bluuebunny/crossref_metadata_2025_split huggingface dataset:
622. The Accessory Genome in Enterococcal Bacteremia: Results from the Vancomycin-Resistant Enterococcal Bacteremia Outcomes Study (VENOUS)
Authors: Simar Shelby , Hanson Blake , Contreras German , Reyes Katherine , Sahasrabhojane Pranoti V , Misikir Helina , Liu Catherine , Doi Yohei , Barberis Fernanda , Abbo Lilian , Dinh An Q , Spencer Maria , Zervos Marcus , Aitken Samuel L , Aitken Samuel L , van Duin David , Shelburne Samuel A , Shelburne Samuel A , Tran Truc T , Munita Jose M , Arias Cesar A , de los Angeles Spencer Maria 
Published: October 2019

Abstract

Background
Vancomycin-resistant enterococci (VRE) are a major cause of nosocomial bloodstream infections. Enterococci exhibit remarkable genomic plasticity and can recombine through the acquisition of genetic material via mobile genetic elements (MGEs), including resistance genes. The accessory genome plays a major role in the evolution of enterococci within the human host. Thus, dissecting the entire genome (pan-genome) is of paramount importance to characterize the population structure of enterococci causing disease.

Methods
VENOUS is an ongoing prospective, observational study of adults with enterococcal bacteremia. From September 2016 to March 2018, E. faecalis (Efs) and E. faecium (Efm) were collected in 14 hospitals of a single hospital system and a major cancer center in Houston, TX, and a general hospital in Detroit, MI. Short- and long-read genomic sequencing were performed with Illumina MiSeq and Oxford Nanopore Technologies GridION X5, respectively. A proprietary bioinformatics pipeline was utilized for genome assembly and further analyses.

Results
156 Efs and 98 Efm isolates from single patients were analyzed. The average proportion of core genes in each genome was 64.6% (53.0–74.1) and 49.1% (45.2–51.0) for Efs and Efm, respectively. The vanA gene cluster was identified in 5.1% (8/157) of Efs and 57.1% (56/98) of Efm. The plasmid-encoded aac(6′)-Ie-aph(2″)-Ia gene conferring high-level resistance to aminoglycosides was found in 37.6% (59/157) Efs, seven of which also possessed vanA. Long-read sequencing of vanA-harboring plasmids from a subset of VRE revealed that the vanA cluster was carried in plasmids ranging from 31.7 to 132.3 kb. Although the vanA operon was fairly conserved, insertions of MGE were identified in the intergenic regions of vanS/vanH and vanX/vanY. Furthermore, a variety of MGE insertions mediated integration of the vanA operon, including IS1216 and IS256 (figure).

Conclusion
Accessory genes, including AMR genes, comprise a significant proportion of the enterococcal pan-genome, indicating major genetic plasticity within these organisms. Acquired resistance genes seem to have a high degree of recombination and play a substantial role in the expansion of the genomic repertoire in clinical isolates.

Disclosures
Samuel L. Aitken, PharmD, Melinta Therapeutics: Grant/Research Support, Research Grant; Merck, Sharpe, and Dohme: Advisory Board; Shionogi: Advisory Board.
627. Molecular Epidemiology of Daptomycin-resistant Staphylococcus aureus Causing Bloodstream Infections
Authors: Gudipati Smitha , Perri Mary , Couto Natacha , Herc Erica , Zervos Marcus 
Published: October 2019

Abstract

Background
Daptomycin (Dap) has become increasingly important to combat infections caused by Staphylococcus aureus (SA). However, reports of daptomycin nonsusceptible (DNS) SA strains have emerged over the recent years, specifically with alteration of the MprF gene. Mutations in this gene lead to an increase in lysyl-phosphatidyl glycerol production resulting in a lower susceptibility to Dap and cationic antimicrobial peptides. Point mutations in the cls2 gene have also been associated with DNS SA through similar mechanisms of action. This study describes the gene mutations involved in our patients with SA bloodstream infections (BSIs) that developed Dap resistance.

