bluuebunny/crossref_metadata_2025_split huggingface dataset:
133. Ceftriaxone-resistant Haemophilus influenzae in Korean children
Authors: Lee Sanghoon , Lee Euntaek , Kim Gahee , Kim Jung Hwa , Kim Mina , Lee Ji-Na 
Published: December 2022

Abstract

Background
Haemophilus influenzae is known to develop resistance to β-lactam antibiotics by either producing β-lactamase or modifying structure of penicillin-binding protein 3 (PBP3) by ftsI gene mutation. Since 2017, H. influenzae with ceftriaxone resistance has been continuously appearing in our hospital, and the genotypic characteristics of these strains was analyzed.

Methods
Among a total of 69 H. influenzae isolated from the patients who admitted to Asan Medical Center Children’s Hospital from March 2014 to April 2019, 23 isolates resistant to ceftriaxone by EUCAST disk diffusion method were included. The ceftriaxone MIC was checked again with the E-test and ceftriaxone MIC ≤ 0.125 mg/L were categorized as susceptible. As test for β-lactamase production, the cefinase test and PCR amplification for blaTEM-1 and blaROB-1 were performed. The sequencing of the ftsI encoding PBP3 amplified by PCR was performed, and amino acid sequences were compared with H. influenzae Rd KW20.

Results
Among total 23 ceftriaxone-resistant isolates by disk diffusion method, 21 isolates restored for further molecular characterization were included, and 19% (4/21) were reported as susceptible by E-test. Among the 21 ceftriaxone-resistant isolates, 76.2% (16/21) were non-susceptible to amoxicillin/clavulanate, and one of them were resistant to meropenem. The prevalence of b-lactamase-producers was 57.1% (12/21), all of which were positive for blaTEM-1. For ftsI gene sequencing, either R517H or N526K amino acid substitution was observed, and none had both. The number of isolates having S385T was 17, of which 15 isolates accompanied with both M377I and L389F. The median ceftriaxone MIC of 3 isolates with only N526K was 0.012 ug/ml (range 0.008-0.125 ug/ml), and 12 isolates with N526K, M377I, S385T, and L389F was 0.19 ug/ml (0.19-0.25 ug/ml). Lastly, the three isolates with R517H, M377I, S385T, and L389F showed the highest median ceftriaxone MIC with 0.25 ug/ml (0.19-0.75 ug/ml).

Conclusion
Ceftriaxone-resistant H. influenzae isolates in Korea seems to be related to the combination of R517H, M377I, S385T, and L389F by ftsI gene mutation. Although clinical concerns about treatment failure may be low, continuous monitoring of the emergence of highly resistant strains is necessary.

Disclosures
All Authors: No reported disclosures.
136. Prevalence of Plasmid-Mediated Antibiotics Resistance Genes in Klebsiella pneumoniae in United States
Authors: Hwang Munok , Choi Hosoon , Jinadatha Chetan 
Published: December 2022

Abstract

Background
Multidrug resistant (MDR) bacteria which resist at least three different antibiotic classes are serious threat to public health and patient treatment. Antimicrobial resistant (AMR) genes are often mediated through plasmids due to its horizontal transferability from bacteria to bacteria. Here, we assessed the prevalence of AMR genes in the USA by analyzing longitudinal K. pneumoniae plasmid genome data obtained from PATRIC (Pathosystems Resources Integration Center) database.

Methods
The PATRIC database have 176 K. pneumoniae plasmid genome data collected in 9 states of US from 2004 to 2019. The isolation source are various patient samples including urine, blood, etc. The sequence information was downloaded from GeneBank. The AMR genes on plasmids of K. pneumoniae were identified using open-source AMR database, Resfinder which search AMR genes for 16 types of antibiotic classes.

