Reducing Hospitalizations and Multidrug-Resistant Organisms via Regional Decolonization in Hospitals and Nursing Homes

Importance

Infections due to multidrug-resistant organisms (MDROs) are associated with increased morbidity, mortality, length of hospitalization, and health care costs. Regional interventions may be advantageous in mitigating MDROs and associated infections.

Objective

To evaluate whether implementation of a decolonization collaborative is associated with reduced regional MDRO prevalence, incident clinical cultures, infection-related hospitalizations, costs, and deaths.

Design, Setting, and Participants

This quality improvement study was conducted from July 1, 2017, to July 31, 2019, across 35 health care facilities in Orange County, California.

Exposures

Chlorhexidine bathing and nasal iodophor antisepsis for residents in long-term care and hospitalized patients in contact precautions (CP).

Main Outcomes and Measures

Baseline and end of intervention MDRO point prevalence among participating facilities; incident MDRO (nonscreening) clinical cultures among participating and nonparticipating facilities; and infection-related hospitalizations and associated costs and deaths among residents in participating and nonparticipating nursing homes (NHs).

Results

Thirty-five facilities (16 hospitals, 16 NHs, 3 long-term acute care hospitals [LTACHs]) adopted the intervention. Comparing decolonization with baseline periods among participating facilities, the mean (SD) MDRO prevalence decreased from 63.9% (12.2%) to 49.9% (11.3%) among NHs, from 80.0% (7.2%) to 53.3% (13.3%) among LTACHs (odds ratio [OR] for NHs and LTACHs, 0.48; 95% CI, 0.40-0.57), and from 64.1% (8.5%) to 55.4% (13.8%) (OR, 0.75; 95% CI, 0.60-0.93) among hospitalized patients in CP. When comparing decolonization with baseline among NHs, the mean (SD) monthly incident MDRO clinical cultures changed from 2.7 (1.9) to 1.7 (1.1) among participating NHs, from 1.7 (1.4) to 1.5 (1.1) among nonparticipating NHs (group × period interaction reduction, 30.4%; 95% CI, 16.4%-42.1%), from 25.5 (18.6) to 25.0 (15.9) among participating hospitals, from 12.5 (10.1) to 14.3 (10.2) among nonparticipating hospitals (group × period interaction reduction, 12.9%; 95% CI, 3.3%-21.5%), and from 14.8 (8.6) to 8.2 (6.1) among LTACHs (all facilities participating; 22.5% reduction; 95% CI, 4.4%-37.1%). For NHs, the rate of infection-related hospitalizations per 1000 resident-days changed from 2.31 during baseline to 1.94 during intervention among participating NHs, and from 1.90 to 2.03 among nonparticipating NHs (group × period interaction reduction, 26.7%; 95% CI, 19.0%-34.5%). Associated hospitalization costs per 1000 resident-days changed from $64 651 to $55 149 among participating NHs and from $55 151 to $59 327 among nonparticipating NHs (group × period interaction reduction, 26.8%; 95% CI, 26.7%-26.9%). Associated hospitalization deaths per 1000 resident-days changed from 0.29 to 0.25 among participating NHs and from 0.23 to 0.24 among nonparticipating NHs (group × period interaction reduction, 23.7%; 95% CI, 4.5%-43.0%).

Conclusions and Relevance

A regional collaborative involving universal decolonization in long-term care facilities and targeted decolonization among hospital patients in CP was associated with lower MDRO carriage, infections, hospitalizations, costs, and deaths.

Characterizing predictors of COVID-19 vaccine refusal in an urban southern California jail population

BACKGROUND

Correctional populations have been disproportionately affected by COVID-19, and many large outbreaks have occurred in jails and prisons. Vaccination is a key strategy to reduce the SARS-CoV-2 transmission in carceral settings. Although implementation can be challenging due to vaccine hesitancy and medical mistrust, correctional settings provide largely equitable healthcare access and present a unique opportunity to identify potential predictors of vaccine hesitancy independent of access issues.

METHODS

We retrospectively analyzed electronic health record data for individuals offered COVID-19 vaccination at the Los Angeles County Jail between January 19, 2021, and January 31, 2023, and used multivariable logistic regression to determine predictors of COVID-19 vaccine refusal.

RESULTS

Of the 21,424 individuals offered COVID-19 vaccination, 2,060 (9.6 %) refused. Refusal was associated with male sex ([aOR] = 2.3, 95 % CI (1.9, 2.8)), age 18-34 ([aOR] = 1.2, 95 % CI (1.1, 1.4), referent group: age 45-54), Black race ([aOR] = 1.2, 95 % CI (1.1, 1.4)), reporting ever being houseless ([aOR] = 1.2, 95 % CI (1.1, 1.3)), and having a history of not receiving influenza vaccination while incarcerated ([aOR] = 2.4, 95 % CI (2.0, 2.8)). When analyzing male and female populations separately, male-specific trends reflected those seen in the overall population, whereas the only significant predictor of vaccine refusal in the female population was not receiving influenza vaccination while in custody ([aOR] = 6.5, 95 % CI (2.4, 17.6)).

CONCLUSION

Identifying predictors of vaccine refusal in correctional populations is an essential first step in the development and implementation of targeted interventions to mitigate vaccine hesitancy.

Decolonization in Nursing Homes to Prevent Infection and Hospitalization

BACKGROUND

Nursing home residents are at high risk for infection, hospitalization, and colonization with multidrug-resistant organisms.

METHODS

We performed a cluster-randomized trial of universal decolonization as compared with routine-care bathing in nursing homes. The trial included an 18-month baseline period and an 18-month intervention period. Decolonization entailed the use of chlorhexidine for all routine bathing and showering and administration of nasal povidone-iodine twice daily for the first 5 days after admission and then twice daily for 5 days every other week. The primary outcome was transfer to a hospital due to infection. The secondary outcome was transfer to a hospital for any reason. An intention-to-treat (as-assigned) difference-in-differences analysis was performed for each outcome with the use of generalized linear mixed models to compare the intervention period with the baseline period across trial groups.

RESULTS

Data were obtained from 28 nursing homes with a total of 28,956 residents. Among the transfers to a hospital in the routine-care group, 62.2% (the mean across facilities) were due to infection during the baseline period and 62.6% were due to infection during the intervention period (risk ratio, 1.00; 95% confidence interval [CI], 0.96 to 1.04). The corresponding values in the decolonization group were 62.9% and 52.2% (risk ratio, 0.83; 95% CI, 0.79 to 0.88), for a difference in risk ratio, as compared with routine care, of 16.6% (95% CI, 11.0 to 21.8; P<0.001). Among the discharges from the nursing home in the routine-care group, transfer to a hospital for any reason accounted for 36.6% during the baseline period and for 39.2% during the intervention period (risk ratio, 1.08; 95% CI, 1.04 to 1.12). The corresponding values in the decolonization group were 35.5% and 32.4% (risk ratio, 0.92; 95% CI, 0.88 to 0.96), for a difference in risk ratio, as compared with routine care, of 14.6% (95% CI, 9.7 to 19.2). The number needed to treat was 9.7 to prevent one infection-related hospitalization and 8.9 to prevent one hospitalization for any reason.

CONCLUSIONS

In nursing homes, universal decolonization with chlorhexidine and nasal iodophor led to a significantly lower risk of transfer to a hospital due to infection than routine care. (Funded by the Agency for Healthcare Research and Quality; Protect ClinicalTrials.gov number, NCT03118232.).

Skin and soft tissue infection incidence before and during the COVID-19 pandemic

Skin and Soft Tissue Infections (SSTIs) are common bacterial infections. We hypothesized that due to the COVID-19 pandemic, SSTI rates would significantly decrease due to directives to avoid unneeded care and attenuated SSTIs risk behaviours. We retrospectively examined all patients with an ICD-10 diagnosis code in the Los Angeles County Department of Health Services, the second largest U.S. safety net healthcare system between 16 March 2017 and 15 March 2022. We then compared pre-pandemic with intra-pandemic SSTI rates using an interrupted time series analysis. We found 72,118 SSTIs, 46,206 during the pre-pandemic period and 25,912 during the intra-pandemic period. Pre-pandemic SSTI rate was significantly higher than the intra-pandemic rate (3.27 vs. 2.31 cases per 1,000 empanelled patient-months, P < 0.0001). The monthly SSTI cases decreased by 1.19 SSTIs/1,000 empanelled patient-months between the pre- and intra-pandemic periods (P = 0.0003). SSTI subgroups (inpatient, observation unit, emergency department, and outpatient clinics), all had significant SSTI decreases between the two time periods (P < 0.05) except for observation unit (P = 0.50). Compared to the pre-COVID-19 pandemic period, medically attended SSTI rates in our large U.S. safety net healthcare system significantly decreased by nearly 30%. Whether findings reflect true SSTI decreases or decreased health system utilization for SSTIs requires further examination.

Priorities and Progress in Gram-positive Bacterial Infection Research by the Antibacterial Resistance Leadership Group: A Narrative Review

The Antibacterial Resistance Leadership Group (ARLG) has prioritized infections caused by gram-positive bacteria as one of its core areas of emphasis. The ARLG Gram-positive Committee has focused on studies responding to 3 main identified research priorities: (1) investigation of strategies or therapies for infections predominantly caused by gram-positive bacteria, (2) evaluation of the efficacy of novel agents for infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci, and (3) optimization of dosing and duration of antimicrobial agents for gram-positive infections. Herein, we summarize ARLG accomplishments in gram-positive bacterial infection research, including studies aiming to (1) inform optimal vancomycin dosing, (2) determine the role of dalbavancin in MRSA bloodstream infection, (3) characterize enterococcal bloodstream infections, (4) demonstrate the benefits of short-course therapy for pediatric community-acquired pneumonia, (5) develop quality of life measures for use in clinical trials, and (6) advance understanding of the microbiome. Future studies will incorporate innovative methodologies with a focus on interventional clinical trials that have the potential to change clinical practice for difficult-to-treat infections, such as MRSA bloodstream infections.

Bayesian modeling of the impact of antibiotic resistance on the efficiency of MRSA decolonization

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of morbidity and mortality. Colonization by MRSA increases the risk of infection and transmission, underscoring the importance of decolonization efforts. However, success of these decolonization protocols varies, raising the possibility that some MRSA strains may be more persistent than others. Here, we studied how the persistence of MRSA colonization correlates with genomic presence of antibiotic resistance genes. Our analysis using a Bayesian mixed effects survival model found that genetic determinants of high-level resistance to mupirocin was strongly associated with failure of the decolonization protocol. However, we did not see a similar effect with genetic resistance to chlorhexidine or other antibiotics. Including strain-specific random effects improved the predictive performance, indicating that some strain characteristics other than resistance also contributed to persistence. Study subject-specific random effects did not improve the model. Our results highlight the need to consider the properties of the colonizing MRSA strain when deciding which treatments to include in the decolonization protocol.

