The role of the hospital bed in hospital-onset Clostridioides difficile: A retrospective study with mediation analysis

OBJECTIVE

To determine whether residing in a hospital bed that previously held an occupant with Clostridioides difficile increases the risk of hospital-onset C. difficile infection (HO-CDI).

METHODS

In this retrospective cohort study, we used a real-time location system to track the movement of hospital beds in 2 academic hospitals from April 2018 to August 2019. We abstracted patient demographics, clinical characteristics, and C. difficile polymerase chain reaction (PCR) results from the medical record. We defined patients as being exposed to a potentially "contaminated" bed or room if, within the preceding 7 days from their HO-CDI diagnosis, they resided in a bed or room respectively, that held an occupant with C. difficile in the previous 90 days. We used multivariable logistic regression to determine whether residing in a contaminated bed was associated with HO-CDI after controlling for time at risk and requiring intensive care. We assessed mediation and interaction from a contaminated hospital room.

RESULTS

Of 25,032 hospital encounters with 18,860 unique patients, we identified 237 cases of HO-CDI. Exposure to a contaminated bed was associated with HO-CDI in unadjusted analyses (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.4-2.31) and adjusted analyses (OR, 1.5; 95% CI, 1.2-2.0). Most of this effect was due to both mediation from and interaction with a contaminated hospital room.

CONCLUSIONS

Residing in a hospital bed or room that previously had a patient with C. difficile increases the risk of HO-CDI. Increased attention to cleaning and disinfecting the healthcare environment may reduce hospital transmission of C. difficile.

Rates of resistance and heteroresistance to newer β-lactam/β-lactamase inhibitors for carbapenem-resistant Enterobacterales

Background

Heteroresistance (HR), the presence of antibiotic-resistant subpopulations within a primary isogenic population, may be a potentially overlooked contributor to newer β-lactam/β-lactamase inhibitor (BL/BLI) treatment failure in carbapenem-resistant Enterobacterales (CRE) infections.

Objectives

To determine rates of susceptibility and HR to BL/BLIs ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam in clinical CRE isolates.

Methods

The first CRE isolate per patient per year from two >500 bed academic hospitals from 1 January 2016 to 31 December 2021, were included. Reference broth microdilution (BMD) was used to determine antibiotic susceptibility, and population analysis profiling (PAP) to determine HR. Carbapenemase production (CP) was determined using the Carba NP assay.

Results

Among 327 CRE isolates, 46% were Enterobacter cloacae, 38% Klebsiella pneumoniae and 16% Escherichia coli. By BMD, 87% to 98% of CRE were susceptible to the three antibiotics tested. From 2016 to 2021, there were incremental decreases in the rates of susceptibility to each of the three BL/BLIs. HR was detected in each species-antibiotic combination, with the highest rates of HR (26%) found in K. pneumoniae isolates with imipenem/relebactam. HR or resistance to at least one BL/BLI by PAP was found in 24% of CRE isolates and 65% of these had detectable CP.

Conclusion

Twenty-four percent of CRE isolates tested were either resistant or heteroresistant (HR) to newer BL/BLIs, with an overall decrease of ∼10% susceptibility over 6 years. While newer BL/BLIs remain active against most CRE, these findings support the need for ongoing antibiotic stewardship and a better understanding of the clinical implications of HR in CRE.

Associations Between HIV and Severe Mpox in an Atlanta Cohort

BACKGROUND

In the Southeastern United States, the 2022 mpox outbreak disproportionately impacted people who are black and people with HIV (PWH).

METHODS

We analyzed a cohort of 395 individuals diagnosed with mpox across 3 health care systems in Atlanta, Georgia between 1 June 2022 and 7 October 2022. We present demographic and clinical characteristics and use multivariable logistic regression analyses to evaluate the association between HIV status and severe mpox (per the US Centers for Disease Control and Prevention definition) and, among PWH, the associations between CD4+ T-cell count and HIV load with severe mpox.

RESULTS

Of 395 people diagnosed with mpox, 384 (97.2%) were cisgender men, 335 (84.8%) identified as black, and 324 (82.0%) were PWH. Of 257 PWH with a known HIV load, 90 (35.0%) had > 200 copies/mL. Severe mpox occurred in 77 (19.5%) individuals and there was 1 (0.3%) death. Tecovirimat was prescribed to 112 (28.4%) people, including 56 (72.7%) people with severe mpox. In the multivariable analysis of the total population, PWH had 2.52 times higher odds of severe mpox (95% confidence interval [CI], 1.01-6.27) compared with people without HIV. In the multivariable analysis of PWH, individuals with HIV load > 200 copies/mL had 2.10 (95% CI, 1.00-4.39) times higher odds of severe mpox than PWH who were virologically suppressed. Lower CD4+ T-cell count showed a significant univariate association with severe mpox but was not found to be significantly associated with severe mpox in multivariable analysis.