Methods
This is a retrospective study in a tertiary healthcare system in southeast Michigan. SA blood isolates were sequenced through a gene-by-gene approach using Ridom SeqSphere. Charts were reviewed for clinical and laboratory data. Dap minimum inhibitory concentrations (MICs) were determined by E-test. DNS was defined as an MIC > 1.0 µg/mL.

Results
From December 3, 2015 to May 8, 2017, 7 patients were identified with DNS SA BSI. Mean age of the patients was 59 (SD = 13.7) and 86% were male. Mean bacteremia duration was 7 days (SD = 6.3), mean hospital length of stay was 13 days (SD = 9.8), 5 isolates were methicillin-resistant SA, and 2 were methicillin-sensitive SA. When comparing molecular sequencing of all seven patients with their Dap-sensitive strains vs. resistant strains, all patients, except for patient 3, had a point mutation at different allele loci in the MprF gene (Table 1). Additionally, two patients had point mutations in the cls2 gene. When comparing all 27 strains from the seven patients, each cluster was attributed to an individual patient with the exception of cluster one that included patients 5 and 6 suggesting transmission (Figure 1).

Conclusion
DNS SA is infrequent; however, the present study shows that it can emerge both from methicillin-resistant and -susceptible SA most commonly when developing MprF and cls2 gene mutations as seen in our patients. Patient 3 was the exception in our analysis and likely developed DNS SA through another gene mutation. Further studies are necessary to know the frequency of each mutation with all genes associated with DNS SA, and epidemiological risk factors of transmission.

Disclosures
All authors: No reported disclosures
636. Genome Epidemiology of Carbapenem-Resistant Acinetobacter baumannii (CRAb) in the United States
Authors: Iovleva Alina , Mustapha Mustapha , Cober Eric , Richter Sandra S , Arias Cesar A , Jacob Jesse T , Salata Robert , Satlin Michael J , Wong Darren , Bonomo Robert A , van Duin David , Doi Yohei 
Published: October 2019

Abstract

Background
CRAb is a major cause of healthcare-associated infections and is associated with high mortality due to the lack of reliable treatment options. We aimed to elucidate the contemporary population structure of CRAb isolates circulating in US hospitals using whole-genome sequencing (WGS).

Methods
A total of 131 CRAb isolates were identified at four tertiary care medical centers located in Ohio, Pennsylvania, Texas and North Carolina between 2017 and 2018. The genomes were sequenced with Illumina NextSeq and de novo assembled. Sequence types (STs) were identified using the Pasteur Institute MLST scheme. β-Lactamase genes were identified by ResFinder and manually curated.

Results
The 131 isolates belonged to 10 different ST types, including 8 known and 2 novel ones. In this collection, 101 isolates (77.1%) belonged to ST2, the dominant drug-resistant clone in the United States and Europe; 20 isolates belonged to ST499, a less common, but also globally distributed clone. Two isolates each belonged to ST46 and ST79, both common in South America. For the chromosomally encoded blaOXA-51-group genes, 11 variants were identified with blaOXA-66, blaOXA-82, and blaOXA-95 being predominant. For the chromosomally encoded blaADC-group genes, 26 variants were identified, with blaADC-161, blaADC-181, and blaADC-30 being the most common. The most frequent acquired carbapenemase gene was blaOXA-23, which was present in 89 isolates (67.9%). Other acquired blaOXA carbapenemase genes were identified much less frequently and included blaOXA-24, blaOXA-72, blaOXA-207, and blaOXA-237. 17 isolates (13.0%) did not contain any known acquired carbapenemase genes despite resistance to carbapenems.

