Colonization Pressure Research Articles

P-312. Elimination of barrier contact precautions for Vancomycin-Resistant Enterococcus (VRE)-colonized patients was not associated with the acquisition of VRE in a tertiary care center

Abstract Background In April 2020, the University of Michigan discontinued barrier contact precautions for Vancomycin-Resistant Enterococcus (VRE) colonized patients while maintaining VRE surveillance. We conducted a retrospective cohort study to assess the impact of this policy change on the risk of VRE acquisition Inclusion and Exclusion Criteria of the Cohort Methods We analyzed patients admitted between 1/2018 and 3/2021 who underwent weekly surveillance. The primary outcome was VRE-free survival; the main exposure was admission before or after the contact precaution policy. Demographics, Elixhauser comorbidity index, antibiotic and PPI exposure, and colonization pressure were incorporated as covariates in an extended Cox proportional hazard model of VRE-free survival. Time-varying covariates were accounted for and modeled using log-transformed time. Patients were censored at discharge or death. VRE-free survival before and after change in contact precautions policy Change in contact precaution policy was not associated with an increased hazard of VRE-acquisition in single variable analysis Results We identified 2,221 patients admitted before the policy change and 1,830 after, with 225 cases of VRE acquisition before and 196 cases after. No significant differences in age, demographics, antibiotic use, or PPI exposure were observed among VRE patients admitted before and after the policy change. However, VRE patients admitted before the policy change had more medical comorbidities (mean Elixhauser: 23.64 before, 20.77 after; p=0.008) and lower exposure to colonization pressure (mean VRE patient days: 13.4 before, 29.9 after; p=0.019). In a multivariable extended Cox proportional hazard model, admission before or after the change in contact precaution policy showed no significant association with VRE-free survival (HR 0.81-1.1), or infection with VRE (HR 1.01, 95% CI 0.92-1.21). The most significant risk factors for VRE acquisition were vancomycin treatment (HR 1.60, 95% CI 1.25-2.03, p< 0.001) and PPI treatment (HR 1.43, 95% CI 1.15-1.77, p=0.001). Multivariable cox-regression model of risk factors for VRE acquisition There was no association between the change in contact precautions policy and risk of VRE acquisition Conclusion The policy change to eliminate isolation and barrier precaution requirements for VRE patients was associated with no detectible increase in the hazard of VRE acquisition. The most significant risk factors for VRE acquisition were vancomycin and PPI treatment. Our results suggest that appropriate use of PPI and antimicrobial stewardship may have a greater impact on preventing the spread and acquisition of VRE than barrier precautions. Disclosures Laraine Washer, MD, Ferring Pharmaceuticals: Advisor/Consultant

P-423. High Burden of Intestinal Colonization with Carbapenem-Resistant Organisms (CRO) at two Greek Intensive Care Units

Abstract Background Screening for CRO intestinal colonization is part of the recommended interventions to limit their spread. We estimated the burden of carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) intestinal colonization at two Greek ICUs: Attikon University Hospital (AUH) and Tzaneio General Hospital of Piraeus (TGHP). Methods From October 2022, all ICU patients were screened for intestinal colonization by CRO; patients admitted post-surgery on a daily basis were excluded. The first isolate per patient was recorded as a colonization event, categorized as positive either at admission (< 3 days from ICU admission) or during ICU stay ( >=3 days). Admission prevalence rates per 100 admissions (APR) and incidence rates of ICU-acquired intestinal colonization per 1,000 patient-days (IR) were calculated. Rates from the 1st, 2nd and 3rd study semester were compared and incidence rate ratios were determined. Results APR and IR of ICU-acquired CRE, CRAB, and CRPA intestinal colonization are presented in Table 1. APR for CRO colonization remained stable, during the study period, with the exception of CRE at TGHP, which exhibited a significant increase (p=0.02). APR were significantly higher at TGHP for all 3 study periods apart from CRE in the first study semester (figure 1). IR of ICU-acquired CRE colonization were also significantly higher at TGHP, in all 3 semesters, possibly due to the higher colonization pressure (figure 2). The IR of ICU-acquired CRE and CRPA colonization remained essentially unchanged over the study period at each hospital. However, a significant reduction in the incidence density of ICU-acquired CRAB colonization was observed (figure 2). Conclusion Our study highlights the high burden of CRO colonization in Greek ICUs, which varies even across settings within the same region. CRE colonization presents the greater challenge, closely followed by CRAB, which however showed a significant reduction in ICU-acquired CRAB colonization during the last year. Active surveillance remains a crucial component of prevention bundles and can guide targeted prevention strategies. Disclosures All Authors: No reported disclosures

