bluuebunny/crossref_metadata_2025_split huggingface dataset:
535. Multicenter Study of the Prevalence of Rectal Colonization by Carbapenem-Resistant Enterobacteriaceae in Patients Admitted to the Intensive Care Units of 7 Major Hospitals in Kuwait
Authors: Al Fadhli Amani , Jamal Wafaa Y , Rotimi Vincent O 
Published: October 2019

Abstract

Background
The emergence of carbapenem-resistant Enterobacteriaceae (CRE) has become an important epidemiological change in infectious diseases in the last 10 years. The gut is an important reservoir for these isolates thereby creating an opportunity for dissemination in a hospital setting especially the intensive care units (ICUs). The objective of this study was to investigate the colonization rates of patients, by CRE, admitted to the ICUs of 7 teaching hospitals.

Methods
Rectal swabs were collected during July 2017 to November 2018 from all patients on the day of ICU admission and 1 week after in each hospital. The samples were screened by direct plating on MacConkey agar containing 10-μg meropenem. Bacterial species identification was performed using the VITEK-2 system. The minimum inhibitory concentrations (MICs) of 14 antibiotics were determined by using Etest. Genes encoding carbapenem resistance was detected by PCR and sequencing. Their clonal relationship was determined by pulsed-field gel electrophoresis (PFGE).

Results
A total of 2580 Enterobacteriaceae were isolated from all patients. Seventy-four (2.9%) were confirmed as CRE most of which were from patients in Adan (AH: 36.5%) and Mubarak (MH: 46%) hospitals. Sixty (81.1%) harbored one or more of the tested carbapenemases genes. Forty-six (62.2%) carried blaOXA-181, 9 (12.2%) blaOXA-48, one blaKPC-2, while 14 (18.9%) carried 2 genes. Combinations of blaKPC-2 and blaOXA-181 genes were found in 5 (6.8%), blaVIM-1 and blaOXA-181 in 4 (5.4%), blaNDM-5 and blaOXA-181 in 3 (4.1%) and blaNDM-1 and blaOXA-181 in 2 (3.3%). The XbaI PFGE profile-based Dendrogram, at 85% similarity criterion, resolved 7 pulsotypes among isolates carrying blaOXA-181 in AH and MH designated A, B, C, D, E, F, and G. Further analysis revealed that 7 subpulsotypes A1, A2, A5, A6, C1, C2, and E1 were from unit D in the medical ICU of MH and A3, A4, B1, B3, D1, D2, D3, D4, F1, F2, F3, G1, and G2 were from surgical/medical ICUs in AH. 100% similarity was demonstrated among 8 isolates from AH and 2 from MH.

Conclusion
The prevalence of rectal colonization by CRE in the ICU patients was lower than expected. Detection of blaOXA-181 variety and blaNDM-5 is new to the milieu of genes so far described in isolates from Kuwait.

Disclosures
All authors: No reported disclosures.
539. Canaries in a Coal Mine?: Early Identification of Regional Spread of Novel Multidrug-resistant Organisms (MDROs) Using Sentinel Surveillance in Skilled Nursing Facilities Caring For Ventilated Patients (vSNFs)
Authors: Paul Prabasaj , Slayton Rachel , Walters Maroya S , Jernigan John A 
Published: October 2019

Abstract

Background
Regional containment of novel or targeted MDROs depends on detecting their presence as soon as possible following their introduction. Prior modeling studies suggest that after importation to a region, novel MDROs appear relatively quickly in certain high-risk post-acute long-term care facilities via patient movement. Sentinel surveillance in such facilities might facilitate early detection of emergent MDROs, thereby enhancing the effectiveness of containment efforts.

Methods
We simulated the introduction and spread of carbapenem-resistant Enterobacteriaceae (CRE) in a region using an adaptation of a previously described susceptible-infectious-susceptible model (Clin Infect Dis. 2019 March 28 doi: 10.1093/cid/ciz248). The model includes the patient sharing network among healthcare facilities in an exemplar US state, using claims data and the Minimum Data Set from the Centers for Medicare & Medicaid Services for 2015. Disease progression, transmission and testing rates were estimated for CRE using data from the literature. Each simulated outbreak was initiated with a single importation to a Dartmouth Atlas of Health Care hospital referral region. The predicted timing of first CRE detection using two different data sources was compared: (1) real-time monitoring of clinical microbiology test results, or (2) results from quarterly point prevalence colonization surveys (PPSs). For each data source, the timing of earliest detection was compared according to availability of data from: (a) all healthcare facilities statewide, (b) only long-term acute care hospitals, (c) only vSNFs, or (d) only the largest acute care hospitals in the state (n = 23).