Results
Multidrug resistance was spread all over the US as most of isolates have AMR genes against more than one antibiotic classes, and some isolates contain against up to 8 antibiotic classes AMR genes. Most common AMR genes are against 9 classes including Aminoglycosides, beta-lactamase (carbapenem), Chloramphenicol, Macrolide, Quinolone, Rifampicin, Sulfonamide, Tetracycline, and Trimethoprim. Aminoglycosides and beta-lactamase including carbapenem resistance genes showed higher frequency than other classes of antibiotics. Carbapenem resistance genes, especially blaKPC showed higher frequency in east region of US including NY, PA, and VA (Fig 1A). While some resistances reduced over time, Aminoglycosides and beta-lactamase resistance genes are sharply increased (Fig 1B). Many isolates contain 3∼4 plasmids and plasmid amplicon types were various by isolates but no co-relation between plasmid types and AMR genes was observed.

Conclusion
Database analysis of K. pneumoniae isolates from different regions and time provides insight of the prevalence of AMR genes. The prevalence of the multidrug resistance obtained from databases analysis showed the abundance of AMR genes regardless of the region or time, especially for Aminoglycoside and beta-lactamase. Bacterial sequence database such as PATRIC is a useful tool for tracking the existence and emergence of AMR genes.

Disclosures
Chetan Jinadatha, MD, MPH, AHRQ R01 Grant-5R01HS025598: Grant/Research Support|EOS Surfaces: Copper Coupons and materials for testing.
138. Description of Repeat Carbapenem-resistant Enterobacterales (CRE) Submitted to a State Laboratory from the Same Individuals, Kentucky - December 2018 - March 2022
Authors: Spicer Kevin B , Elathamna Marwa , Zinner Rachel 
Published: December 2022

Abstract

Background
CRE and carbapenemase-producing CRE (CP-CRE) can be persistently detected during screening in long-term care facilities. Re-identification of these organisms during normal care and movement through healthcare settings is less well described.
Objective: To describe repeated submission of CRE to a state laboratory, including persistence of detection and progression from colonization to infection.

Methods
Submission of CRE isolates was requested from labs in late 2017 and became mandated by legislative regulation in December 2020. Isolates were tested at the Kentucky Division of Laboratory Services (DLS) for CP using the modified carbapenem inactivation method (mCIM), with follow-up testing for specific carbapenemases using the Cepheid Xpert Carba-R assay. Results were maintained in the DLS lab information system. Descriptive statistics were derived for testing results from repeat submissions.

Results
From December 2018 through March 2022, 1,822 isolates were submitted to DLS from 1,498 distinct individuals; 324 repeat submissions were obtained from 214 individuals, with 141 individuals tested &gt; 14 days after the initial result (Figure). Several individuals had &gt; 2 submissions and some cultures had CRE both with and without CP identified. The same CP-CRE (species and mechanism) was identified from 42 individuals (29.8%) when tested &gt; 14 days after initial identification (median 71 days, IQR 40-151, max 857). The same CRE (species) without CP was identified from 66 individuals (44.1%; median 111.5 days, IQR 55-237, max 676). Urine was the most common specimen source among resubmissions (67% of resubmissions). Of 47 individuals with a discrepant result (i.e., different species or mechanism) after &gt; 14 days, only four had the same species identified initially as CP-CRE and then subsequently as non-CP-CRE. Ten individuals (7%) had screening and then clinical specimens with the same CP or species.

Conclusion
Persistence can occur with CP-CRE and with CRE without CP and may continue for &gt;500 days. The in vivo loss of CP by CRE appears to occur infrequently. Clinicians and infection preventionists should remain vigilant for persistent CRE colonization during clinical and infection control decision making.