The transition from resistance to acceptance: Managing a marine invasive species in a changing world

Abstract Marine invasive species can transform coastal ecosystems, yet mitigating their effects can be difficult, and even impractical. Often, marine invasive species are managed at poorly matched spatial scales, and at the same time, rates of spread and establishment are increasing under climate change and can outpace resources available for population suppression. These circumstances challenge traditional conservation goals of maintaining a historic environmental state, especially for a species like the European green crab (Carcinus maenas), a formidable invader with few examples of successful long‐term removal programs. A management paradigm where decision alternatives include resisting or accepting a new ecological trajectory may be needed. We apply mathematical concepts from decision theory to develop a quantitative framework for navigating management decisions in this new resist‐accept paradigm. We develop a model of European green crab growth, removal and colonization, and we find optimal levels of removal effort that minimize both ecological change and removal cost. We establish a benchmark of colonization pressure at which green crab density becomes decoupled from a decision maker's actions, such that population control can no longer shape the invasion trajectory. For informing the decision boundary between resistance and acceptance, our results highlight that a decision maker's understanding of how removal cost scales with removal effort is more important than understanding the density‐impact relationship. We show that assuming stationary system dynamics can result in sub‐optimal levels of species removal effort, highlighting the importance of developing anticipatory management strategies by accounting for non‐stationary dynamics. Policy implications. For marine invasive species that can disperse across long distances and recolonize rapidly after removal, the focus of conservation policy should shift away from understanding how to resist change to understanding when to stop resisting change. Navigating this decision problem involves trade‐offs among competing objectives, highlighting the need for structured approaches to elicit objective weights that reflect the values of the decision maker. For natural resource managers facing possible ecosystem transformation, this decision framework can enable proactive and strategic decisions made under uncertainty in a changing world.

High Burden of Carbapenem-resistant Klebsiella pneumoniae (CRKP) Colonization in Neonates in A Tertiary Care Hospital in India

Neonatal sepsis due to carbapenem-resistant Klebsiella pneumoniae (CRKP) is a global cause of morbidity and mortality, especially in East and Southeast Asia. Among different sources of CRKP implicated in sepsis, neonatal skin and gut colonization are important reservoirs. Despite being endemic for CRKP infections, there is an extreme paucity of data on CRKP colonization in neonates. Therefore, this prospective cohort study was performed to detect the frequency of gut colonization with CRKP in the neonates following admission in the neonatal unit of a tertiary care hospital in India. The study was conducted in the 14 bedded neonatal unit and infection control section. Surface swabs from skin and rectal swabs were cultured for bacterial identification from every neonate at admission and at 24 h, 48 h, and 72 h. Isolates were genotypically tested for phylogeny groups, screened for carbapenem resistance by imipenem E-test and typed by Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR. Data for the CRKP colonized and non-colonized neonates were statistically analyzed. A total of 30 neonates and 180 swabs were studied. Gram-positive cocci in skin, whereas for rectal colonization, K. pneumoniae (genotype K. pneumoniae subsp. pneumoniae) was the commonest. The frequency of CRKP colonization was 33%, with 20% colonization pressure at admission. All the CRKP had blaNDM gene. On ERIC-PCR, multiple clones were seen. The study highlighted the high burden of blaNDM carrying CRKP colonization in neonates at admission, thus emphasizing the urgent need for the implementation of stringent infection control policies to prevent nosocomial transmission of these colonizers.

The Yaya Reserve: From the Evolution of its Plant Cover to Proposals for Sustainable Management

The Yaya reserve, one of the biodiverse forests in Ivory Coast, faces significant threats from agricultural colonization, illegal logging, and demographic pressure, which could jeopardize its sustainability. This paper focuses on contributing to the reserve’s sustainable management. To achieve this, three categories of data were collected: remote sensing data, floristic inventory data, and survey data from the neighboring populations. Remote sensing data were obtained by downloading images from the USGS earth explorer website. Floristic data were obtained through surface and itinerant survey. Survey data were collected using a structured interview. The images were processed to calculate the areas of various land use classes. The floristic data were analyzed for species richness and composition, while the survey data were analyzed to understand local perceptions of landscape dynamics, current management practices, and proposals for participatory management. The results revealed two major periods in the forest’s dynamics: increased deforestation from 1986 to 2005 and subsequent restoration from 2005 to 2022. These phases of degradation and restoration are likely related to recent social and political crises and management challenges. The floristic inventory identified 167 woody species across 134 genera and 47 families. 24 species (14% of the total) are endemic to West Africa, and 21 species (12.42%) are listed on the IUCN red list, indicating a relatively good conservation of the forest. The survey data highlighted the vulnerability of the forest and underscored the importance of centralized decision-making in management. The study suggests that participatory management could be a viable alternative for protecting the reserve. The hypotheses clearly states that the active involvement of local populations in the sustainable exploitation of forest resources can improve living standards, while helping to preserve the forest from exploitative practices.