Conclusion
ST2 is the most prevalent ST type among contemporary CRAb isolates identified in US hospitals, however, new STs are emerging, most notably ST499. Significant diversity was seen among chromosomal blaOXA-51-group carbapenemase, intrinsic blaADC-group cephalosporinase and plasmid-mediated blaOXA-group carbapenemase genes, which likely represented diversification within the STs. Correlations between clinical presentation and outcomes and the genomic features of the infecting isolates are being investigated

Disclosures
All authors: No reported disclosures.
650. Relationship of a Multiplex Molecular Pneumonia Panel (PP) Results with Hospital Outcomes and Clinical Variables
Authors: Rand Kenneth , Beal Stacy , Tremblay Elizabeth , Houck Herbert , Weber Kylie , Sistrom Christopher 
Published: October 2019

Abstract

Background
The Pneumonia Panel (PP) (BioFire Diagnostics, Salt Lake City, UT) detects 15 potentially pathogenic bacteria semiquantitatively (copy #/mL), 8 viruses and 7 resistance genes from the lower respiratory tract in ≈1 hour in the laboratory. Since identification and susceptibility take ≈ 2 days, this rapid result time is very attractive; however, the clinical significance of the PP copy #/mL as well as a predictable group of PP positive but culture negative patients is unknown. We retrospectively studied the relationship of 270 PP results to culture results, clinical data and outcomes.

Methods
Bronchoalveolar lavage fluid (N = 197) and endotracheal aspirates (N = 73) submitted to the UF Health Shands Hospital microbiology laboratory from June-September 2018 were frozen at −70°C, until tested on the PP. Patient data were extracted from the inpatient electronic medical record (Epic).

Results
Of 270 patients tested, 111/270 (41.1%) were PP bacteria negative/culture no growth or normal flora (Group 1), 59/270 (21.9%) were PP positive/culture negative (Group 2), and 100/270 (37.0%) were PP positive/culture positive (Group 3) for at least 1 concordant bacterial potential pathogen. Hospital length of stay (LOS), P = 0.0274, ANOVA; ICU LOS P = 0.0007 and BAL % Polys P < 0.0001 were significantly longer/higher in Group 3 than in Groups 1 and 2 (Table 1). Max daily temp on the day of culture in PP-positive groups 2 and 3 was significantly higher than the PP-negative group 1, P = 0.0260, ANOVA, (Table 1). Age, daily WBC, lowest paO2, max FiO2, % on antibiotics ( ≥80% for all groups), and % with viruses in the PP were not significantly different across groups. When all PP pathogens were grouped by copy # /mL, ICU LOS was significantly longer for 10(7) copies/mL (P = 0.0088), as was BAL % polys (P = 0.0006). Max daily temp was almost significantly higher for PP-positive groups 10(5), 10(6), and 10(7) combined compared with the PP-negative group (Table 2, P = 0.0608).

Conclusion
Hospital LOS was significantly longer and BAL %Polys higher in the bacterial pathogen culture-positive/PP-positive group vs. not positive groups. ICU LOS and BAL %Polys were significantly higher for the PP-positive groups vs. PP negative regardless of culture results. PP results (copy #/mL) independently correlated with outcome and clinical measures.

Disclosures
All authors: No reported disclosures.
652. Impact of FilmArray Meningitis Encephalitis Panel on HSV Testing and Acyclovir Use in Children Beyond the Neonatal Period
Authors: Messacar Kevin , Messacar Kevin , Gaensbauer James , Birkholz Meghan , Levek Claire , Todd James , Tyler Ken , Dominguez Samuel 
Published: October 2019

Abstract

Background
Testing and empiric use of acyclovir for herpes simplex virus (HSV) in children beyond the neonatal period undergoing lumbar puncture for suspected central nervous system (CNS) infection doubled in the past decade, while the incidence of HSV CNS infection is unchanged. A new syndromic multiplex PCR panel (FilmArray Meningitis Encephalitis Panel [MEP]) rapidly detects 14 pathogens in cerebrospinal fluid (CSF), including HSV. The impact of MEP implementation on HSV testing and acyclovir use is unknown.

Methods
We retrospectively compared CSF testing and acyclovir use in the pre-MEP era January 1, 2007–January 22, 2017 to post-implementation era of MEP January 23, 2017–December 31, 2017 amongst children >60 days with a CSF specimen sent to the Children’s Hospital Colorado microbiology laboratory. HSV singleplex PCR testing was available in both the pre-MEP and MEP eras.