Safety and tolerability of tedizolid as oral treatment for bone and joint infections

Bone and joint infections (BJIs) are common infections increasingly managed with oral therapy. However, there are limited safe oral options for many Gram-positive pathogens. In animal studies and short-term human use, tedizolid lacks the hematologic and neurologic toxicity of the other available oxazolidinone, linezolid. However, there are limited prospective safety data. We conducted an open-label, non-comparative trial of oral tedizolid for BJI treatment. Primary outcomes were safety and cure rate. Eligible patients had a BJI caused by documented or suspected Gram-positive pathogen, required 4-12 weeks of therapy, and did not have myelosuppression or peripheral/optic neuropathy. Subjects underwent weekly evaluation for cytopenias and neuropathy. We enrolled 44 subjects; five were lost to follow-up. Two subjects did not complete planned treatment because of rash (n = 1) and urgent surgery (n = 1). Of 37 patients with evaluable outcomes, 17 (46%) had hardware-associated infection, 13 (35%) had osteomyelitis, 5 (14%) had prosthetic joint infection, and 2 (5%) had other BJIs. Median (mean, range) treatment duration was 12 (10.1, 4-12) weeks. There were no cases of cytopenias or peripheral or optic neuropathy. Treatment cure occurred in 13 (35%); 19 (51%) required antibiotic continuation after 12 weeks of tedizolid related to retained hardware at the BJI site, and failure occurred in four (11%), two unlikely, one possibly, and one probably due to tedizolid. We found that oral tedizolid was well tolerated for prolonged BJI treatment without significant toxicity. Clinical failure rate was similar to that of other published BJI investigations. (This study has been registered at Clinicaltrials.gov under identifier NCT03009045.) IMPORTANCE Bone and joint infections are common infections with limited effective and safe oral options for Gram-positive infections. The largest prospective clinical trial of tedizolid therapy for bone and joint infections enrolled 44 patients and tested each in person weekly with detailed safety monitoring including tests for leukopenia, anemia, thrombocytopenia, peripheral neuropathy, and optic neuropathy for up to 12 weeks. Findings demonstrated tedizolid was generally well tolerated and there were no incident cases of cytopenias or neuropathy. Cure rates were similar to that in other bone and joint infection studies. In summary, oral tedizolid appears to be a well-tolerated oral option for Gram-positive bone and joint infections.

Clinical and Bacterial Characteristics Associated with Glove and Gown Contamination by Carbapenem-Resistant Klebsiella pneumoniae in the Health Care Setting

Carbapenem-resistant Klebsiella pneumoniae (CRKp) is a pathogen of significant concern to public health, as it has become increasingly associated with difficult-to-treat community-acquired and hospital-associated infections. Transmission of K. pneumoniae between patients through interactions with shared health care personnel (HCP) has been described as a source of infection in health care settings. However, it is not known whether specific lineages or isolates of K. pneumoniae are associated with increased transmission. Thus, we used whole-genome sequencing to analyze the genetic diversity of 166 carbapenem-resistant K. pneumoniae isolates from five U.S. hospitals in four states as part of a multicenter study examining risk factors for glove and gown contamination by carbapenem-resistant Enterobacterales (CRE). The CRKp isolates exhibited considerable genomic diversity with 58 multilocus sequence types (STs), including four newly designated STs. ST258 was the most prevalent ST, representing 31% (52/166) of the CRKp isolates, but was similarly prevalent among patients who had high, intermediate, and low CRKp transmission. Increased transmission was associated with clinical characteristics including a nasogastric (NG) tube or an endotracheal tube or tracheostomy (ETT/Trach). Overall, our findings provide important insight into the diversity of CRKp associated with transmission from patients to the gloves and gowns of HCP. These findings suggest that certain clinical characteristics and the presence of CRKp in the respiratory tract, rather than specific lineages or genetic content, are more often associated with increased transmission of CRKp from patients to HCP. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKp) is a significant public health concern that has contributed to the spread of carbapenem resistance and has been linked to high morbidity and mortality. Transmission of K. pneumoniae among patients through interactions with shared health care personnel (HCP) has been described as a source of infection in health care settings; however, it remains unknown whether particular bacterial characteristics are associated with increased CRKp transmission. Using comparative genomics, we demonstrate that CRKp isolates associated with high or intermediate transmission exhibit considerable genomic diversity, and there were no K. pneumoniae lineages or genes that were universally predictive of increased transmission. Our findings suggest that certain clinical characteristics and the presence of CRKp, rather than specific lineages or genetic content of CRKp, are more often associated with increased transmission of CRKp from patients to HCP.

Chlorhexidine and Mupirocin for Clearance of Methicillin-Resistant Staphylococcus aureus Colonization After Hospital Discharge: A Secondary Analysis of the Changing Lives by Eradicating Antibiotic Resistance Trial

BACKGROUND

The CLEAR Trial demonstrated that a multisite body decolonization regimen reduced post-discharge infection and hospitalization in methicillin-resistant Staphylococcus aureus (MRSA) carriers. Here, we describe decolonization efficacy.

METHODS

We performed a large, multicenter, randomized clinical trial of MRSA decolonization among adult patients after hospital discharge with MRSA infection or colonization. Participants were randomized 1:1 to either MRSA prevention education or education plus decolonization with topical chlorhexidine, oral chlorhexidine, and nasal mupirocin. Participants were swabbed in the nares, throat, axilla/groin, and wound (if applicable) at baseline and 1, 3, 6, and 9 months after randomization. The primary outcomes of this study are follow-up colonization differences between groups.

RESULTS

Among 2121 participants, 1058 were randomized to decolonization. By 1 month, MRSA colonization was lower in the decolonization group compared with the education-only group (odds ration [OR] = 0.44; 95% confidence interval [CI], .36-.54; P ≤ .001). A similar magnitude of reduction was seen in the nares (OR = 0.34; 95% CI, .27-.42; P < .001), throat (OR = 0.55; 95% CI, .42-.73; P < .001), and axilla/groin (OR = 0.57; 95% CI, .43-.75; P < .001). These differences persisted through month 9 except at the wound site, which had a relatively small sample size. Higher regimen adherence was associated with lower MRSA colonization (P ≤ .01).

CONCLUSIONS

In a randomized, clinical trial, a repeated post-discharge decolonization regimen for MRSA carriers reduced MRSA colonization overall and at multiple body sites. Higher treatment adherence was associated with greater reductions in MRSA colonization.

Characterization of COVID-19 Vaccine Hesitancy Among Essential Workforce Members of a Large Safety Net Urban Medical Center

OBJECTIVES

Vaccine hesitancy among essential workers remains a significant public health challenge. We examined psychological constructs of perceived susceptibility, threat, and self-efficacy and their associations with COVID-19 vaccine hesitancy among a racially and ethnically diverse essential workforce population.

METHODS

We performed a cross-sectional survey of essential workers from September-December 2020 at a large Los Angeles safety-net medical center as part of a program offering free COVID-19 serology testing. Program participants completed a standardized survey at the time of phlebotomy. Hierarchical logistic regression was utilized to determine factors independently associated with vaccine hesitancy.

RESULTS

Among 1327 persons who had serology testing, 1235 (93%) completed the survey. Of these, 958 (78%) were healthcare workers. Based on expressed intent, 22% were vaccine-hesitant 78% were vaccine acceptors. In our multivariate model, vaccine hesitancy was associated with female gender [aOR = 2.09; 95% CI (1.44-3.05)], African American race [aOR = 4.32; (2.16-8.62)], LatinX ethnicity [aOR = 2.47; 95% CI (1.51-4.05)] and history of not/sometimes receiving influenza vaccination [aOR = 4.39; 95% CI (2.98-6.48)]. Compared to nurses, vaccine hesitancy was lower among physicians [aOR = 0.09; 95% CI (0.04-0.23)], non-nursing/non-physician healthcare workers [aOR = 0.55; 95% CI (0.33-0.92)], and non-healthcare care workers [aOR = 0.53; 95% CI (0.36-0.78)].

CONCLUSIONS

Among a racially/ethnically diverse group of safety net medical center essential workers, COVID-19 vaccine hesitancy was associated with racial/ethnic minority groups, employment type, and prior influenza vaccination hesitancy. Interestingly, we found no association with the Health Belief Model construct measures of perceived susceptibility, threat, and self-efficacy. Psychological constructs not assessed may be drivers of vaccine hesitancy in our population.

Longitudinal analysis of SARS-CoV-2 infection and vaccination in the LA-SPARTA cohort reveals increased risk of infection in vaccinated Hispanic participants

Introduction

SARS-CoV-2 is the etiologic agent of coronavirus disease 2019 (COVID-19). Questions remain regarding correlates of risk and immune protection against COVID-19.

Methods

We prospectively enrolled 200 participants with a high risk of SARS-CoV-2 occupational exposure at a U.S. medical center between December 2020 and April 2022. Participant exposure risks, vaccination/infection status, and symptoms were followed longitudinally at 3, 6, and 12 months, with blood and saliva collection. Serological response to the SARS-CoV-2 spike holoprotein (S), receptor binding domain (RBD) and nucleocapsid proteins (NP) were quantified by ELISA assay.

Results

Based on serology, 40 of 200 (20%) participants were infected. Healthcare and non-healthcare occupations had equivalent infection incidence. Only 79.5% of infected participants seroconverted for NP following infection, and 11.5% were unaware they had been infected. The antibody response to S was greater than to RBD. Hispanic ethnicity was associated with 2-fold greater incidence of infection despite vaccination in this cohort.

Discussion

Overall, our findings demonstrate: 1) variability in the antibody response to SARS-CoV-2 infection despite similar exposure risk; 2) the concentration of binding antibody to the SARS-CoV-2 S or RBD proteins is not directly correlated with protection against infection in vaccinated individuals; and 3) determinants of infection risk include Hispanic ethnicity despite vaccination and similar occupational exposure.

239. Acute Thromboembolism in Non-ICU Hospitalized Patients with COVID-19 infection: Examining the Impact of Prior COVID Vaccination

Background

Patients hospitalized with severe COVID-19 infections are at risk for acute thromboembolism. There are few data on the impact of vaccines on COVID-associated acute thromboembolism (CA-ATE) in patients hospitalized with COVID-19 infection.

Methods

Retrospective cohort of CA-ATE between March 2020 and March 2022 (Torrance Memorial Medical Center, pre-pandemic ATE incidence &lt; 1%). Inclusion criteria were confirmed COVID infection, &gt; 18 years, not admitted to ICU, and standard-dose thromboprophylaxis. Exclusion criteria were pregnancy, partial vaccination, and therapeutic dose anticoagulation. Primary outcome was CA-ATE incidence identified by routine clinical testing. We performed a multiple logistic regression for CA-ATE risk factors.