Disclosures
All Authors: No reported disclosures.
140. Enterococcus faecalis CL Synthases Have Redundant Roles and Play A Major Role in Phospholipid Redistribution Associated with Daptomycin Resistance
Authors: Nguyen April , Polamraju Vinathi , Zhang Rutan , Panesso Diana , Khan Ayesha , Mileykovskaya Eugenia , Cecilia Tran Truc , Xu Libin , Vitrac Heidi , Arias Cesar A 
Published: December 2022

Abstract

Background
Daptomycin (DAP) is a lipopeptide antibiotic targeting membrane anionic phospholipids (APLs) at the division septum. DAP resistance (DAP-R) has been associated with activation of the LiaFSR system resulting in redistribution of APL microdomains (likely containing cardiolipin, CL) away from the septum. E. faecalis (Efs) possess two CL synthase genes, (cls1 and cls2) and changes in Cls1 are associated with DAP-R. However, the roles of each enzyme are unknown. Here, we characterize the roles of cls genes in DAP-R in the context of LiaFSR activation.

Methods
cls1 and/or cls2 were deleted from Efs OG117 and OG117ΔliaX (DAP-R strain with an activated LiaFSR response). qRT-PCR was used to study gene expression of cls1 and cls2 in the cls mutants. Membrane lipid content was analyzed using hydrophilic interaction chromatography-mass spectrometry. Mutants were characterized by DAP minimum inhibitory concentration (MIC) using E-test and localization of APL microdomains with 10-N-nonyl-acridine orange.

Results
cls1 and cls2 are upregulated in exponential phase of DAP-R Efs OG117ΔliaX relative to DAP-S Efs OG117, with only cls1 upregulated in stationary phase. Deletion of cls1 or cls2 resulted in upregulation of the other cls gene, independent of activation of LiaFSR. Lipidomics analysis confirmed that deletion of both cls resulted in complete absence of cell membrane CL content. When comparing CL profiles of Δcls1 relative to Δcls2 in both DAP-S and DAP-R, both strains produced similar levels and species of CL. However, development of DAP-R caused a change in membrane lipid content, namely, an increase in CL with no significant difference in phosphatidylglycerol compared to DAP-S strain. Evaluation of CL species in DAP-R shows a shift towards species containing longer fatty acid chains and higher saturation. Independent deletions of cls1 or cls2 did not revert the DAP phenotype. In contrast, deletion of both cls genes decreased the DAP MIC (2-3 fold) relative to the parent strain and restored septal localization of APL microdomains. DAP MIC was restored upon trans complementation of either cls1 or cls2 into the double deletion mutant.

Conclusion
Our results support a major role of Cls in changes in cell membrane architecture and DAP-R in enterococci, with overlapping roles for Cls1 and Cls2.

Disclosures
Cesar A. Arias, MD, PhD, Entasis Phramceuticals: Grant/Research Support|MeMed Diagnostics: Grant/Research Support|Merck: Grant/Research Support.
144. Gram Negative Bacteria with Increased Minimal Inhibitory Concentration for Cefiderocol among Pediatric Patients in a Northern Italy Hospital.
Authors: Russo Chiara , Sette Claudia , Medici Chiara , Losurdo Giuseppe , Palmero Candida , Saffioti Carolina , Mariani Marcello , Ricci Erica , Ugolotti Elisabetta , Bondi Elisabetta , Montalto Shana , Tavella Elisa , Castagnola Elio , Mesini Alessio 
Published: December 2022

Abstract

Background
Cefiderocol is a siderophore cephalosporin active against Gram negative (GN) carbapenem resistant bacteria, approved in Italy in September 2020 for adult patients. In pediatric population off label use is allowed when severe infections from multidrug resistance (MDR) GN bacteria occur. Recently, some authors reported the emergence, among strains of Enterobacterales resistant to ceftazidime avibactam, of cross-resistance with cefiderocol.
The aim of this study is to describe GN strains with increased Minimal Inhibitory Concentration (MIC) for cefiderocol isolated in our hospital.