Non-native species in marine protected areas: Global distribution patterns

Non-native species in marine protected areas: Global distribution patterns

Impact of Transitioning to Single-Patient Rooms on Prevention of Multidrug-Resistant Organisms in a Resource-Limited Facility

Background: Healthcare-associated infections (HAI) substantially increase hospital costs and lead to poor patient outcomes, particularly when caused by multidrug-resistant organisms (MDRO). To decrease MDRO transmission, isolation of colonized or infected patients in single rooms is recommended. However, single-patient isolation rooms are expensive to build and often unavailable in resource-limited hospitals. In 2023, an intensive care unit (ICU) at a large Brazilian tertiary hospital relocated from a space with an open floor plan to a newly built location with single-patient rooms. We evaluated the impact of this transition on acquisition of carbapenem-resistant Enterobacterales (CRE) colonization, HAI, and compliance with Hand Hygiene (HH) and Contact Precaution (CP) activities. Methods: We compared rates of CRE colonization acquisition, CRE colonization pressure, HAI, and compliance with HH and CP between pre- (March 1, 2022 – Feb 28, 2023) and post-implementation of single-rooms (March 1, 2023 - October 31, 2023) in a 12-bed surgical ICU. All patients were screened for CRE colonization on admission to the unit and weekly until discharge using rectal swab cultures. Colonization pressure was defined as the ratio of CRE-positive patient-days (PDs) to the total number of PDs. Rates of central-line associated blood-stream infections, ventilator-associated pneumonia, and catheter-associated urinary tract infections were monitored. HH and CP compliance were monitored weekly by infection prevention staff outside of the unit. Poisson regression and multiple linear regression were used to compare rates between pre- and post-implementation periods. Results: Healthcare acquisition of CRE colonization remainedstable between pre- and post-implementation (incidence rate ratio: 0.88 (95%CI, 0.73-1.05; P=0.16) despite an increase in CRE colonization pressure of 8.6% over baseline (from 7.84% pre- to 16.39% post-implementation (95% confidence interval [CI], 4.13-12.96%; P=.001)). The latter was driven by reduced turnover of CRE-colonized patients in the post-implementation period (mean patient-day reduced by 10.33; 95%CI, 3.06-17.61; P=0.006). Incidence of HAIs also remained stable (global incidence 3.12 vs 3.30, pre- and post-intervention, respectively; P=0.2). HH compliance was high prior to the transition (95.7%) and increased slightly but not significantly post-intervention (97.5%; P=0.3). CP compliance improved by 9.83%, especially in gown and glove changes after each patient interaction, from 90.62% pre- to 100% post-implementation (95%CI, 1.52-17.22; P=.02). Conclusion The move to an ICU with exclusively single-patient rooms was associated with increase in CP compliance. This could help explain why HAI incidence and healthcare acquisition of CRE colonization remained stable despite a significant increase in CRE colonization pressure.Disclosure: Matias Salomao: Speaker - Cepheid

The anthropocene biogeography of alien birds on islands: Drivers of their functional and phylogenetic diversities.

A branch of island biogeography has emerged to explain alien species diversity in the light of the biogeographic and anthropogenic context, yet overlooking the functional and phylogenetic facets. Evaluating alien and native birds of 407 oceanic islands worldwide, we built structural equation models to assess the direct and indirect influence of biotic, geographic, and anthropogenic contexts on alien functional diversity (FD) and phylogenetic diversity (PD). We found that alien taxonomic richness was the main predictor of both diversities. Anthropogenic factors, including colonization pressure, associated with classic biogeographical variables also strongly influenced alien FD and PD. Specifically, habitat modification and human connectivity markedly drove alien FD, especially when controlled by taxonomic richness, whereas the human population size, gross domestic product, and native PD were crucial at explaining alien PD. Our findings suggest that humans not only shape taxonomic richness but also other facets of alien diversity in a complex way.

