Assessing Clinician Utilization of Next-Generation Antibiotics Against Resistant Gram-Negative Infections in U.S. Hospitals : A Retrospective Cohort Study

BACKGROUND

The U.S. antibiotic market failure has threatened future innovation and supply. Understanding when and why clinicians underutilize recently approved gram-negative antibiotics might help prioritize the patient in future antibiotic development and potential market entry rewards.

OBJECTIVE

To determine use patterns of recently U.S. Food and Drug Administration (FDA)-approved gram-negative antibiotics (ceftazidime-avibactam, ceftolozane-tazobactam, meropenem-vaborbactam, plazomicin, eravacycline, imipenem-relebactam-cilastatin, and cefiderocol) and identify factors associated with their preferential use (over traditional generic agents) in patients with gram-negative infections due to pathogens displaying difficult-to-treat resistance (DTR; that is, resistance to all first-line antibiotics).

DESIGN

Retrospective cohort.

SETTING

619 U.S. hospitals.

PARTICIPANTS

Adult inpatients.

MEASUREMENTS

Quarterly percentage change in antibiotic use was calculated using weighted linear regression. Machine learning selected candidate variables, and mixed models identified factors associated with new (vs. traditional) antibiotic use in DTR infections.

RESULTS

Between quarter 1 of 2016 and quarter 2 of 2021, ceftolozane-tazobactam (approved 2014) and ceftazidime-avibactam (2015) predominated new antibiotic usage whereas subsequently approved gram-negative antibiotics saw relatively sluggish uptake. Among gram-negative infection hospitalizations, 0.7% (2551 [2631 episodes] of 362 142) displayed DTR pathogens. Patients were treated exclusively using traditional agents in 1091 of 2631 DTR episodes (41.5%), including "reserve" antibiotics such as polymyxins, aminoglycosides, and tigecycline in 865 of 1091 episodes (79.3%). Patients with bacteremia and chronic diseases had greater adjusted probabilities and those with do-not-resuscitate status, acute liver failure, and Acinetobacter baumannii complex and other nonpseudomonal nonfermenter pathogens had lower adjusted probabilities of receiving newer (vs. traditional) antibiotics for DTR infections, respectively. Availability of susceptibility testing for new antibiotics increased probability of usage.

LIMITATION

Residual confounding.

CONCLUSION

Despite FDA approval of 7 next-generation gram-negative antibiotics between 2014 and 2019, clinicians still frequently treat resistant gram-negative infections with older, generic antibiotics with suboptimal safety-efficacy profiles. Future antibiotics with innovative mechanisms targeting untapped pathogen niches, widely available susceptibility testing, and evidence demonstrating improved outcomes in resistant infections might enhance utilization.

PRIMARY FUNDING SOURCE

U.S. Food and Drug Administration; NIH Intramural Research Program.

Improving Sepsis Outcomes in the Era of Pay-for-Performance and Electronic Quality Measures: A Joint IDSA/ACEP/PIDS/SHEA/SHM/SIDP Position Paper

The Centers for Medicare & Medicaid Services (CMS) introduced the Severe Sepsis/Septic Shock Management Bundle (SEP-1) as a pay-for-reporting measure in 2015 and is now planning to make it a pay-for-performance measure by incorporating it into the Hospital Value-Based Purchasing Program. This joint IDSA/ACEP/PIDS/SHEA/SHM/SIPD position paper highlights concerns with this change. Multiple studies indicate that SEP-1 implementation was associated with increased broad-spectrum antibiotic use, lactate measurements, and aggressive fluid resuscitation for patients with suspected sepsis but not with decreased mortality rates. Increased focus on SEP-1 risks further diverting attention and resources from more effective measures and comprehensive sepsis care. We recommend retiring SEP-1 rather than using it in a payment model and shifting instead to new sepsis metrics that focus on patient outcomes. CMS is developing a community-onset sepsis 30-day mortality electronic clinical quality measure (eCQM) that is an important step in this direction. The eCQM preliminarily identifies sepsis using systemic inflammatory response syndrome (SIRS) criteria, antibiotic administrations or diagnosis codes for infection or sepsis, and clinical indicators of acute organ dysfunction. We support the eCQM but recommend removing SIRS criteria and diagnosis codes to streamline implementation, decrease variability between hospitals, maintain vigilance for patients with sepsis but without SIRS, and avoid promoting antibiotic use in uninfected patients with SIRS. We further advocate for CMS to harmonize the eCQM with the Centers for Disease Control and Prevention's (CDC) Adult Sepsis Event surveillance metric to promote unity in federal measures, decrease reporting burden for hospitals, and facilitate shared prevention initiatives. These steps will result in a more robust measure that will encourage hospitals to pay more attention to the full breadth of sepsis care, stimulate new innovations in diagnosis and treatment, and ultimately bring us closer to our shared goal of improving outcomes for patients.

Clinical and Immunologic Correlates of Vasodilatory Shock Among Ebola Virus-Infected Nonhuman Primates in a Critical Care Model

BACKGROUND

Existing models of Ebola virus infection have not fully characterized the pathophysiology of shock in connection with daily virologic, clinical, and immunologic parameters. We implemented a nonhuman primate critical care model to investigate these associations.

METHODS

Two rhesus macaques received a target dose of 1000 plaque-forming units of Ebola virus intramuscularly with supportive care initiated on day 3. High-dimensional spectral cytometry was used to phenotype neutrophils and peripheral blood mononuclear cells daily.

RESULTS

We observed progressive vasodilatory shock with preserved cardiac function following viremia onset on day 5. Multiorgan dysfunction began on day 6 coincident with the nadir of circulating neutrophils. Consumptive coagulopathy and anemia occurred on days 7 to 8 along with irreversible shock, followed by death. The monocyte repertoire began shifting on day 4 with a decline in classical and expansion of double-negative monocytes. A selective loss of CXCR3-positive B and T cells, expansion of naive B cells, and activation of natural killer cells followed viremia onset.

CONCLUSIONS

Our model allows for high-fidelity characterization of the pathophysiology of acute Ebola virus infection with host innate and adaptive immune responses, which may advance host-targeted therapy design and evaluation for use after the onset of multiorgan failure.

Reliability of Admission Procalcitonin Testing for Capturing Bacteremia Across the Sepsis Spectrum: Real-World Utilization and Performance Characteristics, 65 U.S. Hospitals, 2008-2017

OBJECTIVES

Serum procalcitonin is often ordered at admission for patients with suspected sepsis and bloodstream infections (BSIs), although its performance characteristics in this setting remain contested. This study aimed to evaluate use patterns and performance characteristics of procalcitonin-on-admission in patients with suspected BSI, with or without sepsis.

DESIGN

Retrospective cohort study.

SETTING

Cerner HealthFacts Database (2008-2017).

PATIENTS

Adult inpatients (≥ 18 yr) who had blood cultures and procalcitonin drawn within 24 hours of admission.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Testing frequency of procalcitonin was determined. Sensitivity of procalcitonin-on-admission for detecting BSI due to different pathogens was calculated. Area under the receiver operating characteristic curve (AUC) was calculated to assess discrimination by procalcitonin-on-admission for BSI in patients with and without fever/hypothermia, ICU admission and sepsis defined by Centers for Disease Control and Prevention Adult Sepsis Event criteria. AUCs were compared using Wald test and p values were adjusted for multiple comparisons. At 65 procalcitonin-reporting hospitals, 74,958 of 739,130 patients (10.1%) who had admission blood cultures also had admission procalcitonin testing. Most patients (83%) who had admission day procalcitonin testing did not have a repeat procalcitonin test. Median procalcitonin varied considerably by pathogen, BSI source, and acute illness severity. At a greater than or equal to 0.5 ng/mL cutoff, sensitivity for BSI detection was 68.2% overall, ranging between 58.0% for enterococcal BSI without sepsis and 96.4% for pneumococcal sepsis. Procalcitonin-on-admission displayed moderate discrimination at best for overall BSI (AUC, 0.73; 95% CI, 0.72-0.73) and showed no additional utility in key subgroups. Empiric antibiotic use proportions were not different between blood culture sampled patients with a positive procalcitonin (39.7%) and negative procalcitonin (38.4%) at admission.

CONCLUSIONS

At 65 study hospitals, procalcitonin-on-admission demonstrated poor sensitivity in ruling out BSI, moderate-to-poor discrimination for both bacteremic sepsis and occult BSI and did not appear to meaningfully alter empiric antibiotic usage. Diagnostic stewardship of procalcitonin-on-admission and risk assessment of admission procalcitonin-guided clinical decisions is warranted.

Association between piperacillin/tazobactam MIC and survival among hospitalized patients with Enterobacterales infections: retrospective cohort analysis of electronic health records from 161 US hospitals

Introduction

A recent randomized trial has suggested an increased risk of mortality for ceftriaxone-non-susceptible Enterobacterales infections treated with piperacillin/tazobactam compared with meropenem despite MICs within the susceptible range.

Methods

We conducted a retrospective cohort study of clinical encounters within the Cerner Health Facts database to identify all encounters between 2001 and 2017 in which Enterobacterales infections were treated empirically with piperacillin/tazobactam and for which MICs to the drug were available. Multivariate regression analysis was performed to enable partitioning of MICs into discrete strata based on statistically significant difference in mortality risk.

Results

During the study period, 10 101 inpatient encounters were identified meeting inclusion criteria. The crude in-hospital mortality for the entire cohort was 16.5%. Partitioning analysis identified a breakpoint of ≤16/4 mg/L that dichotomized encounters into lower versus higher mortality risk strata in the primary cohort of overall infections. This finding persisted in sequentially granular subsets where specific MICs ≤8/4 mg/L were reported (in lieu of ranges) as well as in the high-reliability subset with bloodstream infections. A higher clinical breakpoint of ≥128/4 mg/L dichotomized encounters with respiratory tract infection. No breakpoint was identified when restricting to encounters with urinary tract infections, ICU admits or upon restricting analysis to encounters with ceftriaxone-resistant isolates.

Conclusions

Clinical data suggest improved outcomes when piperacillin/tazobactam is prescribed for Enterobacterales infections with an MIC of ≤16/4 mg/L compared with ≥32/4 mg/L.

Association between minimum inhibitory concentration values and mortality risk in patients with Stenotrophomonas maltophilia infections: a retrospective cohort study of electronic health records from 148 US hospitals

Background

Clinical data informing antimicrobial susceptibility breakpoints for Stenotrophomonas maltophilia infections are lacking. We sought to leverage real-world data to identify MIC values within the currently defined susceptible range that could discriminate mortality risk for patients with S. maltophilia infections and guide future breakpoint revisions.

