bluuebunny/crossref_metadata_2025_split huggingface dataset:
1827. Genetic Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates Associated with the Development of Reduced Susceptibility to Vancomycin from Latin America
Authors: Liliana Vargas Ardila Monica , Castro-Cardozo Betsy E , Rios Rafael , Hernandez Angie K , Millan Lina V , Carvajal Lina P , Seas Carlos , Seas Carlos , Munita Jose M , Arias Cesar A , Reyes Jinnethe , Diaz Lorena 
Published: October 2019

Abstract

Background
Vancomycin (VAN) is a first-line therapeutic option for severe MRSA infections, especially in Latin America where other options are limited. However, reduced susceptibility to VAN may lead to therapeutic failures. The molecular mechanisms leading the development of VAN-intermediate S. aureus (VISA) and heterogeneous-VISA (hVISA) phenotypes are still unclear. We explored genetic signatures associated with hVISA phenotype in MRSA isolates recovered from bacteremic patients in 9 Latin American countries (2011–2014) in order to develop a genomic platform to identify these isolates.

Methods
From 538 VAN-susceptible MRSA (MIC90 = 1 µg/mL) we identified 30 hVISA isolates using GRD and macromethod E-tests; from these, 3 were confirmed by PAP-AUC. Whole-genome sequencing was performed in all 30 isolates using Illumina platform. Based on previous studies, we selected 46 genes involved in hVISA development. Multiple Blast alignments were performed using genomes of ATCC29213 and N315 (VAN-susceptible), Mu3 (hVISA) and Mu50 (VISA) as references.

Results
A total of 130 changes in 46 predicted proteins belonging to 8 functional categories were determined: 48 changes related to cell wall biogenesis, 22 to DNA/RNA processing, 17 to regulatory systems, 12 to cofactors and enzymes, 11 to membrane biosynthesis, 9 to virulence, 6 to amino acid metabolism, and 5 to transport of nitrogen and putrescine/spermidine. The most common changes identified in all the hVISA were: Y38H in Atl, N16S in PBP4, S160A in RpoB, L14I in WalK and E156G in YvqF, compared with VSSA strains. The proteins with the highest number of changes detected in the isolates confirmed by PAP-AUC were: CapP, DltA, Pbp4, TcaA, LytM (Cell wall biogenesis); MutL, RpoB (DNA/RNA processing); GraS (Regulatory systems); and PgsA (Membrane biosynthesis).

Conclusion
Changes in genes associated with cell wall biogenesis, DNA/RNA processing, regulatory systems, and membrane biosynthesis were the most prevalent in Latin American hVISA strains. Genetic signatures in genes encoding GraR (N197S), RpoB (H481Y, H481N), VraS (I5N), WalK (L14F, R222K) and MrsR (E146K) are potentially associated with this phenotype. These changes could be used to develop a platform for possible identification of hVISA isolates.

Disclosures
All Authors: No reported Disclosures.
1830. Single-cell Transcriptional Profiling Reveals an Immune Cell State Signature of Bacterial Sepsis
Authors: Reyes Miguel , Bhattacharyya Roby P , Filbin Michael , Billman Kianna , Eisenhaure Thomas , Hung Deborah T , Levy Bruce , Baron Rebecca , Blainey Paul , Goldberg Marcia B , Hacohen Nir 
Published: October 2019

Abstract

Background
Despite intense efforts to understand the immunopathology of sepsis, no clinically reliable diagnostic biomarkers exist. Multiple whole-blood gene expression studies have sought sepsis-associated molecular signatures, but these have not yet resolved immune phenomena at the cellular level. Using single-cell RNA sequencing (scRNA-Seq) to profile peripheral blood mononuclear cells (PBMCs), we identified a novel cellular state enriched in patients with sepsis.

Methods
We performed scRNA-Seq on PBMCs from 26 patients with sepsis and 47 controls at two hospitals (mean age 57.5 years, SD 16.6; 54% male; 82% white), analyzing >200,000 single cells in total on a 10× Genomics platform. We identified immune cell states by stepwise clustering, first to identify the major immune cell types, then clustering each cell type into substates. Substate abundances were compared between cases and controls using the Wilcoxon rank-sum test.