Results

Of 3,218 hospitalized COVID-19 patients, 1,428 patients were included; 185 were vaccinated (13%) and 1,243 unvaccinated (87%). Vaccinated status was associated with older age, diabetes, heart failure, and chronic kidney disease (p&lt; 0.01). CA-ATE was noted in 7.0% (2.2% deep vein thrombosis (DVT), 0.5% pulmonary embolism (PE), 2.7% myocardial infarction (MI), 1.6% Ischemic stroke (IS)) in the vaccinated and 3.9% (2.7% DVT, 1.5% PE, 1.0% MI, 0.8% IS) in the unvaccinated.

In our multivariate model, we found no significant difference in incident CA-ATE between vaccinated and unvaccinated (7.0% vs 3.9%, adj OR=1.35, [95% CI 0.67-2.58], p=0.38). CA-ATE was associated with older age (68 vs 61 years, OR=1.03, [95% CI 1.01-1.05], p=0.01) and heart failure (24% vs 7%, OR=2.84, [95% CI 1.35-6.00], p=0.006).

No significant difference was seen in mortality (3.8% vs 4.8%, OR=0.79, [95% CI 0.35-1.69], p=0.56), CRP AUC24hr (5.7 vs 4.7, p=0.18), or D-dimer AUC24hr (596 vs 653, p=0.77) between vaccinated and unvaccinated patients.

Table 2 Primary Outcomes in SARS-CoV-2 Patients Who Received Standard Chemo-thromboprophylaxis.

After performing a multiple logistic regression, there was no statistically significant difference between vaccinated and unvaccinated groups. Older age (OR=1.03, [95% CI 1.01-1.05], p=0.011) and Heart Failure (OR=2.84, [95% CI 1.35-6.00], p=0.006) were the most influential factors for thrombosis.

Conclusion

Adult, non-ICU, hospitalized, COVID-19 patients are at high risk for ATE. We found no association between vaccination status and ATE, but older age and congestive heart failure were predictive in this population. Decisions to anticoagulate non-ICU patients hospitalized with acute COVID-19 infections may not need to consider COVID vaccination status in as part of medical decision making, but may instead need to focus on underlying, high-risk, co-morbidities.

Disclosures

James McKinnell, M.D., Eli Lilly: Grant/Research Support|Eli Lilly: Funds Paid To Instituion for Clinical Research|Genentech: Grant/Research Support|Genentech: Funds to Insitution for Clinical Trial Work|Gilead: Grant/Research Support|Gilead: Paid to Institution for clinical research|Pfizer Pharmaceutc: Grant/Research Support|Pfizer Pharmaceutc: Funds to Institution for FDA Clinical Research|Thermo Fisher: Advisor/Consultant Loren G. Miller, MD MPH, ContraFect: Grant/Research Support|GSK: Grant/Research Support|Medline: Grant/Research Support|Merck: Grant/Research Support Loren G. Miller, MD MPH, ContraFect: Grant/Research Support|GSK: Grant/Research Support|Medline: Grant/Research Support|Merck: Grant/Research Support.

Clinical Impact of Ceftriaxone Resistance in Escherichia coli Bloodstream Infections: A Multicenter Prospective Cohort Study

Background

Ceftriaxone-resistant (CRO-R) Escherichia coli bloodstream infections (BSIs) are common.

Methods

This is a prospective cohort of patients with E coli BSI at 14 United States hospitals between November 2020 and April 2021. For each patient with a CRO-R E coli BSI enrolled, the next consecutive patient with a ceftriaxone-susceptible (CRO-S) E coli BSI was included. Primary outcome was desirability of outcome ranking (DOOR) at day 30, with 50% probability of worse outcomes in the CRO-R group as the null hypothesis. Inverse probability weighting (IPW) was used to reduce confounding.

Results

Notable differences between patients infected with CRO-R and CRO-S E coli BSI included the proportion with Pitt bacteremia score ≥4 (23% vs 15%, P = .079) and the median time to active antibiotic therapy (12 hours [interquartile range {IQR}, 1-35 hours] vs 1 hour [IQR, 0-6 hours]; P < .001). Unadjusted DOOR analyses indicated a 58% probability (95% confidence interval [CI], 52%-63%) for a worse clinical outcome in CRO-R versus CRO-S BSI. In the IPW-adjusted cohort, no difference was observed (54% [95% CI, 47%-61%]). Secondary outcomes included unadjusted and adjusted differences in the proportion of 30-day mortality between CRO-R and CRO-S BSIs (-5.3% [95% CI, -10.3% to -.4%] and -1.8 [95% CI, -6.7% to 3.2%], respectively), postculture median length of stay (8 days [IQR, 5-13 days] vs 6 days [IQR, 4-9 days]; P < .001), and incident admission to a long-term care facility (22% vs 12%, P = .045).

Conclusions

Patients with CRO-R E coli BSI generally have poorer outcomes compared to patients infected with CRO-S E coli BSI, even after adjusting for important confounders.

PARIS and SPARTA: Finding the Achilles' Heel of SARS-CoV-2

To understand reinfection rates and correlates of protection for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we established eight different longitudinal cohorts in 2020 under the umbrella of the PARIS (Protection Associated with Rapid Immunity to SARS-CoV-2)/SPARTA (SARS SeroPrevalence And Respiratory Tract Assessment) studies. Here, we describe the PARIS/SPARTA cohorts, the harmonized assays and analysis that are performed across the cohorts, as well as case definitions for SARS-CoV-2 infection and reinfection that have been established by the team of PARIS/SPARTA investigators. IMPORTANCE Determining reinfection rates and correlates of protection against SARS-CoV-2 infection induced by both natural infection and vaccination is of high significance for the prevention and control of coronavirus disease 2019 (COVID-19). Furthermore, understanding reinfections or infection after vaccination and the role immune escape plays in these scenarios will inform the need for updates of the current SARS-CoV-2 vaccines and help update guidelines suitable for the postpandemic world.

Comparative Genomics Identifies Features Associated with Methicillin-Resistant Staphylococcus aureus (MRSA) Transmission in Hospital Settings

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious public health concern in the United States. Patients colonized and/or infected can transmit MRSA to healthcare workers and subsequent patients However, the components of this transmission chain are just becoming evident, including certain patient factors, specific patient-healthcare worker interactions, and microbial factors. We conducted a comparative genomic analysis of 388 isolates from four hospitals in three states: Maryland, California, and New York. Isolates from nasal surveillance or clinical cultures were categorized as high, moderate, or low transmission surrogate outcomes based on the number of times the species was identified on the gloves or gowns of healthcare providers. The comparative analyses included a single gene, multigene, and core genome phylogenetic analysis, as well as a genome-wide association analysis to identify molecular signatures associated with the observed transmission surrogate outcomes, geographic origin, or sample source of isolation. Based on the phylogenetic analysis, 95% (n = 372) of the MRSA isolates were from four well-described genomic clades, with most of the isolates being part of the USA300 containing clade (n = 187; 48%). Genome-wide association studies also identified genes that were exclusive or prevalent among specific geographic locations. The identified genes provide insights into the transmission dynamics of MRSA isolates providing additional insights into the basis of the geographical differences of MRSA for molecular diagnostics. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is considered a serious threat to public health and contributes to the dissemination of S. aureus in both the healthcare and community setting. Transmission of MRSA between patients via healthcare worker (HCW) has been described. However, what is not understood are the genetic determinants that contribute to the transmission of MRSA from patients to HCWs. In this study, we demonstrated that certain genes may be associated with transmission in the hospital setting.

Modelling methicillin-resistant Staphylococcus aureus decolonization: interactions between body sites and the impact of site-specific clearance

Methicillin-resistant Staphylococcus aureus (MRSA) can colonize multiple body sites, and carriage is a risk factor for infection. Successful decolonization protocols reduce disease incidence; however, multiple protocols exist, comprising diverse therapies targeting multiple body sites, and the optimal protocol is unclear. Standard methods cannot infer the impact of site-specific components on successful decolonization. Here, we formulate a Bayesian coupled hidden Markov model, which estimates interactions between body sites, quantifies the contribution of each therapy to successful decolonization, and enables predictions of the efficacy of therapy combinations. We applied the model to longitudinal data from a randomized controlled trial (RCT) of an MRSA decolonization protocol consisting of chlorhexidine body and mouthwash and nasal mupirocin. Our findings (i) confirmed nares as a central hub for MRSA colonization and nasal mupirocin as the most crucial therapy and (ii) demonstrated all components contributed significantly to the efficacy of the protocol and the protocol reduced self-inoculation. Finally, we assessed the impact of hypothetical therapy improvements in silico and found that enhancing MRSA clearance at the skin would yield the largest gains. This study demonstrates the use of advanced modelling to go beyond what is typically achieved by RCTs, enabling evidence-based decision-making to streamline clinical protocols.

The Effect of Systemic Antibiotics for Suppurative Skin and Soft Tissue Infections on Skin Microbiome

Background

Skin and soft tissue infections (SSTIs) are very common bacterial infections. There are few data on the microbiome of persons with and without SSTIs and the effects of systemic antibiotic therapy.

Methods

We sampled the skin microbiome from 10 outpatients with acute suppurative SSTI before and after systemic antibiotic therapy and enrolled 10 matched controls. Samples were collected at 6 skin body sites (occipital scalp, axilla, interdigital hand web spaces, gluteal crease, inguinal creases, and popliteal fossa), 2 mucosal sites (throat, anterior nares), and the site of skin infection (for case subjects) at baseline and a week later after abscess incision, drainage, and oral antibiotics.

Result

Among 10 SSTI cases, mean age was 41.5 years and 3 had diabetes mellitus. The gluteal crease at baseline had higher α-diversity in controls vs cases (P = .039); β-diversity analysis showed significant differences in overall bacterial community composition (P = .046). However, at other body sites there were no significant differences by either α- or β-diversity. Systemic antibiotic use did not affect body site diversity indices except at the SSTI site (α-diversity increased, P = .001).

Conclusions

We surprisingly found no significant differences in microbiome comparing noninfected skin sites before and after systemic SSTI antibiotic therapy nor significant differences at noninfected skin sites between SSTI cases and uninfected controls. We also found minimal significant differences between microbiome diversity and bacterial signatures at noninfected skin sites between patients with acute skin infection and uninfected controls. Our findings challenge the dogma that systemic antibiotics impact the skin microbiome.

1. The Relationship Between Chlorhexidine Skin Concentration and Multidrug-Resistant Organism (MDRO) Colonization in ICU Patients

Background

Daily bathing of ICU patients with chlorhexidine gluconate (CHG) is an important method for healthcare-associated infection prevention. We set out to understand the relationship between CHG concentrations and MDRO colonization

Methods

In our trauma/surgical ICU at a large urban medical center, we performed CHG concentrations 2 days/week at 4 times points relative to CHG bathing (Medline, Northfiled, IL) application: 30 min. prior, and 30 min., 6 hrs., and 12 hrs. after application. CHG testing was done at 4 body sites: lateral neck, anterior chest, arm, and inguinal fold. On the contralateral side we tested the presence of the following 4 MDROs: methicillin resistant S. aureus (MRSA), and 3 enteric bacteria--extended spectrum beta-lactamase (ESBL)+ gram-negative rods, vancomycin resistant enterococcus (VRE), and carbapenem resistant enterobacteriaceae (CRE).