Air dispersal of multi-drug-resistant organisms including meticillin-resistant Staphylococcus aureus, carbapenem-resistant Acinetobacter baumannii and carbapenemase-producing Enterobacterales in general wards: surveillance culture of air grilles

The environmental surveillance of air grilles in clinical areas has not been systematically analysed. Samples were collected from frequently touched items (N= 529), air supply (N= 295) and exhaust (N= 184) grilles in six medical and 11 surgical wards for the cultures of multi-drug-resistant organisms (MDROs): meticillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenemase-producing Enterobacterales (CPE), and isolates were selected for whole-genome sequencing (WGS). The contamination rates were correlated with the colonization pressures of the respective MDROs. From 3rd October to 21st November 2023, 9.8% (99/1008) of the samples tested positive, with MRSA (24.2%, 24/99), CRAB (59.6%, 59/99) and CPE (2.0%, 2/99), being the only detected MDROs. The contamination rate in air exhaust grilles (26.6%, 49/184) was significantly higher than in air supply grilles (5.8%, 17/295; P<0.001). The contamination rate of air exhaust grilles with any MDRO in acute medical wards (73.7%, 14/19) was significantly higher than in surgical wards (12.5%, 4/32; P<0.001). However, there was no difference in the contamination rate of air exhaust grilles between those located inside and outside the cohort cubicles for MDROs (27.1%, 13/48 vs 28.8%, 30/104; P=0.823). Nevertheless, the weekly CRAB colonization pressure showed a significant correlation with the overall environmental contamination rate (r= 0.878; 95% confidence interval (CI): 0.136-0.986; P=0.004), as well as with the contamination rate in air supply grilles (r= 0.960; 95% CI: 0.375-0.999; P<0.001) and air exhaust grilles (r= 0.850; 95% CI: 0.401-0.980; P=0.008). WGS demonstrated clonal relatedness of isolates collected from patients and air exhaust grilles. Air grilles may serve as MDRO reservoirs. Cohort nursing in open cubicles may not completely prevent MDRO transmission through air dispersal, prompting the consideration of future hospital design.

Biospheremetrics v1.0.2: an R package to calculate two complementary terrestrial biosphere integrity indicators – human colonization of the biosphere (BioCol) and risk of ecosystem destabilization (EcoRisk)

Abstract. Ecosystems are under multiple stressors, and impacts can be measured with multiple variables. Humans have altered mass and energy flows of basically all ecosystems on Earth towards dangerous levels. However, integrating the data and synthesizing conclusions is becoming more and more complicated. Here we present an automated and easy-to-apply R package to assess terrestrial biosphere integrity that combines two complementary metrics. (i) The BioCol metric that quantifies the human colonization pressure exerted on the biosphere through alteration and extraction (appropriation) of net primary productivity.(ii) The EcoRisk metric that quantifies biogeochemical and vegetation structural changes as a proxy for the risk of ecosystem destabilization. Applied to simulations with the dynamic global vegetation model LPJmL5 for 1500–2016, we find that large regions presently (period 2007–2016) show modification and extraction of &gt;20 % of the preindustrial potential net primary production. The modification (degradation) of net primary production (NPP) as a result of land use change and extraction in terms of biomass removal (e.g., from harvest) leads to drastic alterations in key ecosystem properties, which suggests a high risk of ecosystem destabilization. As a consequence of these dynamics, EcoRisk shows particularly high values in regions with intense land use and deforestation and in regions prone to impacts of climate change, such as the Arctic and boreal zone. The metrics presented here enable spatially explicit global-scale evaluation of historical and future states of the biosphere and are designed for use by the wider scientific community, being applicable not only to assessing biosphere integrity but also to benchmarking model performance. The package will be maintained on GitHub and through that we encourage its future application to other models and data sets.

From acidophilic to ornithogenic: microbial community dynamics in moss banks altered by gentoo penguins.