Results
We identified 18 immune cell substates (Figure 1a), including a novel CD14+ monocyte substate (MS1) that is enriched in patients with sepsis (Figure 1b). The fractional abundance of the MS1 substate alone (ROC AUC 0.88) outperformed published bulk transcriptional signatures in identifying sepsis (AUC 0.68–0.82) across our clinical cohorts. Deconvolution of publicly available bulk transcriptional data to infer the abundance of the MS1 substate externally validated its accuracy in predicting sepsis of various etiologies across diverse geographic locations (Figure 1c), matching the best previously identified bulk signatures. Flow cytometry using cell surface markers unique to MS1 confirmed its marked expansion in sepsis, facilitating quantitation and isolation of this substate for further study.

Conclusion
This study demonstrates the utility of scRNA-Seq in discovering disease-associated cytologic signatures in blood and identifies a cell state signature for sepsis in patients with bacterial infections. This novel monocyte substate matched the performance of the best bulk transcriptional signatures in classifying patients as septic, and pointed to a specific cell state for further molecular and functional characterization of sepsis immunopathogenesis.

Disclosures
All Authors: No reported Disclosures.
1833. Measuring Influenza HA Stem-Specific ADCC in Human Sera Using Novel Stabilized Stem Nanoparticle Probes
Authors: Smatti Maria K , Nasrallah Gheyath , Althani Asmaa , Yassine Hadi 
Published: October 2019

Abstract

Background
Generating a vaccine that confers complete protection and overcomes the high variability among influenza viruses is the major goal in designing a universal influenza vaccine. Currently, there is considerable interest in the broadly neutralizing antibodies (bNAb) targeting the conserved HA stem region. These antibodies have been shown to activate cellular immune responses, such as antibody-dependent cellular cytotoxisity (ADCC), in addition to their neutralization activity. We had previously demonstrated that immunization with H1-based stabilized stem (SS) nanoparticles (np) protects against heterosubtypic lethal challenge with H5N1 influenza virus, despite the absence of detectable H5N1 neutralizing activity. Here, we utilized these novel SS np probes to develop a new protocol to assess the ADCC activity mediated by stem-directed antibodies in human sera.

Methods
Human sera samples were initially screened for binding reactivity to H1 SS trimer using ELISA procedure. Of these, selected samples representing high, moderate, and low binders were further characterized for binding to H1 and H5 SS their corresponding Δstem (Ile45Arg/Thr49Arg) probes, and were analyzed for ADCC activity using a reporter bioassay.

Results
The initial screening revealed 82% (73/90) seroprevalence of anti-HA (H1) stem epitope antibodies, as determined by the differential binding to HA SS and it corresponding epitope-mutant probe. Using equimolar amounts, the multivalent presentation of HA SS on np probes induced significantly higher ADCC activity compared with the monovalent SS probes (2- to 6-fold increase). Further, ADCC activity was similarly reported against different influenza group 1 subtypes: H1, H2, and H5. Importantly, ADCC was mediated mainly by antibodies targeting the bNAb-epitope on the HA stem. In conclusion, we developed an assay to measure stem-specific ADCC activity using SS np probes.

Conclusion
Our results indicate a high prevalence of HA-stem antibodies with cross-reactive ADCC activity. Such assay could be utilized in the assessment of next-generation influenza vaccines.

Disclosures
All Authors: No reported Disclosures.
1839. Contact Precautions’ Effects on MRSA Transmission in Department of Veterans Affairs Hospitals
Authors: Khader Karim , Thomas Alun , Visnovsky Lindsay D , Toth Damon , Keegan Lindsay T , Jones Makoto M , Rubin Michael , Samore Matthew H 
Published: October 2019

Abstract

Background
In 2007, the Department of Veterans Affairs (VA) implemented the methicillin-resistant Staphylococcus aureus (MRSA) Prevention Initiative nationally in acute care facilities (ACFs). The initiative included universal nasal surveillance for MRSA colonization and implementation of contact precautions (CP) for identified carriers for the duration of their stay. Despite subsequent declines in MRSA infection rates in the VA, debate on CP efficacy continues, due to limited and inconclusive direct evidence. This study estimated CP impact on MRSA transmission in the VA.

Methods
We analyzed 1 year of data from 36 VA ACFs in 2014 using a Bayesian transmission model. The data included admission, discharge, and surveillance and clinical test results for MRSA. Per the MRSA Prevention Initiative protocol that placed known carriers on CP, we assumed patients were on CP starting 12 hours after a positive surveillance test, 24 hours after a positive clinical culture, or at admission if the patient had a positive test within 365 days prior to admission. Our model produced estimates of ward-specific transmission rate, surveillance test sensitivity, importation probability, and the CP effect parameter (CPe). For CPe < 1, CP reduced transmission. Additionally, we combined the estimates of CPe using a random-effects model with inverse variance weights to derive pooled estimates and corresponding standard errors.

