bluuebunny/crossref_metadata_2025_split huggingface dataset:
556. Phylogenomic Epidemiology of Methicillin-Resistant Staphylococcus aureus (MRSA) Chilean-Cordobes Clone in Latin America
Authors: Martínez Jose R W , Diaz Lorena , Rojas Marcelo , Rios Rafael , Hanson Blake , Rivas Lina M , Spencer Maria , Moustafa Ahmed M , Araos Bralic Rafael , Peters Anne , Reyes Jinnethe , Carvajal Lina P , Luna Carlos , Salles Mauro , Alvarez Carlos , Labarca Jaime , Seas Carlos , Seas Carlos , Guzmán Manuel , Planet Paul J , Planet Paul J , Arias Cesar A , Munita Jose 
Published: October 2019

Abstract

Background
The MRSA Chilean-Cordobes (ChC) clone belongs to the clonal complex 5 (CC5) and typically carries SCCmec I. The ChC clone predominated widely throughout several countries of Latin America (LA), but during the mid-2000s a CA-MRSA CC8 LA variant (USA300-LV) quickly replaced the ChC in Colombia and Ecuador. Most notably, this replacement was not observed in Peru or Chile. Here, we aimed to understand the phylogenomic relatedness of the CC5 ChC clone obtained from different countries of LA.

Methods
We sequenced and analyzed the genomes of 115 MRSA isolates obtained between 2011–2014 from bloodstream infections in 6 LA countries (Argentina, Brazil, Colombia, Chile, Peru, and Venezuela). All isolates were confirmed as ChC clone by pulsed-field gel electrophoresis (PFGE). We used core genome-based phylogenomic reconstructions and molecular clock analysis to infer the relationships and time of divergence between clades.

Results
Whole-genome-based multilocus sequence typing determined that 110/115 isolates belonged to ST5 and carried SCCmec I. The phylogenomic reconstruction showed ChC isolates clustered into 4 major clades distinctly segregated by country of origin (Figure 1). Interestingly, isolates recovered from Chile divided into 2 different clades that segregate according to the city of origin (Santiago [SCL] or Concepción [CON]), suggesting these clades evolved independently. Molecular clock analyses suggested all clades share a common ancestor with the divergence of the Chilean clades occurring earlier (Figure 2). Of note, analysis of heavy metal genes suggested the divergence between Chilean isolates was characterized by the loss of a mercury resistance gene cluster, which is present in an 88% of CON isolates, but only in 28% of SCL (Figure 2).

Conclusion
MRSA isolates belonging to the ChC clone from 6 LA countries clustered in 4 clades according to the geographical region of isolation. This segregation suggests divergent adaptations that may respond to different selective pressures. Heavy metal resistance could play a role in the ability of the MRSA ChC to disseminate in specific geographical locations.

Disclosures
All authors: No reported disclosures.
559. Two Different Beasts: Comparing Epidemiology of Healthcare-Associated vs. Community-Acquired Methicillin-Resistant Staphylococcus aureus Bacteremia
Authors: McLaughlin Luke , Smith Stephanie 
Published: October 2019

Abstract

Background
Methicillin-resistant staphylococcus aureus (MRSA) bloodstream infection (BSI) is associated with significant morbidity and mortality. Healthcare-associated (HCA) MRSA infection (occurring >48 hours after hospitalization or in those with prior healthcare exposure) has traditionally been associated with severe invasive disease, while community-associated (CA) MRSA infection (occurring within 48 hours of hospitalization and without prior healthcare exposure) has been observed in otherwise healthy individuals. We characterized the epidemiology, resistance patterns, and clinical outcomes associated with MRSA BSI over a 5 year period comparing patients with community-onset bacteremia to those with hospital onset bacteremia.

Methods
We performed a retrospective chart review of 151 MRSA bloodstream infections from 2013–2018 at the University of Alberta Hospital (Edmonton, Canada). We assessed each BSI by: classification (CA vs. HCA), presence of MRSA risk factors, source of infection, MRSA resistance, rate of ICU admission, and 30-day mortality.

Results
The median age of all patients with MRSA BSI was 53 years (range 23–94). MRSA BSI occurred more commonly in males for both CA and HCA infection (53% and 62%). HCA-MRSA infections had a higher rate of previous MRSA colonization (64.8%) compared with CA-MRSA patients (41.7%). Injection drug use was higher in CA-MRSA infections (47% vs. 11%). The most common source of CA-BSI was bone/joint (30%) while line-associated infections were the most common in HCA-BSI. Clindamycin resistance was common (46–53% susceptible) while resistance to tetracyclines (91–97% susceptible) and trimethoprim/sulfamethoxazole (98–100% susceptible) was uncommon. HCA-MRSA BSI was associated with a higher rate of ICU admission (44% vs. 33%) and 30-day mortality (18.7% vs. 11.7%).