Results
Compared with real-time monitoring of clinical microbiology testing results from all facilities statewide, quarterly PPSs at all facilities detected CRE 446 days (median; range 312–608 days) earlier, while PPSs at only vSNFs (representing 4.4% of inpatient beds statewide) detected CRE 385 days (range 194–553 days) earlier (figures).

Conclusion
Regular point prevalence surveys in vSNFs may detect new MDROs in a region approximately one year sooner than real-time monitoring of clinical microbiology results, and may be an efficient strategy for early regional detection and subsequent containment.

Disclosures
All authors: No reported disclosures.
543. Biocide Resistance Genes in Klebsiella spp. Infections from Trauma Patients in Iraq and Afghanistan
Authors: Kiley John L , Blyth Dana M , Blyth Dana M , Beckius Miriam , Kaiser Susan , Carson M Leigh , Lu Dan , Whitman Timothy , Petfield Joseph , Tribble David , Mende Katrin 
Published: October 2019

Abstract

Background
Biocides play an integral role in infection control. Paralleling concern about rising incidence of multidrug-resistant (MDR) organisms is a concern for resistance to biocides. In small studies, several genes involved in the production of efflux pump proteins have been identified as markers of biocide resistance in Klebsiella spp., namely cepA, qacA, qacE, qac∆E, and acrA. This study aimed to analyze the Klebsiella spp. isolates of a previously defined military trauma group with a high incidence of MDR organisms for the presence of these genes and their correlation with other resistance.

Methods
All infecting K. pneumoniae, K. variicola, and K. quasipneumoniae isolates archived by the Trauma Infectious Disease Outcomes Study (June 2009–December 2014) were selected. Additionally, all colonizing isolates linked with infecting isolates were included; the remainder to total 50 MDR and 46 non-MDR colonizing isolates were chosen randomly. Antimicrobial identification and susceptibilities were determined by CLSI criteria using the BD Phoenix Automated Microbiology System. PCR according to published methods for cepA, qacA, qacE, qac∆E, and acrA was accomplished in duplicate. MDR was defined as either resistance to ≥3 classes of aminoglycosides, β-lactams, carbapenems and/or fluoroquinolones or production of an ESBL or KPC.

Results
A total of 237 isolates (221 K. pneumoniae, 10 K. variicola, 6 K. quasipneumoniae) met inclusion criteria, of which 149 (63%) were MDR. All isolates had been exposed to antimicrobials prior to isolation. Of all isolates, 234 (98%) carried cepA: 218 (98%) K. pneumoniae carried cepA, 10 (100%) K. variicola carried cepA, and 6 (100%) of K. quasipneumoniae carried cepA. In addition, 148 (62%) isolates with cepA were MDR. One (10%) K. variicola isolate carried qacE along with cepA. This isolate was the only MDR K. variicola. None of the isolates carried qacA, qac∆E, or acrA.

Conclusion
We confirmed the near universal presence of the cepA biocide resistance gene in Klebsiella spp. isolated from trauma patients in Iraq and Afghanistan. In the largest evaluation of biocide resistance genes in Klebsiella spp. to our knowledge, the presence of qacA, qacE, qac∆E, and acrA was less common than has been reported elsewhere.

Disclosures
All authors: No reported disclosures.
552. Within-Host Evaluation of Colonization During Active Methicillin-Resistant S. aureus Bacteremia
Authors: Berbel Caban Ana B , Dupper Amy , Van de Guchte Adriana , Obla Ajay , Chung Marilyn , Gottlieb Lindsey B , Mills Alexandra , Fox Lindsey , Oussenko Irina , Samaroo Flora , Smith Melissa L , Polanco Jose , Patel Gopi , Gitman Melissa R , Sullivan Mitchell , Van Bakel Harm , Altman Deena R 
Published: October 2019

Abstract

Background
Staphylococcus aureus is a common commensal pathogen and a frequent cause of bacteremia, with nasal and blood isolates from single patients matching >80% of the time. Based on our prior work on paired single-patient isolates,1 our aim was to collect a contemporary set of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections (BSIs), evaluate the within-host diversity by whole-genome sequencing (WGS), and detail the clinical features linked to colonization.

Methods
Adult patients with MRSA BSIs were screened for MRSA in the anterior nares from July 2018 to March 2019. Blood isolates underwent WGS, and spa and agr function screens were performed on three unique nasal isolates per patient. Clinical data from the electronic medical records underwent uni- and multivariate analyses on clinical features and outcomes.

