations of biocide, highlighting the need to examine the effectiveness of infection control measures to prevent spore transmission and to consider the prevalence of biocide resistance when decontaminating health care surfaces.

Interlaboratory reproducibility of a test method following 4-field test methodology to evaluate the susceptibility of Clostridium difficile spores

Sporicidal surface disinfection is recommended to control transmission of Clostridium difficile in healthcare facilities. EN 17126 provides a method to determine the sporicidal activity in suspension and has been approved as a European standard. In addition, a sporicidal surface test has been proposed. To determine the interlaboratory reproducibility of a test method for evaluating the susceptibility of a C.difficile spore preparation to a biocidal formulation following the 4-field test (EN 16615 methodology). Nine laboratories participated. C.difficile NCTC 13366 spores were used. Glutaraldehyde (1% and 6%; 15 min) and peracetic acid (PAA; 0.01% and 0.04%; 15 min) were used to determine the spores' susceptibility in suspension in triplicate. One-percent glutaraldehyde revealed a mean decimal log10 reduction of 1.03 with variable results in the nine laboratories (0.37-1.49) and a reproducibility of 0.38. The effect of 6% glutaraldehyde was stronger (mean: 2.05; range: 0.96-4.29; reproducibility: 0.86). PAA revealed similar results. An exemplary biocidal formulation based on 5% PAA was used at 0.5% (non-effective concentration) and 4% (effective concentration) to determine the sporicidal efficacy (4-field test) under clean conditions in triplicate with a contact time of 15 min. When used at 0.5% it demonstrated an overall log10 reduction of 2.68 (range: 2.35-3.57) and at 4% of 4.61 (range: 3.82-5.71). The residual contamination on the three primarily uncontaminated test fields was <50 cfu/25 cm2 in one out of nine laboratories (0.5%) and in seven out of nine laboratories (4%). The interlaboratory reproducibility seems to be robust.

Clostridium difficile beyond stools: dog nasal discharge as a possible new vector of bacterial transmission

Zoonotic transmission of Clostridium difficile has been largely hypothesised to occur after direct or indirect contact with contaminated animal faeces. Recent studies have reported the presence of the bacterium in the natural environment, including in soils and rivers. If C. difficile spores are scattered in the environment, they can easily enter the respiratory tract of dogs, and therefore, dog nasal discharge could be a direct route of transmission not previously investigated. This study reports for the first time the presence of C. difficile in the respiratory tracts of dogs. The bacterium was isolated from 6 (17.1%) out of 35 nasal samples, with a total of 4 positive dogs (19%). C. difficile was recovered from both proximal and distal nasal cavities. All isolates were toxigenic and belonged to PCR-ribotype 014, which is one of the most predominant types in animals and in community-acquired C. difficile infections in recent years. The findings of this study demonstrate that the nasal cavity of dogs is contaminated with toxigenic C. difficile, and therefore, its secretions could be considered as a new route by which bacteria are spread and transmitted.

Seasonality and community interventions in a mathematical model of Clostridium difficile transmission

Clostridium difficile infection (CDI) is the leading cause of antibiotic-associated diarrhoea with peak incidence in late winter or early autumn. Although CDI is commonly associated with hospitals, community transmission is important. To explore potential drivers of CDI seasonality and the effect of community-based interventions to reduce transmission. A mechanistic compartmental model of C.difficile transmission in a hospital and surrounding community was used to determine the effect of reducing transmission or antibiotic prescriptions in these settings. The model was extended to allow for seasonal antibiotic prescriptions and seasonal transmission. Modelling antibiotic seasonality reproduced the seasonality of CDI, including approximate magnitude (13.9-15.1% above annual mean) and timing of peaks (0.7-1.0 months after peak antibiotics). Halving seasonal excess prescriptions reduced the incidence of CDI by 6-18%. Seasonal transmission produced larger seasonal peaks in the prevalence of community colonization (14.8-22.1% above mean) than seasonal antibiotic prescriptions (0.2-1.7% above mean). Reducing transmission from symptomatic or hospitalized patients had little effect on community-acquired CDI, but reducing transmission in the community by ≥7% or transmission from infants by ≥30% eliminated the pathogen. Reducing antibiotic prescription rates led to approximately proportional reductions in infections, but limited reductions in the prevalence of colonization. Seasonal variation in antibiotic prescription rates can account for the observed magnitude and timing of C.difficile seasonality. Even complete prevention of transmission from hospitalized patients or symptomatic patients cannot eliminate the pathogen, but interventions to reduce transmission from community residents or infants could have a large impact on both hospital- and community-acquired infections.