Results
Facility size varied with a median daily census of 70 patients per day (range: 44–111). During the study period, 144,386 individuals were admitted into one of 36 ACFs, for 215,207 total admissions. The median percentage of admissions requiring contact precautions was 11.0% (range: 6.4%–16.1%). The estimated CPe was less than one in each of the 36 facilities with a median of 0.43 (range: 0.25–0.68). Our pooled estimate of CPe across all facilities was 0.47 (95% CI; 0.40, 0.55).

Conclusion
We found evidence of reduced MRSA transmission from patients on CP. This result was statistically significant in 5 of the 36 facilities and our pooled estimate suggests contact precautions could reduce the transmission rate by half. Further work is needed to account for imperfect compliance with CP, and for patients on CP for other reasons.

Disclosures
All Authors: No reported Disclosures.
1951. Extended Infusions of Β-lactam Antibiotics are Feasible and May Improve Mortality in the Pediatric Population
Authors: Schortemeyer Rachael L , Zembles Tracy N , Bushee Glenn , Kuhn Evelyn , Mitchell Michelle L 
Published: October 2019

Abstract

Background
Infections due to multi-drug-resistant organisms (MDRO) are associated with poor clinical outcomes. Due to limited treatment options for MDROs, it is essential to improve the delivery of available antibiotics. Optimal efficacy of β-lactam antibiotics can be achieved when free drug concentrations exceed the minimum inhibitory concentration of the organism for at least 50% of the dosing interval. This is more feasible when extending the duration of infusion. Adult literature supporting the use of extended infusion β-lactams (EIBL) is robust; however, pediatric data are limited. Furthermore, extended infusions (EI) may be more difficult to achieve in pediatric patients due to limited intravenous line access. The purpose of this study was to determine the feasibility of EIBLs as the standard of care and compare clinical outcomes between standard infusions (SI) and extended infusions (EI).

Methods
This retrospective chart analysis included hospitalized patients less than 18 years old between October 1, 2017 and March 31, 2019 who received at least 72 hours of cefepime, piperacillin/tazobactam, or meropenem. Patients weighing less than 3.5 kg or requiring continuous renal replacement therapy were excluded. EI were defined as antibiotic delivery over 3–4 hours, while SI were delivered over 30 minutes. The percent of patients completing therapy utilizing EI was measured. Clinical outcomes compared hospital length of stay; time to blood culture clearance, defervescence, inflammatory marker normalization; 30-day readmission rates; and 30-day all-cause mortality between the SI and EI groups.

Results
A total of 560 patients were included in the interim analysis. Over 90% of patients were able to complete therapy utilizing EI (Figure 1). The EI group had lower readmission rates, but the interim analysis has not yet controlled for planned admissions. A sub-analysis of critically ill patients requiring vasopressors identified a lower mortality rate (5.1% vs. 23.1%, P = 0.023) and decreased the length of stay (554 vs. 1,055 hours, P = 0.035) in the EI compared with SI group (Table 1).

Conclusion
EIBLs are feasible in the pediatric population and may lead to improved outcomes including decreased all-cause mortality and hospital length of stay, especially in critically ill children.

Disclosures
All Authors: No reported Disclosures.
2854. Enterovirus D68 Infections in Pediatric Patients in Central Ohio: Clinical Characteristics of a New Outbreak in 2018
Authors: Diaz Alejandro , Wang Huanyu , Torrus Isabel , Ara Montojo Fatima , Mele-Casas Maria , Mejias Asuncion , Leber Amy 
Published: October 2019

Abstract

Background
Many aspects of EV-D68 pathogenesis in children are not fully understood. In 2014, we experienced an outbreak of EV-D68-associated acute respiratory illness affecting mostly asthmatic children with no cases of acute flaccid myelitis identified. Late in 2018, a new outbreak occurred. The objective of this study was to describe the differences in clinical presentation in children diagnosed with EV-D68 infection during the 2018 outbreak.

Methods
This is a single-center, observational study. Nasopharyngeal (NP) samples from patients <21 years of age that tested positive for rhinovirus/enterovirus (RV/EV) by the FilmArray respiratory panel v1.7 were prospectively collected. EV-D68 was confirmed using a laboratory-developed RT-PCR. Demographic, clinical characteristics, and semiquantitative EV-D68 loads were analyzed according to the clinical presentation.