Results
Of 55 unique patients with MRSA BSIs, screening of 45 subjects revealed that 67% were colonized with MRSA. The majority (64%) were males, 32% had prior colonization, and the most common infection sources were vascular access (27%), skin (24%), and unknown (24%). For those with nasal colonization, blood isolates were composed of 57% clonal complex (CC)5/t002, 33% CC8/t008, and 10% other. 81% of nasal isolates matched the blood, with 20% of nasal isolates harboring diverse spa types and 23% carried agr mutants. During this time frame, WGS found one transmission event involving a colonized subject. Colonization was associated with male gender (OR=4.52 95% CI [1.05–19.49]; P = 0.04) and prior hospital admission within the last 3 months (OR=6.12 95% CI [1.44–26.09]; P = 0.01) in multivariate analysis, with no differences in outcomes.

Conclusion
Colonization is an important component of invasive MRSA disease, and we found high rates of colonization with a predominance of the CC5. We also noted significant diversity and high proportion of agr mutants. At-risk groups included males and those with prior hospitalization. Combined molecular and clinical analyses can define the intrahost and interhost transmission dynamics of MRSA, and enables the development of targeted approaches in order to curtail disease.
1. Altman, D. R. et al. Genome Plasticity of agr-defective Staphylococcus aureus during clinical infection. Infect. Immun.(2018).

Disclosures
All authors: No reported disclosures.
555. The Burden of Invasive Staphylococcus Aureus Disease Among Native Americans on the Navajo Nation
Authors: Sutcliffe Catherine , Grant Lindsay , Reid Angelina , Douglass Grace K , Weatherholtz Robert , Hubler Robin , Quintana Alvaro , Reid Raymond , Yazzie Del , Santosham Mathuram , O’Brien Katherine , Hammitt Laura 
Published: October 2019

Abstract

Background
Native Americans in the southwestern United States (US) may be at higher risk for invasive infections due to Staphylococcus aureus. The objective of this study was to determine the burden of invasive S. aureus among Native Americans on the Navajo Nation.

Methods
Prospective population and laboratory-based surveillance for invasive S. aureus infections was conducted from May 2016 through April 2018. A case was defined as a Native American individual living on or around the Navajo Nation with S. aureus isolated from a normally sterile body site. Incidence rates were calculated using the Indian Health Service User Population from 2016 and 2017 as the denominators for Years 1 and 2, respectively. Age-standardized incidence rates were calculated using US Census data from 2015 as the reference group.

Results
363 cases were identified (Year 1: 159; Year 2: 204). Most cases were adults (96.9%; median age: 56.0 years) and had ≥1 underlying medical condition (94.5%), of which the most common were diabetes (63.2%), hypertension (39.1%), and obesity (37.2%). 38.0% of cases were categorized as community acquired and 28.7% of infections were methicillin-resistant (MRSA). 83.2% of cases were hospitalized, 10.7% required amputation, and 6.5% died within 30 days of the initial culture. The overall incidence of invasive S. aureus was 74.4 per 100,000 persons (95% confidence interval [CI]: 67.1, 82.4) with a significantly higher incidence in the second year (Year 1: 64.9; Year 2: 84.0; incidence rate ratio: 1.29; 95% CI: 1.05, 1.59). The overall incidence of invasive MRSA was 21.3 per 100,000 persons (95% CI: 17.6, 25.8) with no significant difference by year (Year 1: 21.2; Year 2: 21.4; incidence rate ratio: 1.01; 95% CI: 0.69, 1.48). The incidence of invasive S. aureus and MRSA increased with age and was highest among individuals ≥65 years of age. The overall age-standardized incidence of invasive MRSA was 25.9 per 100,000 persons (Year 1: 26.0; Year 2: 25.7; for comparison US 2015 general population: 18.8 per 100,000 persons).

Conclusion
The Navajo Nation has a higher burden of invasive MRSA than the general US population. Further research is needed to evaluate trends over time and identify prevention strategies and opportunities for intervention.

Disclosures
All authors: No reported disclosures.
558. Evaluating Length of Stay Data for Use in Targeting Prevention of Methicillin-Resistant Staphylococcus aureus (MRSA) Bloodstream Infections
Authors: Gouin Katryna , Hatfield Kelly M , Yi Sarah H , Reddy Sujan , Wolford Hannah , Li Qunna , Edwards Jonathan R , Slayton Rachel , Baggs James , O’Hagan Justin 
Published: October 2019

Abstract

Background
Evidence suggests that interventions such as MRSA decolonization are useful in the prevention of MRSA bloodstream infections (BSI) both during hospitalization and post-discharge. However, decolonization may be costly and have diminishing effectiveness when used on all inpatients. Hospital length of stay (LOS) is a known risk factor for MRSA BSI. To determine whether LOS could be useful in prioritizing patients for intervention, we aimed to evaluate (i) distribution of time from admission to hospital-onset (HO) MRSA BSI, and (ii) frequency and LOS of hospitalizations that preceded community-onset (CO) MRSA BSI.