Evidence of transmission of Clostridium difficile in asymptomatic patients following admission screening in a tertiary care hospital.

BackgroundClostridium difficile (CD) is the leading cause of infectious health-care associated diarrhea. However, little is known regarding CD carriage and transmission amongst asymptomatic colonizers. We evaluated carriage, characterized strains and examined epidemiologic linkages in asymptomatic colonized CD patients.MethodsRectal swabs from asymptomatic patients admitted to the general medicine ward from April 1-June 30 2012 were collected. PCR-confirmed CD colonies were ribotyped and characterized by Modified-Multi Locus Variable Number Tandem Repeat Analysis (MMLVA).Results1549-swabs were collected from 474-patients. Overall, 50/474(10.6%) were CD PCR-positive, 24/50 were colonized at admission, while 26/50 were first identified > = 72 hours after admission. Amongst the 50 CD PCR-positive patients, 90% were asymptomatically colonized and 80% of individuals carried toxigenic CD-strains, including ribotype-027 (5/45:11%). MMLVA revealed five-clusters involving 15-patients harboring toxigenic (4/5) and non-toxigenic CD strains (1/5). In two clusters, patients were CD positive on admission while in the other three clusters involving 10 patients, we observed CD transmission from asymptomatically colonized patients to 8 previously CD-negative patients.ConclusionsWe identified increasing rates of colonization during admission to medical wards. MMLVA typing effectively discriminated between strains and suggests that 20% of patients with CD colonization acquired their strain(s) from asymptomatically colonized individuals in hospital.

Prevalence of Clostridium difficile Isolated from Beef and Chicken Meat Products in Turkey.

The concern about the possibility of food can be a vehicle for the transmission of Clostridium difficile to humans has been raised recently due to the similarities among the strains isolated from patients, foods and food animals. In this study, therefore, the prevalence of C. difficile was investigated in beef and chicken meat products collected from 57 different butcher shops, markets and fast food restaurants in Sakarya province of Turkey. Two out of 101 samples (1.98%) was positive for C. difficile indicating a very low prevalence. The pathogen was isolated from an uncooked meatball sample and a cooked meat döner sample, whereas not detected in chicken meat samples. The meatball isolate was resistant to vancomycin and tetracycline, while the cooked meat döner isolate was resistant to vancomycin and metronidazole. Both isolates were sensitive to moxifloxacin and clindamycin. Toxins A and B were not detected. This study reveals the presence of C. difficile in further processed beef products in Turkey.

Patient and Strain Characteristics Associated With Clostridium difficile Transmission and Adverse Outcomes.

No study has used whole-genome sequencing (WGS) to investigate risk factors for Clostridium difficile (CD) transmission between cases, or assessed the impact of recent acquisition on patient outcome. This 20 month retrospective cohort study included consecutive cytotoxin-positive diarrheal samples, which underwent culture, ribotyping, and WGS (Illumina). Sequenced isolates were compared using single nucleotide variants (SNVs). Independent predictors of acquisition from another case, onward transmission, 120-day recurrence, and 30-day mortality were identified using logistic regression with backwards elimination. Of 660 CD cases, 640 (97%) were sequenced, of which 567 (89%) shared a ribotype with a prior case, but only 227 (35%) were ≤2 SNVs from a prior case, supporting recent acquisition. Plausible (<2 SNVs) recent ward-based acquisition from a symptomatic case was more frequent in certain ribotypes; 64% (67/105) for ribotype-027 cases, compared with 11% (6/57) for ribotype-078. Independent risk factors (adjusted P < .05) for CD acquisition included older age, longer inpatient duration, and ribotype; these factors, and male sex, increased onward transmission. Patients with a plausible donor had a greater risk of recurrence (adjusted P = .001) and trended towards greater 30-day mortality (adjusted P = .06). Ribotype had no additional mortality or recurrence impact after adjusting for acquisition (P > .1). Greater transmission of certain lineages suggests CD may have different reservoirs and modes of transmission. Acquiring CD from a recent case is associated with poorer clinical outcomes. Clinical characteristics associated with increased healthcare-associated CD transmission could be used to target preventative interventions.