Conclusion
Invasive MRSA infection continues to be associated with significant morbidity and mortality. We found that healthcare-associated MRSA BSI was associated with a high rate of prior MRSA colonization as well as a higher rate of ICU admission and 30-day mortality. There are significant differences in the demographics of patients with CA BSI compared with HCA BSI. Interventions to prevent these infections need to be targeted to the geographic location of acquisition.

Disclosures
All authors: No reported disclosures.
583. Improving Catheter Scrub Technique and Compliance in a Level IV Neonatal ICU
Authors: Ellsworth Misti G , Milligan Sarah , Yager Lauren , Kubanda Ann , Webber Krysten , Khan Amir M 
Published: October 2019

Abstract

Background
Central line-associated bloodstream infections (CLABSIs) are challenging to prevent in the neonatal population due to the long-term necessity of central access for nutrition and medication. Neonates are a population at high risk for CLABSIs, and infections in this group are associated with prolonged hospitalization, greater healthcare costs, and increased mortality. Current bundles for CLABSI prevention include a friction scrub of the catheter hub prior to each use. Real-time audits of correct technique can be challenging. In July of 2018, our team developed a new strategy for auditing scrub technique in an attempt to reduce CLABSI rates.

Methods
This project took place in a NICU with 118 level 4 beds from July 2018 to February 2019. Our NICU is located in a large metropolitan area and serves as a referral center for complex neonates throughout the region. The intervention period encompassed 25,085 patient-days and 6,206 line days. Real-time friction scrub audits were performed for both dedicated line team staff as well as bedside nurses. In order to determine whether a healthcare worker’s (HCW) scrub technique was successful, a colorless luminescent product was applied to a practice catheter hub that adhered to the hub, but was not visible to the HCW. The HCW would then demonstrate a friction scrub on the practice catheter, and the hub was placed under a black light to show where any residual product may be present. This process was repeated until the staff member was able to remove the product from the hub. Once the staff was successful, monthly real-time audits were continued to reinforce the correct technique.

Results
Between July 2018 and February 2019, compliance with scrub technique and ability to clear product from catheter hubs increased by 50%. The CLABSI rate in the first 9 months after intervention was 0.806 per 1000 line days as compared with 2.170 per 1000 line days in the previous fiscal year.

Conclusion
The number of CLABSI’s during the intervention period was 63% less when compared with the previous fiscal year. This process, in conjunction with our other CLABSI prevention practices, has significantly decreased both our CLABSI rate and overall numbers. This project emphasizes the importance of focusing on the basics of infection prevention practices and continual auditing to prevent practice creep.

Disclosures
All authors: No reported disclosures.
586. Multidrug-Resistant Organisms from Three Pedaitric Inpatient Units in the Domincan Republic
Authors: De Luna David , Mena Lora Alfredo J , Roque Yori , López Franceschini Micheilisse , del Carmen Perez Maria , Cabán Lizamarie 
Published: October 2019

Abstract

Background
Multidrug-resistant organisms (MDRO) are a major global public health threat. Antimicorbial consumption and resistance in low- and middle-income countries (LMICs) are rising. This trend can be consequential for vulnerable populations such as children who have high rates of febrile illnesses. The aim of our study is to asses the burden of MDRO in hospitalized pediatric patients in the Dominican Republic (DR).

Methods
Retrospective review of all positive cultures in patients ages 0–17 at three tertiary referral centers in Santiago, DR. Culture-positive cases from January 2016 to December 2017 were reviewed. Repeat cultures from the same patient were excluded. Phenotypic susceptibility data were collected from automated susceptibility testing systems using WHOnet interface.

Results
A total of 1,584 cultures were reviewed, of which 1,041 (65%) were Gram-negative and 514 (32%) Gram-positive. The most common microorganisms were E. coli (23%)and S. aureus (11%). Sample were obtained from stool (26.9%), blood (23.5%), urine (16.2%), secretions (5.4%), and central line catheters (7.2%). Phenotypic resistance consistent with extended-spectrum β-lactamase (ESBL) and carbapenem-resistant Enterobacteriaceae (CRE) was found in 524 (50.3%) and 179 (17.2%) of Gram-negatives, respectively. MDRO rates by organism are in Figure 2. A total of 72 (21.0%) S aureusisolates were methicillin resistant (MRSA) and 62 (18%) showed suspected inducible resistance to clindamycin (Figure 3).