Methods
This is a retrospective, single-center study conducted in Istituto Giannina Gaslini Pediatric Hospital (Genoa, Italy) from 1st January 2020 to 31st April 2022. We collected all strains of MDR GN bacteria whit increased MIC for cefiderocol isolated in our hospital. Cefiderocol susceptibility testing was performed by disk diffusion assay with the disk of 30 μg (Kirby-Bauer method, KB) according to EUCAST’s recommendations and KB breakpoints. We collected demographical data, previous colonization (if note), carbapenemases production, clinical outcomes (infections from MDR; death at 7 and 30 days; ICU admission).

Results
Overall, 10 GN strains with increased MIC for cefiderocol were collected. 9/10 were Enterobacterales (4 Escherichia coli, 2 Enterobacter cloacae complex, 3 Klebsiella pneumoniae), one was Acinetobacter baumannii. 8/10 patients were admitted to other hospital in the six months before admission in our hospital, data about previous colonization were unknown. All MDR isolated produced metallo-β-lactamase [MBL] (5/10 New Delhi metallo-β-lactamase [NDM], 5/10 Verona integron-encoded metallo β-lactamase [VIM]). Four patients developed infection due to MDR (2 urinary tract infections, 1 bloodstream infection, 1 surgical wound), 2/4 patients died during the hospitalization.

Conclusion
Our study confirms that MDR producing MBL carbapenemases may have reduce susceptibility to cefiderocol, even if never exposed to this siderophore cephalosporin.
Due to the possibility of cross resistance with MDR resistant to ceftazidime/avibactam, cefiderocol should be carefully prescribe in empirical treatment of MBL producers strains.

Disclosures
All Authors: No reported disclosures.
147. Identification of Novel Colistin Resistance Genes in an Extremely Colistin Resistant Pseudomonas aeruginosa Clinical Isolate
Authors: Gatesy Samuel W , Bertucci Hanna , Vessely Madeleine , Vessely Madeleine , Valdes Aliki , Alisoltanidehkordi Arghavan , Ozer Egon A , Marty Francisco M , Mekalanos John , Hauser Alan R , Bachta Kelly E R 
Published: December 2022

Abstract

Background
Pseudomonas aeruginosa (PA) readily acquires genomic mutations and exogenous genetic elements that confer antimicrobial resistance (AMR). With the rise in AMR, there are limited antibiotics available to treat multidrug-resistant (MDR) PA. As such, clinicians have returned to previously used antibiotics. Colistin, sidelined for neurotoxicity and nephrotoxicity, has returned to clinical practice as a viable but suboptimal option for MDR-PA treatment. The most common mechanism of resistance to colistin involves modifications of the lipid A moiety within the bacterial lipopolysaccharide (LPS). Following the identification of a MDR PA isolate, BWH047, we experimentally determined its colistin MIC to be &gt; 1,280 µg/mL and used genomic approaches to identify novel genetic mechanisms of extreme colistin resistance.

Methods
We created a random, saturated transposon (Tn) insertion library in PA BWH047 using the Himar1 mariner system. After exposure of the library to 640 µg/mL colistin for 10 hours, genomic DNA was harvested, and the Tn insertion sites were sequenced. Insertion sequencing (INSeq) analysis was performed. We identified 27 genes conditionally important for BWH047 growth in the presence of colistin. We selected five initial targets arnC, dedA, wapH, speE2, and bchE and tested their impact on colistin resistance using standard microbroth dilution methods.

Results
Of our deletion mutants, three showed loss of resistance to colistin. ArnC was chosen as a positive control as its role in colistin resistance in PA is well described. Colistin MICs of BWH047 ΔarnC, ΔdedA, ΔwapH, ΔspeE2, and ΔbchE were determined to be 0.5, 0.5, 1, &gt; 1,280 and &gt; 1280 μg/mL, respectively.

Conclusion
Here, we used INSeq to identify novel genes involved in extreme colistin resistance. Thus far, we have identified two new candidate genes dedA and wapH, critical for colistin resistance in PA BWH047. Neither gene has been associated with colistin resistance in PA; However, dedA orthologs in Burkholderia thailandenesis and Klebsiella pneumoniae have been shown to be important for colistin resistance. The gene wapH is part of the LPS core oligosaccharide biosynthetic pathway and its discovery hints that additional alterations in the bacterial outer membrane may impact colistin resistance.