Results

We performed testing for 256 patient-days total, of which 42 were swabbed 1 time, 38 swabbed twice, 79 swabbed 3 times, and 97 swabbed 4 times (patient movement for tests, ICU transfer were limitations). Mean CHG skin concentrations were above the MICs of pathogens at all post-CHG application time points at all body sites at all times points (Figure) and decreased during the time points after bathing. In a logistic regression model controlling for patient characteristics, MRSA detection was inversely associated with CHG concentration with an 18% increase in odds of recovery for each 2-fold decrease in CHG concentration, as well as presence of a GI device and lack of ability to sit and roll. In a logistic regression model controlling for patient characteristics, resistant enteric bacteria detection was inversely associated with CHG concentration with an 11% increase in odds of recovery for each 2-fold decrease in CHG concentration, as well as mechanical ventilation, GI device, central line, and ICU duration.

Conclusion

In our large study of CHG use and its association with MDRO detection, CHG concentrations decreased during the 24 hours after application, but were typically above concentrations considered adequate to kill MDROs. CHG concentration were inversely associated with the presence of MRSA and resistant enterics, suggesting that CHG application quality is a key component of the CHG bathing process.

Disclosures

Loren G. Miller, MD, MPH, Medline (Grant/Research Support, Other Financial or Material Support, Contributed product) Stryker (Other Financial or Material Support, Contributed product) Xttrium (Other Financial or Material Support, Contributed product) James A. McKinnell, MD, Medline (Grant/Research Support)

5. The PROTECT Trial: A Cluster Randomized Clinical Trial of Universal Decolonization with Chlorhexidine and Nasal Povidone Iodine Versus Standard of Care for Prevention of Infections and Hospital Readmissions among Nursing Home Residents

Background

Nursing home (NH) residents are at high infection and hospital readmission risk. Colonization with multidrug-resistant organisms (MDROs) is common. In ICU and post-hospital discharge settings, decolonization has reduced infection rates. However, the effectiveness of this strategy in NHs is unclear.

Methods

We performed a cluster randomized trial of 1:1 universal decolonization (decol) vs standard of care bathing (control) in 28 California NHs. After an 18 month baseline evaluation of hospitalization rates due to infection and MDRO prevalence, NHs were randomized to decol or control. Decol consisted of 1) chlorhexidine bathing; 2) nasal povidone iodine bid on admission x 5d and then M-F biweekly x 18 mo. Primary outcome was the probability that a transfer to a hospital was due to infection. Secondary outcome was the probability that a NH discharge was to a hospital.

Results

Four of 28 NHs dropped from the trial (3 decol, 1 control). Mean facility baseline of hospital transfers due to infection was 58% and 57% in the control and decol groups. In the intervention period, proportions were 57% and 48% in the control and decol groups. When accounting for clustering within NHs, hospital transfers due to infection had an OR of 0.91 (95% CI: 0.82-1.02) in the control group and an OR of 0.73 (95% CI: 0.56-0.95) in the decol group when comparing intervention to baseline period. For the primary outcome, decol had a 18% greater impact v. control (P=0.005, Fig. A). Baseline proportion of NH discharges due to hospitalization was 37% and 39% in the control and decol groups. In the intervention period, proportions were 36% and 33%. When accounting for clustering within NHs, the proportion of discharges due to hospitalization had an OR of 1.14 (95% CI: 1.06-1.22) in the control group and 0.91 (CI: 0.77-1.07) in the decol group when comparing the intervention period to the baseline period. For the secondary outcome, decol had a 23% greater impact v. control (P&lt; 0.0001, Fig. B).

Conclusion

Universal NH decolonization with chlorhexidine and nasal iodophor significantly reduced the proportion of transfers to hospitals due to infection and discharges due to hospitalization. Our findings suggest that NH decolonization reduces serious infections and can decrease morbidity in this vulnerable population.

Disclosures

Loren G. Miller, MD, MPH, Medline (Grant/Research Support, Other Financial or Material Support, Contributed product) Stryker (Other Financial or Material Support, Contributed product) Xttrium (Other Financial or Material Support, Contributed product) James A. McKinnell, MD, Medline (Grant/Research Support) Raveena Singh, MA, Medline (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Stryker (Sage) (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Xttrium (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Gabrielle Gussin, MS, Medline (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Stryker (Sage) (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Xttrium (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Ken Kleinman, PhD, Medline (Other Financial or Material Support, Conducted studies in which participating hospitals received contributed antiseptic products) Molnlycke (Other Financial or Material Support, Conducted studies in which participating hospitals received contributed antiseptic products) Raheeb Saavedra, AS, Medline (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Stryker (Sage) (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Xttrium (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic products) Lauren Heim, MPH, Medline (Other Financial or Material Support, Conducted clinical trials and studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Molnlycke (Other Financial or Material Support, Conducted studies in which participating hospitals received contributed antiseptic product) Stryker (Sage) (Other Financial or Material Support, Conducted clinical trials and studies in which participating hospitals and nursing homes received contributed antiseptic product) Xttrium (Other Financial or Material Support, Conducted clinical trials and studies in which participating hospitals and nursing homes received contributed antiseptic product) Shruti K. Gohil, MD, MPH, Medline (Other Financial or Material Support, Co-Investigator in studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Molnycke (Other Financial or Material Support, Co-Investigator in studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Stryker (Sage) (Other Financial or Material Support, Co-Investigator in studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Susan S. Huang, MD, MPH, Medline (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Molnlycke (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products) Stryker (Sage) (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products)Xttrium (Other Financial or Material Support, Conducted studies in which participating hospitals and nursing homes received contributed antiseptic and cleaning products)

Treatment barriers in PANS/PANDAS: Observations from eleven health care provider families

INTRODUCTION

Pediatric acute-onset neuropsychiatric syndrome (PANS) and pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS) are severe but highly treatable postinfectious inflammatory brain conditions. Despite published diagnostic and treatment guidelines for this condition, there are long delays in obtaining appropriate care. The reasons for these delays are poorly understood. We sought to identify health care system barriers to timely treatment by examining cases of PANDAS/PANS occurring in children of health care professionals.

METHOD

We recruited families via e-mail request through the PANDAS Physicians Network. Participating parents completed a structured questionnaire and provided a written case description.

RESULTS

Eleven families completed data collection, representing a broad spectrum of disease (child disease onset age 4-15, 7 males/4 females, mild to severe). Parents included 11 physicians, 2 mental health professionals, 2 nurses, and a PharmD. Nine cases (82%) had "very delayed" diagnosis and treatment (>4 weeks after onset). The most commonly encountered causes for treatment delay were clinician lack of awareness (82%), clinician skepticism (82%), overdependence on diagnostic testing (91%), and out-of-pocket expenses >$100 US (82%). Other common challenges included difficulties finding a provider to spearhead care (64%), psychological misdiagnosis (55%), and children's suppression of behaviors during assessments (55%).

CONCLUSIONS

We found numerous barriers to treatment of PANDAS/PANS among children of health care providers. Our findings suggest that even among the medically sophisticated, PANDAS/PANS diagnosis and treatment remains challenging. Improvement in PANDAS/PANS education of clinicians who may encounter children with this disorder is 1 key step toward addressing our identified barriers. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Modeling Interventions to Reduce the Spread of Multidrug-Resistant Organisms Between Health Care Facilities in a Region

IMPORTANCE

Multidrug-resistant organisms (MDROs) can spread across health care facilities in a region. Because of limited resources, certain interventions can be implemented in only some facilities; thus, decision-makers need to evaluate which interventions may be best to implement.

OBJECTIVE

To identify a group of target facilities and assess which MDRO intervention would be best to implement in the Shared Healthcare Intervention to Eliminate Life-threatening Dissemination of MDROs in Orange County, a large regional public health collaborative in Orange County, California.

DESIGN, SETTING, AND PARTICIPANTS

An agent-based model of health care facilities was developed in 2016 to simulate the spread of methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Enterobacteriaceae (CRE) for 10 years starting in 2010 and to simulate the use of various MDRO interventions for 3 years starting in 2017. All health care facilities (23 hospitals, 5 long-term acute care hospitals, and 74 nursing homes) serving adult inpatients in Orange County, California, were included, and 42 target facilities were identified via network analyses.

EXPOSURES

Increasing contact precaution effectiveness, increasing interfacility communication about patients' MDRO status, and performing decolonization using antiseptic bathing soap and a nasal product in a specific group of target facilities.

MAIN OUTCOMES AND MEASURES

MRSA and CRE prevalence and number of new carriers (ie, transmission events).

RESULTS

Compared with continuing infection control measures used in Orange County as of 2017, increasing contact precaution effectiveness from 40% to 64% in 42 target facilities yielded relative reductions of 0.8% (range, 0.5%-1.1%) in MRSA prevalence and 2.4% (range, 0.8%-4.6%) in CRE prevalence in health care facilities countywide after 3 years, averting 761 new MRSA transmission events (95% CI, 756-765 events) and 166 new CRE transmission events (95% CI, 158-174 events). Increasing interfacility communication of patients' MDRO status to 80% in these target facilities produced no changes in the prevalence or transmission of MRDOs. Implementing decolonization procedures (clearance probability: 39% in hospitals, 27% in long-term acute care facilities, and 3% in nursing homes) yielded a relative reduction of 23.7% (range, 23.5%-23.9%) in MRSA prevalence, averting 3515 new transmission events (95% CI, 3509-3521 events). Increasing the effectiveness of antiseptic bathing soap to 48% yielded a relative reduction of 39.9% (range, 38.5%-41.5%) in CRE prevalence, averting 1435 new transmission events (95% CI, 1427-1442 events).

CONCLUSIONS AND RELEVANCE

The findings of this study highlight the ways in which modeling can inform design of regional interventions and suggested that decolonization would be the best strategy for the Shared Healthcare Intervention to Eliminate Life-threatening Dissemination of MDROs in Orange County.

Oral fosfomycin use for pyelonephritis and complicated urinary tract infections: a 1 year review of outcomes and prescribing habits in a large municipal healthcare system

BACKGROUND

The rising incidence of MDR uropathogens has driven increased use of oral fosfomycin for treatment of complicated urinary tract infections (cUTIs). However, there are limited data to support its use for cUTI, especially pyelonephritis.

METHODS

We performed a retrospective review of all oral fosfomycin prescriptions between 1 January and 31 December 2017 in the Los Angeles County Department of Health Service system, the second largest US municipal health system. We examined demographics, clinical characteristics, adverse events and 30 day treatment success for patients with cUTI. Follow-up urine cultures till 31 December 2018 were examined for emergence of fosfomycin resistance.