Methods

Inpatients with S. maltophilia infection who received single-agent targeted therapy with levofloxacin or trimethoprim/sulfamethoxazole were identified in the Cerner HealthFacts electronic health record database. Encounters were restricted to those with MIC values reported to be in the susceptible range for both agents. Curation for exact (non-range) MIC values yielded sequentially granular model populations. Logistic regression was used to calculate adjusted OR (aOR) of mortality or hospice discharge associated with different susceptible-range MICs, controlling for patient- and centre-related factors, and infection site, polymicrobial infection and receipt of empirical therapy.

Results

Seventy-three of 851 levofloxacin-treated patients had levofloxacin MIC of exactly 2 mg/L (current Clinical and Laboratory Standards Institute (CLSI) susceptibility breakpoint) and served as the reference category for levofloxacin breakpoint models. In breakpoint model I (n = 501), aOR of mortality associated with infection due to isolates with levofloxacin MIC of ≤1 versus 2 mg/L were similar [aOR = 1.79 (95% CI 0.88-3.62), P = 0.11]. In breakpoint model IIa (n = 358), aOR of mortality associated with MIC ≤0.5 versus 2 mg/L were also similar [aOR 0.1.36 (95% CI 0.65-2.83), P = 0.41]. However, breakpoint model IIb (n = 297) displayed higher aOR of mortality associated with an MIC of 1 versus 2 mg/L [aOR 2.36 (95% CI 1.14-4.88), P = 0.02]. Only 9/645 trimethoprim/sulfamethoxazole-treated patients had trimethoprim/sulfamethoxazole MIC of exactly 2/38 mg/L precluding informative models for this agent.

Conclusions

In this retrospective study of real-world patients with S. maltophilia infection, risk-adjusted survival data do not appear to stratify patients clinically within current susceptible-range MIC breakpoint for levofloxacin (≤2 mg/L) by mortality.

Semi-parametric modeling of SARS-CoV-2 transmission using tests, cases, deaths, and seroprevalence data

Mechanistic models fit to streaming surveillance data are critical to understanding the transmission dynamics of an outbreak as it unfolds in real-time. However, transmission model parameter estimation can be imprecise, and sometimes even impossible, because surveillance data are noisy and not informative about all aspects of the mechanistic model. To partially overcome this obstacle, Bayesian models have been proposed to integrate multiple surveillance data streams. We devised a modeling framework for integrating SARS-CoV-2 diagnostics test and mortality time series data, as well as seroprevalence data from cross-sectional studies, and tested the importance of individual data streams for both inference and forecasting. Importantly, our model for incidence data accounts for changes in the total number of tests performed. We model the transmission rate, infection-to-fatality ratio, and a parameter controlling a functional relationship between the true case incidence and the fraction of positive tests as time-varying quantities and estimate changes of these parameters nonparametrically. We compare our base model against modified versions which do not use diagnostics test counts or seroprevalence data to demonstrate the utility of including these often unused data streams. We apply our Bayesian data integration method to COVID-19 surveillance data collected in Orange County, California between March 2020 and February 2021 and find that 32-72% of the Orange County residents experienced SARS-CoV-2 infection by mid-January, 2021. Despite this high number of infections, our results suggest that the abrupt end of the winter surge in January 2021 was due to both behavioral changes and a high level of accumulated natural immunity.

Vaccination Ameliorates Cellular Inflammatory Responses in SARS-CoV-2 Breakthrough Infections

BACKGROUND

Data on cellular immune responses in persons with SARS-CoV-2 infection following vaccination are limited. The evaluation of these patients with SARS-CoV-2 breakthrough infections may provide insight into how vaccinations limit the escalation of deleterious host inflammatory responses.

METHODS

We conducted a prospective study of peripheral blood cellular immune responses to SARS-CoV-2 infection in 21 vaccinated patients, all with mild disease, and 97 unvaccinated patients stratified based on disease severity.

RESULTS

We enrolled 118 persons (50±14.5 years, 52 women) with SARS-CoV-2 infection. Compared to unvaccinated patients, vaccinated patients with breakthrough infections had a higher percentage of antigen presenting monocytes (HLA-DR+), mature monocytes (CD83+), functionally competent T cells (CD127+), and mature neutrophils (CD10+); and lower percentages of activated T cells (CD38+), activated neutrophils (CD64+) and immature B cells (CD127+CD19+). These differences widened with increased disease severity in unvaccinated patients. Longitudinal analysis showed that cellular activation decreased over time but persisted in unvaccinated patients with mild disease at 8-month follow-up.

CONCLUSIONS

Patients with SARS-CoV-2 breakthrough infections exhibit cellular immune responses that limit the progression of inflammatory responses and suggest mechanisms by which vaccination limits disease severity. These data may have implications for developing more effective vaccines and therapies.

Spleen tyrosine kinase inhibition restores myeloid homeostasis in COVID-19

Spleen tyrosine kinase (SYK) is a previously unidentified therapeutic target that inhibits neutrophil and macrophage activation in coronavirus disease 2019 (COVID-19). Fostamatinib, a SYK inhibitor, was studied in a phase 2 placebo-controlled randomized clinical trial and was associated with improvements in many secondary end points related to efficacy. Here, we used a multiomic approach to evaluate cellular and soluble immune mediator responses of patients enrolled in this trial. We demonstrated that SYK inhibition was associated with reduced neutrophil activation, increased circulation of mature neutrophils (CD10⁺CD33^-), and decreased circulation of low-density granulocytes and polymorphonuclear myeloid-derived suppressor cells (HLA-DR^-CD33⁺CD11b^-). SYK inhibition was also associated with normalization of transcriptional activity in circulating monocytes relative to healthy controls, an increase in frequency of circulating nonclassical and HLA-DR^hi classical monocyte populations, and restoration of interferon responses. Together, these data suggest that SYK inhibition may mitigate proinflammatory myeloid cellular and soluble mediator responses thought to contribute to immunopathogenesis of severe COVID-19.

1072. SARS-CoV-2 Antibody Levels Associate with Neutrophil Activation

Background

COVID-19 disease severity and outcomes have been linked to high antibody titers and a dysregulated neutrophil immune response. Here we query associations and connections between the endogenous SARS-CoV-2 antibody response and neutrophil activation in COVID-19.

Methods

Baseline serum or plasma samples from 57 patients hospitalized on oxygen with COVID-19 were used to perform; 1) quantitative measurements of SARS-CoV-2 specific antibodies using a luciferase-based immunoprecipitation system assay, 2) quantitative measurements of neutrophil specific biomarkers using Luminex technology, and 3) neutrophil extracellular traps (NETs) as measured by myeloperoxidase-DNA (MPO-DNA) complexes by ELISA. Absolute neutrophil count (ANC) and immature granulocyte count (IGC) were measured from complete blood counts (CBC). Antibody levels were compared by disease severity using Wilcoxon rank-sum test and correlations were generated between antibody levels and neutrophil activation markers using Spearman’s correlation (SC).

Results

In a cohort of hospitalized patients, severe/critical COVID-19 was associated with higher levels of nucleocapsid-IgA (p=0.011) as well as spike-IgG (p= 0.0007) compared to moderate disease, while spike-IgA and nucleocapsid-IgG showed similar associations, trending towards significance (Figure 1A). Levels of IgG-spike and IgG-nucleocapsid both had significant correlations with the ANC (SC 0.33, p = 0.029; SC 0.38 p = 0.012). All four antibody titers showed strong correlations with IGC, lactoferrin and lipocalin-2, evidence of emergency granulopoiesis. Further, S100A9, a component calprotectin correlated with spike-IgG and nucleocapsid-IgA levels (SC 0.29, p = 0.030, SC 0.29 p = 0.029). Lastly, we found circulating NETs correlated with spike IgA levels (SC 0.38 p = 0.006), and its correlations with IgG-spike and IgA-nucleocapsid additionally approached significance with NETs levels as well (Figure 1B).

Antibody Levels Correlate with Disease Severity and Neutrophil Activation Markers

Figure 1: A) Levels of anti-Spike and anti-Nucleocapsid IgA and IgG levels measured in the serum of 57 unvaccinated hospitalized COVID-19 patients. Moderate illness represents ordinal scale 5 requiring low flow oxygen, while severe/critical patients represent ordinal scale 6 and 7, requiring high flow oxygen, non-invasive or mechanical ventilation, respectively. P values are compared by a Wilcoxon ranked sum test. B) Heatmap showing Spearman correlations between levels of anti-Spike and anti-Nucleocapsid IgA and IgG and markers of neutrophil activation. P values for individual correlations are represented in parentheses. MPO (myeloperoxidase), ANC (absolute neutrophil count), S100A9 (S100 calcium binding protein A9).

Conclusion

Higher anti-spike and anti-nucleocapsid IgG and IgA levels associate with more severe COVID-19 illness. Further, endogenous SARS-CoV-2 specific antibody levels associate with markers of emergency granulopoiesis and neutrophil activation. Inhibiting antibody mediated neutrophil activation may improve outcomes in COVID-19.

Disclosures

All Authors: No reported disclosures.

1044. Identification and Characterization of an Unconventional NK Subset in COVID-19

Background

Coronavirus Disease 2019 (COVID-19) caused by the SARS-CoV-2 virus is associated with dysregulation in the innate immune response including NK cells. NK cells are integral in the innate immune response against viral infections. Canonical NK cells are classified as CD56dim CD16+ and CD56bright CD16-. An unconventional subset of CD56dim CD16- NK cells has previously been identified in COVID-19 that is not present in other viral infections. Here we characterize phenotypic changes in the NK cells of patients with severe COVID-19 as work towards determining the functional status of this unconventional subset.

Methods

Peripheral blood mononuclear cells (PBMCs) and plasma were isolated from healthy donors (n=5) and patients with severe COVID-19 on Extra Corporeal Membrane Oxygenation (ECMO) (n=15). Primary NK cells were stimulated in vitro with plasma from patients with severe COVID-19 or healthy donors. Flow cytometry was used to phenotype the NK cells. A separate cohort of PBMC samples (n=7) from patients requiring hospitalization for COVID-19 underwent Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-Seq) analysis.

Results

The CD56bright CD16- NK subset was expanded in PBMCs from patients with severe COVID-19 as compared to healthy controls. CITE-Seq demonstrated that NK cells without surface CD16 clustered separately based on transcriptional profiling and did express FCGR3A at the translational level. Stimulation with COVID-19 plasma recapitulated the loss of CD16 from primary human NK cells and led to increased activity of Caspase 3/7. Figure 1.NK cells shift from the CD56dim CD16+ subset to the CD56dim CD16-subset in patients with severe COVID-19.

a) Representative gating of NK cell subsets by Flow Cytometry in healthy and COVID-19 patient peripheral blood mononuclear cells (PBMCs). b) Percentage of total NK cells belonging to a particular cell subset compared between healthy donor samples (n=4) and COVID-19 patient samples (n=8). Data points represent an individual patient sample. Error bars represent the standard deviation of the mean. Differences between groups was analyzed using a two tailed t-test. *: p< 0.05, ns: not significant Figure 2.NK cells shift from the CD56dim CD16+ subset to the CD56dim CD16-subset after stimulation with COVID-19 plasma in vitro

a) Representative gating of NK cell subsets by Flow Cytometry analysis in healthy donor NK cells stimulated by healthy plasma and COVID-19 patient plasma. b)Relative change in percentage of total NK cells belonging to a particular cell subset compared between healthy donor plasma (n=6)and COVID-19 patient plasma (n=15) stimulation conditions. Error bars represent the standard deviation of the mean and the difference between groups was analyzed using a two-tailed T-test. **: p< 0.01, ***: p< 0.001, ns: not significant.