The study explores the indirect impact of climate change driven by gentoo's penguin colonization pressure on the microbial communities of moss banks formed by Tall moss turf subformation in central maritime Antarctica. Microbial communities and chemical composition of the differently affected moss banks (Unaffected, Impacted and Desolated) located on Galindez Island and Сape Tuxen on the mainland of Kyiv Peninsula were analyzed. The native microbiota of the moss banks' peat was analyzed for the first time, revealing a predominant presence of Acidobacteria (32.2 ± 14.4%), followed by Actinobacteria (15.1 ± 4.0%) and Alphaproteobacteria (9.7 ± 4.1%). Penguin colonization and subsequent desolation of moss banks resulted in an increase in peat pH (from 4.7 ± 0.05 to 7.2 ± 0.6) and elevated concentrations of soluble nitrogen (from 1.8 ± 0.4 to 46.9 ± 2.1 DIN, mg/kg) and soluble phosphorus compounds (from 3.6 ± 2.6 to 20.0 ± 1.8 DIP, mg/kg). The contrasting composition of peat and penguin feces led to the elimination of the initial peat microbiota, with an increase in Betaproteobacteria (from 1.3 ± 0.8% to 30.5 ± 23%) and Bacteroidota (from 5.5 ± 3.7% to 19.0 ± 3.7%) proportional to the intensity of penguins' impact, accompanied by a decrease in community diversity. Microbial taxa associated with birds' guts, such as Gottschalkia and Tissierella, emerged in Impacted and Desolated moss banks, along with bacteria likely benefiting from eutrophication. The changes in the functional capacity of the penguin-affected peat microbial communities were also detected. The nitrogen-cycling genes that regulate the conversion of urea into ammonia, nitrite oxide, and nitrate oxide (ureC, amoA, nirS, nosZ, nxrB) had elevated copy numbers in the affected peat. Desolated peat samples exhibit the highest nitrogen-cycle gene numbers, significantly differing from Unaffected peat (p < 0.05). The expansion of gentoo penguins induced by climate change led to the replacement of acidophilic microbiomes associated with moss banks, shaping a new microbial community influenced by penguin guano's chemical and microbial composition.

Biogeography and global flows of 100 major alien fungal and fungus‐like oomycete pathogens

AbstractAimSpreading infectious diseases associated with introduced pathogens can have devastating effects on native biota and human livelihoods. We analyse the global distribution of 100 major alien fungal and oomycete pathogens with substantial socio‐economic and environmental impacts and examine their taxonomy, ecological characteristics, temporal accumulation trajectories, regional hot‐ and coldspots of taxon richness and taxon flows between continents.LocationGlobal.TaxonAlien/cryptogenic fungi and fungus‐like oomycetes, pathogenic to plants or animals.MethodsTo identify over/underrepresented classes and phyla, we performed Chi2 tests of independence. To describe spatial patterns, we calculated the region‐wise richness and identified hot‐ and coldspots, defined as residuals after correcting taxon richness for region area and sampling effort via a quasi‐Poisson regression. We examined the relationship with environmental and socio‐economic drivers with a multiple linear regression and evaluated a potential island effect. Regional first records were pooled over 20‐year periods, and for global flows the links between the native range to the alien regions were mapped.ResultsPeronosporomycetes (Oomycota) were overrepresented among taxa and regional taxon richness was positively correlated with area and sampling effort. While no island effect was found, likely due to host limitations, hotspots were correlated with human modification of terrestrial land, per capita gross domestic product, temperate and tropical forest biomes, and orobiomes. Regional first records have increased steeply in recent decades. While Europe and Northern America were major recipients, about half of the taxa originate from Asia.Main ConclusionsWe highlight the putative importance of anthropogenic drivers, such as land use providing a conducive environment, contact opportunities and susceptible hosts, as well as economic wealth likely increasing colonisation pressure. While most taxa were associated with socio‐economic impacts, possibly partly due to a bias in research focus, about a third show substantial impacts to both socio‐economy and the environment, underscoring the importance of maintaining a wholescale perspective across natural and managed systems.

Quantifying global colonization pressures of alien vertebrates from wildlife trade

The global trade in live wildlife elevates the risk of biological invasions by increasing colonization pressure (the number of alien species introduced to an area). Yet, our understanding of species traded as aliens remains limited. We created a comprehensive global database on live terrestrial vertebrate trade and use it to investigate the number of traded alien species, and correlates of establishment richness for aliens. We identify 7,780 species involved in this trade globally. Approximately 85.7% of these species are traded as aliens, and 12.2% of aliens establish populations. Countries with greater trading power, higher incomes, and larger human populations import more alien species. These countries, along with island nations, emerge as hotspots for establishment richness of aliens. Colonization pressure and insularity consistently promote establishment richness across countries, while socio-economic factors impact specific taxa. Governments must prioritize policies to mitigate the release or escape of traded animals and protect global biosecurity.