Conclusion
Data from automated culture systems suggests a high prevalence of ESBL and CRE in this city-wide cohort from three pediatric facilities. Prospective confirmatory studies with manual susceptibility testing may help clarify the true prevalence of MDRO. Further studies are needed to understand the epidemiology and risk factors pediatric patients colonized or infected with MDROs in LMICs and in the DR. Exposure to antimicrobials may be an important risk factor. Understanding antimicrobial use in children and possible exposure to antimicrobials in the environment may help identify antimicrobial stewardship targets and help curb antimicrobial pressure and resistance.

Disclosures
All authors: No reported disclosures.
602. Mechanism of LiaY-Mediated Daptomycin Resistance in Enterococcus faecalis
Authors: Nguyen April , Tran Truc T , Panesso Diana , Khan Ayesha , Mileykovskaya Eugenia , Vitrac Heidi , Arias Cesar A 
Published: October 2019

Abstract

Background
Daptomycin (DAP) is a lipopeptide antibiotic that targets the cell membrane (CM) at the division septum. DAP resistance (DAP-R) in E. faecalis (Efs) has been linked to mutations in genes encoding the LiaFSR stress response system and lipid biosynthetic enzymes, including cardiolipin synthase (Cls). The signature phenotype of DAP-R is redistribution of CM anionic phospholipid (APL) microdomains. Using a genetic approach, we have identified a transmembrane protein (LiaY) as a major mediator of cell membrane APL redistribution associated with DAP-R. Here, we explore the mechanism of LiaY-mediated changes in the CM under the hypothesis that CM remodeling occurs through interactions with Cls.

Methods
Efs encodes two cls genes (cls1 and cls2). Deletion mutants of both cls genes were generated using the Crispr/cas9 system in the daptomycin-sensitive strain Efs OG117 and Efs OG117∆liaX (a DAP-R derivative of OG117). DAP minimum inhibitory concentration (MIC) was determined using E-test on Mueller–Hinton II agar. Visualization of APL microdomains was performed by staining mid-logarithmic phase cells with 1 µM of 10-N-nonyl-acridine orange (NAO) and fluorescence microscopy. Bacterial two-hybrid system was used to study interactions between LiaY with Cls1 or Cls2.

Results
Single or double deletion of cls1 or cls2 in Efs OG117 did not affect DAP MIC, and no changes in CM architecture were seen by NAO staining. In contrast,deletion of cls1 (alone or in conjunction with a deletion of cls2) in a DAP-R derivative of OG117 OG117∆liaX, resulted in a marked decrease in DAP MIC, and NAO staining of Efs OG117∆liaX∆cls1∆cls2 shows a restoration of septal APL microdomain localization.In the same DAP-R background, deletion of cls2 alone did not have any effect on DAP MIC or APL microdomain distribution. Additionally, bacterial two-hybrid assays showed a positive interaction of LiaY with Cls1 but not with Cls2.

Conclusion
We have identified the biochemical basis for DAP-R associated CM remodeling. In a proposed model, the LiaR-mediated activation of the LiaY triggers specific interactions with Cls1 displacing the protein away from the septum, resulting in local generation of APL microdomains that prevents DAP-mediated damage to the CM.

Disclosures
All authors: No reported disclosures.
606. Identification and Characterization of HMB-2, a Novel Metallo-β-Lactamase in a Pseudomonas aeruginosa Isolate
Authors: Zhu Wenming , McAllister Gillian A , Jose Machado Maria , Campbell Davina , Karlsson Maria , Rasheed James , Kainer Marion A , Muleta Daniel , Walters Maroya S , Grass Julian E , Halpin Alison L , Stanton Richard A 
Published: October 2019

Abstract

Background
Carbapenemases, a global health threat, are a diverse group of β-lactamases active against cephalosporins and carbapenems, which are often last resort treatments for multidrug-resistant gram-negative infections. The most common carbapenemases reported among Pseudomonas aeruginosa are metallo-β-lactamase (MBLs). We describe a novel MBL (designated HMB-2) identified in a P. aeruginosa isolate from a urine specimen collected in 2015 as part of CDC’s Emerging Infections Program.

Methods
We performed antimicrobial susceptibility testing (AST) by broth microdilution, real-time PCR to screen for common carbapenemases (IMP, KPC, NDM, VIM, and OXA-48), and modified carbapenem inactivation method (mCIM) to test for carbapenemase production. The isolate underwent whole-genome sequencing (WGS) using Illumina MiSeq and PacBio RS II (Pacific Biosciences) platforms. Long read sequences were polished using Quiver and corrected by Pilon utilizing Illumina reads. We further characterized a putative novel MBL identified in WGS data by amplifying and cloning the gene into the pCR2.1-TOPO II vector (Invitrogen), which was then sub-cloned into a pET21 expression vector (Sigma–Aldrich). The resulting hmb2+ pET21 plasmid was transformed into a susceptible Escherichia coli for AST, including the imipenem-EDTA method to confirm MBL activity.