Results
From May to October 2018, 1,987/3,633 (55%) samples were RV/EV positive. Of those 399/1,028 (39%) tested positive for EV-D68 (121 outpatients; 278 inpatients). Inpatients were older (3.1 vs. 1.8 year olds; P < 0.01) with no differences in sex or EV-D68 loads (P > 0.05). Within the inpatient cohort, 67 (1.4 year olds) children were previously healthy, 146 (4.1 year olds) had underlying asthma and 65 (2.5 year olds) had chronic medical conditions (24% vs. 53% vs. 23%, respectively). Most patients presented with respiratory symptoms (>95%), followed by fever (51%) or gastrointestinal symptoms (28%). Eleven children (4%) presented with neurologic manifestations including: acute flaccid myelitis in two children, opsoclonus myoclonus syndrome in one child, and seizures in the remaining eight. Rates of viral co-detection were low (8%) and none of the children with neurologic manifestations had another respiratory virus identified. Patients with neurologic findings had lower EV-D68 loads than those who did not (29 vs. 25 Ct values; P = 0.03).

Conclusion
EV-D68 infection was associated with significant morbidity, affecting children with underlying asthma at greater rates. It was associated with severe neurologic manifestations despite these children having lower EV-D68 loads. Active surveillance for EV-D68 should be routine to allow a better understanding of the epidemiology and severity of disease.

Disclosures
All Authors: No reported Disclosures.
2887. Identifying Candida albicans Transcription Factors (TFs) That Regulate Pathogenesis of Intra-abdominal Candidiasis (IAC) by Screening a Deletion Mutant Library
Authors: Clancy Cornelius J , Cheng Shaoji , Squires Kevin , Nguyen Minh-Hong 
Published: October 2019

Abstract

Background
IAC is a common manifestation of invasive candidiasis, but its pathogenesis is poorly understood. We developed a mouse model of C. albicans IAC, in which disease progresses from peritonitis to abscesses (IAA) in a manner that recapitulates human infection. Our goal was to use the model to identify C. albicans TFs that regulate virulence during IAC.

Methods
We screened a signature-tagged library (48 unique oligonucleotide markers) of homozygous deletion mutants for 165 C. albicans TF genes, created in duplicate in strain SC5314 (S. Noble). Mice were infected intra-peritoneally in triplicate with pools of 24 mutants and wild-type, and strains harvested at 72 hours in IAA.

Results
Twenty-one TF mutants were significantly attenuated for virulence in both libraries, and 2 TF mutants were significantly more virulent in both libraries, as measured by tissue burdens (figure). Biologic processes over-represented among attenuated mutants were regulation of pH responses, biofilm, hyphal formation, echinocandin responses, and copper metabolism. pH responses are likely to be crucial to pathogenesis of IAC, as C. albicans transitions from pH 8 during peritonitis to pH 6.8 within IAA. 9 pH response regulators contributing to virulence included RIM101, STP2 (alkaline), ASH1, SFL1, SFL2 (neutral), MNL1, SKO1, PHO4 (weak acid), and CSR1 (acid). We created rim101 null mutant and reconstitution strains, and demonstrated that the gene was essential for complete virulence during peritonitis and IAA. Transcriptional profiling of strains by RT-PCR during peritonitis and in vitro showed both conserved and rewired Rim101 targets. SAP5, which encodes an aspartyl protease, is a major Rim101 target in vivo and in vitro; over-expression of SAP5 in rim101 restored virulence during IAA at 3, 7, and 10 days, but not during peritonitis. Other pH regulatory TF genes are currently being validated as virulence determinants, and pathway relationships between MNL1, SKO1, and PHO4 during IAA formation are being explored through epistasis approaches.

Conclusion
Screening of a C. albicans TF mutant library identified pH responses and other biologic processes as important during pathogenesis of IAC. Rim101, an alkaline pH response regulator, contributes to both peritonitis and IAA, the latter at least in part through its effects on Sap5.

Disclosures
All Authors: No reported Disclosures.
2893. The Michigan Hospital Medicine Safety Consortium: Improving Patient Care by Reducing Excessive Antibiotic Use in Patients Hospitalized with Community-Acquired Pneumonia
Authors: Gandhi Tejal N , Vaughn Valerie M , Petty Lindsay A , Conlon Anna , Malani Anurag N , Mclaughlin Elizabeth , Weinmann Allison J , Osterholzer Danielle , Chopra Vineet , Flanders Scott A 
Published: October 2019

Abstract

Background
Most patients hospitalized with community-acquired pneumonia (CAP) can be safely treated with 5 days of antibiotics, but many are not. We determined whether a hospitalist-collaborative can reduce excess antibiotic duration in patients with CAP through partnership with antibiotic stewardship teams (AST), data feedback, pay-for-performance, and sharing best practices.