Incorporation of colonization pressure into the propagule pressure‐based global ballast water standard

AbstractAimIn 2024, cargo vessels must meet the International Maritime Organization's global ballast water discharge standards (IMO D‐2) that limit the concentration of living organisms. D‐2 focuses on reducing invasion risk by reducing ‘community propagule pressure (CPP)’, though it does not consider colonization pressure (CP).LocationGlobal.MethodsWe modelled risk differences in IMO D‐2‐compliant discharges (10 ind. m−3) for communities that had inverse patterns of CP and species' individual propagule pressures (IPP). Secondly, we determined the effect on risk of varying CPP and CP. As part of this, we tested whether the IMO D‐2 standard for zooplankton‐sized organisms of &lt;10 individuals m−3 was an optimal choice. Risk was defined as probability of at least one species invading using four risk–release models.ResultsRisk differed strongly at the D‐2 limit based on community composition. At low CPP (&lt;25 ind. m−3), risk was strongly affected by CP for hyperbolic and linear risk–release models and weakly for exponential and logistic models, while CPP affected only the former two model types. Across a much wider range of CPP values, risk was affected by CP, CPP and by their interaction for all models.Main ConclusionThe IMO D‐2 standard for zooplankton‐sized organisms requires very low CPP and even lower IPPs in mixed‐species releases, which will impede successful colonization. Species‐abundance theory predicts that discharges meeting the D‐2 standard (low CPP) will also have low CP. Much more empirical data are required to determine whether vessels can consistently reduce CP as it lowers CPP in order to meet these requirements.

Colonization With Antibiotic-Resistant Bacteria in a Hospital and Associated Communities in Guatemala: An Antibiotic Resistance in Communities and Hospitals (ARCH) Study.

We estimated the prevalence of colonization with extended-spectrum cephalosporin-resistant Enterobacterales (ESCrE) and carbapenem-resistant Enterobacterales (CRE) from a hospital and associated communities in western Guatemala. Randomly selected infants, children, and adults (<1, 1-17, and ≥18 years, respectively) were enrolled from the hospital (n = 641) during the coronavirus disease 2019 (COVID-19) pandemic, March to September 2021. Community participants were enrolled using a 3-stage cluster design between November 2019 and March 2020 (phase 1, n = 381) and between July 2020 and May 2021 (phase 2, with COVID-19 pandemic restrictions, n = 538). Stool samples were streaked onto selective chromogenic agar, and a Vitek 2 instrument was used to verify ESCrE or CRE classification. Prevalence estimates were weighted to account for sampling design. The prevalence of colonization with ESCrE and CRE was higher among hospital patients compared to community participants (ESCrE: 67% vs 46%, P < .01; CRE: 37% vs 1%, P < .01). Hospital ESCrE colonization was higher for adults (72%) compared with children (65%) and infants (60%) (P < .05). Colonization was higher for adults (50%) than children (40%) in the community (P < .05). There was no difference in ESCrE colonization between phase 1 and 2 (45% and 47%, respectively, P > .05), although reported use of antibiotics among households declined (23% and 7%, respectively, P < .001). While hospitals remain foci for ESCrE and CRE colonization, consistent with the need for infection control programs, community prevalence of ESCrE in this study was high, potentially adding to colonization pressure and transmission in healthcare settings. Better understanding of transmission dynamics and age-related factors is needed.

Examining the impact of the COVID-19 pandemic on hospital-associated Clostridioides difficile infection