Results
The isolate displayed resistance to carbapenems and demonstrated phenotypic carbapenemase activity (mCIM positive), but was negative for carbapenemase genes by PCR. WGS analyses identified a putative MBL gene located on the chromosome. The gene shared 98% DNA and protein sequence identity with an MBL reported in 2016 in a P. aeruginosa isolate from Germany (HMB-1) and thus was named hmb-2. The cloned hmb-2 gene conferred resistance to carbapenems (meropenem and ertapenem) and third-generation cephalosporins (cefotaxime and ceftazidime) in transformed E. coli. The Minimum Inhibitory Concentrationratio for the imipenem-EDTA method was ≥4.

Conclusion
A putative, novel β-lactamase gene, blaHMB-2, was identified and cloned. The imipenem-EDTA results indicated that HMB-2 is an MBL. This discovery underscores the important role WGS plays in identifying new mechanisms of antimicrobial resistance.

Disclosures
All authors: No reported disclosures.
616. Evaluation of In Vitro Susceptibility to Ceftazidime/Avibactam of Clinical Isolates of Carbapenem Nonsusceptible Gram-Negative Bacilli from Colombia
Authors: Appel Tobias M , Mojica Maria F , De La Cadena Elsa , Pallares Christian , Virginia Villegas Maria 
Published: October 2019

Abstract

Background
Ceftazidime/avibactam (CZA) is a combination of a third-generation cephalosporin and a diazabicyclooctane β-lactamase inhibitor, which is active against a broad range of class A, C and D β-lactamases. In Colombia, high rates of multidrug-resistant Enterobacteriaceae (Ent)and P. aeruginosa (Pae) have been reported. Of special concern are KPC enzymes endemic in Ent and found in Pae, which are associated with higher mortality and healthcare costs, as well as limited therapeutic options. Herein, we evaluate the susceptibility of clinical isolates of carbapenem nonsusceptible Ent (CNS-E) and Pae (CNS-P) to CZA with the aim of understanding its role as a therapeutic option for these bacteria.

Methods
Three hundred ninety-nine nonduplicate clinical isolates of carbapenem nonsusceptible Gram-negative bacilli were collected in 13 medical centers from 12 Colombian cities, from January 2016 to October 2017 (137 K. pneumoniae [Kpn], 76 E. coli, 34 Enterobacter spp., 21 S. marcescens [Sma] and 131 Pae). CNS-E was defined as minimum inhibitory concentrations (MIC) ≥1 mg/L for ertapenem and CNS-P was defined as MIC ≥4 mg/L for meropenem. MIC were determined by broth microdilution and interpreted according to current CLSI guidelines. CZA MIC were determined using double dilutions of ceftazidime and a fixed concentration of avibactam of 4 mg/L. Comparator agents were ceftazidime, cefepime, piperacillin/tazobactam, imipenem, meropenem, tigecycline (TGC), and fosfomycin (FOS).

Results
Antimicrobial activity of CZA and comparators is shown in Table 1. CZA susceptibility ranged from 69% in Kpn to 81% in Sma, whereas 49% of CNS-P were susceptible to CZA. In both, CNS-E and CNS-P, CZA was superior to all other tested β-lactam compounds. Notably, in CNS-E CZA susceptibility was comparable to FOS and TGC (except for TGC in Sma).

Conclusion
CZA is the most active β-lactam against CNS-E and CNS-P. CZA nonsusceptibility suggests the presence of other resistance mechanisms, such as class B β-lactamases that are not inhibited by avibactam, and which are more frequently reported in CNS-P. Our results highlight the key role of new agents such as CZA in KPC endemic countries and the need for surveillance studies to determine the nature of resistance mechanisms.

Disclosures
All authors: No reported disclosures.
626. Mobile Genetic Element Dynamics of Co-Circulating Klebsiella pneumoniae Sequence Types Carrying blaKPC in Houston, Texas
Authors: Shropshire William C , Dinh An Q , Miller William R , Ecklund Heather , Wanger Audrey , Tran Truc T , Arias Cesar A , Hanson Blake 
Published: October 2019

Abstract

Background
Carbapenem-resistant Klebsiella pneumoniae (CR-Kpn) are a significant cause of hospital-associated infections. Class A β-lactamases, e.g., Klebsiella pneumoniae carbapenemases (KPCs), are major contributors to carbapenem resistance. Sequence type 258 (ST258) is the most common genetic lineage of CR-Kpn associated with blaKPC carriage. Recently, a newly emergent lineage ST307 has been identified within the Houston metropolitan region. The transmission of blaKPC and other antimicrobial resistance (AMR) genes is driven largely by exchange of mobile genetic elements (MGEs). We sought to describe the dynamics of horizontal gene transfer (HGT) in particular between co-circulating strains of ST307 and ST258.

