bluuebunny/crossref_metadata_2025_split huggingface dataset:
469. Contributions of Infections among Persons Who Inject Drugs to the Changing Incidence of Healthcare-Associated, Community-Onset Methicillin-Resistant Staphylococcus aureus Infections, 2009–2017
Authors: Jackson Kelly A , Gokhale Runa Hatti , Nadle Joelle , Petit Susan , Ray Susan , Harrison Lee , Lynfield Ruth , Dumyati Ghinwa , Schaffner William , See Isaac 
Published: October 2019

Abstract

Background
Recently, overall reductions for invasive MRSA infections (isolation from a normally sterile site) have slowed. Healthcare-associated community-onset (HACO) invasive methicillin-resistant Staphylococcus aureus (MRSA) infections are those with recent healthcare exposures who develop MRSA infection outside acute care hospitals, and account for most invasive MRSA infections. HACO incidence decreased 6.6% per year during 2005–2008; the contribution of persons who inject drugs (PWID) to HACO incidence has not been reported.

Methods
We identified invasive MRSA infections using active, population- and laboratory-based surveillance data during 2009–2017 from 25 counties in 7 sites (CA, CT, GA, MD, MN, NY, TN). Cases were HACO if culture was obtained from an outpatient, or ≤3 days after hospitalization in a patient with ≥1 of the following healthcare exposures (HEs): hospitalization, surgery, dialysis, or residence in a long-term care facility (LTCF) in the past year; or central vascular catheter ≤2 days before culture. We calculated incidence (per census population) overall, for PWID cases and others, and for cases associated with each HE. For each HE, we calculated the proportion of overall incidence increase for PWID and others.

Results
HACO MRSA incidence declined overall from 2009 to 2016 but increased from 2016 to 2017 overall (8%), for both PWID (63%) and others (5%) (figure). For both PWID and non-PWID, incidence from 2016 to 2017 increased by 0.5 cases/100,000 population; 91% of the increase in PWID occurred in cases with a past year hospitalization while 78% of the increase in cases not associated with injection drug use (IDU) occurred in cases with past year LTCF residence. Past year LTCF residence was less common among PWID (16%) then among other cases (38%, P < 0.01).

Conclusion
After years of declines, HACO MRSA incidence increased equally in 2017 for cases associated with IDU and in cases unrelated to IDU. Increases in PWID-associated cases account for half the overall increase, indicating that efforts to reduce HACO MRSA should address PWID risk factors as these infections may be due to self-injection. In addition, increases not related to PWID, if sustained, would be a reversal of historic trends and require further investigation into causes.

Disclosures
All authors: No reported disclosures.
482. Time Series Analysis of Antimicrobial Consumption and Pseudomonas aeruginosa Resistance in an Academic Medical Center in the United States (2013–2018)
Authors: Dewart Courtney M , Hebert Courtney , Pancholi Preeti , Stevenson Kurt 
Published: October 2019

Abstract

Background
Monitoring antimicrobial use and resistance are key components of initiatives to promote antimicrobial stewardship and prevent antimicrobial-resistant infections. In this surveillance study, we evaluated trends in resistance among healthcare-associated P. aeruginosa isolates and potential associations with antimicrobial consumption.

Methods
We established a retrospective cohort of P. aeruginosa isolates collected ≥48 hours after inpatient admission at a 1,300-bed academic medical center from July 1, 2013 to July 31, 2018. We included isolates from all clinical cultures and retained the first isolate for a patient encounter. We defined the multidrug-resistant (MDR) status in accordance with the phenotype definitions established by the Centers for Disease Control and Prevention. We calculated the monthly percentage of class-specific resistance and MDR status among isolates. We measured monthly antimicrobial consumption as days of therapy per 1,000 patient-days. To evaluate potential associations between identified trends in resistance and antimicrobial use, we constructed autoregressive integrated moving average models (ARIMA) with transfer functions.

Results
Of 1,897 isolates included in the analysis, 303 (16.0%) were classified as MDR P. aeruginosa. The rate of healthcare-associated P. aeruginosa infections and percent of MDR isolates remained stable over the five-year study period. However, we identified trends in resistance to specific antimicrobial classes: there was a significant increase in resistance to antipseudomonal carbapenems, while resistance to aminoglycosides and extended-spectrum cephalosporins decreased. Using the ARIMA modeling strategy, bivariable analyses of resistance and antimicrobial use revealed that carbapenem-resistant P. aeruginosa was positively correlated with the use of antipseudomonal carbapenems at a 1-month lag and ertapenem at a 5-month lag.