Conclusion

We demonstrate and characterize a nonclassical population of CD56dim CD16- NK cells that are present in patients with severe COVID-19 and replicate this phenotype in vitro. Reproduction of this in vivo phenotype in an in vitro system will allow for additional studies on the functional state of NK cell subsets in COVID-19. The presence of this NK cell population may reflect a dysregulated innate immune response and immunopathogenesis of COVID-19.

Disclosures

All Authors: No reported disclosures.

1649. Ceftolozane-Tazobactam or Ceftazidime-Avibactam Versus Best Available Therapy in the Treatment of Difficult-to-Treat Pseudomonas aeruginosa Infections: a Retrospective Comparative Effectiveness Analysis of 195 U.S. Hospitals, 2016–2020

Background

Infections due to Pseudomonas aeruginosa displaying difficult-to-treat resistance (DTR-PA) necessitate the use of sub-efficacious and/or toxic “reserve” antibiotics and are associated with considerable morbidity and mortality. Ceftazidime-avibactam (CAZ-AVY) and ceftolozane-tazobactam (CEF-TAZO) are novel ß-lactam/ß-lactamase inhibitors (BLBLI) that tend to retain in vitro activity against DTR-PA. However, little is known about their in vivo effectiveness compared to reserve agents.

Methods

Inpatients aged ≥ 18 years with ≥1 blood, urine, respiratory, or body fluid culture growing DTR-PA who received targeted therapy with either CAZ-AVY, CEF-TAZO, or Best-Available Therapy (BAT) were identified in the Premier Healthcare Database. Primary outcome was in-hospital mortality or discharge to hospice and secondary outcome was length of hospital stay (LOS) for survivors. The primary outcome was compared for CAZ-AVY vs CEF-TAZO and novel agents (CAZ-AVY or CEF-TAZO) vs BAT using overlap weighting and binomial regression with downstream adjustment controlling for patient and treatment characteristics. The secondary outcomes were compared using overlap weighting and poisson regression with downstream adjustment controlling for patient and treatment characteristics.

Results

Between 2016 and 2020, 1,552 patients with DTR-PA infections were identified at 105 hospitals, of which 202 (13.0%) were treated with CAZ-AVY, 906 (58.4%) with CEF-TAZO, and 444 (28.6%) with BAT. Patient characteristics were similar among treatment groups (Table 1, Table 2). Overall crude mortality was 15.5%. The adjusted risk of mortality was lower in patients treated with CAZ-AVI (12.5%, 95% CI 7.9–17.1) vs CEF-TAZO (18.8%, 95% CI 15.9–21.8) for a risk difference of 6.3% (95% 1.1–11.5, p = 0.02). The novel agents were not associated with a reduced mortality risk when collectively compared to BAT (risk difference -1.1%, 95% CI -5.4; 3.2%). LOS favoured novel agents and were comparable for CAZ-AVY and CEF-TAZO.

Conclusion

In this real-world observational study of patients with DTR-PA infections, the novel ß-lactam/ß-lactamase inhibitors were comparably effective against BAT, though the use of CAZ-AVY was associated with a reduced mortality compared to CEF-TAZO.

Disclosures

All Authors: No reported disclosures.

272. Do Empiric Antibiotics Improve Outcomes in Clinically Stable Patients Admitted with COVID-19 Pneumonia? Retrospective Cohort Study of 221 U.S. Hospitals, March 1st, 2020-December 31st, 2020

Background

Patients admitted with COVID19 pneumonia often receive initial empiric antibacterial therapy (IEAT) despite a known low probability of bacterial co-infection. However, evidence supporting this practice is lacking. We studied the impact of IEAT on the risk of in-hospital mortality, clinical deterioration and antibiotic-associated risks in stable inpatients with COVID-19.

Methods

Adult inpatients coded for COVID-19 pneumonia stable (no mechanical ventilation or vasopressors) on admission (+1 day) without a clear indication for antibiotics, were identified at hospitals in the Premier Healthcare Database. Patients who received IEAT, defined as the receipt of ≥ 1 antibacterial agent on admission (+1 day), were compared to a control group, using binomial regression with overlap weight matching and downstream adjustment for baseline characteristics (age, gender, race, admission month, surge index, Elixhauser score, any AOFS organ failure POA, ICU admission on day 0 to +2, receipt of remdesivir, corticosteroids, and tocilizumab). The primary outcome was in-hospital mortality or discharge to hospice; secondary outcomes included need for mechanical ventilation on day2+, and rates of non-POA-acute kidney injury (AKI).

Results

At 221 hospitals between March–December 2020, 39,517 (74%) of 53,431 stable COVID-19 admits received IEAT. Patient and encounter characteristics are shown in Table 1. The crude mortality rates were 12.2% in IEAT recipients and 10.9% in controls. In adjusted analysis of patients who survived beyond admission day, mortality was 11.57% (95% CI 11.24-11.90%) in IEAT recipients and 11.23% (95% CI 10.72-11.74) in controls, for a difference of 0.34% (95% CI -0.23-0.91%, p = 0.24). Subsequent mechanical ventilation occurred similarly between groups (5.72% vs. 5.77%, p=0.83). The adjusted rate of AKI was 2.47% (95% CI 2.31-2.64%) in IEAT recipients, and 3.04% (95% CI 2.74-3.35%) in controls, for a difference of -0.57% (95% CI -0.92-0.22%, p = 0.0014). Table 1.

652. Ceftazidime-avibactam Alone or as Combination Therapy? Multicenter Retrospective Cohort Analysis of Clinical Outcomes in Patients with Carbapenem-resistant Gram-negative Infection

Background

Ceftazidime-avibactam (caz-avi), a novel β-lactam/β-lactamase inhibitor, is commonly utilized for carbapenem-resistant gram-negative infections (CR-GNI). However, the benefits vs risks of combining caz-avi with other agents are unclear.

Methods

In this retrospective cohort study, inpatients with CR-GNI treated with caz-avi were identified at 9 U.S. hospitals. The impact of caz-avi monotherapy (MT) or combination therapy (CT; i.e., any concomitant use of gram-negative-active antibiotics) was studied using logistic regression, controlling for baseline patient and hospital factors. The primary outcome was in-hospital mortality or discharge to hospice (death), and secondary outcomes were length of stay (LOS), resolution of infectious signs and symptoms (clinical response), 90-day recurrent infection and future caz-avi–resistant organism. An adjusted odds ratio (aOR) with 95% confidence interval (CI) was used to assess the primary and secondary outcomes.

Results

328/499 (65.7%) patients received caz-avi as targeted therapy for a CR-GNI. Overall patients treated with MT and CT were similar at baseline and had comparable baseline demographics although patients treated with CT were more likely to be in the ICU and receive a concomitant empiric in vitro-concordant antibiotic (table 1). The most common organism was Klebsiella spp. (44.6%) followed by Pseudomonas aeruginosa (27.7%) (table 2). Concomitant gram-negative agents are shown in table 3. Overall, 92 (28.1%) patients died and CT (vs MT) displayed similar adjusted mortality risk (27.7% vs 28.7%; aOR [95%CI]: 0.67 [0.34-1.33]) and LOS (19 [9, 37] and 20 [9, 42.5] days). CT (vs MT) was associated with greater odds of clinical response (aOR: 2.25 [95%CI:1.15-4.41]). Among survivors, similar rates of 90-day recurrent infection (50/154 (32.5%) were observed in CT vs 18/82 (22.0%) in MT group (p=0.09) and 5 (2.19%) patients had future infection with a caz-avi–resistant pathogen (3 in CT and 2 in MT group).

Conclusion

Compared to patients with CR-GNI treated with caz-avi alone, those who received CT including caz-avy had similar survival and LOS but higher clinical response. The role of CT in the era of novel antibiotics warrants additional study.

Disclosures

Helen W. Boucher, MD, American Society of Microbiology: Honoraria|Elsevier: Honoraria|Sanford Guide: Honoraria.

Epidemiology of ICU-Onset Bloodstream Infection: Prevalence, Pathogens, and Risk Factors Among 150,948 ICU Patients at 85 U.S. Hospitals

OBJECTIVES

Bloodstream infections (BSIs) acquired in the ICU represent a detrimental yet potentially preventable condition. We determined the prevalence of BSI acquired in the ICU (ICU-onset BSI), pathogen profile, and associated risk factors.

DESIGN

Retrospective cohort study.

DATA SOURCES

Eighty-five U.S. hospitals in the Cerner Healthfacts Database.

PATIENT SELECTION

Adult hospitalizations between January 2009 and December 2015 including a (≥ 3 d) ICU stay.

DATA EXTRACTION AND DATA SYNTHESIS

Prevalence of ICU-onset BSI (between ICU Day 3 and ICU discharge) and associated pathogen and antibiotic resistance distributions were compared with BSI present on (ICU) admission (ICU-BSI POA ); and BSI present on ICU admission day or Day 2. Cox models identified risk factors for ICU-onset BSI among host, care setting, and treatment-related factors. Among 150,948 ICU patients, 5,600 (3.7%) had ICU-BSI POA and 1,306 (0.9%) had ICU-onset BSI. Of those with ICU-BSI POA , 4,359 (77.8%) were admitted to ICU at hospital admission day. Patients with ICU-onset BSI (vs ICU-BSI POA ) displayed higher crude mortality of 37.9% (vs 20.4%) ( p < 0.001) and longer median (interquartile range) length of stay of 13 days (8-23 d) (vs 5 d [3-8 d]) ( p < 0.001) (considering all ICU stay). Compared with ICU-BSI POA , ICU-onset BSI displayed more Pseudomonas , Acinetobacter , Enterococcus, Candida , and Coagulase-negative Staphylococcus species, and more methicillin-resistant staphylococci, vancomycin-resistant enterococci, ceftriaxone-resistant Enterobacter , and carbapenem-resistant Enterobacterales and Acinetobacter species, respectively. Being younger, male, Black, Hispanic, having greater comorbidity burden, sepsis, trauma, acute pulmonary or gastrointestinal presentations, and pre-ICU exposure to antibacterial and antifungal agents was associated with greater ICU-onset BSI risk after adjusted analysis. Mixed ICUs (vs medical or surgical ICUs) and urban and small/medium rural hospitals were also associated with greater ICU-onset BSI risk. The associated risk of acquiring ICU-onset BSI manifested with any duration of mechanical ventilation and 7 days after insertion of central venous or arterial catheters.