CONCLUSIONS

PWH with nonsuppressed HIV loads had more mpox complications, hospitalizations, and protracted disease courses than people without HIV or PWH with suppressed viral loads. PWH with nonsuppressed HIV loads who are diagnosed with mpox warrant particularly aggressive monitoring and treatment.

Early Tecovirimat Treatment for Mpox Disease Among People With HIV

Importance

Despite a lack of effectiveness data in humans, tecovirimat was widely prescribed to people with HIV (PWH) with mpox during the 2022 mpox epidemic, particularly PWH with low CD4+ T-cell counts or severe mpox clinical manifestations.

Objective

To evaluate if PWH with mpox who were treated with tecovirimat within 7 days of symptom onset were less likely to have mpox disease progression.

Design, Setting, and Participants

This cohort study included PWH diagnosed with mpox at 4 hospitals in Atlanta, Georgia, between June 1 and October 7, 2022. Patients were grouped according to whether they were treated with tecovirimat within 7 days of mpox symptom onset (early tecovirimat cohort) or they did not receive tecovirimat or received the drug 7 or more days after symptom onset (late or no tecovirimat cohort). Multivariable logistic regression models were used to identify factors associated with progression of mpox disease. The 2 cohorts were then matched 1:1 using propensity scores based on the identified factors, and mpox disease progression was compared.

Exposures

Treatment with tecovirimat within 7 days of mpox symptom onset.

Main Outcome and Measures

Progression of mpox disease, defined as the development of at least 1 severe mpox criterion established by the US Centers for Disease Control and Prevention, after symptom day 7.

Results

After propensity score matching, a total of 112 PWH were included in the analysis; 56 received tecovirimat within 7 days of mpox symptom onset (early tecovirimat group) and 56 were either treated later or did not receive tecovirimat (late or no tecovirimat group). In the early tecovirimat group, the median (IQR) age was 35 (30-42) years; 54 individuals (96.4%) were cisgender men, 46 (82.1%) were Black individuals, and 10 (17.9%) were individuals of other races (American Indian or Alaska Native, Asian, Native Hawaiian or Other Pacific Islander, or White) or unknown race. In the late or no tecovirimat group, the median (IQR) age was 36 (32-43) years; 54 (96.4%) were cisgender men, 49 (87.5%) were Black individuals, and 7 (12.5%) were individuals of other races or unknown race. Mpox disease progression occurred in 3 PWH (5.4%) in the early tecovirimat group and in 15 PWH (26.8%) in the late or no tecovirimat group (paired odds ratio, 13.00 [95% CI, 1.71-99.40]; P = .002).

Conclusion and Relevance

Results of this cohort study support starting tecovirimat in all PWH as soon as an mpox diagnosis is suspected. Additional research is warranted to confirm these findings.

Evaluating indwelling devices and other risk factors for mortality in invasive Carbapenem-resistant Enterobacterales infections in Georgia, 2012-2019

Objective

Carbapenem-resistant Enterobacterales (CRE) infections are a public health threat due to the risk of transmission between patients and high associated mortality. We sought to identify risk factors for mortality in patients with invasive CRE infections and to specifically evaluate whether there was an association between indwelling medical devices and 90-day mortality.

Design

Retrospective observational cohort study of patients infected with CRE in the eight-county metropolitan Atlanta area between 2012 and 2019.

Methods

Patients with invasive CRE infections were identified via the Georgia Emerging Infections Program's active, population- and laboratory-based surveillance system and linked with the Georgia Vital Statistics database. We used bivariate analysis to identify risk factors for mortality and completed log binomial multivariable regression to estimate risk ratios (RR) for the association between indwelling devices and mortality.

Results

In total, 154 invasive CRE infections were identified, with indwelling devices present in most patients (87.7%) around the time of infection. Admission to an intensive care unit was found to be associated with 90-day mortality (adjusted RR [aRR] 1.55, 95% CI 1.07, 2.24); however, the presence of any indwelling device was not associated with increased risk of 90-day mortality in multivariable analysis (aRR 1.22, 95% CI 0.55, 2.73). Having at least two indwelling devices was associated with increased mortality (aRR 1.79, 95% CI 1.05, 3.05).

Conclusions

Indwelling devices were prevalent in our cohort but were not consistently associated with an increased risk of mortality. Further studies are needed to examine this relationship and the role of device removal.

