bluuebunny/crossref_metadata_2025_split huggingface dataset:
545. Incidence of Carbapenem Non-Susceptible Acinetobacter spp. and Carbapenem-Resistant Pseudomonas aeruginosa Clinical Cultures among Patients in US Acute Care Hospitals, 2012–2017
Authors: Kazakova Sophia , Baggs James , Wolford Hannah , Olubajo Babatunde , Hatfield Kelly M , See Isaac , Bulens Sandra N , Reddy Sujan , Jernigan John A 
Published: October 2019

Abstract

Background
Carbapenem-nonsusceptible Acinetobacter spp. (CNAB) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) are recognized causes of severe and difficult to treat healthcare-associated infections. This study estimated and compared the incidence of CNAB and CRPA among patients admitted to US acute care hospitals in 2012–2017.

Methods
We measured the incidence of positive clinical cultures from inpatient encounters in a cohort of over 300 hospitals submitting data to the Premier Healthcare Database and Cerner Health Facts in 2012–2017. We included clinical cultures from any body site yielding Acinetobacter spp./P. aeruginosa non-susceptible/resistant to imipenem, meropenem, or doripenem. Cultures collected on days 1–3 of hospitalization were considered community-onset (CO) and cultures from later were hospital-onset (HO). Duplicate isolates identified within 14 days of an incident culture and surveillance cultures were excluded. For each year, a raking procedure generated weights to extrapolate the sample estimate to match the American Hospital Association distributions based on US census division, hospital bed capacity, teaching status, and urban designation. We compared estimated rates in 2017 vs. 2012 using weighted multivariable logistic regression adjusting for hospital characteristics and hospital-level clustering.

Results
In 2017, the estimated rates of HO and CO CNAB rates were 0.77 and 1.39/10,000 discharges, and HO and CO CRPA rates were 3.14 and 6.57, respectively. Compared with 2017, rates of HO CNAB decreased 49% (Odds Ratio (OR) 0.51; 95% CI: 0.34–0.75) and rates of CO CNAB decreased 29% (OR 0.71; 95% CI: 0.54–0.92). For CRPA, the incidence of HO decreased (OR 0.66; CI: 0.49–0.88) with no change in CO rates (OR 0.93; CI: 0.79–1.11). Assessment of cultures from sterile sites alone showed similar results, but they did not reach statistical significance, Figure 1.

Conclusion
We estimate significant national decreases in the rates of HO and CO CNAB, and HO CRPA. Risk factors and effective interventions to reduce CO CRPA might differ from CNAB and HO CRPA. Additional prevention strategies are needed to address CO CRPA.

Disclosures
All authors: No reported disclosures.
547. Multidrug-Resistant Pseudomonas aeruginosa in an Academic Regional Burn Intensive Care Unit
Authors: Estelle Carolee D , Sreeramoju Pranavi , Collinsworth Katherine A , Gaffney Donna , Yerks Lisa , Blast Daniel L , Hollaway Rita , Cavuoti Dominick , Voy-Hatter Karla , Ehrhart Kathryn L , Potithavoranant Katrina , Perl Trish M , Perl Trish M 
Published: October 2019

Abstract

Background
Pseudomonas aeruginosa infection can lead to morbidity, mortality and increased hospital length of stay especially in Burn Intensive Care Units (BICU) patients. Reports of multi-drug-resistant Pseudomonas aeruginosa outbreaks in the BICU are increasing. We investigated the epidemiology of Carbapenem-Resistant Pseudomonas aeruginosa (CRPA) in our BICU.

Methods
Clinical and laboratory characteristics of all CRPA isolates identified between 5/8/16 and 3/14/19, in an 11-bed BICU in an academic 870-bed public safety-net hospital were reviewed and defined as Meropenem MIC 4 or greater. Retained isolates were sent for pulse-field gel electrophoresis (PFGE). Infection prevention (IP) observations and interventions were intensified and environmental cultures were collected. Patient charts were reviewed.

Results
27 patients between ages 5–61 years old were found to have CRPA (only 2 patients < 18 years). 21/27 (77.7%) were male. 21/27 (77.7%) had >40% total body surface area (TBSA) burns, 3/27 (11.1%) had 20–39% TBSA burn and 1/27 (3.7%) had < 20% TBSA burn. 19/27 (70.3%) patients had bacteremia, 6 had respiratory infections with 3 (11.1%) Infection-related Ventilator-Associated Complications (IVAC), 3 had urinary tract infection, and 1 had CRPA from a central venous catheter tip. There were very few co-morbidities. Twenty isolates from 11 different patients were typed and revealed 2 different clonal strains. 5/11 (45%) patients had strain A, and 2/11 (18%) patients had strain B. 3/11 (27.2%) patients had unique strains. CRPA was isolated from 5 different rooms. Water cultures did not reveal CRPA. Failure of hand hygiene, non-adherence to isolation/PPE protocols and clutter were found. Each failure was corrected. No new CRPA patient isolates have been identified.