Disclosures
All Authors: No reported disclosures.
175. Evaluation of Optimal Urinalysis Criteria for Conditional Urine Culturing
Authors: Li Cecilia , Claeys Kimberly C , Morgan Daniel J , Coffey K C , Tadesse Yeabsera 
Published: December 2022

Abstract

Background
Asymptomatic bacteriuria is a common condition that is often treated unnecessarily with antimicrobials. Conditional urine reflex culturing leverages the negative predictive value of the absence of pyuria, often defined by a minimum urine white blood cell (WBC) count cutoff &gt; 10 cells/hpf. This value has not been extensively validated. This study evaluated parameters from urinalysis (UA), including various WBC cutoffs, and their ability to detect urinary tract infections (UTIs).

Methods
Retrospective cohort study of adult patients with or without urinary catheters with at least one UA between July 2020 to July 2021. Conditional reflex urine culturing with urine WBC cutoff of &gt; 10 cells/hpf was standard practice. Pregnant patients, patients with urologic procedures, and those who were mechanically ventilated at time of UA were excluded. UTIs were defined as definitive, probable, possible, or unlikely (Table 1). Comparisons between definitions and those with definitive/probable versus possible/unlikely UTIs were made using Chi-squared test. Table 1.UTI definitions

Results
368 patients were included in the final analysis. 154 (41.8%) were male and mean age was 56.9 ± 17.9 years. 117 (31.8%) had urinary catheters. 296 (80.4%) of UAs were treated with antibiotics which were administered after UA collection 89.2% of the time. The total incidence of definitive, probable, possible, and unlikely UTIs according to WBC count is listed in Table 2. UA parameters including leukocyte esterase positivity and presence of nitrites did not differ when compared between definitive/probable versus possible/unlikely UTIs (94.3% vs. 97.1% and 23.9% vs 26.4% respectively). Differences in leukocyte esterase positivity and presence of nitrites were not seen for non-catheterized patients when compared between definitive/probable versus possible/unlikely UTIs (92.3% vs. 96.5% and 21.2% and 29.3% respectively). Table 2.Urine WBC categorization stratified by UTI definition

Conclusion
Urine WBC cutoff &gt; 10 cells/hpf identifies many patients with unlikely UTIs. Current UA parameters do not definitively differentiate UTIs from not in catheterized or non-catheterized patients. Most patients with a positive UA were treated.

Disclosures
Kimberly C. Claeys, PharmD, BioFire Diagnostics: Honoraria.
197. The Clinical Impact of Early Detection of ESBL-Producing Enterobacterales with PCR-Based Blood Culture Assays
Authors: Chang Kai-Ming , Haghamad Aya , Saunders-Hao Patricia , Jain Sumeet , Epstein Marcia , Streva Vincent , Juretschko Stefan , Gautam-Goyal Pranisha 
Published: December 2022

Abstract

Background
Bloodstream infections (BSIs) due to extended spectrum beta-lactamase (ESBL) producing Enterobacterales can cause significant morbidity and mortality. The first-line treatment for these is a carbapenem. ESBL-encoding genes such as blactx-m can be detected by ePlex® Blood Culture Identification (BCID) panels by utilizing polymerase chain reaction (PCR)-based techniques. Our primary objective was to assess the impact of BCID on time to appropriate therapy; secondary objectives were to assess the clinical impact on mortality, 30-day readmission, and length of stay (LOS).