RESULTS

Of 154 patients prescribed fosfomycin, 99 (64%) had cUTI. Of these, 39 (39%) had lower tract, 37 (37%) pyelonephritis and 23 (23%) non-pyelonephritis upper tract cUTI. Escherichia coli ESBL producers were the predominant pathogens (73%). Of the 63 patients with 30 day follow-up, 49 (78%) had clinical success, including 16/20 (80%) treated for pyelonephritis. Treatment failure was associated with male sex (P < 0.01), urological abnormalities (P = 0.05), non-E. coli cUTI (P = 0.03) and receipt of <25% IV therapy prior to fosfomycin switch (P = 0.03). Of patients prescribed fosfomycin (n = 154), fosfomycin-resistant E. coli were found in 9/64 (14%) of the patients with follow-up urine cultures >30 days after initial treatment.

CONCLUSIONS

Despite the lack of data supporting its use, we found that most patients receiving oral fosfomycin off-label for cUTI, including pyelonephritis, had clinical success. However, emergence of subsequent resistance warrants caution. Prospective comparative studies should be done to better evaluate oral fosfomycin use for cUTI.

Antibiotic Duration, but Not Abscess Size, Impacts Clinical Cure of Limited Skin and Soft Tissue Infection After Incision and Drainage

Antibiotics are frequently prescribed following incision and drainage of cutaneous abscesses. In subgroup analyses from a recent clinical trial, we observed higher likelihood of cure with antibiotic courses beyond 5 or 7 days (up to 10). Among this cohort, for abscesses ≤5 cm, size did not modify the antibiotic effect.

Risk factors for transmission of carbapenem-resistant Enterobacterales to healthcare personnel gloves and gowns in the USA

BACKGROUND

Hospitals are sources for acquisition of carbapenem-resistant Entero-bacterales (CRE), and it is believed that the contamination of healthcare personnel (HCP) hands and clothing play a major role in patient-to-patient transmission of antibiotic-resistant bacteria.

AIM

The aim of this study was to determine which HCP types, HCP-patient interactions, and patient characteristics are associated with greater transmission of CRE to HCP gloves and gowns in the hospital.

METHODS

This was a prospective observational cohort study that enrolled patients with recent surveillance or clinical cultures positive for CRE at five hospitals in four states in the USA. HCP gloves and gown were cultured after patient care. Samples were also obtained from patients' stool, perianal area, and skin of the chest and arm to assess bacterial burden.

FINDINGS

Among 313 CRE-colonized patients and 3070 glove and gown cultures obtained after patient care, HCP gloves and gowns were found to be contaminated with CRE 7.9% and 4.3% of the time, respectively. Contamination of either gloves or gowns occurred in 10.0% of interactions. Contamination was highest (15.3%) among respiratory therapists (odds ratio: 3.79; 95% confidence interval: 1.61-8.94) and when any HCP touched the patient (1.52; 1.10-2.12). Associations were also found between CRE transmission to HCP gloves or gown and: being in the intensive care unit, having a positive clinical culture, and increasing bacterial burden on the patient.

CONCLUSION

CRE transmission to HCP gloves and gown occurred frequently. These findings may inform evidence-based policies about what situations and for which patients contact precautions are most important.

167. A Phase 1b, Randomized, Double-blind, Placebo-controlled, Multiple-ascending Dose Study to Investigate the Safety, Tolerability, and Pharmacokinetics of DSTA4637S in Patients with staphylococcus Aureus Bacteremia Receiving Standard-of-care Antibiotics

Background

New treatment approaches for complicated Staphylococcus aureus bacteremia (SAB) are needed. DSTA4637S is a THIOMAB^TM antibody-antibiotic conjugate consisting of an engineered human IgG1 monoclonal antibody that binds to wall teichoic acid at the surface of S. aureus, a protease-cleavable linker, and a novel rifamycin class antibiotic, dmDNA31. This Phase 1b study assessed the safety, tolerability, and pharmacokinetics of DSTA4637S in patients with complicated SAB.

Methods

Multicenter, double-blind, placebo controlled, multiple-ascending dose clinical trial. Patients 18–79 years old with complicated SAB requiring at least 4 weeks of IV anti-staphylococcal standard-of-care (SOC) antibiotics were randomized to receive 4–6 doses of 15, 45, and 100 mg/kg IV DSTA4637S or placebo (6 active:2 placebo) every 7 days in combination with SOC antibiotics. Patients needed ≥ 1 blood culture positive for S. aureus collected within 120 hours prior to randomization. Patients were followed for 120 days after the end of treatment.

Results

Twenty-five patients with complicated SAB (bone & joint, n=14; endocarditis, n=5; other endovascular, n=5; pneumonia, n=1) were randomized and received 1–6 doses of study drug (19 active:6 placebo). Nine patients (36%) had MRSA. Ten patients completed ≥4 doses of DSTA4637S. The most common treatment-related adverse events were infusion-related reactions (IRRs) (5/19), and abnormal serum color (5/19)/skin discoloration (3/19 (due to dmDNA31). IRRs were not dose-dependent and were reversible with supportive care. Ten of 19 patients (40%) discontinued study drug (9 DSTA4637S,1 placebo); 4/19 (21%) due to IRR. DSTA4637S recipients showed no dose-related changes in laboratory values or vital signs vs. placebo. Observed exposures (C_max and AUC) were lower in patients immediately after dosing compared to a prior study in healthy volunteers; minimal accumulation occurred. No obvious trends in exploratory bacterial and inflammatory biomarkers were observed between treatment groups.

Conclusion

DSTA4637S in patients with complicated SAB demonstrated increased IRRs and decreased exposure compared to healthy volunteers, highlighting the importance of Phase I studies of novel treatments in infected SAB patients and not simply healthy controls.

Disclosures

Jeremy Lim, PharmD, Roche (Employee, Shareholder) Nicholas Lewin-Koh, PhD, Genentech (Employee) Tom Chu, MD, PhD, Genentech (Employee) Sharon M. Rymut, PhD, Genentech (Employee, Shareholder) Aklile Berhanu, PhD, Genentech, Inc. (Employee, Equity interest (Stock/Stock Options)) Montserrat Carrasco-Triguero, PhD, Genentech (Employee) Carrie C. Rosenberger, PhD, Genentech (Employee, Shareholder) Wouter L. Hazenbos, PhD, Genentech (Employee) Loren G. Miller, MD, MPH, genentech (Grant/Research Support) Vance G. Fowler, Jr., MD, MHS, Achaogen (Consultant)Actavis (Grant/Research Support)Advanced Liquid Logics (Grant/Research Support)Affinergy (Consultant, Research Grant or Support)Affinium (Consultant)Allergan (Grant/Research Support)Ampliphi Biosciences (Consultant)Basilea (Consultant, Research Grant or Support)Bayer (Consultant)C3J (Consultant)Cerexa (Consultant, Research Grant or Support)Contrafect (Consultant, Research Grant or Support)Cubist (Grant/Research Support)Debiopharm (Consultant)Destiny (Consultant)Durata (Consultant)Forest (Grant/Research Support)Genentech (Consultant, Research Grant or Support)Integrated Biotherapeutics (Consultant)Janssen (Consultant, Research Grant or Support)Karius (Grant/Research Support)Locus (Grant/Research Support)Medical Biosurfaces (Grant/Research Support)Medicines Co. (Consultant)Medimmune (Consultant, Research Grant or Support)Merck (Consultant, Research Grant or Support)NIH (Grant/Research Support)Novadigm (Consultant)Novartis (Consultant, Research Grant or Support)Pfizer (Grant/Research Support)Regeneron (Consultant, Research Grant or Support)Tetraphase (Consultant)Theravance (Consultant, Research Grant or Support)Trius (Consultant)xBiotech (Consultant) Jose M Miro, MD PhD, GENENTECH (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member) Jessica A. Couch, PhD, Genentech (Employee, Shareholder) Melicent C. Peck, MD, PhD, Genentech (Employee)

A multifaceted intervention improves antibiotic stewardship for skin and soft tissues infections

OBJECTIVE

Assess the effectiveness of a multifaceted stewardship intervention to reduce frequency and duration of inappropriate antibiotic use for emergency department (ED) patients with skin and soft tissue infections (SSTI). We hypothesized the antibiotic stewardship program would reduce antibiotic duration and improve guideline adherence in discharged SSTI patients.

DESIGN

Nonrandomized controlled trial.

SETTING

Academic EDs (intervention site and control site).

PATIENTS OR PARTICIPANTS

Attending physicians and nurse practitioners at participating EDs.

INTERVENTION(S)

Education regarding guideline-based treatment of SSTI, tests of antimicrobial treatment of SSTI, implementation of a clinical treatment algorithm and order set in the electronic health record, and ED clinicians' audit and feedback.

RESULTS

We examined 583 SSTIs. At the intervention site, clinician adherence to guidelines improved from 41% to 51% (aOR = 2.13 [95% CI: 1.20-3.79]). At the control site, there were no changes in adherence during the "intervention" period (aOR = 1.17 [0.65-2.12]). The between-site comparison of these during vs. pre-intervention odds ratios was not different (aOR = 1.82 [0.79-4.21]). Antibiotic duration decreased by 26% at the intervention site during the intervention compared to pre-intervention (Adjusted Geometric Mean Ratio [95% CI] = 0.74 [0.66-0.84]). Adherence was inversely associated with SSTI severity (severe vs mild; adjusted OR 0.42 [0.20-0.89]) and purulence (0.32 [0.21-0.47]). Mean antibiotic prescription duration was 1.95 days shorter (95% CI: 1.54-2.33) in the time period following the intervention than pre-intervention period.

CONCLUSIONS

A multifaceted intervention resulted in modest improvement in adherence to guidelines compared to a control site, driven by treatment duration reductions.

Optimizing Contact Precautions to Curb the Spread of Antibiotic-resistant Bacteria in Hospitals: A Multicenter Cohort Study to Identify Patient Characteristics and Healthcare Personnel Interactions Associated With Transmission of Methicillin-resistant Staphylococcus aureus

Background

Healthcare personnel (HCP) acquire antibiotic-resistant bacteria on their gloves and gowns when caring for intensive care unit (ICU) patients. Yet, contact precautions for patients with methicillin-resistant Staphylococcus aureus (MRSA) remains controversial despite existing guidelines. We sought to understand which patients are more likely to transfer MRSA to HCP and to identify which HCP interactions are more likely to lead to glove or gown contamination.

Methods

This was a prospective, multicenter cohort study of cultured HCP gloves and gowns for MRSA. Samples were obtained from patients’ anterior nares, perianal area, and skin of the chest and arm to assess bacterial burden.