Background: The epidemiology of Clostridioides difficile infection (CDI) is complex, and the COVID-19 pandemic has had extreme impacts on known risk factors such as comorbidity burden and antibiotic prescribing. However, whether these changes have affected the incidence of hospital-associated CDI (HA-CDI) remains unknown. We compared incidence and trends of HA-CDI before and after the pandemic onset, and we assessed the impact of changes in key CDI-related risk factors. Methods: We conducted an interrupted time-series study (March 2018–March 2021) of adult inpatients hospitalized 4 or more days with no known CDI on admission at a 576-bed academic medical center. Our primary outcome was monthly HA-CDI per 10,000 patient days. We performed segmented linear regression to compare the preinterruption trend in HA-CDI rate to the postinterruption slope and level change. We established a series of 30-day intervals before and after the interruption timepoint of March 23, 2020, which corresponds with the Oregon stay-at-home executive order. The data included 24 preinterruption time points and 12 postinterruption time points. We also assessed changes in slope and trend for known HA-CDI risk factors. Results: We included 34,592 inpatient encounters in our prepandemic period and 10,932 encounters in our postinterruption period. The mean prepandemic HA-CDI rate was 4.07 cases per 10,000 patient days. After the pandemic onset, the rate was 3.6 per 10,000 patient days. However, the observed differences in rate (both in terms of slope and level) were not statistically significant (P = .90 for level; P = .60 for slope change). We observed a significant decrease in admissions per 30 days (1,441 vs 911; level-change P &lt; .0001) and a slight increase in the mean number of Elixhauser comorbidities (1.96 vs 2.07; level-change P = .05). We also observed significant increases in both frequency and intensity of antibiotic use, with an increase average days of therapy per encounter (5.8 vs 7.2; level-change P = .01; slope-change P &lt; .0001) and in antibiotic spectrum index (ASI) points per antibiotic day (4.4 vs 4.9; P &lt; .0001). We observed a consistent downward trend for case days of CDI colonization pressure per hospital day (preinterruption slope P &lt; .0001), which remained consistent after the pandemic onset (P = 0.5 for postinterruption slope change) (Fig. 1). Conclusions: Despite significant increases in high-intensity antibiotic use and comorbidity burden, we did not observe significant differences in HA-CDI after the pandemic onset. This may be due to the significant decrease in colonization pressure in the postpandemic period. Further research is required to fully understand the impact of the pandemic-related changes onDisclosures: None

Validating agent-based simulation model of hospital-associated Clostridioides difficile infection using primary hospital data.

As agent-based models (ABMs) are increasingly used for modeling infectious diseases, model validation is becoming more crucial. In this study, we present an alternate approach to validating hospital ABMs that focuses on replicating hospital-specific conditions and proposes a new metric for validating the social-environmental network structure of ABMs. We adapted an established ABM representing Clostridioides difficile infection (CDI) spread in a generic hospital to a 426-bed Midwestern academic hospital. We incorporated hospital-specific layout, agent behaviors, and input parameters estimated from primary hospital data into the model, referred to as H-ABM. We compared the predicted CDI rate against the observed rate from 2013-2018. We used colonization pressure, a measure of nearby infectious agents, to validate the socio-environmental agent networks in the ABM. Finally, we conducted additional experiments to compare the performance of individual infection control interventions in the H-ABM and the generic model. We find that the H-ABM is able to replicate CDI trends during 2013-2018, including a roughly 46% drop during a period of greater infection control investment. High CDI burden in socio-environmental networks was associated with a significantly increased risk of C. difficile colonization or infection (Risk ratio: 1.37; 95% CI: [1.17, 1.59]). Finally, we found that several high-impact infection control interventions have diminished impact in the H-ABM. This study presents an alternate approach to validation of ABMs when large-scale calibration is not appropriate for specific settings and proposes a new metric for validating socio-environmental network structure of ABMs. Our findings also demonstrate the utility of hospital-specific modeling.

Risk factors for acquisition of carbapenemase-producing versus non-carbapenemase-producing enterobacterales: a case-control study

We aimed to assess the association between carbapenem-resistant Enterobacterales (CRE) colonization pressure and carbapenem exposure and acquisition of carbapenemase-producing Enterobacterales (CPE) and non-carbapenemase-producing carbapenem-resistant Enterobacterales (non-CP-CRE). We conducted a parallel 1:2 matched case-control study at Rambam Health Care Campus, Israel, from January 2014 to June 2017. The cases included all adults who acquired CPE or non-CP-CRE in hospital. The controls were hospitalized patients who were negative for CRE on screening and matched by age, hospitalization division and the number of hospitalization days 90days prior to CRE screening. The exposures of interest were high CRE colonization pressure, defined as a higher-than-median proportion of CRE carriers in the concurrent patient's department before acquisition, and carbapenem exposure, assessed as days of treatment. Conditional logistic regression was used for analyses of CPE and non-CP-CRE. In total, 1058 patients were included: 278 CPE and 75 non-CP-CRE cases, matched to 556 and 149 controls, respectively. High CRE colonization pressure was associated with CPE acquisition (adjusted odds ratio [aOR], 2.6; 95% CI, 1.69-4.02); however, the duration of carbapenem treatment was not (aOR, 1.004; 95% CI, 0.98-1.03; 1-day increment). The duration of carbapenem treatment was significantly associated with non-CP-CRE acquisition (aOR per day, 1.07; 95% CI, 1.03-1.11). A source patient was identified significantly more frequently in epidemiological acquisition investigations of CPE than in those of non-CP-CRE (107/240, 44.6% vs. 18/64, 28.1%, respectively; p 0.017). CPE acquisition was associated with horizontal transmission, whereas non-CP-CRE was associated with carbapenem exposure. Differences in the drivers of acquisition mandate tailored infection prevention efforts.