Effect of an initial specimen diversion device on blood-culture contamination rates and vancomycin usage: A quasi-experimental study

Initial specimen diversion devices (ISDDs) are a potential solution for reducing blood-culture contamination rates. We report the implementation of an ISDD associated with a sustained reduction in blood-culture contamination rates for >18 months after implementation. We did not observe a clinically significant reduction in inpatient vancomycin usage.

Trends in Incidence of Carbapenem-Resistant Enterobacterales in 7 US Sites, 2016─2020

Background

We described changes in 2016─2020 carbapenem-resistant Enterobacterales (CRE) incidence rates in 7 US sites that conduct population-based CRE surveillance.

Methods

An incident CRE case was defined as the first isolation of Escherichia coli, Klebsiella spp., or Enterobacter spp. resistant to ≥1 carbapenem from a sterile site or urine in a surveillance area resident in a 30-day period. We reviewed medical records and classified cases as hospital-onset (HO), healthcare-associated community-onset (HACO), or community-associated (CA) CRE based on healthcare exposures and location of disease onset. We calculated incidence rates using census data. We used Poisson mixed effects regression models to perform 2016─2020 trend analyses, adjusting for sex, race/ethnicity, and age. We compared adjusted incidence rates between 2016 and subsequent years using incidence rate ratios (RRs) and 95% confidence intervals (CIs).

Results

Of 4996 CRE cases, 62% were HACO, 21% CA, and 14% HO. The crude CRE incidence rate per 100 000 was 7.51 in 2016 and 6.08 in 2020 and was highest for HACO, followed by CA and HO. From 2016 to 2020, the adjusted overall CRE incidence rate decreased by 24% (RR, 0.76 [95% CI, .70-.83]). Significant decreases in incidence rates in 2020 were seen for HACO (RR, 0.75 [95% CI, .67-.84]) and CA (0.75 [.61-.92]) but not for HO CRE.

Conclusions

Adjusted CRE incidence rates declined from 2016 to 2020, but changes over time varied by epidemiologic class. Continued surveillance and effective control strategies are needed to prevent CRE in all settings.

Development of a Broth Microdilution Method To Characterize Chlorhexidine MICs among Bacteria Collected from 2005 to 2019 at Three U.S. Sites

Chlorhexidine bathing to prevent transmission of multidrug-resistant organisms has been adopted by many U.S. hospitals, but increasing chlorhexidine use has raised concerns about possible emergence of resistance. We sought to establish a broth microdilution method for determining chlorhexidine MICs and then used the method to evaluate chlorhexidine MICs for bacteria that can cause health care-associated infections. We adapted a broth microdilution method for determining chlorhexidine MICs, poured panels, established quality control ranges, and tested Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae complex isolates collected at three U.S. sites. Chlorhexidine MICs were determined for 535 isolates including 129 S. aureus, 156 E. coli, 142 K. pneumoniae, and 108 E. cloacae complex isolates. The respective MIC distributions for each species ranged from 1 to 8 mg/L (MIC50 = 2 mg/L and MIC90 = 4 mg/L), 1 to 64 mg/L (MIC50 = 2 mg/L and MIC90 = 4 mg/L), 4 to 64 mg/L (MIC50 = 16 mg/L and MIC90 = 32 mg/L), and 1 to >64 mg/L (MIC50 = 16 mg/L and MIC90 = 64 mg/L). We successfully adapted a broth microdilution procedure that several laboratories were able to use to determine the chlorhexidine MICs of bacterial isolates. This method could be used to investigate whether chlorhexidine MICs are increasing. IMPORTANCE Chlorhexidine bathing to prevent transmission of multidrug-resistant organisms and reduce health care-associated infections has been adopted by many hospitals. There is concern about the possible unintended consequences of using this agent widely. One possible unintended consequence is decreased susceptibility to chlorhexidine, but there are not readily available methods to perform this evaluation. We developed a method for chlorhexidine MIC testing that can be used to evaluate for possible unintended consequences.

Carbapenem-Resistant enterobacterales in individuals with and without health care risk factors -Emerging infections program, United States, 2012-2015

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are usually healthcare-associated but are also emerging in the community.

METHODS

Active, population-based surveillance was conducted to identify case-patients with cultures positive for Enterobacterales not susceptible to a carbapenem (excluding ertapenem) and resistant to all third-generation cephalosporins tested at 8 US sites from January 2012 to December 2015. Medical records were used to classify cases as health care-associated, or as community-associated (CA) if a patient had no known health care risk factors and a culture was collected <3 days after hospital admission. Enterobacterales isolates from selected cases were submitted to CDC for whole genome sequencing.