Conclusion
Risk assessments that only measure rates of MDR organisms may miss underlying trends in class resistance. Increasing carbapenem resistance despite a stable proportion of MDR isolates highlights a critical area for continued monitoring and antimicrobial stewardship initiatives targeted at carbapenem use in our hospital.

Disclosures
All authors: No reported disclosures.
497. Changing Molecular Epidemiology of CRE from 2016–2018, Increase in the Unknown
Authors: Le Mi , Bhaurla Sandeep , OYong Kelsey , McKinnell James , Yang Yang , Manalo Audrey , Ramirez Julio , Hemarajata Peera , Green Nicole , Terashita Dawn 
Published: October 2019

Abstract

Background
Historically, endemic Klebsiella pneumoniae carbapenemase (KPC) has accounted for the majority of carbapenem-resistant Enterobacteriaceae (CRE) in Los Angeles County (LAC). The LAC Department of Public Health (DPH) initiated enhanced CRE surveillance in 2016 to determine CRE prevalence and track emerging non-KPC resistance mechanisms (IMP, NDM, OXA, and VIM) among CRE to describe characteristics and identify local epidemiology for novel multi-drug-resistant organism (N-MDRO) infection and colonization.

Methods
CRE isolates were voluntarily submitted by local clinical laboratories for mechanism detection by LAC Public Health Laboratory via MALDI-TOF and Nanosphere BC-GN. Baseline isolates were collected in 2016. Results are then presented by year through 2018. For N-MDRO cases, LACDPH interviewed healthcare facility (HCF) staff and cases to obtain case characteristics. Data were analyzed via Microsoft Access and SAS.

Results
CRE surveillance isolates were voluntarily submitted by 31 labs representing 34% (34/96) LAC hospitals and 1 large regional lab serving 60% of skilled nursing facilities from January 2016 to December 2018. LACDPH tested 1438 CRE isolates during the study period, 1168 (81%) were carbapenemase producing (CP). The proportion of CP CRE and KPC CRE declined over the study period (Table 1). NDM was the most common non-KPC (n = 30) followed by OXA (n = 28). The proportion of CRE with no genotypic marker increased over the course of the study. Case characteristics were obtained from 41 non-KPC CP CRE cases; median age was 66 years (range: 6–94 years); 12 (29%) expired. Among the 41 cases, 20 (49%) had a central line; 11 (27%) had surgery; 14 (34%) had antibiotics in the 6 months prior to culture date. Of the 41 cases, 11 (27%) had international healthcare exposure within 12 months with an invasive procedure and/or antibiotics.

Conclusion
Surveillance in a large urban setting suggests the molecular epidemiology of CRE is changing, with declining prevalence of KPC, increasing metallo-β-lactamase CP, and large proportion of isolates without resistance markers detected. Given the worrisome trends in non-KPC CRE, more systematic surveillance is warranted, potentially using more robust molecular epidemiology.

Disclosures
All authors: No reported disclosures.
499. Carbapenem-resistant Enterobacteriaceae (CRE)-associated Infections and Prolonged Colonization among Hospitalized Patients Colonized by CRE
Authors: Khawcharoenporn Thana , Laichuthai Wipada 
Published: October 2019

Abstract

Background
This study aims to determine rates of subsequent carbapenem-resistance Enterobacteriaceae (CRE)-associated infections and prolonged colonization among patients colonized by CRE and to identify risk factors of such conditions.

Methods
This study was conducted among a cohort of hospitalized adult patients colonized by CRE at any sites from June 1, 2015 to December 31, 2018. The patients had been prospectively identified by the Infection Control (IC) Division of a Thai tertiary-care hospital. According to the hospital’s IC protocol, patients with CRE colonization/infections were isolated and underwent CRE cultured at the colonized/infected sites every week until the cultures have turned negative for 2 consecutive times. Prolonged colonization was defined as having CRE colonization more than 30 days.

Results
Of the 125 patients identified, 25 were excluded due to death, being transferred, or discharged within 48 hours of CRE colonization detected. The final cohort included 100 patients, the median age was 74 years, 48% were male, the most common colonized site was rectum (37%) and 20 patients (20%) developed subsequent CRE-associated infections. The median time from colonization to infection was 13 days and the most common site of infection was bloodstream (45%). Independent factors associated with subsequent CRE-associated infections were the number of colonization sites [adjusted odds ratio (aOR) 7.98, P < 0.001)], central line insertion during admission (aOR 7.97, P = 0.009) and receipt of vancomycin during admission (aOR 24.77, P = 0.02). Prolonged colonization was observed in 13 of 77 evaluable patients (17%). There were trends toward significance that the length of hospital stay and duration of antibiotic prior to colonization were associated with prolonged colonization (P < 0.10).