Conclusion
Transmission was halted by reinforcement of IP measures. Importantly water was not a source of CRPA in this setting and the data suggest transmission due to environmental contamination.

Disclosures
Trish M. Perl, MD; MSc, 7–11: Advisory Board; medimmune: Research Grant
562. Reducing MRSA Bacteremia in Adult Patients through MRSA Decolonization Bundle
Authors: Goldman Erin , LeRose Jennifer , Ramos-Mercado Abdiel , Oring Justin , Chopra Teena 
Published: October 2019

Abstract

Background
Patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at an increased risk of developing a subsequent MRSA infection. Moreover, these individuals may serve as an endogenous reservoir to spread the bacteria to other patients. In an attempt to reduce MRSA bacteremia rates, a decolonization protocol was developed and implemented at a tertiary teaching hospital in Detroit, Michigan. In this study, we evaluate the intervention’s impact on community-onset (CO) and hospital onset (HO) MRSA bacteremia rates.

Methods
Infection Control developed an MRSA decolonization bundle for adults that consisted of daily Chlorhexidine gluconate (CHG) bathing and twice-daily nasal swabs with 10% Povidone–iodine (PI) or Nozin for individuals with iodine allergies. Patients with known risk factors for developing an MRSA infection, such as patients residing in an intensive care unit and/or undergoing specified procedure, were prescribed the bundle for their length of stay (Figure 1). Countraindications for nasal decolonization included inhalation injuries, CSF leaks, ENT surgeries, and transphenoidal surgeries. A retrospective chart review of high-risk patients was conducted to determine compliance with the elements of the MRSA decolonization bundle. Rates of CO and HO MRSA bacteremia per 1,000 patient-days were graphed against compliance with bundle elements (2 nasal swabs and 1 CHG bath per day). To quantify the correlation, a linear regression model and the Pearson coefficient was used.

Results
Approximately 2,000 and 1,000 opportunities for nasal decolonization and CHG bathing, respectively, were identified between September 2018 and March 2019. The data suggest a strong correlation between compliance with MRSA decolonization elements and rate of HO MRSA bacteremia (R2 = 0.785) and a moderate association between nasal decolonization and rate of CO bacteremia (R2 = 0.322) (Figures 2 and 3).

Conclusion
The MRSA decolonization bundle of CHG bathing and nasal swabs appears to be an effective strategy to decrease HO MRSA bacteremia rates with higher bundle compliance being associated with lower rates of infection.

Disclosures
All authors: No reported disclosures.
575. Evaluation of Risk Factors and Clinical Outcomes of Patients with Vancomycin-Resistant Enterococcus Infections
Authors: Chauhan Gauri , Vyas Nikunj M , Levin Todd P , Kim Sungwook 
Published: October 2019

Abstract

Background
Vancomycin-resistant Enterococci (VRE) occurs with enhanced frequency in hospitalized patients and are usually associated with poor clinical outcomes. The purpose of this study was to evaluate the risk factors and clinical outcomes of patients with VRE infections.

Methods
This study was an IRB-approved multi-center retrospective chart review conducted at a three-hospital health system between August 2016-November 2018. Inclusion criteria were patients ≥18 years and admitted for ≥24 hours with cultures positive for VRE. Patients pregnant or colonized with VRE were excluded. The primary endpoint was to analyze the association of potential risk factors with all-cause in-hospital mortality (ACM) and 30-day readmission. The subgroup analysis focused on the association of risk factors with VRE bacteremia. The secondary endpoint was to evaluate the impact of different treatment groups of high dose daptomycin (HDD) (≥10 mg/kg/day) vs. low dose daptomycin (LDD) (< 10 mg/kg/day) vs. linezolid (LZD) on ACM and 30-day readmission. Subgroup analysis focused on the difference of length of stay (LOS), length of therapy (LOT), duration of bacteremia (DOB) and clinical success (CS) between the treatment groups.