Clostridium difficile Whole Genome Sequencing Reveals Limited Transmission Among Symptomatic Children: A Single-Center Analysis.

Although pediatric Clostridium difficile infections (CDIs) are increasing, C. difficile transmission patterns among children are poorly understood. We performed whole genome sequencing (WGS) on C. difficile isolates collected from children diagnosed with CDI between December 2012 and December 2013 at a single academic medical center. Genome sequences of isolates from CDIs diagnosed ≥8 weeks after study initiation were compared to all study isolate genome sequences. Among patients with isogenic isolates (≤2-3 core genome single nucleotide variants [SNVs] identified by pairwise SNV analyses), common inpatient and/or outpatient healthcare exposures were investigated. Among 131 CDIs in 107 children, WGS identified 104 genetically distinct isolates. Of 84 incident CDIs occurring ≥8 weeks after study initiation, only 10 (11.9%) were caused by a strain isogenic to another cohort CDI isolate (putative transmission events). Proportions of each CDI class putatively associated with transmission were hospital-onset healthcare facility-associated (HCFA), 2/16 (12.5%); community-onset HCFA, 1/17 (5.9%); indeterminate, 1/11 (9.1%); community-associated (CA), 5/40 (12.5%); and recurrent, 1/21 (4.8%). Transmission events among CA and HCFA CDIs were similarly infrequent (5/40 [12.5%] vs 3/33 [9.1%]; P = .64). Shared healthcare facility exposures were only identified among 7/10 putative transmission events. Potential community transmission (same postal code) was not identified. WGS identified a highly diverse group of C. difficile isolates among children with CDI, including those with HCFA CDI. Clostridium difficile transmission among symptomatic children was very uncommon. Among putatively transmitted cases, investigation of shared healthcare exposures often did not identify a potential transmission source.

Economic evaluation of interventions designed to reduce Clostridium difficile infection.

IntroductionHealthcare decision-makers are increasingly expected to balance increasing demand for health services with a finite budget. The role of economic evaluation in healthcare is increasing and this research provides decision-makers with new information about the management of Clostridium difficile infection, from an economic perspective.MethodsA model-based economic evaluation was undertaken to identify the most cost-effective healthcare intervention relating to the reduction of Clostridium difficile transmission. Efficacy evidence was synthesised from the literature and was used to inform the effectiveness of both bundled approaches and stand-alone interventions, where appropriate intervention combinations were coupled together. Changes in health outcomes were estimated by combining information about intervention effectiveness and its subsequent impact on quality of life.ResultsA bundled approach of improving hand hygiene and environmental cleaning produces the best combination of increased health benefits and cost-savings. It has the highest mean net monetary benefit when compared to all other interventions. This intervention remains the optimal decision under different clinical circumstances, such as when mortality rate and patient length of stay are increased. Bundled interventions offered the best opportunity for health improvements.ConclusionThese findings provide healthcare decision-makers with novel information about the allocation of scarce resources relating to Clostridium difficile. If investments are not made in interventions that clearly yield gains in health outcomes, the allocation and use of scarce healthcare resources is inappropriate and improvements in health outcomes will be forgone.

Using Spatial and Temporal Mapping to Identify Nosocomial Disease Transmission of Clostridium difficile

This study evaluates the use of spatial and temporal mapping to identify nosocomial disease transmission of Clostridium difficile.