CONCLUSIONS

ICU-onset BSI is a serious condition that displays a unique pathogen and resistance profile compared with ICU-BSI POA . Further scrutiny of modifiable risk factors for ICU-onset BSI may inform control strategies.

Antiviral innate immunity is diminished in the upper respiratory tract of severe COVID-19 patients

Understanding early innate immune responses to coronavirus disease 2019 (COVID-19) is crucial to developing targeted therapies to mitigate disease severity. Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection elicits interferon expression leading to transcription of IFN-stimulated genes (ISGs) to control viral replication and spread. SARS-CoV-2 infection also elicits NF-κB signaling which regulates inflammatory cytokine expression contributing to viral control and likely disease severity. Few studies have simultaneously characterized these two components of innate immunity to COVID-19. We designed a study to characterize the expression of interferon alpha-2 (IFNA2) and interferon beta-1 (IFNB1), both type-1 interferons (IFN-1), interferon-gamma (IFNG), a type-2 interferon (IFN-2), ISGs, and NF-κB response genes in the upper respiratory tract (URT) of patients with mild (outpatient) versus severe (hospitalized) COVID-19. Further, we characterized the weekly dynamics of these responses in the upper and lower respiratory tracts (LRTs) and blood of severe patients to evaluate for compartmental differences. We observed significantly increased ISG and NF-κB responses in the URT of mild compared with severe patients early during illness. This pattern was associated with increased IFNA2 and IFNG expression in the URT of mild patients, a trend toward increased IFNB1-expression and significantly increased STING/IRF3/cGAS expression in the URT of severe patients. Our by-week across-compartment analysis in severe patients revealed significantly higher ISG responses in the blood compared with the URT and LRT of these patients during the first week of illness, despite significantly lower expression of IFNA2, IFNB1, and IFNG in blood. NF-κB responses, however, were significantly elevated in the LRT compared with the URT and blood of severe patients during peak illness (week 2). Our data support that severe COVID-19 is associated with impaired interferon signaling in the URT during early illness and robust pro-inflammatory responses in the LRT during peak illness.

Machine Learning in Infectious Disease for Risk Factor Identification and Hypothesis Generation: Proof of Concept Using Invasive Candidiasis

Background

Machine learning (ML) models can handle large datasets without assuming underlying relationships and can be useful for evaluating disease characteristics; yet, they are more commonly used for predicting individual disease risk rather than identifying factors at the population level. We offer a proof of concept applying random forest (RF) algorithms to Candida-positive hospital encounters in an electronic health record database of patients in the U.S.

Methods

Candida-positive encounters were extracted from the Cerner HealthFacts database; invasive infections were laboratory positive sterile site Candida infections. Features included demographics, admission source, care setting, physician specialty, diagnostic and procedure codes, and medications received prior to the first positive Candida culture. We used RF to assess risk factors for three outcomes: any invasive candidiasis (IC) vs non-IC, within-species IC vs non-IC (e.g. invasive C. glabrata vs non-invasive C. glabrata), and between-species IC (e.g. invasive C. glabrata vs all other IC).

Results

14 of 169 (8%) variables were consistently identified as important features in the ML models. When evaluating within-species IC, for example invasive C. glabrata vs non-invasive C. glabrata, we identified known features like central venous catheters, ICU stay, and gastrointestinal operations. In contrast, important variables for invasive C. glabrata vs all other IC included renal disease and medications like diabetes therapeutics, cholesterol medications, and antiarrhythmics.

Conclusions

Known and novel risk factors for IC were identified using ML, demonstrating the hypotheses generating utility of this approach for infectious disease conditions about which less is known, specifically at the species-level or for rarer diseases.

Association Between Caseload Surge and COVID-19 Survival in 558 U.S. Hospitals, March to August 2020

BACKGROUND

Several U.S. hospitals had surges in COVID-19 caseload, but their effect on COVID-19 survival rates remains unclear, especially independent of temporal changes in survival.

OBJECTIVE

To determine the association between hospitals' severity-weighted COVID-19 caseload and COVID-19 mortality risk and identify effect modifiers of this relationship.

DESIGN

Retrospective cohort study. (ClinicalTrials.gov: NCT04688372).

SETTING

558 U.S. hospitals in the Premier Healthcare Database.

PARTICIPANTS

Adult COVID-19-coded inpatients admitted from March to August 2020 with discharge dispositions by October 2020.

MEASUREMENTS

Each hospital-month was stratified by percentile rank on a surge index (a severity-weighted measure of COVID-19 caseload relative to pre-COVID-19 bed capacity). The effect of surge index on risk-adjusted odds ratio (aOR) of in-hospital mortality or discharge to hospice was calculated using hierarchical modeling; interaction by surge attributes was assessed.

RESULTS

Of 144 116 inpatients with COVID-19 at 558 U.S. hospitals, 78 144 (54.2%) were admitted to hospitals in the top surge index decile. Overall, 25 344 (17.6%) died; crude COVID-19 mortality decreased over time across all surge index strata. However, compared with nonsurging (<50th surge index percentile) hospital-months, aORs in the 50th to 75th, 75th to 90th, 90th to 95th, 95th to 99th, and greater than 99th percentiles were 1.11 (95% CI, 1.01 to 1.23), 1.24 (CI, 1.12 to 1.38), 1.42 (CI, 1.27 to 1.60), 1.59 (CI, 1.41 to 1.80), and 2.00 (CI, 1.69 to 2.38), respectively. The surge index was associated with mortality across ward, intensive care unit, and intubated patients. The surge-mortality relationship was stronger in June to August than in March to May (slope difference, 0.10 [CI, 0.033 to 0.16]) despite greater corticosteroid use and more judicious intubation during later and higher-surging months. Nearly 1 in 4 COVID-19 deaths (5868 [CI, 3584 to 8171]; 23.2%) was potentially attributable to hospitals strained by surging caseload.

LIMITATION

Residual confounding.

CONCLUSION

Despite improvements in COVID-19 survival between March and August 2020, surges in hospital COVID-19 caseload remained detrimental to survival and potentially eroded benefits gained from emerging treatments. Bolstering preventive measures and supporting surging hospitals will save many lives.

PRIMARY FUNDING SOURCE

Intramural Research Program of the National Institutes of Health Clinical Center, the National Institute of Allergy and Infectious Diseases, and the National Cancer Institute.

Fostamatinib for the Treatment of Hospitalized Adults With Coronavirus Disease 2019: A Randomized Trial

BACKGROUND

Coronavirus disease 2019 (COVID-19) requiring hospitalization is characterized by robust antibody production, dysregulated immune response, and immunothrombosis. Fostamatinib is a novel spleen tyrosine kinase inhibitor that we hypothesize will ameliorate Fc activation and attenuate harmful effects of the anti-COVID-19 immune response.

METHODS

We conducted a double-blind, randomized, placebo-controlled trial in hospitalized adults requiring oxygen with COVID-19 where patients receiving standard of care were randomized to receive fostamatinib or placebo. The primary outcome was serious adverse events by day 29.

RESULTS

A total of 59 patients underwent randomization (30 to fostamatinib and 29 to placebo). Serious adverse events occurred in 10.5% of patients in the fostamatinib group compared with 22% in placebo (P = .2). Three deaths occurred by day 29, all receiving placebo. The mean change in ordinal score at day 15 was greater in the fostamatinib group (-3.6 ± 0.3 vs -2.6 ± 0.4, P = .035) and the median length in the intensive care unit was 3 days in the fostamatinib group vs 7 days in placebo (P = .07). Differences in clinical improvement were most evident in patients with severe or critical disease (median days on oxygen, 10 vs 28, P = .027). There were trends toward more rapid reductions in C-reactive protein, D-dimer, fibrinogen, and ferritin levels in the fostamatinib group.

CONCLUSION

For COVID-19 requiring hospitalization, the addition of fostamatinib to standard of care was safe and patients were observed to have improved clinical outcomes compared with placebo. These results warrant further validation in larger confirmatory trials.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov, NCT04579393.

Pre-vaccination and early B cell signatures predict antibody response to SARS-CoV-2 mRNA vaccine

SARS-CoV-2 mRNA vaccines are highly effective, although weak antibody responses are seen in some individuals with correlates of immunity that remain poorly understood. Here we longitudinally dissected antibody, plasmablast, and memory B cell (MBC) responses to the two-dose Moderna mRNA vaccine in SARS-CoV-2-uninfected adults. Robust, coordinated IgA and IgG antibody responses were preceded by bursts of spike-specific plasmablasts after both doses, but earlier and more intensely after dose two. Distinct antigen-specific MBC populations also emerged post-vaccination with varying kinetics. We identified antigen non-specific pre-vaccination MBC and post-vaccination plasmablasts after dose one and their spike-specific counterparts early after dose two that correlated with subsequent antibody levels. These baseline and response signatures can thus provide early indicators of serological efficacy and explain response variability in the population.

Infectious Diseases Society of America Position Paper: Recommended Revisions to the National Severe Sepsis and Septic Shock Early Management Bundle (SEP-1) Sepsis Quality Measure

The Centers for Medicare & Medicaid Services' Severe Sepsis and Septic Shock Early Management Bundle (SEP-1) measure has appropriately established sepsis as a national priority. However, the Infectious Diseases Society of America (IDSA and five additional endorsing societies) is concerned about SEP-1's potential to drive antibiotic overuse because it does not account for the high rate of sepsis overdiagnosis and encourages aggressive antibiotics for all patients with possible sepsis, regardless of the certainty of diagnosis or severity of illness. IDSA is also concerned that SEP-1's complex "time zero" definition is not evidence-based and is prone to inter-observer variation. In this position paper, IDSA outlines several recommendations aimed at reducing the risk of unintended consequences of SEP-1 while maintaining focus on its evidence-based elements. IDSA's core recommendation is to limit SEP-1 to septic shock, for which the evidence supporting the benefit of immediate antibiotics is greatest. Prompt empiric antibiotics are often appropriate for suspected sepsis without shock, but IDSA believes there is too much heterogeneity and difficulty defining this population, uncertainty about the presence of infection, and insufficient data on the necessity of immediate antibiotics to support a mandatory treatment standard for all patients in this category. IDSA believes guidance on managing possible sepsis without shock is more appropriate for guidelines that can delineate the strengths and limitations of supporting evidence and allow clinicians discretion in applying specific recommendations to individual patients. Removing sepsis without shock from SEP-1 will mitigate the risk of unnecessary antibiotic prescribing for noninfectious syndromes, simplify data abstraction, increase measure reliability, and focus attention on the population most likely to benefit from immediate empiric broad-spectrum antibiotics.