Methods
Long-read sequencing technologies allow us to resolve plasmid sequences and their associated AMR genes as well as characterize a comprehensive range of MGEs enabling transmission of these clinically important resistance mechanisms. CR-Kpn isolates were collected as part of a study to describe CRE burden within a Houston metropolitan hospital system. The Oxford Nanopore Technology (ONT) GridION X5 was used for long-read sequencing with Illumina short-read data used to refine and generate high-quality, consensus assemblies. A custom bioinformatic pipeline was used to resolve plasmid structures and identify the genomic context of plasmids carrying blaKPC variants.

Results
95 Kpn isolates were collected from May to December 2017. Phylogenetic and in silico MLST analysis revealed 38/95 (40%) and 35/95 (37%) were ST258 and ST307, respectively. 86% of Kpn isolates carried one or more IncF-type conjugative plasmids, which were the prime vectors for blaKPC intercellular transmission. Interestingly, we found similar AMR-harboring plasmids within ST258 and ST307 composed of mosaic, modular IS26 and Tn3-like transposase mediated elements that carried multiple AMR determinants including blaKPC variants (Figure 1).

Conclusion
We were able to characterize mechanisms by which ST307 and ST258 lineages may transfer AMR determinants. There are clinically relevant implications to these HGT events that occur between these lineages as they may provide insights into how resistance differentially develops.

Disclosures
All authors: No reported disclosures.
632. Genetic Diversity of Carbapenem-Resistant Klebsiella pneumoniae Causing Late-Onset Neonatal Sepsis in Intensive Care Unit of Caro University Hospital, Cairo, Egypt
Authors: Ghaith Doaa , Mufeed Halaa , Elanwary Sherif , Zafer Mai , Alagamy Mohamed , Bohol Marie , Elsaban Salwa , Qahtani Ahmed , Al-Ahdal Mohammed 
Published: October 2019

Abstract

Background
Neonatal sepsis poses a great challenge for clinicians and infection control practitioners. Carbapenem-resistant Klebsiella pneumoniae (CRKP) is rapidly increasing and poses a major threat to neonates. Our research aim was to examine the phenotypes, genotypes, and genetic relatedness of CRKP in late-onset neonatal sepsis in the neonatal intensive care unit (NICU) at Cairo University Hospital.

Methods
Our study included 88 neonates diagnosed with sepsis; 58 with late-onset sepsis (LOS) and 30 with early-onset sepsis (EOS) admitted to the NICU between November 2015 and April 2016. Laboratory investigations included (vomplete blood count, C-reactive protein, serum interleukin-6 level by ELISA technique and blood culture). bacterial identification and antibiotic susceptibility testing were done by automated VITEK 2 compact system (BioMérieux, France). Detection of carbapenemases (OXA-48, NDM, IMP, KPC, and VIM) by multiplex PCR and pulsed-field gel electrophoresis (PFGE).

Results
K. pneumoniae was the most common encountered pathogen in the LOS group (37.9%) with a mean sepsis score of 6.39 when compared with the 33 EOS group (P < 0.005). The interleukin ratio, C-reactive protein, and interleukin-6 levels were significantly high in the K. group (P ˂ 0.001). The most prevalent 35 carbapenemase gene in the NICU, OXA-48, was identified in 14/23 (60.8%) 36 isolates followed by NDM-1 in 12/23 (52.2%) isolates as detected by multiplex 37 PCR. Coexistence of both carbapenemases was found in 52.2% (12/23). By investigating the genetic relatedness of CRKP by pulsed-field gel electrophoresis, 23 isolates of K. pneumoniae revealed various PFGE patterns, demonstrating that 40 the isolates were nonclonal.

Conclusion
In conclusion, carbapenam-resistant Klebsiella pneumoniae remains the most frequent organism detected in neonatal sepsis. Our results revealed that CRKP isolates were not clonal. Extra data are required on the rates of birth asphyxia and microbiology of neonatal infection since reduced records of diseases sets gaps in understanding how to improve existing practices. Infection control actions including antibiotic stewardship programs with continuous surveillance to trace emerging CRKP infections in the early hours as possible particularly in units at risk as NICUs.

Disclosures
All authors: No reported disclosures.