Enhanced Cleaning and Education to Prevent Transmission of Clostridium difficile in Pediatrics

BackgroundTransmission of healthcare-associated Clostridium difficile infection (HA-CDI) has been shown to occur directly or indirectly through a contaminated environment. At a tertiary-care cancer center, HA-CDI rates were higher for pediatric units than for other general oncology units. To address the problem, a multidisciplinary team, including Infection Control, Nursing, and Environmental Services (EVS), was convened and identified refusals and room clutter as barriers to proper cleaning of rooms on the unit.Aim: The aim of this study seeks to reduce HA-CDI in the inpatient pediatrics setting through environmental and educational interventions.MethodsIn the first phase of the study from February to April 2016, a baseline assessment of prevalent environmental disinfection practices was made among Nursing, EVS, Physicians, and Patient Representatives. Based on this feedback, the following were implemented during Phase 2, from June through October 2016: 1) Unit-wide disinfection with bleach twice a day including common and high traffic areas; 2) Initiation of a “preferred time for cleaning” program to engage families; 3) Enhanced visitor and family education on PPE use; 4) Creation of a communication plan in case of refusal to clean rooms; and 5) Dedicated use of diaper scales.ResultsDuring the first phase of the study, the following barriers to cleaning were identified: 1) High refusal rate as cleaning was perceived as inconvenient by families due to timing; 2) Common perception among EVS staff that multiple requests for cleaning the room may appear intrusive to the families; 3) Excessive clutter in the room; 4) Lack of education regarding PPE use; and 5) Shared equipment for diapers. To overcome these barriers, several interventions as outlined in methods were implemented. In Phase 2, there were 0 cases of HA-CDI identified in pediatric patients starting in July through October, 2016.ConclusionControl of CDI on pediatric units poses unique challenges. Engagement of key stakeholders is essential to identify and meet these challenges and to devise effective strategies that will ultimately lead to reduced hospital-based transmission of CDI.Disclosures All authors: No reported disclosures.

Stochastic modelling and inference in electronic hospital databases for the spread of infections: Clostridium difficile transmission in Oxfordshire hospitals 2007-2010.

The combination of genetic information with electronic patient records promises to provide a powerful new resource for understanding human disease and its treatment. Here we develop and apply a novel stochastic compartmental model to a large dataset on Clostridium difficile infection (CDI) in three Oxfordshire hospitals over a 2.5 year period which combines genetic information on 858 confirmed cases of CDI with a database of 750,000 patient records. C. difficile is a major cause of healthcare-associated diarrhoea and is responsible for substantial mortality and morbidity, with relatively little known about its biology or its transmission epidemiology. Bayesian analysis of our model, via Markov chain Monte Carlo, provides new information about the biology of CDI, including genetic heterogeneity in infectiousness across different sequence types, and evidence for ward contamination as a significant mode of transmission, and allows inferences about the contribution of particular individuals, wards, or hospitals to transmission of the bacterium, and assessment of changes in these over time following changes in hospital practice. Our work demonstrates the value of using statistical modelling and computational inference on large-scale hospital patient databases and genetic data.

Transmission of Clostridium difficile across Multiple Healthcare Facilities Revealed through Whole-Genome Sequencing

Transmission of Clostridium difficile across Multiple Healthcare Facilities Revealed through Whole-Genome Sequencing

Strategic Approach of an Urban 900-Bed Academic Medical Center to Combat Clostridium difficile Infection Transmission Using Staff Engagement

BACKGROUND: Preventing hospital-associated Clostridium difficile infection (HA-CDI) is crucial to modern healthcare systems for reducing mortality, healthcare costs and length of stay. As of 2011, Clostridium difficile infection (CDI) caused nearly 500,000 illnesses with 29,000 deaths in the United States. There are multiple risk factors for CDI; failure to comply with hand hygiene, ineffective equipment and surface cleaning as well as diagnosis delays can increase disease transmission. The objective is to promptly engage staff in discussion after HA-CDI to identify gaps and reduce infection rates in our facility.

Optimal control of vaccination rate in an epidemiological model of Clostridium difficile transmission.

The spore-forming, gram-negative bacteria Clostridium difficile can cause severe intestinal illness. A striking increase in the number of cases of C. difficile infection (CDI) among hospitals has highlighted the need to better understand how to prevent the spread of CDI. In our paper, we modify and update a compartmental model of nosocomial C. difficile transmission to include vaccination. We then apply optimal control theory to determine the time-varying optimal vaccination rate that minimizes a combination of disease prevalence and spread in the hospital population as well as cost, in terms of time and money, associated with vaccination. Various hospital scenarios are considered, such as times of increased antibiotic prescription rate and times of outbreak, to see how such scenarios modify the optimal vaccination rate. By comparing the values of the objective functional with constant vaccination rates to those with time-varying optimal vaccination rates, we illustrate the benefits of time-varying controls.