Results
There were 81 patients included for analysis; overall mortality was observed at 16%. Utilizing multivariate logistic regression analyses, patients presenting from long-term care facilities (LTCF) were found to have increased risk for mortality (OR 4.125, 95% CI 1.149–14.814). No specific risk factors were associated with 30-day readmission. Patients with previous exposure to fluoroquinolones (FQ) and cephalosporins (CPS), nosocomial exposure and history of heart failure (HF) showed association with VRE bacteremia. ACM was similar between HDD vs. LDD vs. LZD (16.7% vs. 15.4% vs. 0%, P = 0.52). No differences were seen between LOS, LOT, CS, and DOB between the groups.

Conclusion
Admission from LTCFs was a risk factor associated with in-hospital mortality in VRE patients. Individuals with history of FQ, CPS and nosocomial exposure as well as history of HF showed increased risk of acquiring VRE bacteremia. There was no difference in ACM, LOS, LOT, and DOB between HDD, LDD and LZD.

Disclosures
All authors: No reported disclosures.
578. Microbiology Laboratory-Driven Standardized Urine Culture Reporting Increases Aminopenicillin Prescribing in Vancomycin-Resistant Enterococci Urinary Infections
Authors: Cheung Genevieve , Javier Diane , Kachouei Farrnam , Pasiliao Roxanne , Ta Michelle , Estevez Dennys , Bolaris Michael , Ha David 
Published: October 2019

Abstract

Background
Vancomycin-resistant Enterococcus (VRE) urinary tract infections (UTI) are traditionally treated with therapies like linezolid or daptomycin. Multiple recent studies have demonstrated that aminopencillins (APs) have equivalent clinical efficacy outcomes as these therapies are able to achieve high urinary drug concentrations and may also have favorable comparative safety profiles and lower costs. Our institution implemented a standardized microbiology report for urine cultures positive for VRE which encouraged prescribing of APs and blinded sensitivity results.

Methods
This was a single-center, retrospective, observational study evaluating the impact of this microbiology report on prescribing outcomes in patients being treated for VRE UTI at a community regional medical center. The study was conducted over 7.5 years with January 2011 to September 2014 representing the pre-intervention cohort and October 2014 to July 2018 representing the post-intervention cohort. Patients were included if they were 18 years or older and received antibiotic therapy for a diagnosed VRE UTI. The primary outcome measure was terminal antibiotic therapy.

Results
Out of 388 patients with VRE positive urine cultures, 102 were included for analysis, 38 in the pre-intervention cohort and 64 in the post-intervention cohort. Cohorts were similar in terms of age, Charlson Comorbidity Index (CCI), β-lactam allergy, ID consultation, and urologic abnormalities. AP prescribing significantly increased from 3% (1/38) in the pre-intervention cohort to 44% (28/64) in the post-intervention cohort both in univariate (OR 29.8, 95% CI 3.7–222.8) and multivariate (OR 38.7, 95% CI 4.8–312.3) analyses. In the post-intervention cohort, age, gender, CCI, β-lactam allergy, and urologic abnormalities were not significantly associated with differences in aminopenicillin prescribing. There was no difference in in-hospital mortality between cohorts.

Conclusion
The results from this study demonstrate that a simple microbiology report for VRE positive urine cultures encouraging AP prescribing is significantly associated with an increase in AP prescribing for diagnosed VRE UTI and should be considered as a supplementary antimicrobial stewardship intervention.

Disclosures
All authors: No reported disclosures.
584. Use of Multi-Disciplinary Prevention Rounds to Reduce Central Line-Associated Bloodstream Infections in a Neonatal Intensive Care Unit
Authors: Linam Matthew , Wright Jessica , Kim Kum , Van Treek Cara , Spafford Patrick 
Published: October 2019

Abstract

Background
Despite successful implementation of evidence-based prevention bundles, central line-associated bloodstream infections (CLABSIs) continue to occur in neonatal intensive care units (NICUs). We hypothesized that multi-disciplinary prevention rounds may be able to further reduce CLABSIs.

Methods
We implemented bedside rounds in a 39-bed tertiary NICU in November 2018 with the focus of reducing CLABSIs. Standardized rounds for all patients with a central venous line (CVL) occurred 2–3 times/week on weekdays during either the day or evening shifts. Rounds included NICU nursing leadership, the Hospital Epidemiologist and the patient’s nurse. Questions focused on the CVL maintenance bundle, reducing line access, and patient-specific CLABSI risk factors. Best practices were reinforced and solutions for identified risk factors were developed. Recommendations were communicated to the physician, as appropriate. Prevention rounds data were collected. Nurses and providers in the NICU were surveyed about their perceptions of the rounds. CLABSIs were identified by Infection Prevention using standard definitions.