Fostamatinib Inhibits Neutrophils Extracellular Traps Induced by COVID-19 Patient Plasma: A Potential Therapeutic

Neutrophil extracellular traps (NETs) contribute to immunothrombosis and have been associated with mortality in coronavirus disease 2019 (COVID-19). We stimulated donor neutrophils with plasma from patients with COVID-19 and demonstrated that R406 can abrogate the release of NETs. These data provide evidence for how fostamatinib may mitigate neutrophil-associated mechanisms contributing to COVID-19 immunopathogenesis.

High-throughput, single-copy sequencing reveals SARS-CoV-2 spike variants coincident with mounting humoral immunity during acute COVID-19

Tracking evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within infected individuals will help elucidate coronavirus disease 2019 (COVID-19) pathogenesis and inform use of antiviral interventions. In this study, we developed an approach for sequencing the region encoding the SARS-CoV-2 virion surface proteins from large numbers of individual virus RNA genomes per sample. We applied this approach to the WA-1 reference clinical isolate of SARS-CoV-2 passaged in vitro and to upper respiratory samples from 7 study participants with COVID-19. SARS-CoV-2 genomes from cell culture were diverse, including 18 haplotypes with non-synonymous mutations clustered in the spike NH2-terminal domain (NTD) and furin cleavage site regions. By contrast, cross-sectional analysis of samples from participants with COVID-19 showed fewer virus variants, without structural clustering of mutations. However, longitudinal analysis in one individual revealed 4 virus haplotypes bearing 3 independent mutations in a spike NTD epitope targeted by autologous antibodies. These mutations arose coincident with a 6.2-fold rise in serum binding to spike and a transient increase in virus burden. We conclude that SARS-CoV-2 exhibits a capacity for rapid genetic adaptation that becomes detectable in vivo with the onset of humoral immunity, with the potential to contribute to delayed virologic clearance in the acute setting.

High-Throughput, Single-Copy Sequencing Reveals SARS-CoV-2 Spike Variants Coincident with Mounting Humoral Immunity during Acute COVID-19

Tracking evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within infected individuals will help elucidate coronavirus disease 2019 (COVID-19) pathogenesis and inform use of antiviral interventions. In this study, we developed an approach for sequencing the region encoding the SARS-CoV-2 virion surface proteins from large numbers of individual virus RNA genomes per sample. We applied this approach to the WA-1 reference clinical isolate of SARS-CoV-2 passaged in vitro and to upper respiratory samples from 7 study participants with COVID-19. SARS-CoV-2 genomes from cell culture were diverse, including 18 haplotypes with non-synonymous mutations clustered in the spike NH 2 -terminal domain (NTD) and furin cleavage site regions. By contrast, cross-sectional analysis of samples from participants with COVID-19 showed fewer virus variants, without structural clustering of mutations. However, longitudinal analysis in one individual revealed 4 virus haplotypes bearing 3 independent mutations in a spike NTD epitope targeted by autologous antibodies. These mutations arose coincident with a 6.2-fold rise in serum binding to spike and a transient increase in virus burden. We conclude that SARS-CoV-2 exhibits a capacity for rapid genetic adaptation that becomes detectable in vivo with the onset of humoral immunity, with the potential to contribute to delayed virologic clearance in the acute setting.

AUTHOR SUMMARY

Mutant sequences of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) arising during any individual case of coronavirus disease 2019 (COVID-19) could theoretically enable the virus to evade immune responses or antiviral therapies that target the predominant infecting virus sequence. However, commonly used sequencing technologies are not optimally designed to detect variant virus sequences within each sample. To address this issue, we developed novel technology for sequencing large numbers of individual SARS-CoV-2 genomic RNA molecules across the region encoding the virus surface proteins. This technology revealed extensive genetic diversity in cultured viruses from a clinical isolate of SARS-CoV-2, but lower diversity in samples from 7 individuals with COVID-19. Importantly, concurrent analysis of paired serum samples in selected individuals revealed relatively low levels of antibody binding to the SARS-CoV-2 spike protein at the time of initial sequencing. With increased serum binding to spike protein, we detected multiple SARS-CoV-2 variants bearing independent mutations in a single epitope, as well as a transient increase in virus burden. These findings suggest that SARS-CoV-2 replication creates sufficient virus genetic diversity to allow immune-mediated selection of variants within the time frame of acute COVID-19. Large-scale studies of SARS-CoV-2 variation and specific immune responses will help define the contributions of intra-individual SARS-CoV-2 evolution to COVID-19 clinical outcomes and antiviral drug susceptibility.

Pharmacoepidemiology of Ceftazidime-Avibactam Use: A Retrospective Cohort Analysis of 210 US Hospitals

BACKGROUND

Ceftazidime-avibactam has in vitro activity against some carbapenem-resistant gram-negative infections (GNIs), and therefore may be a useful alternative to more toxic antibiotics such as colistin. Understanding ceftazidime-avibactam uptake and usage patterns would inform hospital formularies, stewardship, and antibiotic development.

METHODS

A retrospective cohort study assessed inpatient encounters in the Vizient database. Ceftazidime-avibactam and colistin administrations were categorized into presumed empiric (3 consecutive days of therapy or less with qualifying exclusions) versus targeted therapy (≥4 consecutive days of therapy) for presumed carbapenem-resistant GNIs. Quarterly percentage change (QPC) using modified Poisson regression and relative change in frequency of targeted ceftazidime-avibactam to colistin encounters was calculated. Factors associated with preferentially receiving targeted ceftazidime-avibactam versus colistin were identified using generalized estimating equations.

RESULTS

Between 2015 quarter (q) 1 and 2017q4, ceftazidime-avibactam was administered 21 215 times across 1901 encounters. Inpatient prescriptions for ceftazidime-avibactam increased from 0.44/10 000 hospitalizations in 2015q1 to 7.7/10 000 in 2017q4 (QPC, +11%; 95% CI, 10-13%; P < .01), while conversely colistin prescriptions decreased quarterly by 5% (95% CI, 4-6%; P < .01). Ceftazidime-avibactam therapy was categorized as empiric 25% of the time, targeted 65% of the time, and indeterminate 10% of the time. Patients with chronic kidney disease were twice as likely to receive targeted ceftazidime-avibactam versus colistin (RR, 2.02; 95% CI, 1.82-2.25), whereas those on dialysis were less likely to receive ceftazidime-avibactam than colistin (RR, 0.71; 95% CI, .61-.83).

CONCLUSIONS

Since approval in 2015, ceftazidime-avibactam use has grown for presumed carbapenem-resistant GNIs, while colistin has correspondingly declined. Renal function drove the choice between ceftazidime-avibactam and colistin as targeted therapy.

Real-World Inpatient Use of Medications Repurposed for Coronavirus Disease 2019 in United States Hospitals, March-May 2020

We report off-label use patterns for medications repurposed for coronavirus disease 2019 (COVID-19) at 318 US hospitals. Inpatient hydroxychloroquine use declined by 80%, whereas corticosteroids and tocilizumab were initiated 2 days earlier in May versus March 2020. Two thirds of ventilated COVID-19 patients were already receiving corticosteroids during March-May 2020, resembling pre-COVID use in mechanically ventilated influenza patients.

Effectiveness of adjunctive clindamycin in β-lactam antibiotic-treated patients with invasive β-haemolytic streptococcal infections in US hospitals: a retrospective multicentre cohort study

BACKGROUND

Clindamycin is strongly recommended as an adjunctive treatment to β-lactam antibiotics in patients with severe invasive group A β-haemolytic streptococcal (iGAS) infections. However, there is little evidence of a benefit in the use of clindamycin in humans, and its role, if any, in treating patients with invasive non-group A/B β-haemolytic streptococcal (iNABS) infections is unclear.

METHODS

For this retrospective multicentre cohort study, we used a dataset from patients in the Cerner Health Facts database, which contains electronic health-based data from 233 US hospitals. We queried the Cerner Health Facts database for inpatients (no age restriction) admitted to hospital in 2000-15, with any clinical cultures positive for β-haemolytic streptococcal taxa of interest, and who had received β-lactam antibiotics within 3 days either side of culture sampling. This group of patients was then queried for those who had also received intravenous or oral clindamycin within 3 days either side of culture sampling. Patients were excluded if they had polymicrobial growth or clindamycin non-susceptible isolates, received linezolid, or had missing variable data needed for analysis. Patients were categorised by Lancefield group (iGAS or iNABS); β-lactam antibiotic-treated patients who had received clindamycin were propensity-matched (1:2) to those who did not receive clindamycin separately for iGAS and iNABS cohorts, and logistic regression was then used to account for residual confounding factors. The primary outcome was the adjusted odds ratio (aOR) of in-hospital mortality in propensity-matched patients treated with adjunctive clindamycin versus those not treated with clindamycin in the iGAS and iNABS infection cohorts.

FINDINGS

We identified 1956 inpatients with invasive β-haemolytic streptococcal infection who had been treated with β-lactam antibiotics across 118 hospitals (1079 with iGAS infections and 877 with iNABS infections). 459 (23·4%) of these patients had received adjunctive clindamycin treatment (343 [31·7%] patients with iGAS infections and 116 [13·2%] patients with iNABS infections). The effect of adjunctive clindamycin therapy on in-hospital mortality differed significantly and showed the opposite trend in iGAS and iNABS infection cohorts (p=0·013 for an interaction). In the iGAS cohort, in-hospital mortality in propensity-matched patients who received adjunctive clindamycin (18 [6·5%] of 277 patients) was significantly lower than in those who did not (55 [11·0%] of 500 patients; aOR 0·44 [95% CI 0·23-0·81]). This survival benefit was maintained even in patients without shock or necrotising fasciitis (six [2·6%] of 239 patients treated with adjunctive clindamycin vs 27 [6·1%] of 422 patients not treated with adjunctive clindamycin; aOR 0·40 [0·15-0·91]). By contrast, in the iNABS infection cohort, in-hospital mortality in propensity-matched patients who received adjunctive clindamycin (ten [9·8%] of 102) was higher than in those who did not (nine [4·6%] of 193), but this difference was not significant (aOR 2·60 [0·94-7·52]). Several subset analyses found qualitatively similar results.

INTERPRETATION

Real-world data suggest that increased use of adjunctive clindamycin for invasive iGAS infections, but not iNABS infections, could improve outcomes, even in patients without shock or necrotising fasciitis.

FUNDING

Intramural Research Program of the National Institutes of Health Clinical Center and the National Institute of Allergy and Infectious Disease.

Needs assessment for novel Gram-negative antibiotics in US hospitals: a retrospective cohort study

BACKGROUND

Evidence-based needs assessments for novel antibiotics against highly-resistant Gram-negative infections (GNIs) are scarce. We aimed to use real-world data from an electronic health record repository to identify treatment opportunities in US hospitals for GNIs resistant to all first-line drugs.