Methods
From April 2017 to October 2018, abstractors collected data (medical record, phone calls 30-days post-discharge) on adult, non-ICU patients hospitalized with CAP at 43 hospitals in Michigan. We used a guideline-based algorithm1 to determine appropriate antibiotic duration based on patient factors (e.g., clinical stability). All hospitals received a) quarterly reports on appropriate 5-day treatment rates (2016—current), b) best practice recommendations (2017—current) including toolkit and webinar (3/2018), and c) pay-for-performance based on 5-day CAP metric (2018—current). Generalized linear mixed models were used to evaluate change over time in a) proportion of patients with CAP eligible for 5-day treatment who received 5 ± 1 days and, after adjusting for patient factors and weighting by inverse probability of treatment, b) patient outcomes 30-days post-discharge.

Results
Of 6,229 patients hospitalized with CAP, 4,769 (76.6%) were eligible for 5-days of antibiotic treatment; 283 (5.9%) were excluded due to inability to determine antibiotic duration. Between April 2017 and October 2018, the proportion of patients eligible for a 5-day duration of antibiotic treatment who received 5 ± 1 days increased from 19.8% (181/914) to 30.9% (207/670; P = 0.01), a relative improvement of 56.1% (Figure 1). During this time period, there were no changes in 30-day post-discharge death, readmission, emergency room visit, Clostridioides difficile infection, or provider-documented antibiotic-associated adverse-events (Table 1). However, there was a decrease (3.3% to 1.7%, P = 0.03 for change over time; relative reduction: 48.5%) in patient-reported antibiotic-associated adverse events (Figure 2).

Conclusion
A hospitalist collaborative partnering with AST can safely reduce excess antibiotic duration and antibiotic-associated adverse-events in hospitalized patients with CAP.

Disclosures
All Authors: No reported Disclosures.
1156. Running on Empty: Enlisting Transportation Services in Quality Improvement Initiatives as a Safeguard Against Catheter-Associated Urinary Tract Infections
Authors: Lobo Dale , Wright Dominique , Suarez-Ponce Sylvia , Green Melissa , Parilla Deborah , Seidler Lisa M , Parada Jorge P 
Published: October 2019

Abstract

Background
Patient transportation for off unit procedures is associated with transfers from bed to chair to examination tables, frequent elevation of the urine collection bag (UCB) above the bladder and urinary reflux (UR) of bacteria-laden urine into the bladder, significantly increasing risks of catheter-associated urinary tract infection (CAUTIs). If UCBs were systematically emptied prior to transportation the likelihood of UR would be greatly diminished, potentially reducing CAUTIs.

Methods
During a 5-week period transportation services (TS) collected baseline data on UCB status of all ICU patients, classifying them as empty/good to go vs. full/not good to go (Phase 1). Then, TS were educated on the importance of reducing UR as part of CAUTI reduction and were empowered to request UCBs be emptied. In parallel, unit-based staff were instructed to drain CBs prior to patient transport off unit and to expect the TS would refuse transport if CB was not emptied (Figure 1). Wireless voice-activated communications devices were used to improve coordination between TS and unit staff. During a 3 month (Phase 2) period, TS again collected data on the UCB status of ICU patients while reinforcing the need to empty UCBs.

Results
At baseline it was a coin toss as to whether a patient’s UCB would be empty or full at the time of transportation, while over 90% of UCB were emptied in Phase 2 (47.1% and 52.9%, vs. 90.6% and 9.4%, empty and unemptied in Phase 1 and Phase 2, respectfully, P < 0.001) (Figure 2). Figure 3 shows the detailed UCB status (empty at TS arrival, emptied upon TS request, transported full, transport refused) during Phase 2, with significant month upon month improvements (P = 0.014).

Conclusion
Despite longstanding existing hospital policies promoting best practices, including the need to empty UCBs prior to transport, we found this was commonly ignored in usual practice. Recruiting the TS to enforce UCBs are empty at the time of transportation proved a very effective way to markedly improve best practices. If representative of general practices elsewhere, this suggests leveraging TS can help ensure UCBs are emptied prior to patient transport and reduce CAUTI risk. It also exemplifies how ancillary services can be recruited to play an active role in quality improvement/patient safety projects.

Disclosures
All authors: No reported disclosures.