Results
The average daily NICU census was 35.6, with an average of 14 patients with CVLs/day. The average duration of rounds was 45 minutes. Recommendations to physicians, such as changing medications from intravenous to oral or line removal, were accepted 85% of the time. 74.5% of nurses and 87.5% of providers thought that prevention rounds had at least some impact on CLABSI prevention. Nurse and provider responses to the perceived impact of CLABSI prevention rounds are in Tables 1 and 2, respectively. In the 12 months prior to starting prevention rounds, the CLABSI rate was 1.53 /1000 line days and the CLABSI rate for the 6 months after starting rounds was 0.99/1,000 line days, a 65% decrease.

Conclusion
CLABSI prevention rounds helped reinforce evidence-based prevention practices, identified patient-specific risk factors and improved physician-nurse communication. CLABSIs in NICU were reduced.

Disclosures
All authors: No reported disclosures.
594. A Multi-Centered Study of the Clinical and Molecular Epidemiology of AmpC Cephalosporinase-Producing (AmpC) Enterobacteriaceae (Ent) Infections in Children
Authors: Medernach Rachel L , Domitrovic T Nicholas , Hayani Karen C , Hujer Andrea M , Qureshi Nadia K , Marshall Steven H , Nguyen David C , Rudin Susan D , Rispens Jared R , Zheng Xiaotian , Weinstein Robert A , Bonomo Robert A , Logan Latania K 
Published: October 2019

Abstract

Background
AmpC producing Ent are an important cause of multidrug-resistant (MDR) infections in pediatrics. Since most AmpC Ent studies have been conducted in adults, we characterized the molecular epidemiology of AmpC Ent strains with transmissible resistance and identified factors associated with AmpC Ent infections in children.

Methods
A case–control study of children (0–18 years) at 4 Chicago hospitals during 2011–18 was performed. Cases were 44 children with infections due to Ent harboring an AmpC as detected by DNA microarray (Check-Points®). PCR, DNA sequencing, MLST, and phylogenetic analyses were performed. Controls (ctrls) were 132 children with expanded-spectrum cephalosporin-susceptible Ent infections matched by age and hospital. Demographics; residence; comorbidities; device, antibiotic, and healthcare exposures were evaluated. Predictors of AmpC Ent infection were assessed by logistic regression.

Results
The median age of AmpC Ent patients was 3.0 years; 50% were male. Of blaAmpC genes, 68% were blaACT/MIR-type and 25% blaCMY-type. Predominant organisms were Enterobacter cloacae (59%) and Escherichia coli (32%); 27% of AmpC E. cloacae belonged to ST114 and 62% co-harbored a blaESBL gene, predominately blaSHV (94%). Most AmpC E. coli strains were unrelated; 71% carried blaCMY, 64% belonged to phylogroups B2/D, and 50% co-harbored blaCTX-M. On bivariate analysis vs. ctrls, AmpC Ent infections were more likely to be respiratory (39% vs. 18%, P < 0.01) and less likely to be urinary tract (41% vs. 67%, P < 0.01) or community-acquired (14% vs. 33%, P < 0.02). By multivariable analysis, children with AmpC Ent infections were more likely to be nonwhite, non-black, non-Hispanic (OR 4.7, CI 1.4–16.1) and have infections due to Enterobacter (OR 7.7, CI 3.5–17). Differences in gender, healthcare location, residential neighborhood, antibiotic exposures, comorbidities, devices or outcomes were not found.

Conclusion
AmpC Ent infections often had healthcare onset, were due to Enterobacter, and occurred in nonwhite, non-black, non-Hispanic children. AmpC Ent commonly co-harbored blaSHV and blaCTX-M ESBL genes which affects therapeutic options and suggests the need for contact precautions. Control of AmpC Ent infections in children will require validating sources and risk factors.