METHODS

For this retrospective cohort study, population estimates with an unmet need for novel Gram-negative antibiotics were quantified using the Cerner Health Facts database (2009-15), aggregating episodes of infection in US hospitals with pathogens displaying difficult-to-treat resistance (DTR; resistance to carbapenems, other β-lactams, and fluoroquinolones) and episodes involving empirical coverage with reserve drugs (colistin or polymyxin B and aminoglycosides). Episodes displaying extended-spectrum cephalosporin resistance (ECR) were also estimated. Episodes were multiplied by site-specific and fixed 14-day treatment durations for conservative and liberal days-of-therapy (DOT) estimates and stratified by site and taxon. Hospital type-specific DOT rates were reliability adjusted to account for random variation; cluster analyses quantified contribution from outbreaks.

FINDINGS

Across 2 996 271 inpatient encounters and 134 hospitals, there were 1352 DTR-GNI episodes, 1765 episodes involving empirical therapy with colistin or polymyxin B, and 16 632 episodes involving aminoglycosides. Collectively, these yielded 39·0 (conservative estimate) to 138·2 (liberal estimate) DOT per 10 000 encounters for a novel DTR-GNI-targeted drug, whereas greater treatment opportunities were identified for ECR (six times greater) and β-lactam susceptible GNIs (70 times greater). The most common DTR-GNI site and pathogen was lower respiratory (14·3 [43·3%] of 33 DOT per 10 000 encounters) and Pseudomonas aeruginosa (522 [38·1%] of 1371 episodes), whereas Enterobacteriaceae urinary-tract infections dominated the ECR or carbapenem-sparing niche (59·0% [5589 of 9535 episodes]) equating to 210·7 DOT per 10 000 encounters. DTR Stenotrophomonas maltophilia, Burkholderia spp, and Achromobacter spp represented less than 1 DOT per 10 000 encounters each. The estimated need for DTR-GNI-targeted antibiotics saw minor contributions by outbreaks and varied from 0·5 to 73·1 DOT per 10 000 encounters by hospital type.

INTERPRETATION

Suspected or documented GNIs with no or suboptimal treatment options are relatively infrequent. Non-revenue-based strategies and innovative trial designs are probably essential to the development of antibiotics with improved effectiveness for these GNIs.

FUNDING

Center for Drug Evaluation and Research, US Food and Drug Administration; Intramural Research Program, National Institutes of Health Clinical Center and the National Institute of Allergy and Infectious Diseases and the National Cancer Institute.

Inappropriate empirical antibiotic therapy for bloodstream infections based on discordant in-vitro susceptibilities: a retrospective cohort analysis of prevalence, predictors, and mortality risk in US hospitals

BACKGROUND

The prevalence and effects of inappropriate empirical antibiotic therapy for bloodstream infections are unclear. We aimed to establish the population-level burden, predictors, and mortality risk of in-vitro susceptibility-discordant empirical antibiotic therapy among patients with bloodstream infections.

METHODS

Our retrospective cohort analysis of electronic health record data from 131 hospitals in the USA included patients with suspected-and subsequently confirmed-bloodstream infections who were treated empirically with systemic antibiotics between Jan 1, 2005, and Dec 31, 2014. We included all patients with monomicrobial bacteraemia caused by common bloodstream pathogens who received at least one systemic antibiotic either on the day blood cultures were drawn or the day after, and for whom susceptibility data were available. We calculated the prevalence of discordant empirical antibiotic therapy-which was defined as receiving antibiotics on the day blood culture samples were drawn to which the cultured isolate was not susceptible in vitro-overall and by hospital type by using regression tree analysis. We used generalised estimating equations to identify predictors of receiving discordant empirical antibiotic therapy, and used logistic regression to calculate adjusted odds ratios for the relationship between in-hospital mortality and discordant empirical antibiotic therapy.

FINDINGS

21 608 patients with bloodstream infections received empirical antibiotic therapy on the day of first blood culture collection. Of these patients, 4165 (19%) received discordant empirical antibiotic therapy. Discordant empirical antibiotic therapy was independently associated with increased risk of mortality (adjusted odds ratio 1·46 [95% CI, 1·28-1·66]; p<0·0001), a relationship that was unaffected by the presence or absence of resistance or sepsis or septic shock. Infection with antibiotic-resistant species strongly predicted receiving discordant empirical therapy (adjusted odds ratio 9·09 [95% CI 7·68-10·76]; p<0·0001). Most incidences of discordant empirical antibiotic therapy and associated deaths occurred among patients with bloodstream infections caused by Staphylococcus aureus or Enterobacterales.

INTERPRETATION

Approximately one in five patients with bloodstream infections in US hospitals received discordant empirical antibiotic therapy, receipt of which was closely associated with infection with antibiotic-resistant pathogens. Receiving discordant empirical antibiotic therapy was associated with increased odds of mortality overall, even in patients without sepsis. Early identification of bloodstream pathogens and resistance will probably improve population-level outcomes.

FUNDING

US National Institutes of Health, US Centers for Disease Control and Prevention, and US Agency for Healthcare Research and Quality.

Invasive Candidiasis Species Distribution and Trends, United States, 2009-2017

BACKGROUND

Invasive candidiasis (IC) is a growing concern among US healthcare facilities. A large-scale study evaluating incidence and trends of IC in the United States by species and body site is needed to understand the distribution of infection.

METHODS

An electronic medical record database was used to calculate incidence and trends of IC in the United States by species and infection site from 2009 through 2017. Hospital incidence was calculated using total unique inpatient hospitalizations in hospitals reporting at least 1 Candida case as the denominator. IC incidence trends were assessed using generalized estimating equations with exchangeable correlation structure to fit Poisson regression models, controlling for changes in hospital characteristics and case mix over time.

RESULTS

Candida albicans remains the leading cause of IC in the United States, followed by Candida glabrata. The overall incidence of IC was 90/100 000 patients, which did not change significantly over time. There were no changes in incidence among C. albicans, C. glabrata, C. parapsilosis, or C. tropicalis; the incidence of other Candida spp. as a whole increased 7.2% annually. While there was no change in candidemia 2009-2017, abdominal and nonabdominal sterile site IC increased significantly.

CONCLUSIONS

Nonbloodstream IC is increasing in the United States. Understanding the epidemiology of IC should facilitate improved management of infected patients.

Considerations for Empiric Antimicrobial Therapy in Sepsis and Septic Shock in an Era of Antimicrobial Resistance

Patients with sepsis present across a spectrum of infection sites and severity of illnesses requiring complex decision making at the bedside as to when prompt antibiotics are indicated and which regimen is warranted. Many hemodynamically stable patients with sepsis and low acuity of illness may benefit from further work up before initiating therapy, whereas patients with septic shock warrant emergent broad-spectrum antibiotics. The precise empiric regimen is determined by assessing patient and epidemiological risk factors, likely source of infection based on presenting signs and symptoms, and severity of illness. Hospitals should implement quality improvement measures to aid in the rapid and accurate diagnosis of septic patients and to ensure antibiotics are given to patients in an expedited fashion after antibiotic order.

Sensitivity in Detection of Antibodies to Nucleocapsid and Spike Proteins of Severe Acute Respiratory Syndrome Coronavirus 2 in Patients With Coronavirus Disease 2019

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is associated with respiratory-related disease and death. Assays to detect virus-specific antibodies are important to understand the prevalence of infection and the course of the immune response.

METHODS

Quantitative measurements of plasma or serum antibodies to the nucleocapsid and spike proteins were analyzed using luciferase immunoprecipitation system assays in 100 cross-sectional or longitudinal samples from patients with SARS-CoV-2 infection. A subset of samples was tested both with and without heat inactivation.

RESULTS

At >14 days after symptom onset, antibodies against SARS-CoV-2 nucleocapsid protein showed 100% sensitivity and 100% specificity, whereas antibodies to spike protein were detected with 91% sensitivity and 100% specificity. Neither antibody levels nor the rate of seropositivity were significantly reduced by heat inactivation of samples. Analysis of daily samples from 6 patients with COVID-19 showed anti-nucleocapsid and spike protein antibodies appearing between days 8 and 14 after initial symptoms. Immunocompromised patients generally had a delayed antibody response to SARS-CoV-2, compared with immunocompetent patients.

CONCLUSIONS

Antibody to the nucleocapsid protein of SARS-CoV-2 is more sensitive than spike protein antibody for detecting early infection. Analyzing heat-inactivated samples with a luciferase immunoprecipitation system assay is a safe and sensitive method for detecting SARS-CoV-2 antibodies.

Detection of Nucleocapsid Antibody to SARS-CoV-2 is More Sensitive than Antibody to Spike Protein in COVID-19 Patients

Background

SARS-CoV-2, the cause of coronavirus disease 2019 (COVID-19), is associated with respiratory-related morbidity and mortality. Assays to detect virus-specific antibodies are important to understand the prevalence of infection and the course of the immune response.

Methodology

Quantitative measurements of plasma or serum antibodies by luciferase immunoprecipitation assay systems (LIPS) to the nucleocapsid and spike proteins were analyzed in 100 cross-sectional or longitudinal samples from SARS-CoV-2-infected patients. A subset of samples was tested with and without heat inactivation.

Results

Fifteen or more days after symptom onset, antibodies against SARS-CoV-2 nucleocapsid protein showed 100% sensitivity and 100% specificity, while antibodies to spike protein were detected with 91% sensitivity and 100% specificity. Neither antibody levels nor the rate of seropositivity were significantly reduced by heat inactivation of samples. Analysis of daily samples from six patients with COVID-19 showed anti-nucleocapsid and spike antibodies appearing between day 8 to day 14 after initial symptoms. Immunocompromised patients generally had a delayed antibody response to SARS-CoV-2 compared to immunocompetent patients.

Conclusions

Antibody to the nucleocapsid protein of SARS-CoV-2 is more sensitive than spike protein antibody for detecting early infection. Analyzing heat-inactivated samples by LIPS is a safe and sensitive method for detecting SARS-CoV-2 antibodies.

Driving blind: instituting SEP-1 without high quality outcomes data

In 2015, the Centers for Medicare and Medicaid Services (CMS) instituted an all-or-none sepsis performance measure bundle (SEP-1) to promote high-quality, cost-effective care. Systematic reviews demonstrated only low-quality evidence supporting most of SEP-1's interventions. CMS has removed some but not all of these unproven components. The current SEP-1 version requires patients with suspected sepsis have a lactate level, blood cultures, broad-spectrum antibiotics and, if hypotensive, a fixed 30 mL/kg fluid infusion within 3 hours, and a repeat lactate if initially elevated within 6 hours. Experts have continued to raise concerns that SEP-1 remains overly prescriptive, lacks a sound scientific basis and presents risks (overuse of antibiotics and inappropriate fluids not titrated to need). To incentivize compliance with SEP-1, CMS now publicly publishes how often hospitals complete all interventions in individual patients. However, compliance measured across hospitals (5 studies, 48-2,851 hospitals) or patients (three studies, 110-851 patients) has been low (approximately 50%) which is not surprising given SEP-1's lack of scientific basis. The largest observational study (1,738 patients) reporting survival rates employing SEP-1 found they were not significantly improved with the measure (P=0.53) as did the next largest study (851 patients, adjusted survival odds ratio 1.36, 95% CI, 0.85 to 2.18). Two smaller observational studies (158 and 450 patients) reported SEP-1 improved unadjusted survival (P≤0.05) but were confounded either by baseline imbalances or by simultaneous introduction of a code sepsis protocol to improve compliance. Regardless, retrospective studies have well known biases related to non-randomized designs, uncontrolled data collection and failure to adjust for unrecognized influential variables. Such low-quality science should not be the basis for a national mandate compelling care for a rapidly lethal disease with a high mortality rate. Instead, SEP-1 should be based on high quality reproducible evidence from randomized controlled trials (RCT) demonstrating its benefit and thereby safety. Otherwise we risk not only doing harm but standardizing it.