Conclusion
The findings suggest high rates of subsequent CRE-associated infections and prolonged colonization among the study population. Patients with risk factors for subsequent infections should be closely monitored and empirically-treated with antibiotics active against CRE while those with risk factors for prolonged colonization should receive continued surveillance and isolation to prevent CRE transmission.

Disclosures
All authors: No reported disclosures.
503. Comparison of IMP Carbapenemase-Producing Enterobacteriaceae (CPE) and Non-Carbapenemase-Producing Enterobacteriaceae: A Multicenter Prospective Study of Clinical and Molecular Epidemiology in Japan
Authors: Hayakawa Kayoko , Nakano Ryuichi , Hase Ryota , Shimatani Michitsugu , Kato Hideaki , Hasumi Jumpei , Doi Asako , Sekiya Noritaka , Nei Takahito , Okinaka Keiji , Kasahara Kei , Kurai Hanako , Nagashima Maki , Miyoshi-Akiyama Tohru , Kakuta Risako , Yano Hisakazu , Ohmagari Norio 
Published: October 2019

Abstract

Background
IMP CPE are the dominant CPE type in Japan. We aimed to compare its epidemiology to that of non-CPE (NCPE).

Methods
Patients with isolation of carbapenem-resistant Enterobacteriaceae (CRE) with meropenem MIC ≥2 mg/L or imipenem MIC ≥2 mg/L and cefmetazole MIC ≥64 mg/L were included from August 2016 to March 2018. Adjusted outcome analyses were conducted using a generalized estimating equation model with weighting based on the inverse probability of propensity scores (PS).

Results
Ninety isolates (27 CPE and 63 NCPE) were collected from 88 patients (53 male) in 7 hospitals. CPE included 10 E. cloacae (ENC), 6 K. pneumoniae (KP), 4 E. coli (EC), 3 C. freundii (CF), 2 K. oxytoca, and 1 each of E. aerogenes (EA) and S. marcescens (SM). NCPE included 34 EA, 15 ENC, 4 each of KP, SM, and 2 CF. All CPE were positive for IMP carbapenemase (11 IMP-11, 6 IMP-42, 4 IMP-6, and 3 each of IMP-10 and IMP-1). Most of CPE/NCPE were isolated from sputum (39%), intra-abdomen (21%), and urine (20%). Levofloxacin, gentamicin, and amikacin resistance were found in 6 (22%), 4 (15%), and 1 (4%) CPE, respectively, and 6 (10%), 6 (10%), and 0 NCPE, respectively. Eighteen (67%) blaIMP were transferable by conjugation. Cases of CPE involved older patients with more frequent use of devices and carbapenem exposure than those in cases of NCPE (table). The mortality was similar in the 2 groups. Length of hospital stay (LOS) after CPE/NCPE isolation was significantly higher in the CPE group after PS adjustment (P = 0.02).

Conclusion
CPE had distinct epidemiological characteristics, and CPE isolation was associated with a prolonged hospital stay. Defining the underlying resistance mechanism of CRE is important for appropriate management.

Disclosures
All authors: No reported disclosures.
522. In Vitro Antimicrobial Activity of Ceftazidime/Avibactam Compared with Ceftolozane/Tazobactam Against Real-world Clinical Isolates of Pseudomonas aeruginosa at a Large Academic Tertiary Care Hospital
Authors: Patel Twisha S , Kaye Keith S , Marshall Vince , Krishnan Jay , Mills John , Albin Owen , Smith Aaron , Young Carol , Lephart Paul , Pogue Jason M 
Published: October 2019

Abstract

Background
Ceftazidime/avibactam (CZA) and ceftolozane-tazobactam (CT) are new additions to the antibiotic armamentarium with activity against gram-negative pathogens, most notably drug-resistant Pseudomonas aeruginosa (PSA). The purpose of this study was to compare the in vitro activity of CZA and CT against a large real-world sample of clinical isolates of PSA displaying different phenotypes of resistance to conventional β-lactams at an institution where both CZA and CT are routinely tested on all isolates.