Results

Among 402 MRSA-colonized patients with 3982 interactions, we found that HCP gloves and gowns were contaminated with MRSA 14.3% and 5.9% of the time, respectively. Contamination of either gloves or gowns occurred in 16.2% of interactions. Contamination was highest among occupational/physical therapists (odds ratio [OR], 6.96; 95% confidence interval [CI], 3.51, 13.79), respiratory therapists (OR, 5.34; 95% CI, 3.04, 9.39), and when any HCP touched the patient (OR, 2.59; 95% CI, 1.04, 6.51). Touching the endotracheal tube (OR, 1.75; 95% CI, 1.38, 2.19), bedding (OR, 1.43; 95% CI, 1.20, 1.70), and bathing (OR, 1.32; 95% CI, 1.01, 1.75) increased the odds of contamination. We found an association between increasing bacterial burden on the patient and HCP glove or gown contamination.

Conclusions

Gloves and gowns are frequently contaminated with MRSA in the ICU. Hospitals may consider using fewer precautions for low-risk interactions and more for high-risk interactions and personnel.

The SHIELD Orange County Project: Multidrug-resistant Organism Prevalence in 21 Nursing Homes and Long-term Acute Care Facilities in Southern California

BACKGROUND

Multidrug-resistant organisms (MDROs) spread between hospitals, nursing homes (NHs), and long-term acute care facilities (LTACs) via patient transfers. The Shared Healthcare Intervention to Eliminate Life-threatening Dissemination of MDROs in Orange County is a regional public health collaborative involving decolonization at 38 healthcare facilities selected based on their high degree of patient sharing. We report baseline MDRO prevalence in 21 NHs/LTACs.

METHODS

A random sample of 50 adults for 21 NHs/LTACs (18 NHs, 3 LTACs) were screened for methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum β-lactamase-producing organisms (ESBL), and carbapenem-resistant Enterobacteriaceae (CRE) using nares, skin (axilla/groin), and peri-rectal swabs. Facility and resident characteristics associated with MDRO carriage were assessed using multivariable models clustering by person and facility.

RESULTS

Prevalence of MDROs was 65% in NHs and 80% in LTACs. The most common MDROs in NHs were MRSA (42%) and ESBL (34%); in LTACs they were VRE (55%) and ESBL (38%). CRE prevalence was higher in facilities that manage ventilated LTAC patients and NH residents (8% vs <1%, P < .001). MDRO status was known for 18% of NH residents and 49% of LTAC patients. MDRO-colonized adults commonly harbored additional MDROs (54% MDRO+ NH residents and 62% MDRO+ LTACs patients). History of MRSA (odds ratio [OR] = 1.7; confidence interval [CI]: 1.2, 2.4; P = .004), VRE (OR = 2.1; CI: 1.2, 3.8; P = .01), ESBL (OR = 1.6; CI: 1.1, 2.3; P = .03), and diabetes (OR = 1.3; CI: 1.0, 1.7; P = .03) were associated with any MDRO carriage.

CONCLUSIONS

The majority of NH residents and LTAC patients harbor MDROs. MDRO status is frequently unknown to the facility. The high MDRO prevalence highlights the need for prevention efforts in NHs/LTACs as part of regional efforts to control MDRO spread.

Epidemiologic and Microbiologic Characteristics of Hospitalized Patients Co-colonized With Multiple Species of Carbapenem-Resistant Enterobacteriaceae in the United States

We describe the epidemiologic and microbiologic characteristics of patients co-colonized with different species of carbapenem-resistant Enterobacteriaceae (CRE) from 5 hospitals in 4 states. Twenty-eight of 313 patients (8.9%) were co-colonized with at least 2 different CRE species. Different species within the same patient showed identical mechanism resistance in 18/28 (64%) cases.

High Prevalence of Multidrug-Resistant Organism Colonization in 28 Nursing Homes: An "Iceberg Effect"

OBJECTIVE

Determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), extended-spectrum beta-lactamase producing organisms (ESBLs), and carbapenem-resistant Enterobacteriaceae (CRE) among residents and in the environment of nursing homes (NHs).

DESIGN

Point prevalence sampling of residents and environmental sampling of high-touch objects in resident rooms and common areas.

SETTING

Twenty-eight NHs in Southern California from 2016 to 2017.

PARTICIPANTS

NH participants in Project PROTECT, a cluster-randomized trial of enhanced bathing and decolonization vs routine care.

METHODS

Fifty residents were randomly sampled per NH. Twenty objects were sampled, including 5 common room objects plus 5 objects in each of 3 rooms (ambulatory, total care, and dementia care residents).

RESULTS

A total of 2797 swabs were obtained from 1400 residents in 28 NHs. Median prevalence of multidrug-resistant organism (MDRO) carriage per NH was 50% (range: 24%-70%). Median prevalence of specific MDROs were as follows: MRSA, 36% (range: 20%-54%); ESBL, 16% (range: 2%-34%); VRE, 5% (range: 0%-30%); and CRE, 0% (range: 0%-8%). A median of 45% of residents (range: 24%-67%) harbored an MDRO without a known MDRO history. Environmental MDRO contamination was found in 74% of resident rooms and 93% of common areas.

CONCLUSIONS AND IMPLICATIONS

In more than half of the NHs, more than 50% of residents were colonized with MDROs of clinical and public health significance, most commonly MRSA and ESBL. Additionally, the vast majority of resident rooms and common areas were MDRO contaminated. The unknown submerged portion of the iceberg of MDRO carriers in NHs may warrant changes to infection prevention and control practices, particularly high-fidelity adoption of universal strategies such as hand hygiene, environmental cleaning, and decolonization.

Knowing More of the Iceberg: How Detecting a Greater Proportion of Carbapenem-Resistant Enterobacteriaceae Carriers Influences Transmission

BACKGROUND

Clinical testing detects a fraction of carbapenem-resistant Enterobacteriaceae (CRE) carriers. Detecting a greater proportion could lead to increased use of infection prevention and control measures but requires resources. Therefore, it is important to understand the impact of detecting increasing proportions of CRE carriers.

METHODS

We used our Regional Healthcare Ecosystem Analyst-generated agent-based model of adult inpatient healthcare facilities in Orange County, California, to explore the impact that detecting greater proportions of carriers has on the spread of CRE.

RESULTS

Detecting and placing 1 in 9 carriers on contact precautions increased the prevalence of CRE from 0% to 8.0% countywide over 10 years. Increasing the proportion of detected carriers from 1 in 9 up to 1 in 5 yielded linear reductions in transmission; at proportions >1 in 5, reductions were greater than linear. Transmission reductions did not occur for 1, 4, or 5 years, varying by facility type. With a contact precautions effectiveness of ≤70%, the detection level yielding nonlinear reductions remained unchanged; with an effectiveness of >80%, detecting only 1 in 5 carriers garnered large reductions in the number of new CRE carriers. Trends held when CRE was already present in the region.

CONCLUSION

Although detection of all carriers provided the most benefits for preventing new CRE carriers, if this is not feasible, it may be worthwhile to aim for detecting >1 in 5 carriers.

Carbapenem-Resistant Enterobacteriaceae Detection Practices in California: What Are We Missing?

Background

The Clinical and Laboratory Standards Institute (CLSI) revised the carbapenem breakpoints for Enterobacteriaceae in 2010. The number of hospitals that adopted revised breakpoints and the clinical impact of delayed adoption has not been explored.

Methods

We performed a cross-sectional, voluntary survey of microbiology laboratories from California acute care hospitals and long-term acute care hospitals (LTAC) to determine use of revised CLSI breakpoints. Carbapenem-resistant Enterobacteriaceae (CRE) clinical isolates from a single tertiary-care hospital from 2013 to 2017 were examined. All isolates with an elevated minimum inhibitory concentration (MIC; ≥2 µg/mL) to imipenem or meropenem were tested for the presence of carbapenemase genes by polymerase chain reaction (PCR).

Results

We received responses from 128 laboratories that serve 264/393 (67%) of hospitals and LTACs. Current CLSI carbapenem breakpoints for Enterobacteriaceae were used by 92/128 (72%) laboratories. Among laboratories that used current breakpoints, time to implementation varied from 0 to 68 months (mean, 41 months; median, 55 months). Application of historical breakpoints to isolates with a carbapenemase gene detected by PCR resulted in susceptibility rates of 8.9%, 18.6%, and 18.6% to ertapenem, imipenem, and meropenem, respectively. By current breakpoints, <1% of these isolates were susceptible to ertapenem or imipenem and 2.6% to meropenem.

Conclusion

Clinicians and epidemiologists should be aware that use of outdated MIC breakpoints for Enterobacteriaceae remains common and can result in reports of false susceptibility to carbapenems and missed identification of carbapenemase producers. This misclassification could have consequences for patient care and infection control efforts to address carbapenemase-producing Enterobacteriaceae.

2263. Fosfomycin Trometerol Use for Complicated UTIs Including Pyelonephritis, a 1-year Review of Outcomes and Prescribing Habits

Background

Methods

Results

Conclusion

Disclosures

894. Universal Decolonization in Nursing Homes: Effect of Chlorhexidine and Nasal Povidone–Iodine on Prevalence of Multi-Drug-Resistant Organisms (MDROs) in the PROTECT Trial

Background

The prevalence of MDROs in nursing homes (NH) is much higher than that of hospitals. Decolonization to reduce the reservoir of MDRO carriage in NH residents may be a strategy to address MDRO spread within and among healthcare facilities.

Methods

PROTECT is an 18-month cluster randomized trial of 1:1 universal decolonization vs. routine care in 28 NHs in California. Decolonization consists of chlorhexidine (CHG) bathing plus twice daily nasal iodophor on admission and Monday–Friday biweekly. We assessed pre- vs. post-intervention MDRO prevalence by sampling 50 randomly selected residents at each NH as an outcome unrelated to the trial’s primary intent (infection, hospitalization reduction). NH residents had nasal swabs cultured for methicillin-resistant S. aureus (MRSA), and skin (axilla/groin) swabs taken for MRSA, vancomycin-resistant Enterococcus (VRE), extended-spectrum β-lactamase producers (ESBL), and carbapenem-resistant Enterobacteriaceae (CRE). Generalized linear mixed models (GLM) assessed the difference in differences of MDRO prevalence using an arm by period interaction term, clustering by NH.

Results

Four NHs dropped from the trial. Among the 24 NHs that remained, MDRO colonization at baseline was 49.4% and 47.5% of residents in control (N = 650) vs. decolonization (N = 550) NHs, with no difference in MRSA, VRE, ESBL, and CRE (Table 1). Among remaining NHs, decolonization was associated with 28.8% raw decrease in MDRO prevalence in decolonization sites (GLM OR = 0.51, P < 0.001), 24.3% raw decrease in MRSA (OR = 0.66, P = 0.03), 61.0% raw decrease in VRE (OR = 0.17, P < 0.001), and 51.9% raw decrease in ESBL (OR = 0.40, P < 0.001). CRE increased, but numbers were small (Control arm: 10 in baseline, 4 in intervention; intervention arm: 1 in baseline, 2 in intervention, P = NS).