1333. Utility of Admission Procalcitonin Level in Patients Presenting to the Hospital with Bloodstream Infection: Real-World Evidence from 250 US Hospitals

Background

Serum procalcitonin (PCT) may aid in early detection and treatment of bacterial bloodstream infections (BSI), yet evidence for this indication is inconclusive. We leveraged real-world data to examine biological variability in PCT across host and pathogen factors and its utility for ruling out BSI on admission.

Methods

PCT measurements within 24 hours of admission were examined in patients presenting with monomicrobial BSI to 250 hospitals in the Cerner Healthfacts Database. The reliability of admission PCT for ruling out BSI at hospital presentation was assessed using two different thresholds (<0.5 and <0.25ng/mL) and then stratifying results by presence vs. absence of sepsis (using CDC Adult Sepsis Event criteria), fever or hypothermia vs. normothermia, various presumed sources of BSI, and organism taxon.

Results

Between 2007 and 2017, PCT was measured on admission in 4,358/42,465 (10.3%) adults with BSI present on admission at 60 hospitals. Of these, 870 (20%) met CDC surveillance criteria for sepsis. The median admission PCT was 4.89 [0.93, 23.98] and varied by taxon, BSI source, patient temperature, and the presence and severity of sepsis; acute illness severity was the greatest driver of high PCT levels (Fig 1). Using a threshold of ≥ 0.50 ng/mL, the sensitivity of PCT for detection of BSI was 84% for all patients. Notably, BSI without sepsis was 4-fold more likely to yield a false negative PCT (<0.5ng/mL) than bacteremic sepsis. Sensitivity ranged from 77% with normothermia to 83% with fever/hypothermia (P = 0.06), between 81 and 88% across sources of BSI (P = 0.13) and more widely between 64 and 91% across taxa (P = 0.02). Enterococcal BSI was 2- and 4-fold more likely to have a falsely negative PCT than S. aureus or S. pneumoniae BSIs, whereas non-glucose fermenters other than P. aeruginosa had a 2 and 3-fold higher likelihood of being missed compared with P. aeruginosa and Enterobacteriaceae BSIs respectively (Fig 2). Pathogen-level variation in PCT sensitivity was also observed for BSI without sepsis (62–90%; P = 0.02) and upon using a stricter rule-out threshold of <0.25 ng/mL (P = 0.01).

Conclusion

PCT levels and the reliability of this test for ruling out bacteremia at hospital presentation varies by pathogen, presenting signs, and presence vs. absence of sepsis.

Disclosures

All authors: No reported disclosures.

2251. Estimating the Need for Novel Gram-Negative Active Antibiotics in US Hospitals

Background

Assessing the unmet need for novel antibiotics could inform appropriate utilization, enrollment in trials and ensure balance in aligning incentives and investments in therapeutic development.

Methods

The Cerner Healthfacts electronic health record repository was queried to identify inpatient treatment opportunities for Gram-negative active agents (GNAA) displaying either difficult-to-treat resistance (DTR; resistance to all β-lactams including carbapenems and fluoroquinolones) or extended-spectrum cephalosporin resistance (ECR). The former was quantified by aggregating episodes of confirmed DTR infection (i.e., DTR strain isolated and concomitant antibiotic(s) received) or suspected (i.e., 1–2 days of empiric colistin/polymyxin-B or aminoglycosides and no DTR pathogen isolated). Aggregate days of therapy (DOT) were reported as a range, multiplying episodes by site-specific or uniform 14-day treatment durations, respectively. Recursive partition and cluster analyses were performed for hospital characteristics and contributions of outbreaks to DTR treatment opportunities, respectively.

Results

Between 2009 and 2015, across 2,996,271 encounters, 1,352 episodes of potential targeted treatment were identified, which combined with empiric treatment episodes, represent 39–138 DOT/10,000 encounters for a DTR-GNAA. Similarly, 9,535 episodes of potential targeted therapy for an ECR-GNAA were identified (representing 211-466 DOT/10,000 encounters). The most common candidate site and pathogens for DTR-GNAA were lower respiratory and A. baumannii and P. aeruginosa respectively; DTR bloodstream infections displayed the highest crude mortality at 45%. Enterobacteriaceae urinary infections dominated the ECR group. Teaching hospitals with ≥100 beds were the most likely to encounter a DTR infection; potential outbreaks contributed to 10.6% of DTR treatment opportunities.

Conclusion

The candidate population for new antibacterials directed against highly resistant GN infections with limited treatment options is small but critical, indicating a role for non-revenue-based strategies to develop more effective antibiotics, as well as mechanisms to support trials that address real-world unmet needs.

Disclosures

All authors: No reported disclosures.

Difficult-to-Treat Antibiotic-Resistant Gram-Negative Pathogens in the Intensive Care Unit: Epidemiology, Outcomes, and Treatment

Antibiotic resistance among gram-negative pathogens is a world-wide problem that poses a constant threat to patients in the intensive care unit and a therapeutic challenge for the intensivist. Furthermore, the substantial economic burden and increased mortality associated with infections due to highly resistant gram-negative pathogens exacerbate these challenges. Understanding the mechanisms, epidemiology, and risk factors for these infections is paramount to the successful control of outbreaks and for guiding therapy which often entails use of antibiotics with suboptimal efficacy and/or toxicity profiles. In this review we will discuss the global epidemiology, burden, risk factors, and treatment of highly resistant gram-negative infections as they apply to the intensive care population.

Attributable mortality from extensively drug-resistant gram-negative infections using propensity-matched tracer antibiotic algorithms

BACKGROUND

Tracer antibiotic algorithms using administrative data were investigated to estimate mortality attributable to extensively drug-resistant gram-negative infections (GNIs).

METHODS

Among adult inpatients coded for GNIs, colistin cases and 2 comparator cohorts (non-carbapenem β-lactams or carbapenems) treated for ≥4 consecutive days, or died while receiving the antibiotic, were separately propensity score-matched (1:2). Attributable mortality was the in-hospital mortality difference among propensity-matched groups. Infection characteristics and sepsis severity influences on attributable mortality were examined. Algorithm accuracy was assessed by chart review.

RESULTS

Of 232,834 GNIs between 2010 and 2013 at 79 hospitals, 1,023 per 3,350 (30.5%) colistin and 9,188 per 105,641 (8.7%) β-lactam (non-carbapenem) comparator cases died. Propensity-matched colistin and β-lactam case mortality was 29.2% and 16.6%, respectively, for an attributable mortality of 12.6% (95% confidence interval 10.8-14.4%). Attributable mortality varied from 11.0% (7.5%-14.7%) for urinary to 15.5% (12.6%-18.4%) for respiratory (P < .0001), and 4.6% (2.1%-7.4%) for early (≤4 days) to 16.6% (14.3%-18.9%) for late-onset infections (P < .0001). Attributable mortality decreased to 7.5% (5.6%-9.4%) using a carbapenem comparator cohort but increased 9-fold in patients coded for severe sepsis or septic shock (P < .0001). Our colistin algorithm had a positive predictive value of 60.4% and sensitivity of 65.3%.

CONCLUSIONS

Mortality attributable to treatment-limiting resistance during GNIs varied considerably by site, onset, and severity of infection.

External Validation of Difficult-to-Treat Resistance Prevalence and Mortality Risk in Gram-Negative Bloodstream Infection Using Electronic Health Record Data From 140 US Hospitals

Difficult-to-treat resistance (DTR; ie, co-resistance to all first-line antibiotics) in gram-negative bloodstream infection (GNBSI) is associated with decreased survival in administrative data models. We externally validated DTR prevalence and associated mortality risk in GNBSI using detailed clinical data from electronic health records to adjust for baseline differences in acute illness severity.

Rapid detection of colistin resistance protein MCR-1 by LC-MS/MS

Background

Colistin (polymyxin E) and polymixin B are important bactericidal antibiotics used in the treatment of serious infections caused by multi-drug resistant Gram-negative organisms. Transferrable plasmid-mediated colistin resistance, conferred by the product of the mcr-1 gene, has emerged as a global healthcare threat. Consequently, the rapid detection of the MCR-1 protein in clinical bacterial isolates has become increasingly important. We used a genoproteomic approach to identify unique peptides of the MCR-1 protein that could be detected rapidly by liquid chromatography tandem mass spectrometry (LC–MS/MS).

Methods

MCR-1 tryptic peptides that were efficiently ionized and readily detectable were characterized in a set of mcr-1-containing isolates with triple quadrupole LC–MS. Three optimal peptides were selected for the development of a rapid multiple reaction monitoring LC–MS/MS assay for the MCR-1 protein. To investigate the feasibility of rapid detection of the MCR-1 protein in bacterial isolates using this assay, a blinded 99-sample test set was built that included three additional mcr-1-containing clinical isolates tested in triplicate (9 samples) and 90 negative control isolates.

Results

All of the mcr-1-containing isolates in the test set were accurately identified with no false positive detections by three independent, blinded operators, yielding an overall performance of 100% sensitivity and specificity for multiple operators. Among the three peptides tested in this study, the best performing was DTFPQLAK. The isolate-to-result time for the assay as implemented is less than 90 min.

Conclusions

This work demonstrates the feasibility of rapid detection of the MCR-1 protein in bacterial isolates by LC–MS/MS.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9228-2) contains supplementary material, which is available to authorized users.

2398. Utilization Practices of Ceftazidime–Avibactam at Academic Medical Centers in the United States

Background

Ceftazidime–avibactam (CAV) was US FDA-approved for complicated intra-abdominal/urinary tract infections in 2015, and for hospital-acquired/ventilator-associated pneumonia in 2018. However, little is known about its real-world use.

Methods

Encounters of inpatients receiving CAV at academic hospitals in the Vizient^TM Clinical Resource Manager were identified (CAV encounters). CAV administered for ≤2 consecutive days during an encounter or any duration of CAV within 2 days of admission (excluding acute care hospital transfers) was considered empiric therapy. Targeted therapy was defined as ≥4 consecutive days or death within 2 days of therapy; empiric and targeted therapy cohorts were mutually inclusive. CAV-encounter characteristics, use patterns and Infectious Disease (ID) consultation were examined. Quarterly hospital uptake of CAV and % change in CAV encounter prevalence (using Poisson regression) were calculated.