2146. Impact of MRSA colonization pressure on MRSA acquisition and MRSA infection in pediatric intensive care unit

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) colonization pressure (CP) is a useful indicator for measuring the extent of MRSA reservoir in healthcare settings. The purpose of this study is to determine the MRSA colonization rate and invasive MRSA infection rate in severely ill pediatric patients requiring pediatric intensive care unit (PICU) stay, and to evaluate the association between MRSA CP and MRSA acquisition/invasive infection. Methods From January 2016 to December 2020, pediatric patients admitted to 2 PICUs with a total of 25 beds were retrospectively analyzed. Routine nasal and/or endotracheal cultures were performed on MRSA at the time of PCIU admission and thereafter, every week. MRSA CP was defined as the ratio of the monthly MRSA positive number of patients to 100 patient days. Among MRSA colonizers, MRSA obtained after 2 days of PICU admission was defined as an acquired colonizer, and imported colonizer was defined when it was confirmed as an MRSA colonizer at the time or within 2 days of entry. When MRSA was cultured in a normally sterile body fluids, it was defined as an invasive MRSA infection. Results Of the total 6,907 patients admitted to the PICUs during this study period, 8.4% (487/6,907) were MRSA colonizers; 30% (139/487) were acquired colonizers, and invasive MRSA infections occurred in 3.3% (16/487). During the stay in the PICUs, the MRSA acquisition rate was 4.1%. A total of 22 invasive MRSA infections occurred during this study period, with an incidence rate of 3.1/1,000 patient days, of which 72.7% (n=16) occurred to the patients with MRSA colonization. Invasive MRSA infection occurred in 2.4% (8/348) of imported colonizers, and 5.2% (8/139) of acquired colonizers (p=0.108). The median duration from the time of colonization to invasive infection was 24 days(IQR; 2.25-49.75). Although MRSA CP was not correlated with the incidence of invasive MRSA infection (p=0.101), MRSA CP itself affected MRSA acquisition in PICU (p&amp;lt; 0.001). Conclusion MRSA CP influenced the new acquisition of MRSA during PICU stay, and newly acquired colonizers are more likely to experience invasive MRSA infection. Continuous multi-faceted efforts to minimize MRSA CP can provide opportunities for reducing MRSA colonization and infections rates in PICU settings. Disclosures All Authors: No reported disclosures.

Reservoir of Carbapenem-Resistant Acinetobacter baumannii in the Hospital Environment and Colonization Pressure: A Surveillance-Based Study in Indian Intensive Care Unit.

The endemicity of Acinetobacter baumannii in intensive care units (ICUs) is a serious concern. We studied the reservoirs of A. baumannii in the ICU and their effects on colonization pressure and transmission. A prospective surveillance (6 months) was conducted. Screening culture (rectal and axillary) swabs were collected within 48 hours admission and in 120 hours. Surveillance cultures from patients' surroundings, health care workers (HCWs), and hospital sewage were collected. A. baumannii was identified by phenotypic and genotypic methods. Carbapenem resistance and insertion sequence element were detected. Typing was done by repetitive extragenic palindromic-polymerase chain reaction and multilocus sequence typing. Colonization pressure was calculated and compared with environment colonizers. Of the 87 patients, 21.83% (19) were colonized with A. baumannii, 73.68% (14/19) were imported, and 26.31% (5/19) acquired carriers. Axilla was the commonest site. From the environment (15), bed rails 33.33% (5/15) and suction tubes 26.66% (4/15) were the common sites. HCWs showed 7.5% (3/40) carriage. Carbapenem resistance with blaOXA-51, blaOXA-23, and ISAba1 were 91.89% (34/37). Strong correlation between colonization pressures and environmental colonizers was seen (r2 = 0.719, p = 0.032). Carbapenem and polymyxin B were (p ≤ 0.05) significant exposures. Sequence type 623 was the predominant cluster with isolates from carriers, HCWs, and environment. Colonization pressure of carbapenem-resistant A. baumannii depends on their presence in the hospital. Hands of HCWs were an important vehicle for transmission. Infection control measure should consider reducing the environmental reservoir.