Methods
MRSA-positive blood cultures among adults admitted to New York hospitals from 2013 to 20s16 were identified in the Centers for Disease Control and Prevention’s (CDC’s) National Healthcare Safety Network (NHSN). We linked these data to admissions in New York’s hospital discharge dataset, the Statewide Planning and Research Cooperative System (SPARCS), where the NHSN blood culture collection date was between a patient’s SPARCS admission and discharge dates and there was an exact match for birth date, gender and facility. Time to MRSA BSI was defined as the number of days from admission (day 1) to collection of a blood culture positive for MRSA. We defined positive blood cultures collected on days 1–3 as CO, and those collected ≥day 4 as HO.

Results
We linked 10,425 (79%) MRSA BSIs from NHSN to SPARCS. 78% (8,147) of MRSA BSIs were CO and 22% (2,278) were HO. The median time to HO MRSA BSI was 10 days (IQR 6–21) (Figure 1), in contrast to the median LOS for all hospitalizations of 4 days (IQR 3–7). By definition, 35% of all hospitalizations were never at risk of HO MRSA BSI because their LOS was < 4 days. Among CO MRSA BSI, 48% were discharged from a hospital in the 90 days preceding their BSI (Figure 2). The median LOS of these prior hospitalizations was 8 days (IQR 5–14), and 87% were at least 4 days in length.

Conclusion
Over half of HO MRSA BSI occur on or after day 10 of hospitalization and a large fraction of CO MRSA BSI had a lengthy hospitalization shortly before their BSI diagnosis. Our results suggest that patients likely to have a long LOS could be evaluated as potential targets for prevention strategies (e.g., decolonization) to reduce both HO and CO MRSA BSI.

Disclosures
All authors: No reported disclosures.
561. Genomic Epidemiology of Methicillin-Resistant Staphylococcus aureus in Two Cohorts of High-Risk Military Trainees
Authors: Lee Robyn S , Millar Eugene V , Callendrello Alanna , English Caroline E , Krasniewski Alexander E , Bennett Jason W , Hanage William P 
Published: October 2019

Abstract

Background
Methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infections (SSTIs) are common among military recruits. Identifying which strains are responsible for SSTI and understanding the underlying transmission dynamics is critical to developing appropriate interventions for this high-risk population.

Methods
A cohort study of US Army Infantry trainees at Fort Benning, GA (June and September 2015). Participants from two training Companies were screened for colonization on multiple anatomic sites throughout the 14-week cycle as well as the time of clinical infection. MRSA+ samples were sequenced with Illumina HiSeq. Multi-locus sequence type (MLST) and virulence genes were identified in silico. Single nucleotide polymorphism (SNP) distances between soldiers’ bacteria were compared with assessing for potential transmission.

Results
Of 383 soldiers enrolled, 84 (22%) were colonized with MRSA during the study. Forty-two of 84 had a single positive colonization sample, of which 76% were from anatomical sites other than the nares (36% oropharyngeal, 26% perianal, 14% inguinal). Twelve trainees had MRSA SSTI during training (50% had colonization detected prior to or at infection). All were PFGE-type US300 (ST8) and were lukS/lukF-positive. SNP-based phylogenetic analyses and epidemiologic data indicate that most MRSA positives at baseline were due to unique importations from various community origins, suggesting that the ongoing MRSA epidemic is not due to a single endemic strain circulating on base. Following importation, extensive transmission then occurred, with multiple STs implicated. Transmission appeared restricted to within Companies, and predominantly within platoons.

Conclusion
Frequent colonization at baseline suggests a need for extensive MRSA screening and decolonization upon arrival to base, followed by ongoing infection control measures throughout training to prevent recolonization/infection. As multiple anatomical sites appear to play a role in transmission of MRSA, this may have important implications for screening protocols and control both in community and hospital-based settings.