Methods
This study was a retrospective multicenter observational study of hospitalized patients with ESBL-producing Enterobacterales positive blood cultures. Patients with ESBLs identified in the final blood culture by conventional methods pre-ePlex® BCID (Jan 1 to Sep 30, 2019) were compared to patients with ESBLs identified by ePlex® BCID (Jan 1 to Sep 30, 2021). Patients who expired or were discharged prior to Gram stain results were excluded. Time to appropriate therapy was defined as the time from Gram stain result to ordering a carbapenem. In-hospital mortality, 30-day readmission rate, and LOS were analyzed for each cohort. T-test and Chi-square test were performed.
Inclusion and exclusion criteria for pre-ePlex BICD (2019) and post-ePlex BCID (2021) groups

Results
ESBL BSIs in 503 patients across 11 hospitals were identified and a total of 281 patients (pre-ePlex® BCID n=130; ePlex® BCID n=151) were included. A significant decrease in the median time to carbapenem order was observed (44.5 hours in the pre-ePlex® BCID group vs. 8 hours in the ePlex® BCID group (p&lt; 0.001)). No significant difference was observed in in-hospital mortality, 30-day readmissions, or LOS. The mortality rates were 6.9% and 6.6%, the 30-day readmission rates were 7.7% and 12.6%, and the LOS were 8 days and 10 days, respectively in the pre- and post-ePlex® BCID groups.
Comparison of outcome measure results between the pre-ePlex BICD (2019) and post-ePlex BCID (2021) groups.
Box and whisker graphs for time from Gram stain result to ordering carbapenems (hours)

Conclusion
Implementing ePlex® BCID to detect ESBL BSIs decreased the median time to escalation to carbapenems by 36 hours. Despite the decrease in time to appropriate therapy, no change in in-hospital mortality, 30-day readmission, and LOS was observed.

Disclosures
All Authors: No reported disclosures.
212. Outcomes of Weekly Fluconazole Antifungal Prophylaxis in Pancreas Transplant Recipients
Authors: Williams Samantha M , Vijayvargiya Prakhar , Rizwan Sohail M , Beam Elena , Garrigos Zerelda Esquer 
Published: December 2022

Abstract

Background
Fungal infections following pancreas transplantation carry significant morbidity and mortality with an estimated incidence of 3 to 28%. The American Society of Transplantation (AST) suggests considering fluconazole prophylaxis in pancreas transplant recipients (PTR) at high-risk of invasive candidiasis (IC). However, optimal dosage and duration of prophylaxis is unclear. Weekly fluconazole for prevention of IC has been previously reported in liver and bone marrow transplant recipients. We analyzed outcomes of once weekly fluconazole prophylaxis in PTR.

Methods
We retrospectively reviewed all pancreas transplants performed at our institution from January 2017 through September 2021. PTR at high-risk for IC were defined per AST criteria as those with enteric drainage, vascular thrombosis, and post-perfusion pancreatitis. Patients received once weekly oral fluconazole 200 mg for 12 weeks post-transplant for IC prophylaxis. We analyzed incidence of breakthrough IC within the first 6 months post-transplant.

Results
We identified a total of 22 PTR, all of whom received simultaneous kidney transplantation from deceased donors. Of these, 12/22 (55%) were male and 11/22 (50%) were African American. Median age at the time of transplantation was 39 years (IQR 34-46). The most common indication for transplantation was type 1 diabetes mellitus (17/22, 21%) with associated nephropathy. No donor organ cultures were positive for fungi and all pancreas transplants were performed using enteric drainage. Notably, one patient developed pancreas allograft thrombosis while another developed pancreatitis. No patients required early discontinuation of fluconazole due to intolerance or side effects and none developed breakthrough IC within 6 months post-transplant (Table 1). Table 1.

Conclusion
Weekly fluconazole prophylaxis has not been previously studied in PTR. In our cohort, this approach was well tolerated, with no cases of IC at 6 months post-transplantation in patients at high-risk. Randomized controlled clinical trials are needed to define the optimal strategy in this population.

Disclosures
M. Rizwan Sohail, MD, Aziyo Biologics: Honoraria|Boston Scientific Corporation: Honoraria|Medtronic: Grant/Research Support|TRYX: Grant/Research Support.