Conclusion

Universal NH decolonization with CHG bathing and nasal iodophor resulted in a marked decrease in Gram-positive and Gram-negative MDRO prevalence. This decrease may lower MDRO acquisition, infection, and antibiotic use within NHs, as well as regional MDRO spread to other healthcare facilities.

Disclosures

All Authors: No reported Disclosures.

893. The SHIELD Orange County Project: A Decolonization Strategy in 35 Hospitals and Nursing Homes Reduces Multi-Drug-Resistant Organism (MDRO) Prevalence in a Southern California Region

Background

Patient movement between hospitals, nursing homes (NH), and long-term acute care facilities (LTACs) contributes to MDRO spread. SHIELD OC is a regional decolonization collaborative among adult facilities with high patient sharing designed to reduce countywide MDRO prevalence. We report pre- and post-intervention MDRO colonization prevalence.

Methods

Decolonization included chlorhexidine bath (CHG) (4% liquid or 2% cloth) and twice-daily nasal swab 10% povidone–iodine (PI). LTAC and NH used CHG for all baths and PI 5 days on admission and Monday–Friday every other week. Patients in contact precautions (CP) at hospitals had daily CHG and 5-days PI on admission. Point-prevalence screening for MRSA, VRE, ESBL, and CRE using nares, axilla/groin, and peri-rectal swabs was conducted pre-intervention (September 2016–March 2017) and post-intervention (August 2018–April 2019); 50 random LTAC and 50 CP hospitalized patients were sampled; for NH up to 50 were sampled at baseline and all residents post-intervention. Raw impact of the intervention was assessed by the average change in colonization prevalence, with each facility carrying equal weight. Generalized linear mixed models (GLM) stratified by facility type were used to assess the impact on MDRO colonization when clustering by facility.

Results

Across 35 facilities (16 hospitals, 16 NHs, 3 LTACs), the overall MDRO prevalence was reduced 22% in NHs (OR 0.58, P < 0.001), 34% LTACs (OR = 0.27, P < 0.001), and 11% CP patients (OR = 0.67, P < 0.001, Table 1). For MRSA, raw reductions were 31% NHs (OR = 0.58, P < 0.001), 39% LTACs (OR = 0.51, P = 0.01), and 3% CP patients (OR = 0.88, P = NS). For VRE, raw reductions were 40% NHs (OR = 0.62, P = 0.001), 55% LTACs (OR = 0.26, P < 0.001), and 15% CP patients (OR = 0.67, P = 0.004). For ESBLs, raw reductions were 24% NHs (OR = 0.65, P < 0.001), 34% LTACs (OR = 0.53, P = 0.01), and 26% CP patients (OR = 0.64, P < 0.001). For CRE, raw reductions were 24% NHs (OR = 0.70, P = NS), and 23% LTACs (OR = 0.75, P = NS). CRE increased by 26% in CP averaged across hospitals, although patient -level CRE declined 2.4% to 1.8% (OR = 0.74, P = NS).

Conclusion

MDRO carriage was common in highly inter-connected NHs, LTACs and hospitals. A regional collaborative of universal decolonization in long-term care and targeted decolonization of CP patients in hospitals led to sizeable reductions in MDRO carriage.

Disclosures

All Authors: No reported Disclosures.

1837. Considerations for a Targeted Approach to Contact Precautions for Patients with MRSA in Hospitals: A Multicenter Cohort Study to Identify High-Risk Patient Characteristics and Healthcare Personnel Interactions

Background

Healthcare personnel’s (HCP) gloves and gowns are frequently contaminated with antibiotic-resistant bacteria in the intensive care unit (ICU). Guidelines recommend contact precautions for patients with methicillin-resistant Staphylococcus aureus (MRSA); however, this approach remains controversial. This study aimed to identify which patients are more likely to transfer MRSA to HCP gloves or gowns and to identify HCP interactions more likely to lead to glove or gown contamination.

Methods

In a multicenter cohort study of MRSA colonized patients, we observed HCP–patient interactions and cultured HCP’s gloves and gowns before doffing. We also assessed the association between bacterial burden and contamination by sampling patients’ anterior nares, perianal area, chest, and arm.

Results

We enrolled 402 MRSA-colonized patients and observed 3,982 HCP interactions. MRSA contamination of HCP gloves and gown occurred in 14.3% and 5.9% of interactions, respectively. Contamination of either gloves or gown occurred in 16.2% of interactions. Occupational/physical therapists had the highest rates of contamination (OR: 6.96 [95% CI: 3.51–13.79]), followed by respiratory therapists (OR: 5.34 [95% CI: 3.04–9.39]) when compared with the “Other” category. Touching the patient was associated with higher contamination (OR: 2.59 [95% CI: 1.04–6.51]) when compared with touching nothing in the room. Touching only the environment was not associated with glove or gown contamination (OR: 1.13 [95% CI: 0.43, 3.00]) when compared with touching nothing. Touching the endotracheal tube (OR: 1.75 [95% CI: 1.38–2.19]), bedding (OR: 1.43 [95% CI: 1.20–1.70]) and bathing a patient (OR: 1.32 [95% CI: 1.01–1.75]) increased odds of contamination when compared with not having such contacts (Figures 1 and 2). We found an association between increasing bacterial burden in the patient’s nares, perianal area, and chest skin and glove or gown contamination.

Conclusion

Contamination of HCP gloves and gowns with MRSA occurs frequently when caring for ICU patients. We identified interactions that are high-risk for transmission. Hospitals may consider optimizing contact precautions by using less precautions for low-risk interactions and more precautions for high-risk interactions.

Disclosures

All Authors: No reported Disclosures.

Hospital Influenza Admissions as a Harbinger for Nursing Home Influenza Cases

OBJECTIVES

To determine temporal associations of local measures of influenza morbidity and mortality by the Centers for Disease Control and Prevention (CDC) with influenza hospitalizations in nursing home residents.

DESIGN

Retrospective, longitudinal panel study.

SETTING AND PARTICIPANTS

Long-stay nursing home residents, aged 65 years or older in 823 nursing homes from 2011 to 2015.

MEASURES

CDC-reported rates of influenza and pneumonia mortality and laboratory-confirmed influenza hospitalizations. We compared the CDC measures to nursing home resident hospitalizations due to (1) all-cause, (2) a primary diagnosis of respiratory or circulatory illness, and (3) a primary diagnosis of pneumonia or influenza based on Medicare Part A Claims data.

RESULTS

Our final sample included 273,743 unique residents in 819 nursing homes in 108 cities. National laboratory-confirmed influenza-associated hospitalizations for the group aged 65 and older occurred 0 to 1 week prior to nursing home resident influenza-related hospitalizations (Spearman ρ = 0.54). CDC-reported influenza hospitalizations occurred 3 weeks prior to CDC-reported influenza deaths (ρ = 0.59). Nursing home resident influenza hospitalizations occurred 2 weeks before local CDC-reported pneumonia and influenza deaths occurred (ρ = 0.44).

CONCLUSIONS/IMPLICATIONS

Publicly reported CDC measures correlate well with nursing home hospitalizations for pneumonia and influenza. Rates of laboratory-confirmed influenza hospitalizations (as reported by the CDC) may be a useful surrogate for nursing home influenza outbreaks but should be considered along with local indicators of disease outbreaks. Early community signals could be clinically leveraged as a trigger for increased infection control measures in nursing homes.

A Bayesian model of acquisition and clearance of bacterial colonization incorporating within-host variation

Bacterial populations that colonize a host can play important roles in host health, including serving as a reservoir that transmits to other hosts and from which invasive strains emerge, thus emphasizing the importance of understanding rates of acquisition and clearance of colonizing populations. Studies of colonization dynamics have been based on assessment of whether serial samples represent a single population or distinct colonization events. With the use of whole genome sequencing to determine genetic distance between isolates, a common solution to estimate acquisition and clearance rates has been to assume a fixed genetic distance threshold below which isolates are considered to represent the same strain. However, this approach is often inadequate to account for the diversity of the underlying within-host evolving population, the time intervals between consecutive measurements, and the uncertainty in the estimated acquisition and clearance rates. Here, we present a fully Bayesian model that provides probabilities of whether two strains should be considered the same, allowing us to determine bacterial clearance and acquisition from genomes sampled over time. Our method explicitly models the within-host variation using population genetic simulation, and the inference is done using a combination of Approximate Bayesian Computation (ABC) and Markov Chain Monte Carlo (MCMC). We validate the method with multiple carefully conducted simulations and demonstrate its use in practice by analyzing a collection of methicillin resistant Staphylococcus aureus (MRSA) isolates from a large recently completed longitudinal clinical study. An R-code implementation of the method is freely available at: https://github.com/mjarvenpaa/bacterial-colonization-model.

Once-Daily Plazomicin for Complicated Urinary Tract Infections

BACKGROUND

The increasing multidrug resistance among gram-negative uropathogens necessitates new treatments for serious infections. Plazomicin is an aminoglycoside with bactericidal activity against multidrug-resistant (including carbapenem-resistant) Enterobacteriaceae.

METHODS

We randomly assigned 609 patients with complicated urinary tract infections (UTIs), including acute pyelonephritis, in a 1:1 ratio to receive intravenous plazomicin (15 mg per kilogram of body weight once daily) or meropenem (1 g every 8 hours), with optional oral step-down therapy after at least 4 days of intravenous therapy, for a total of 7 to 10 days of therapy. The primary objective was to show the noninferiority of plazomicin to meropenem in the treatment of complicated UTIs, including acute pyelonephritis, with a noninferiority margin of 15 percentage points. The primary end points were composite cure (clinical cure and microbiologic eradication) at day 5 and at the test-of-cure visit (15 to 19 days after initiation of therapy) in the microbiologic modified intention-to-treat population.

RESULTS

Plazomicin was noninferior to meropenem with respect to the primary efficacy end points. At day 5, composite cure was observed in 88.0% of the patients (168 of 191 patients) in the plazomicin group and in 91.4% (180 of 197 patients) in the meropenem group (difference, -3.4 percentage points; 95% confidence interval [CI], -10.0 to 3.1). At the test-of-cure visit, composite cure was observed in 81.7% (156 of 191 patients) and 70.1% (138 of 197 patients), respectively (difference, 11.6 percentage points; 95% CI, 2.7 to 20.3). At the test-of-cure visit, a higher percentage of patients in the plazomicin group than in the meropenem group were found to have microbiologic eradication, including eradication of Enterobacteriaceae that were not susceptible to aminoglycosides (78.8% vs. 68.6%) and Enterobacteriaceae that produce extended-spectrum β-lactamases (82.4% vs. 75.0%). At late follow-up (24 to 32 days after initiation of therapy), fewer patients in the plazomicin group than in the meropenem group had microbiologic recurrence (3.7% vs. 8.1%) or clinical relapse (1.6% vs. 7.1%). Increases in serum creatinine levels of 0.5 mg or more per deciliter (≥40 μmol per liter) above baseline occurred in 7.0% of patients in the plazomicin group and in 4.0% in the meropenem group.