Results
The proportion of CSF specimens from children with suspected CNS infection undergoing HSV testing (MEP or HSV PCR) doubled from 25% in the pre-MEP era to 54% in the MEP era (P < 0.01; Figure 1). In the MEP era, HSV testing was conducted by MEP in 96% of cases and HSV PCR in 8% of cases. In both eras, a majority of CSF specimens undergoing HSV testing had no pleocytosis (63% vs. 59%, P = 0.27). Children with negative HSV testing by MEP were less likely to be started on acyclovir than those with negative HSV testing by singleplex PCR (18% vs. 50%, P < 0.01) and, amongst those started, acyclovir was discontinued sooner, after a median 3 vs 5 doses (P = 0.05). Overall, however, a similar proportion of children with suspected CNS infection received acyclovir in the MEP and pre-MEP eras (13% vs. 12%), despite a low rate of HSV positivity (0.5% vs. 0%).

Conclusion
Implementation of MEP for syndromic CSF testing in children >60 days with suspected CNS infection doubled HSV testing without affecting the rate of empiric acyclovir initiation. Patients with negative HSV testing on MEP were less likely to be started on acyclovir, and if started, received fewer doses than those who tested negative on HSV singleplex PCR, likely due to more rapid turnaround time. However, increased MEP testing offset this, suggesting increased use of newer rapid syndromic tests will not cure creeping empiricism. Diagnostic stewardship targeting MEP use toward children with pleocytosis to decrease unnecessary test utilization are warranted.

Disclosures
All authors: No reported disclosures.
668. Quality of Life Changes in Patients with Clostridium difficile Infection (CDI): A Randomized, Double-Blind Trial of Ridinilazole (RDZ) Compared with Vancomycin (VAN)
Authors: Paul Sumita , Vickers Richard , Garey Kevin W 
Published: October 2019

Abstract

Background
C. difficile is the most frequent hospital-acquired bacteria in the United States. CDI is associated with significant morbidity and mortality, and a 46% lower mean EQ-5D index of Health-Related Quality of Life (HRQoL) compared with the general population. However, data on the impact of antibiotic treatment for CDI on HRQoL are lacking.

Methods
RDZ is a novel, narrow-spectrum antibiotic with targeted activity against C. difficile, under development for the treatment of CDI and prevention of recurrence. We evaluated HRQoL prospectively with the EQ-5D-3L in 69 patients enrolled in a Phase 2 randomized, double-blind trial comparing RDZ (n = 36) with VAN (n = 33). EQ-5D-3L was obtained at five time points (baseline, days 5, 10, 12, and 40) with summary index values calculated using US weights (Shaw 2005) evaluating raw scores for mobility, self-care, usual activities, pain/discomfort, and anxiety/depression, and visual analog scale (VAS) scores.

Results
As early as Day 5, CDI patients on RDZ had significant improvements in mean change from baseline in index scores (P = 0.008) and VAS scores (P = 0.01) but no significant improvements were seen in patients on VAN. Time to resolution of diarrhea also occurred sooner with RDZ with a hazard ratio 1.19 in favor of RDZ (90% CI: 0.76, 1.87). Mean changes in index scores in the VAN group took longer to improve significantly compared with baseline and became higher on VAN on Day 12 and Day 40. Treatment-related improvements in pain/discomfort and anxiety/depression are shown in Figures 1 and 2. The mean change from baseline in EQ-5D-3L domains showed the highest (significant) improvements in the pain/discomfort domain for both treatment groups across all time points. However, by Day 40, anxiety/depression improved significantly more with RDZ than with VAN (P = 0.039).

Conclusion
We believe this is the first study to document improvements in HRQoL after antimicrobial treatment for CDI. Patients receiving ridinilazole experienced greater improvements in HRQoL sooner than those on VAN. Anxiety/depression and pain/discomfort improved significantly with treatment. HRQoL should be evaluated in Phase 3 interventional studies for CDI. These results will need to be validated in the ongoing Phase 3 randomized, double-blind, global trials comparing RDZ to VAN for the treatment of CDI.