Disclosures
All authors: No reported disclosures.
564. A Five-Year Evolutionary Study of the Minimum Inhibitory Concentrations of Methicillin-resistant Staphylococcus aureus to Mupirocin, Chlorhexidine, and Octenidine in a Singaporean Tertiary Institution
Authors: Zheng Shuwei , Jasmine Chung Shimin , Chiak James Sim Heng , Zhu Xiaoyi , Xuan Tan Si , Chlebicka Tara M , Huak Chan Yiong , Peng Lim Tze , Hoon Andrea Kwa Lay , Piotr Chlebicki Maciej 
Published: October 2019

Abstract

Background
Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of healthcare-associated infection. Eradication of MRSA carriage reduces clinical infection and prevents transmission. In Singapore General Hospital, a series of hospital-wide measures were instituted over three years (Figure 1) to reduce mupirocin (MUP) resistance, and to decrease the bioburden of MRSA colonization amongst inpatients using octenidine (OCT)-based products.

Methods
A prevalence study was conducted at three time points (TPs) on consecutive MRSA screening isolates to evaluate for their minimum inhibitory concentrations (MICs) to CHG, OCT and MUP using broth microdilution sensitive plates and the presence of the ileS-2 gene, in 2013 (pre-intervention TP, TP1; n = 160), 2016 (early post-intervention TP, TP2; n = 99) and 2017 (late post-intervention TP, TP3; n = 76). Statistical analyses were performed using the Chi-square test with reference from TP1.

Results
A significant improvement in MUP susceptibility by MIC (256 µg/mL) and ileS-2 testing reduced from 25.0% (TP1) to 12.1% (TP2; P = 0.014) to 5.3% (TP3; P = 0.001) and 30.0% (TP1) to 18.2% (TP2; P = 0.036) to 9.2% (TP3; P = 0.001), respectively. OCT MIC range remained stable at 0.5 to 1 across all three TPs. The number of isolates with reduced CHG susceptibility (MIC ≥4 mg/L) increased over the three TPs from 23.1% to 27.2% (P = 0.45) to 42.1% (P = 0.003), despite decreasing CHG prescription.

Conclusion
A restrictive MUP usage policy can improve MUP susceptibility amongst MRSA isolates over time. Widespread OCT use did not appear to result in a rise of OCT MIC over the intervention period. Although the clinical significance of reduced susceptibility to CHG remains uncertain, this worrying trend in our institution deserves further studies to better understand mechanisms of CHG resistance.

Disclosures
All authors: No reported disclosures.
566. Reduction of Hospital-Onset Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia in an Acute Care Hospital: Impact of Bundles and Universal Decolonization
Authors: Jimenez Adriana , Sposato Kathleen , de Leon-Sanchez Alicia , Williams Regina , Francois Reynande , Wilson Juliana , Lisondra Benjamin , Abbo Lilian 
Published: October 2019

Abstract

Background
MRSA is a major concern for hospitalized patients in the United States. Hospital-Onset (HO) MRSA bacteremia is used as a proxy measurement of MRSA healthcare acquisition, exposure, and infection burden. HO MRSA bacteremia standardized infection ratio (SIR) is used by several national agencies as a quality report metric. Our institution had more than expected HO MRSA bacteremia cases despite several interventions. We describe the impact of a bundle of interventions aimed to decrease HO MRSA bacteremia in an acute care facility.

Methods
This quality improvement project was implemented in a 380-bed community hospital in Miami, FL from January 2015 to March 2019. HO MRSA bacteremia was defined as non-duplicate MRSA isolated from a blood culture collected >3 days after admission. SIR was calculated dividing the number of observed events by the number of predicted events; predicted events were obtained from the NHSN report. During baseline period (Figure1 Phase 1 January 2015–August 2016) all adult patients in the intensive care unit (ICU) were screened for MRSA nasal colonization on admission and weekly thereafter, ICU patients received daily Chlorhexidine (CHG) bathing, and colonized/infected patients with MRSA were placed in contact precautions. In Phase 2 (September 2016–June 2017)daily CHG bathing was switched from 2% wipes to 4% soap foam and expanded to all adult patients; ICU patients also received nasal decolonization with mupirocin. Nasal mupirocin in ICU was replaced with alcohol-based nasal sanitizer for all adult units in July 2017 (Phase 3). In April 2017 we discontinued using contact precautions for MRSA patients; nasal surveillance cultures were discontinued in October 2017. In May 2018 (Phase 4) we introduced alcohol-based wipes for patient hand hygiene at the bedside. SIR were compared by exact binomial test.

Results
We observed 48 HO MRSA bacteremia cases during the study period. The SIR decreased from 3.66 to 0.97 from baseline to postintervention periods (P = 0.003). The largest decrease in cases and SIR was attained using combined hospital-wide daily CHG bathing, alcohol-based nasal sanitizer, and alcohol wipes for patient hand hygiene during Phase 4 (Table 1).

Conclusion
Our bundle of interventions for universal decolonization was successful in decreasing HO MRSA bacteremia.

Disclosures
All authors: No reported disclosures.