A mathematical model of Clostridium difficile transmission in medical wards and a cost-effectiveness analysis comparing different strategies for laboratory diagnosis and patient isolation.

BackgroundClostridium difficile infection (CDI) is a common and potentially fatal healthcare-associated infection. Improving diagnostic tests and infection control measures may prevent transmission. We aimed to determine, in resource-limited settings, whether it is more effective and cost-effective to allocate resources to isolation or to diagnostics.MethodsWe constructed a mathematical model of CDI transmission based on hospital data (9 medical wards, 350 beds) between March 2010 and February 2013. The model consisted of three compartments: susceptible patients, asymptomatic carriers and CDI patients. We used our model results to perform a cost-effectiveness analysis, comparing four strategies that were different combinations of 2 test methods (the two-step test and uniform PCR) and 2 infection control measures (contact isolation in multiple-bed rooms or single-bed rooms/cohorting). For each strategy, we calculated the annual cost (of CDI diagnosis and isolation) for a decrease of 1 in the average daily number of CDI patients; the strategy of the two-step test and contact isolation in multiple-bed rooms was the reference strategy.ResultsOur model showed that the average number of CDI patients increased exponentially as the transmission rate increased. Improving diagnosis by adopting uniform PCR assay reduced the average number of CDI cases per day per 350 beds from 9.4 to 8.5, while improving isolation by using single-bed rooms reduced the number to about 1; the latter was cost saving.ConclusionsCDI can be decreased by better isolation and more sensitive laboratory methods. From the hospital perspective, improving isolation is more cost-effective than improving diagnostics.

Contribution to Clostridium Difficile Transmission of Symptomatic Patients With Toxigenic Strains Who Are Fecal Toxin Negative.

The role of symptomatic patients who are toxigenic strain positive (TS+) but fecal toxin negative (FT-) in transmission of Clostridium difficile is currently unknown. We investigated the contribution of symptomatic TS+/FT- and TS+/FT+ patients in C. difficile transmission in 2 UK regions. From 2-step testing, all glutamate dehydrogenase (GDH)-positive specimens, regardless of fecal toxin result, from Oxford (April 2012 through April 2013) and Leeds (July 2012 through April 2013) microbiology laboratories underwent culture and whole-genome sequencing (WGS), using WGS to identify toxigenic strains. Plausible sources for each TS+/FT+ case, including TS+/FT- and TS+/FT+ patients, were determined using WGS, with and without hospital admission data. A total of 1447 of 12772 (11%) fecal samples were GDH positive, 866 of 1447 (60%) contained toxigenic C. difficile, and fecal toxin was detected in 511 of 866 (59%), representing 235 Leeds and 191 Oxford TS+/FT+ cases. TS+/FT+ cases were 3 times more likely to be plausibly acquired from a previous TS+/FT+ case than a TS+/FT- patient. Fifty-one of 265 (19%) TS+/FT+ cases diagnosed >3 months into the study were genetically related (≤2 single-nucleotide polymorphisms) to ≥1 previous TS+/FT+ case or TS+/FT- patient: 27 (10%) to only TS+/FT+ cases, 9 (3%) to only TS+/FT- patients, and 15 (6%) to both. Only 10 of 265 (4%) were genetically related to a previous TS+/FT+ or TS+/FT- patient and shared the same ward simultaneously or within 28 days. Symptomatic TS+/FT- patients were a source of C. difficile transmission, although they accounted for less onward transmission than TS+/FT+ cases. Although transmission from symptomatic patients with either fecal toxin status accounted for a low overall proportion of new cases, both groups should be infection control targets.

Antimicrobial Stewardship and Environmental Decontamination for the Control of Clostridium difficile Transmission in Healthcare Settings.

We implement an agent-based model for Clostridium difficile transmission in hospitals that accounts for several processes and individual factors including environmental and antibiotic heterogeneity in order to evaluate the efficacy of various control measures aimed at reducing environmental contamination and mitigating the effects of antibiotic use on transmission. In particular, we account for local contamination levels that contribute to the probability of colonization and we account for both the number and type of antibiotic treatments given to patients. Simulations illustrate the relative efficacy of several strategies for the reduction of nosocomial colonizations and nosocomial diseases.