Disclosures
All authors: No reported disclosures.
674. Pre-Clinical and Phase I Safety Data for Anti-Pseudomonas aeruginosa Human Monoclonal Antibody AR-105
Authors: Loos Andreas , Weich Nadine , Woo Jennifer , Lalonde Guy , Yee Luisa , Dummer Wolfgang , Truong Vu L 
Published: October 2019

Abstract

Background
Anti-bacterial monoclonal antibodies can serve as a new treatment modality for difficult to treat infections. AR-105 is a fully human IgG1 monoclonal antibody (mAb) that binds to an extracellular polysaccharide epitope of Pseudomonas aeruginosa (PA) and was shown to mediate in vitro complement-dependent opsonophagocytic killing. AR-105 is currently being tested in a global Phase 2 clinical trial as an adjunctive treatment to standard of care antibiotics in ventilator-associated pneumonia patients. Here we present pre-clinical efficacy and clinical safety data for AR-105.

Methods
Efficacy in nonclinical studies against PA pneumonia was tested in prophylactic and therapeutic mouse models, either as a stand-alone therapy or in combination with antibiotics. Mice were dosed intranasally or by intravenous infusion with AR-105 post or prior to infection with PA and survival or lung bacteriology were monitored. In a clinical Phase 1 open-label study, 16 healthy volunteers received 2, 8, or 20 mg/kg of AR-105. Adverse events, immunogenicity, and pharmacokinetic (PK) profiles were evaluated for up to 84 days following administration.

Results
In the animal models, AR-105 reduced lung bacterial counts in a dose-dependent manner, and improved survival (80% in the treated group vs. 0% in the control group). Combination of AR-105 with antibiotics was more effective than monotherapy. In the Phase I study, no serious adverse events (AE) were observed in any cohort. Few AE were deemed related to the investigational drug, and all were mild and transient. AR-105 was found to be well tolerated in healthy volunteers with no anti-drug antibodies (ADA) detected. The PK profile was comparable with other human IgG1 mAbs, exhibiting a serum half-life of approximately 20 days.

Conclusion
AR-105 was confirmed to be effective in PA pneumonia animal models, either as stand-alone therapeutic or in combination with antibiotics. In the Phase 1 clinical study, AR-105 was shown to be safe and well-tolerated, with a PK profile similar to that of other IgG1 mAbs. AR-105 is a promising drug candidate for therapy of PA pneumonia.

Disclosures
All authors: No reported disclosures.
681. In vitro Activity of the β-Lactamase Inhibitor QPX7728 in Combination with Several β-Lactams Against Acinetobacter baumannii (AB) and Pseudomonas aeruginosa (PSA)
Authors: Lomovskaya Olga , Lindley Jill , Rubio-Aparicio Debora , Nelson Kirk J , Castanheira Mariana 
Published: October 2019

Abstract

Background
QPX7728 (QPX) is a novel broad-spectrum boron-containing inhibitor of serine- and metallo-β-lactamases (MBLs). We evaluated the in vitro activity of QPX combined with several β-lactams against carbapenem-resistant AB (CRAB) and PSA clinical isolates with varying β-lactam resistance mechanisms.

Methods
A total of 503 CRAB (meropenem [MEM] MIC ≥8 µg/mL) and 762 PSA clinical isolates were tested by the reference broth microdilution method against β-lactams alone and combined with QPX (4 µg/mL and 8 µg/mL). PSA isolates were selected to represent the normal distribution of MEM, ceftazidime–avibactam (CAZ-AVI), and ceftolozane-tazobactam (TOL-TAZ) resistance according to 2017 surveillance data (representative panel). Additionally, 262 PSA isolates that were either nonsusceptible (NS) to MEM (MIC, ≥4 µg/mL) or to TOL-TAZ (MIC, ≥8 µg/mL), or resistant (R) to CAZ-AVI (MIC, ≥16 µg/mL) (challenge panel) were also tested. Within this 262 strain challenge set, 56 strains carried MBLs and the majority also had nonfunctional OprD.