Methods
All cultures from patient infections with PSA from May 2018 to February 2019 at Michigan Medicine were included. Minimum inhibitory concentrations (MICs) for all β-lactams were determined using TREK broth microdilution panels and isolates were considered susceptible to CZA if the MIC was ≤8 mg/L and CT if the MIC was ≤4 mg/L.

Results
A total of 2,972 isolates of PSA from clinical specimens were included. Table 1 compares CZA and CT susceptibility, MIC50, MIC90, and MIC range for all isolates including those displaying resistance to various β-lactams. Among all isolates of PSA, CZA (96.2% susceptible) was slightly more active than CT (94.2%) and both agents were ~10% more active than the closest comparator (ceftazidime, 86.6%). In vitro activity of cefepime, piperacillin/tazobactam, and meropenem were 84.8%, 78%, and 80.3%, respectively. The activity of both CZA and CT dropped significantly among isolates with pan-β-lactam resistance (i.e., resistance to all conventional anti-pseudomonal β lactams, PBR) but CZA remained more active than CT (59.4% vs. 41.5%, P < 0.001). Of isolates displaying resistance to CT, 84 (48.6%) were susceptible to CZA. However, of those with resistance to CZA, only 24 (21.2%) were susceptible to CT (Table 2).

Conclusion
CZA was the most active β-lactam against PSA isolates at Michigan Medicine. Among PSA with PBR, CZA demonstrated superior activity compared with CT. Additionally, a significant number of isolates with resistance to CT were susceptible to CZA. Our findings are unique compared with other published reports where CT has consistently demonstrated greater activity than CZA against resistant P. aeruginosa and suggest routine testing of both CT and CZA should occur.

Disclosures
All authors: No reported disclosures.
524. Understanding the Treatment of Carbapenem-Resistant Enterobacteriaceae (CRE) Infections in the United States (US): Insights from a Survey of Hospital-Based Pharmacists
Authors: Potoski Brian , Buehrle Deanna , Nguyen Minh-Hong , Clancy Cornelius J 
Published: October 2019

Abstract

Background
New anti-CRE antibiotics (ceftazidime–avibactam, C-A; meropenem-vaborbactam, M-V; plazomicin, PLZ) are associated with improved outcomes and lower toxicity than polymixins (PMs; colistin; polymyxin B) in treating CRE infections. We previously demonstrated that ~40% (range: 28–71%) and ~23% (16–41%) of CRE infections in the United States were treated with PMs or new agents, respectively, as of 1/19.

Methods
To understand formulary status, availability and positioning of new anti-CRE agents and PMs, we surveyed hospital-based Society of ID Pharmacists (SIDP) members (11–12/18; Qualtrics).

Results
There were 218 respondents from 41 states. Mean CRE infections encountered were 2.7/mo (0–36). C-A, M-V, PLZ were formulary restricted or non-formulary but available at 84%, 68% and 31% of hospitals, respectively; agents were stocked at 80%, 37% and 4%. In 33% of instances, C-A was presented to P&T a second time prior to approval. In rank order, reasons for adding a new agent to formulary were improved outcomes/efficacy, safety/toxicity, and local stewardship (ASP) opinion. Ranked reasons for not adding a new agent were infrequency of CRE, cost, concern for misuse, and limited data. A new agent was positioned as first-line against CRE pneumonia (PNA), bacteremia (BSI), abdominal (IAI) and urinary infections by 87%, 90%, 83% and 56% of respondents [Table]. Smaller hospitals (stratified as ≤200, 201–400, >400 beds) were more likely to have not made a formulary decision or have new agents as no buy (P = 0.0005), and less likely to have a new agent stocked (P = 7e-8) or to position a new agent as first line against CRE PNA, BSI and IAI (P = 0.009). Similar associations were not evident by hospital type (academic, community teaching, or non-teaching).

Conclusion
New agents are positioned as the first line against CRE PNA, BSI and IAI at most US hospitals with an SIDP member pharmacist, but they are still prescribed less against CRE infections than PMs nationally. Smaller hospitals are less likely to have mechanisms for using new agents or to position them as the first line. Discrepancies between positioning and use of new agents may reflect a bias in SIDP membership toward larger hospitals with ASP, lags between endorsing a first-line agent and incorporating it into care, and/or conservative ASP approval of agents in individual cases.