Results

From January 2015 to December 2017, 20,590 CAV doses occurred in 2,128 encounters among 1,652 patients. Mean duration of therapy was 8 ± 7.9 days (range 1–86); overall mortality was 24%. The number of hospitals prescribing CAV increased from 5 to 92/168 and quarterly prevalence of CAV encounters increased from 5/10,000 hospitalizations in 2015q1 to 9.8 in 2017q4 (% change=2.1[0.7–3.6] %/quarter; (P = 0.004). Therapy was empiric in 904 (42%) encounters and targeted in 1,472 (69%); 63% of empiric CAV was initiated within 2 days of admission. CAV was initiated in the ICU in 862 (40.5%) encounters. Infection site was coded as respiratory in 34%, urinary in 26% and abdominal in 16% of encounters. Within 31 hospitals reporting consultant specialty, 29% of targeted therapy occurred without ID consultation. For targeted therapy encounters, CAV monotherapy occurred in 841 (57%) and combination therapy in 631 (43%) encounters, which most often included aminoglycosides, colistin or tigecycline. Mortality was 22% in the monotherapy and 25% in the combination therapy group (P = 0.08).

Conclusion

CAV use across US academic medical centers has increased modestly over 3 years. More than 40% of CAV prescriptions appear to be empiric and targeted therapy often occurs without ID consultation at academic centers.

Disclosures

All authors: No reported disclosures.

Use of sacubitril/valsartan in acute decompensated heart failure: a case report

Refractory heart failure typically requires costly long-term, continuous intravenous inodilator infusions while patients await mechanical circulatory support or cardiac transplantation. The combined angiotensin receptor blocker-neprilysin inhibitor, sacubitril/valsartan, is a novel therapy that can increase levels of endogenous vasoactive peptides. This therapy has been recommended as an alternative agent in patients with chronic heart failure with reduced ejection fraction and New York Heart Association class II-III symptoms. Here, we report a case of a patient with refractory stage D heart failure with reduced ejection fraction who was successfully weaned off continuous intravenous inodilator support using sacubitril/valsartan after prior failed attempts using standard therapies.

Successful salvage chemotherapy and allogeneic transplantation of an acute myeloid leukemia patient with disseminated Fusarium solani infection

Disseminated Fusarium infection is associated with high mortality in immunocompromised patients. Patients with acute myeloid leukemia (AML) often have an extended duration of neutropenia during intensive induction chemotherapy, consolidation chemotherapy, and hematopoietic stem cell transplantation (SCT). There is no consensus regarding management of invasive disseminated Fusarium infections in the setting of prolonged neutropenia (Tortorano et al., 2014) [1]. We report a case of disseminated Fusarium in a patient with relapsed AML who underwent successful chemotherapy and haplo-identical allogeneic SCT with administration of granulocyte colony stimulating factor (G-CSF) and granulocyte infusions.

Preventing Transmission of Multidrug-Resistant Pathogens in the Intensive Care Unit

Infection control in the intensive care unit (ICU) has seen many advances, including rapid molecular screening tests for resistant organisms and chlorhexidine use in daily baths. Although these developments advance the cause of infection prevention, compliance with some of the basic measures remains elusive. Hand hygiene, antimicrobial stewardship, and reduction in device use remain the low-technology interventions that could have a major impact on nosocomial transmission of antimicrobial-resistant organisms. Although continued research is needed on new and old ways of preventing nosocomial infections, ICU staff must persevere in improving adherence with the measures that are known to be effective.

Estimating Ten-Year Trends in Septic Shock Incidence and Mortality in United States Academic Medical Centers Using Clinical Data

BACKGROUND

Reports that septic shock incidence is rising and mortality rates declining may be confounded by improving recognition of sepsis and changing coding practices. We compared trends in septic shock incidence and mortality in academic hospitals using clinical vs claims data.

METHODS

We identified all patients with concurrent blood cultures, antibiotics, and vasopressors for ≥ two consecutive days, and all patients with International Classification of Diseases, 9th edition (ICD-9) codes for septic shock, at 27 academic hospitals from 2005 to 2014. We compared annual incidence and mortality trends. We reviewed 967 records from three hospitals to estimate the accuracy of each method.

RESULTS

Of 6.5 million adult hospitalizations, 99,312 (1.5%) were flagged by clinical criteria, 82,350 (1.3%) by ICD-9 codes, and 44,651 (0.7%) by both. Sensitivity for clinical criteria was higher than claims (74.8% vs 48.3%; P < .01), whereas positive predictive value was comparable (83% vs 89%; P = .23). Septic shock incidence, based on clinical criteria, rose from 12.8 to 18.6 cases per 1,000 hospitalizations (average, 4.9% increase/y; 95% CI, 4.0%-5.9%), while mortality declined from 54.9% to 50.7% (average, 0.6% decline/y; 95% CI, 0.4%-0.8%). In contrast, septic shock incidence, based on ICD-9 codes, increased from 6.7 to 19.3 per 1,000 hospitalizations (19.8% increase/y; 95% CI, 16.6%-20.9%), while mortality decreased from 48.3% to 39.3% (1.2% decline/y; 95% CI, 0.9%-1.6%).

CONCLUSIONS

A clinical surveillance definition based on concurrent vasopressors, blood cultures, and antibiotics accurately identifies septic shock hospitalizations and suggests that the incidence of patients receiving treatment for septic shock has risen and mortality rates have fallen, but less dramatically than estimated on the basis of ICD-9 codes.

Synergy, Salary, and Satisfaction: Benefits of Training in Critical Care Medicine and Infectious Diseases Gleaned From a National Pilot Survey of Dually Trained Physicians

BACKGROUND

An increasing number of physicians are seeking dual training in critical care medicine (CCM) and infectious diseases (ID). Understanding experiences and perceptions of CCM-ID physicians could inform career choices and programmatic innovation.

METHODS

All physicians trained and/or certified in both CCM and ID to date in the United States were sent a Web-based questionnaire in 2015. Responses enabled a cross-sectional analysis of physician demographics and training and practice characteristics and satisfaction.

RESULTS

Of 202 CCM-ID physicians, 196 were alive and reachable. The response rate was 79%. Forty-six percent trained and 34% practice in the northeastern United States. Only 40% received dual training at the same institution. Eighty-three percent identified as either an intensivist with ID expertise (44%) or as equally an intensivist and ID physician (38%). Median salary was $265 000 (interquartile range [IQR], $215 000-$350 000). Practice settings were split between academic (45%) and community settings (42%). Two-thirds are clinicians but 62% conduct some research and 26% practice outpatient ID. Top reasons to dually specialize included clinical synergy (70%), procedural activity (50%), and less interest in pulmonology (49%). Although 38% cited less proficiency with bronchoscopy as a disadvantage, 87% seldom need pulmonary consultation in the intensive care unit. Median career satisfaction was 4 (IQR, 4-5) out of 5, and 76% would dually train again.

CONCLUSIONS

CCM-ID graduates prefer the acute care setting, predominantly CCM or a combination of CCM and ID. They find combination training and practice to be synergistic and satisfying, but most have had to seek CCM and ID training independently at separate institutions. Given these findings, avenues for combined training in CCM-ID should be considered.

Role of granulocyte transfusions in invasive fusariosis: systematic review and single-center experience

BACKGROUND

Invasive Fusarium infection is relatively refractory to available antifungal agents. Invasive fusariosis (IF) occurs almost exclusively in the setting of profound neutropenia and/or systemic corticosteroid use. Treatment guidelines for IF are not well established, including the role of granulocyte transfusions (GTs) to counter neutropenia.

STUDY DESIGN AND METHODS

We conducted a systematic review, identifying IF cases where GTs were used as adjunctive therapy to antifungal agents and also report a single-center case series detailing our experience (1996-2012) of all IF cases treated with antifungal agents and GTs. In the systematic review cases, GTs were predominantly collected from nonstimulated donors whereas, in the case series, they were universally derived from dexamethasone- and granulocyte-colony-stimulating factor-stimulated donors.

RESULTS

Twenty-three patients met inclusion criteria for the systematic review and 11 for the case series. Response rates after GTs were 30 and 91% in the review and case series, respectively. Survival to hospital discharge remained low at 30 and 45%, respectively. Ten patients in the systematic review and three in the case series failed to achieve hematopoietic recovery and none of these survived. In the case series, donor-stimulated GTs generated mean "same-day" neutrophil increments of 3.35 × 10(9)  ± 1.24 × 10(9) /L and mean overall posttransfusion neutrophil increments of 2.46 × 10(9)  ± 0.85 × 10(9) /L. Progressive decrements in neutrophil response to GTs in two cases were attributed to GT-related HLA alloimmunization.

CONCLUSION

In patients with IF, donor-stimulated GTs may contribute to high response rates by effectively bridging periods of neutropenia or marrow suppression. However, their utility in the absence of neutrophil recovery remains questionable.

Tracking colistin-treated patients to monitor the incidence and outcome of carbapenem-resistant Gram-negative infections

BACKGROUND

Existing surveillance mechanisms may underestimate the incidence of carbapenem-resistant gram-negative infections (CRGNIs). Although carbapenem resistance increases the risk of death, the trend in mortality over time is unknown.

METHODS

A retrospective cohort study was conducted at 40 academic medical centers using a discharge database to identify adult hospital admissions without cystic fibrosis in 2006-2012 and received intravenous colistin for >3 consecutive days or died during therapy (termed colistin cases). The primary outcomes were the number of colistin cases per 100,000 admissions per year and change in the hospital mortality rate over time compared with the rate of discharges to home. Secondary outcomes included median overall and intensive care unit lengths of stay.

RESULTS

From 2006 to 2012, a total of 5011 unique patients were identified as colistin cases. The number per 100,000 admissions per year increased from 35.56 to 92.98 during the 7-year study (P < .001). The odds of in-hospital death among colistin cases (compared with discharge to home) decreased by a mean of 5.2%/y (P = .04), whereas discharge to an institution (P = .24) or hospice (P = .89) remained steady over time. The median overall and intensive care unit lengths of stay decreased by 7.5 and 6 days, respectively (P < .001). In a 4-hospital chart review, 81.6% of colistin cases were found to have culture-positive CRGNIs. Conversely, 53% of extensively drug-resistant bloodstream CRGNIs at 2 of these hospitals met colistin case criteria.

CONCLUSIONS

Colistin cases represent a severely ill population with a high probability of having culture-confirmed CRGNIs. Colistin tracking is a novel strategy for monitoring the incidence and mortality of CRGNIs, particularly those caused by extensively drug-resistant bacteria. Although the incidence of colistin cases nearly tripled within 7 years, more of these patients are surviving hospitalization and going home.