CONCLUSIONS

Once-daily plazomicin was noninferior to meropenem for the treatment of complicated UTIs and acute pyelonephritis caused by Enterobacteriaceae, including multidrug-resistant strains. (Funded by Achaogen and the Biomedical Advanced Research and Development Authority; EPIC ClinicalTrials.gov number, NCT02486627.).

Decolonization to Reduce Postdischarge Infection Risk among MRSA Carriers

BACKGROUND

Hospitalized patients who are colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at high risk for infection after discharge.

METHODS

We conducted a multicenter, randomized, controlled trial of postdischarge hygiene education, as compared with education plus decolonization, in patients colonized with MRSA (carriers). Decolonization involved chlorhexidine mouthwash, baths or showers with chlorhexidine, and nasal mupirocin for 5 days twice per month for 6 months. Participants were followed for 1 year. The primary outcome was MRSA infection as defined according to Centers for Disease Control and Prevention (CDC) criteria. Secondary outcomes included MRSA infection determined on the basis of clinical judgment, infection from any cause, and infection-related hospitalization. All analyses were performed with the use of proportional-hazards models in the per-protocol population (all participants who underwent randomization, met the inclusion criteria, and survived beyond the recruitment hospitalization) and as-treated population (participants stratified according to adherence).

RESULTS

In the per-protocol population, MRSA infection occurred in 98 of 1063 participants (9.2%) in the education group and in 67 of 1058 (6.3%) in the decolonization group; 84.8% of the MRSA infections led to hospitalization. Infection from any cause occurred in 23.7% of the participants in the education group and 19.6% of those in the decolonization group; 85.8% of the infections led to hospitalization. The hazard of MRSA infection was significantly lower in the decolonization group than in the education group (hazard ratio, 0.70; 95% confidence interval [CI], 0.52 to 0.96; P=0.03; number needed to treat to prevent one infection, 30; 95% CI, 18 to 230); this lower hazard led to a lower risk of hospitalization due to MRSA infection (hazard ratio, 0.71; 95% CI, 0.51 to 0.99). The decolonization group had lower likelihoods of clinically judged infection from any cause (hazard ratio, 0.83; 95% CI, 0.70 to 0.99) and infection-related hospitalization (hazard ratio, 0.76; 95% CI, 0.62 to 0.93); treatment effects for secondary outcomes should be interpreted with caution owing to a lack of prespecified adjustment for multiple comparisons. In as-treated analyses, participants in the decolonization group who adhered fully to the regimen had 44% fewer MRSA infections than the education group (hazard ratio, 0.56; 95% CI, 0.36 to 0.86) and had 40% fewer infections from any cause (hazard ratio, 0.60; 95% CI, 0.46 to 0.78). Side effects (all mild) occurred in 4.2% of the participants.

CONCLUSIONS

Postdischarge MRSA decolonization with chlorhexidine and mupirocin led to a 30% lower risk of MRSA infection than education alone. (Funded by the AHRQ Healthcare-Associated Infections Program and others; ClinicalTrials.gov number, NCT01209234 .).

Bacterial burden is associated with increased transmission to health care workers from patients colonized with vancomycin-resistant Enterococcus

BACKGROUND

Health care workers (HCWs) are significant vectors for transmission of multidrug-resistant organisms among patients in intensive care units (ICUs). We studied ICU patients on contact precautions, colonized with vancomycin-resistant Enterococcus (VRE), to assess whether bacterial burden is associated with transmission to HCWs' gloves or gowns, a surrogate outcome for transmission to subsequent patients.

METHODS

From this prospective cohort study, we analyzed 96 VRE-colonized ICU patients and 5 HCWs per patient. We obtained samples from patients' perianal area, skin, and stool to assess bacterial burden and cultured HCWs' gloves and gowns for VRE after patient care.

RESULTS

Seventy-one of 479 (15%) HCW-patient interactions led to contamination of HCWs' gloves or gowns with VRE. HCW contamination was associated with VRE burden on the perianal swab (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.19, 1.57), skin swabs (OR, 2.14; 95% CI, 1.51, 3.02), and in stool (OR, 1.95; 95% CI, 1.39, 2.72). Compared with colonization with Enterococcus faecalis, colonization with Enterococcus faecium was associated with higher bacterial burden and higher odds of transmission to HCWs.

CONCLUSIONS

We show that ICU patients with higher bacterial burden are more likely to transmit VRE to HCWs. These findings have implications for VRE decolonization and other infection control interventions.

2320. Decolonization of the Oropharynx, an Important and Neglected Reservoir of Staphylococcus aureus Colonization

Background

Community-associated S. aureus skin and soft-tissue infections are common and recur in 20 to >50% of cases. Decolonization trials have been disappointing for unclear reasons, but may be related to untreated reservoirs. Given recent data that oropharyngeal (OP) S. aureus colonization is common with a prevalence comparable to nasal colonization, we performed a double-blind, placebo controlled trial of the efficacy of oral chlorhexidine gluconate (CHG) for OP S. aureus colonization.

Methods

We enrolled healthy outpatient children from ages 5 to 17 who were tested for OP S. aureus colonization. Colonized subjects were randomized to 0.12% CHG or placebo gargle twice daily × 7 days. Primary endpoint was OP colonization at the End of Therapy (EOT) visit using an intention to treat (ITT) model. We also measured OP colonization at 28 days and nasal S. aureus colonization at all study visits.

Results

Among 189 consented subjects, 120 (63%) had OP colonization; 81/120 (66%) were randomized and 67 were analyzable (CHG: N = 33; Placebo: N = 34). Fourteen subjects were not analyzable due to product error or loss to follow-up prior to study drug receipt (figure). In the ITT analysis, EOT OP S. aureus colonization was 45% (15/33) in the CHG group and 79% (27/34) in the placebo group (P = 0.004). In the as treated analysis, OP colonization was 40% (11/29) and 77% (23/30) in the CHG group and placebo groups (P = 0.003). At Day 28 in the ITT model, OP colonization was 61% (20/33) vs. 85% (29/34) in the CHG and placebo groups (P = 0.03). At EOT nasal colonization in those without OP colonization was 11/25 (44%) vs. 15/34 (44%) in those still OP colonized. At Day 28, nasal colonization was 0/18 (0%) in those without OP colonization vs. 19/38 (50%) in those with OP colonization.

Conclusion

One week of 0.12% oral CHG gargle was more effective than the placebo at eradicating S. aureus OP colonization in S. aureus colonized children. Significant differences persisted at Day 28. Persistent OP colonization at Day 28 was associated with nasal S. aureus colonization, suggesting that nasal colonization may contribute to persistence and relapse of OP S. aureus colonization. Our findings support decolonization trials that include OP S. aureus decolonization as part of a more aggressive S. aureus decolonization strategy.

Disclosures

All authors: No reported disclosures.

306. Safety and Tolerability of Tedizolid as Oral Treatment for Bone and Joint Infections

Background

Bone and joint infections (BJIs) are common infections managed by infectious diseases specialists. There are increasing data that oral therapy is equivalent to intravenous therapy and is typically preferred by patients. However, there are limited safe oral options to treat some causative pathogens. Tedizolid is an oxazolidinone with broad Gram-positive coverage that in animal studies lacks the hematologic and neurologic toxicity of linezolid.

Methods

We are conducting an open-label single-center trial of oral tedizolid for the treatment of BJIs. The primary outcome of this study is patient safety. Patients are eligible if they have a BJI caused by documented or suspected Gram-positive pathogen and require at least 4 weeks of therapy (up to 12 weeks). Enrolled patients undergo weekly monitoring for neurologic and visual, side effects and weekly hematologic and comprehensive chemistry panel lab monitoring. Patients with peripheral neuropathy and cytopenias are excluded from participation.

Results

To date, we have enrolled 19 subjects (17 (89%) male) with BJIs (11 (58%) hardware associated infection, 5 (26%) osteomyelitis without prosthesis, 3 (16%) prosthetic joint infection). Significant comorbidities include six (32%) with diabetes and one (5%) with systemic lupus. Fourteen (74%) patients have completed therapy, two (11%) remain on therapy, one (5%) withdrew from the study, and two (11%) were lost to follow-up. Mean (median) duration of treatment has been 9.7 (11) weeks with a range of 4–12 weeks. Significant drug-related adverse events occurred in two patients (11%), both with non-life-threatening maculopapular rashes, one of whom required treatment discontinuation. To date, there have been 10/14 (71%) treatment successes. Failures have been associated with previously undetected retained hardware (n = 1), sequestrum requiring surgery (n = 1), and failure to achieve cure after the designated treatment course (n = 2). There have been no cases of cytopenias, peripheral or optic neuropathy.

Conclusion

Tedizolid appears to be a well-tolerated oral antibiotic for the treatment of bone and joint infections for 4 weeks or greater. Clinical failure rates appear roughly similar to that of other oral options. Further study of tedizolid for BJIs is warranted.

Disclosures

L. G. Miller, Merck: Grant Investigator, Research grant.

226. An Emergency Department Antimicrobial Stewardship Intervention to Improve Antibiotic Selection and Duration for Skin and Soft-tissue infections in Adult and Pediatric Outpatients

Background

Methods

Results

Conclusion

Disclosures

Clonally expanded γδ T cells protect against Staphylococcus aureus skin reinfection

The mechanisms that mediate durable protection against Staphylococcus aureus skin reinfections are unclear, as recurrences are common despite high antibody titers and memory T cells. Here, we developed a mouse model of S. aureus skin reinfection to investigate protective memory responses. In contrast with WT mice, IL-1β-deficient mice exhibited poor neutrophil recruitment and bacterial clearance during primary infection that was rescued during secondary S. aureus challenge. The γδ T cells from skin-draining LNs utilized compensatory T cell-intrinsic TLR2/MyD88 signaling to mediate rescue by trafficking and producing TNF and IFN-γ, which restored neutrophil recruitment and promoted bacterial clearance. RNA-sequencing (RNA-seq) of the LNs revealed a clonotypic S. aureus-induced γδ T cell expansion with a complementarity-determining region 3 (CDR3) aa sequence identical to that of invariant Vγ5+ dendritic epidermal T cells. However, this T cell receptor γ (TRG) aa sequence of the dominant CDR3 sequence was generated from multiple gene rearrangements of TRGV5 and TRGV6, indicating clonotypic expansion. TNF- and IFN-γ-producing γδ T cells were also expanded in peripheral blood of IRAK4-deficient humans no longer predisposed to S. aureus skin infections. Thus, clonally expanded γδ T cells represent a mechanism for long-lasting immunity against recurrent S. aureus skin infections.