Disclosures
All authors: No reported disclosures.
607. Scope and Predictive Genetic/Phenotypic Signatures of “Bicarbonate [NaHCO3]-Responsivity” and β-Lactam Sensitization among Methicillin-Resistant Staphylococcus aureus (MRSA)
Authors: Ceren. Ersoy Selvi , Zapata-Davila Brianne , Otmishi Mariam , Milan Vanessa , Li Liang , Chambers Henry , Chambers Henry , Xiong Yan , Bayer Arnold 
Published: October 2019

Abstract

Background
Selected MRSA strains become susceptible to β-lactams (e.g., oxacillin [OX]; cefazolin [CFZ]) in vitro when tested in a standard medium (cation-adjusted Mueller–Hinton Broth; CA-MHB) supplemented with NaHCO3 (“NaHCO3-responsivity”). In vivo activity of β-lactams was demonstrated for MRSA strains with this phenotype in a rabbit endocarditis model (Ersoy et al Antimicrob Agents Chemother 2019). The current study was designed to: (i) determine the prevalence of the NaHCO3-responsive phenotype in a large collection of clinical MRSA isolates; and (ii) identify genetic and phenotypic predictors of this phenotype. Methods. 58 recent MRSA bloodstream isolates representing contemporary clonal complex (CC) genotypes were screened for the NaHCO3-responsive phenotype by broth microdilution MICs in CA-MHB, with or without NaHCO3 supplementation (25–44 mM).

Methods
58 recent MRSA bloodstream isolates representing contemporary clonal complex (CC) genotypes were screened for the NaHCO3-responsive phenotype by broth microdilution MICs in CA-MHB, with or without NaHCO3 supplementation (25–44 mM).

Results
43/58 (74.1%) and 21/58 (36.2%) were rendered susceptible to CFZ and OX, respectively, in the presence of NaHCO3; 20 of the 21 OX-susceptible strains were also susceptible to CFZ in the presence of NaHCO3. High baseline β-lactam MICs (i.e., MICs in CA-MHB alone ≥64 µg/mL) was not predictive of NaHCO3 responsivity. The CC8 genotype was correlated with NaHCO3 responsivity for OX, but not CFZ (P < 0.05).

Conclusion
The NaHCO3-responsive phenotype is relatively common for both OX and especially CFZ among clinical MRSA isolates. Identification of specific genetic factors linked to this phenotype remains ongoing. Confirmation in relevant animal models that this phenotype is predictive of β-lactam efficacy in vivo could provide a solid foundation for a paradigm shift in antimicrobial susceptibility testing of MRSA.

Disclosures
All authors: No reported disclosures.
613. Suppression of Daptomycin Resistance Development in Staphylococcus aureus Is a Class Effect of β-Lactams and Is Independent of Daptomycin–β Lactam Synergy
Authors: Miller Christopher R , Dey Somrita , Smolenski Paula , Kulkarni Pushkar S , Baines Sarah L , David. Berti Andrew 
Published: October 2019

Abstract

Background
Previous studies demonstrate that adding oxacillin during daptomycin (DAP) exposure can prevent DAP resistance development in community-acquired (ST8/USA300) MRSA, presumably by preventing mprF mutation. Hospital-acquired strains, such as MRSA sequence types 5 and 239, typically have higher β-lactam (BL) minimum inhibitory concentrations (MICs) than their community-acquired counterparts and are often less toxigenic, more multidrug-resistant and more refractory to primary antistaphylococcal therapies. It is unknown whether DAP resistance prevention occurs in hospital-acquired MRSA lineages or if augmenting DAP therapy with BL antibiotics other than oxacillin would prevent DAP resistance development.

Methods
MRSA ST5/USA100 (D592) and ST239 (JKD6004) differ in the degree to which BL enhances DAP activity. D592 and JKD6004 were passaged in escalating concentrations of DAP in a stepwise fashion in vitro as described previously. Following 28 days of serial passage all replicates were passaged twice on mannitol-salt agar and tested for DAP MIC by Etest. Parallel passages were performed in media supplemented with BL antibiotics. Between-group differences in DAP MIC suppression effectiveness among individual BLs compared with nafcillin was evaluated using Kruskal–Wallis rank-sum testing with Holm-adjusted post-hoc Dunn testing.

Results
Passage of D592 or JKD6004 in DAP resulted in highly DAP-resistant isolates (median ≥256 mg/L, IQR [96,256]). In contrast, when passages were performed in the presence of DAP+BL, DAP resistance development was suppressed. No between-group differences in DAP MIC suppression effectiveness were observed among individual BLs compared with nafcillin. Highly DAP-resistant isolates demonstrated variable collateral susceptibility to BL monotherapy but were frequently susceptible to combination antibiotic exposure.

Conclusion
Addition of β-lactams to DAP can prevent DAP resistance development in vitro in ST5/USA100 and ST239 MRSA, consistent with findings in ST8/USA300 lineages. Furthermore, this ability appears to be a class effect of β-lactam antibiotics and is independent of the extent of DAP-BL synergy. This provides evidence to support the use of BL combination therapy without regard to staphylococcal lineage or specific BL used.

Disclosures
All authors: No reported disclosures.