Disclosures
All authors: No reported disclosures.
527. Project “Isolation Zero”: Discontinuing Contact Precautions for Patients Colonized/Infected with Multidrug-Resistant Organisms through Community-Level Follow-Up in Spain
Authors: Pérez Martínez Olaia , Rapela Freire Alba , José Pereira Rodríguez Mª 
Published: October 2019

Abstract

Background
In an effort to prevent and control the spread of multidrug-resistant organisms (MDROs), hospitals implement contact precautions (CP) for patients colonized/infected with MDROs. All agencies related to the prevention and control of infections recommend this practice, but they also recognize that is not exempt from unintended consequences. In 2017, SHEA published an expert guideline where they provide recommendations for discontinuation of CP. Currently, the most accepted recommendation is to perform at least one microbiological culture prior to discontinuing CP. The main objective of this project is to implement and evaluate a novel community -level approach to safely discontinue CP in patients with a history of colonization/infection with an MDRO.

Methods
The “Isolation Zero” project (IZ) was rolled out in November 2018 in the healthcare area of A Coruña, Spain. All clinical records of patients included in the MDROs alert system between 2005–2012 in A Coruña were reviewed. Patients included in the study were those who reside in the healthcare area of A Coruña and did not have any positive microbiological culture for MDROs in the last 2 years (Figure 1). Those who met the inclusion criteria were sent a letter suggesting that they obtain a nurse consultation in the next 2 months and that they provide specific MDRO cultures (Figure 2). Finally, the Department of Preventive Medicine (PM) reviewed all the results and identified patients for which CP could be safely discontinued in future hospitalizations.

Results
A total of 792 clinical records were reviewed (Table 1). 184 patients met the inclusion criteria. The response rate was 60.3% (111 patients). The most frequent MDRO tested was MRSA (84.8%), followed by MDR Acinetobacter (7.6%). CP were withdrawn for a total of 83 patients, while 15 patients continued to test positive (Table 2).

Conclusion
These results suggest that even after more than 2 years without a positive result, 13,5% of patients remain positive for MDROs. Therefore, in order to safely minimize the use of CP, we conclude that an approach similar to that used in IZ is a good option for PM Departments. Follow-up at the community -level can help reduce the number of hospital isolations required and can help improve the overall quality of care.

Disclosures
All authors: No reported disclosures.
528. Longitudinal Evaluation of Chlorhexidine Resistance Among Multidrug-Resistant Organisms in Relation to Intervention of Daily Chlorhexidine Bathing in Adult Intensive Care Units
Authors: Ja Kim Min , Seung Chung You , Lee Hojin , Woong Suh Jin , Cheong Yoojung , Kyu Lee Chang 
Published: October 2019

Abstract

Background
Chlorhexidine digluconate (CHG), the most widely used antiseptic, has recently been applied to patient washing to decolonize the multidrug-resistant organisms (MDROs), but there are little data on susceptibilities of MDROs to CHG. The purpose of this study was to evaluate CHG resistance among MDROs before and after the intervention of daily CHG bathing in adult intensive care units (ICUs).

Methods
The intervention of daily body washing with 2% CHG cloths were taken in adult patients the medical or surgical ICU of 23-bed by a crossover manner for 6 months (MICU, July to December 2017; SICU, January to June 2018) in a 1,050-bed, university hospital in the Republic of Korea. Available MDRO isolates were randomly selected from clinical cultures of ICU patients within 6 months before, during and after the intervention, including MRSA, MR-CoNS, VRE, Carbapenem-resistant Pseudomonas aeruginosa (CR-PA), CR-Acinetobacter baumannii (CR-AB). Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method set by the Clinical Laboratory Standards Institute. Determination of the minimum bactericidal concentrations (MBCs) was performed by subculturing 10 µL from each well without visible microbial growth. Cumulative amounts of CHG used in both ICUs was estimated across the study period from January 2008 to June 2018.

Results
The cumulative CHG consumption from both ICUs increased sharply from 27,503 g to 29,556 g after one-year intervention. The ranges of MICs and MBCs of CHG among MDRO clinical isolates selected by a 6-month phase are summarized in Table 1. Particularly, CR-PA and CR-AB isolates revealed four to eight times higher MICs and MBCs compared with the majority of Gram-positives excepting some VRE isolates. On the other hand, neither MICs and MBCs ranges of CHG from the MDRO isolates nor the monthly incidence of the MDROs from both ICUs were significantly increased before and after the intervention of daily CHG bathing.

Conclusion
This study indicates that some Gram-negative MDRO isolates with higher MICs and MBCs of CHG might be from longstanding exposure to CHG or efflux pumps. Although 2% daily CHG bathing uses over 1,000 times higher concentrations than the lethal concentration, it might be needed to monitor CHG resistance among MDROs.

Disclosures
All authors: No reported disclosures.