Results
Against CRAB, QPX at 4 and 8 µg/mL increased the potency of all β-lactams tested. MEM-QPX was the most potent combination (table) displaying MIC50/MIC90 at 1/8 and 0.5/4 µg/mL with QPX at fixed 4 and 8 µg/mL, respectively. Susceptibility (S) to MEM was restored in >95% of strains. Against the 500 PSA from the representative panel, S for all QPX combinations was >90%. For the challenge panel, TOL-QPX and piperacillin (PIP)-QPX were the most potent combinations, restoring S in 76–77% of strains. TOL-QPX and MEM-QPX or cefepime (FEP)-QPX restored the MIC values to S rates when applying the CLSI breakpoint for the compound alone (comparison purposes only) in ~90% and ~75% of non-MBL-producing strains, respectively, vs. 60–70% for TOL-TAZ and CAZ-AVI. PIP-QPX reduce the MIC values to S values for PIP-TAZ in ~60% of MBL-producing strains vs. 20–30% and 3–7% for other QPX combinations and non-QPX tested combinations, respectively.

Conclusion
Combinations of QPX with various β-lactam antibiotics displayed potent activity against CRAB and resistant PSA isolates and warrant further investigation.

Disclosures
All authors: No reported disclosures.
683. Assessment of Biofilm Eradication and Cytotoxicity of a Novel Polygalacturonic Acid + Caprylic Acid Wound Ointment Compared with Antiseptic Wound Ointments
Authors: Gerges Bahgat , Reitzel Ruth A , Rosenblatt Joel , Hachem Ray Y , Raad Issam I 
Published: October 2019

Abstract

Background
Antiseptic wound ointments are increasing importance from safety, microbiological and public health points of view. Previously, Rosenblatt et al. (2017) has assessed polygalacturonic acid (PG) + caprylic acid (CAP) solution for biofilm eradication efficacy and cytotoxicity. In this study, we assessed biofilm eradication and cytotoxicity of PG+CAP wound ointment compared with commercially available wound ointment comparators.

Methods
Assessment of antimicrobial efficacy was conducted using a well-established biofilm model. Twenty-four-hour biofilm was formed on silicone discs and exposed wound ointments for 2 hours. Discs were then sonicated and cultured to quantitate any remaining viable biofilm. To assess cytotoxic effects of wound ointments, L-929 fibroblasts were exposed to 2% extracts of each ointment. The trypan exclusion test was used to access cell viability and Alamar blue was used to assess metabolic function. Ointments tested include, PG+CAP formulated in an inert ointment base, benzalkonium chloride quaternary ammonia antiseptic ointment (BZK), polyhexamethylene biguanide (PHMB) antiseptic ointment, and 2-hydroxyethylcellulose + glycerol inert ointment base. Untreated fibroblast cells were used as controls.

Results
Within 2 hours of exposure, PG+CAP ointment able to completely eradicate C. albicans (CA), MDR Pseudomonas aeruginosa (PS), and MRSA. Additionally, PG+CAP was significantly more efficacious than BZK for MRSA (P = 0.002) and PS (P = 0.015) and PHMB for MRSA (P = 0.02).
In the trypan blue exclusion test PG+CAP yielded 96.29% viable cells compared with 77.83% and 83.25%, for the QUAT and PHMB ointments, respectively. Fibroblasts treated with 2% PG+CAP, retained 86.6% of metabolic activity compared with untreated cells while the QUAT and PHMB ointments retained 37.5% and 44.5% metabolic activity, respectively.

Conclusion
PG+CAP has enhanced effects on eradication of biofilm in vitro as well as less toxicity in vitro relative to the antiseptic wound ointments. Further in vivo studies are warranted.

Disclosures
All authors: No reported disclosures.