RESULTS

We identified 1499 CRE cases in 1194 case-patients; 149 cases (10%) in 139 case-patients were CA. The incidence of CRE cases per 100,000 population was 2.96 (95% CI: 2.81, 3.11) overall and 0.29 (95% CI: 0.25, 0.35) for CA-CRE. Most CA-CRE cases were in White persons (73%), females (84%) and identified from urine cultures (98%). Among the 12 sequenced CA-CRE isolates, 5 (42%) harbored a carbapenemase gene.

CONCLUSIONS

Ten percent of CRE cases were CA; some isolates from CA-CRE cases harbored carbapenemase genes. Continued CRE surveillance in the community is critical to monitor emergence outside of traditional health care settings.

The impact of COVID-19 on multidrug-resistant organisms causing healthcare-associated infections: a narrative review

Coronavirus disease 2019 (COVID-19) changed healthcare across the world. With this change came an increase in healthcare-associated infections (HAIs) and a concerning concurrent proliferation of MDR organisms (MDROs). In this narrative review, we describe the impact of COVID-19 on HAIs and MDROs, describe potential causes of these changes, and discuss future directions to combat the observed rise in rates of HAIs and MDRO infections.

416. Evaluating Indwelling Devices and Mortality in Invasive Carbapenem-Resistant Enterobacterales Infections, Atlanta, GA, 2012–2019

Background

Carbapenem-resistant Enterobacterales (CRE) infections pose a grave public health threat due to the potentially silent transmission leading to outbreaks, limited therapeutic options and high mortality. We sought to identify risk factors for mortality in patients with invasive CRE infections and describe the association between indwelling medical devices and 90-day mortality.

Methods

The Georgia Emerging Infections Program performs active population and laboratory based surveillance for CRE in the Atlanta, Georgia metropolitan area. Using this data we created a retrospective observational cohort of patients with invasive CRE infections between 2012 and 2019. Invasive infections were defined as resistant isolates obtained from a normally sterile site (Table 1). Indwelling medical devices, including central venous catheters (CVCs), were present within two calendar days prior to infection.

We completed bivariate analyses examining the relationship between covariates and mortality. Multivariable log binomial regression was used to estimate adjusted risk ratios (aRR) for the association of covariates and all-cause 90-day mortality. Sub-group analyses were completed evaluating only those patients with CVCs and those with at least two indwelling devices. Table 1.

86. Antibiotic-resistant gram-negative bacterial infections among persons with or without a prior positive test for SARS-CoV-2 in 10 U.S. sites, 2020

Background

The Centers for Disease Control and Prevention’s Emerging Infections Program (EIP) conducts active laboratory- and population-based surveillance for carbapenem-resistant Enterobacterales (CRE), extended spectrum beta-lactamase-producing Enterobacterales (ESBL-E), and carbapenem-resistant Acinetobacter baumannii (CRAB) in 10 U.S. sites. To describe the impact of the COVID-19 pandemic on the epidemiology of these antibiotic-resistant gram-negative bacteria (AR-GNB), we assessed characteristics of AR-GNB patients with and without a prior SARS-CoV-2 positive (SC2+) viral test.

Methods

In 2020 among EIP catchment-area residents, an incident CRAB or CRE case was defined as the first isolation of A. baumannii complex, Escherichia coli, Enterobacter cloacae complex, Klebsiella aerogenes, K. oxytoca, K. pneumonia, or K. variicola in a 30-day period resistant to ≥1 carbapenem (excluding ertapenem for CRAB) from a normally sterile site or urine. An incident ESBL-E case was defined as the first isolation of E. coli, K. pneumonia, or K. oxytoca in a 30-day period resistant to any third-generation cephalosporin and non-resistant to all carbapenems from a normally sterile site or urine. Patient charts were reviewed.

Results

Of 3904 AR-GNB cases with data available, 163 (4%) had a prior SC2+ test (85 ESBL-E, 70 CRE, and 8 CRAB). Median time from the most recent SC2+ test to AR-GNB culture date was 20 days (IQR 1–48 days). AR-GNB cases with a SC2+ test versus those without were more likely to be Black, non-Hispanic than another race/ethnicity (31% vs 15%; P< 0.0001), aged ≥65 years (62% vs 52%; P=0.0139), and to have prior healthcare exposures (63% vs 49%; P=0.0003) and indwelling devices (51% vs 28%; P< 0.0001). They were also more likely to have bacteremia (24% vs 11%; P< 0.0001), pneumonia (6% vs 1%; P< 0.0001) and be hospitalized around the time of their AR-GNB culture (67% vs 36%; P< 0.0001); median time from SC2+ test to hospital admission was 0.5 day (IQR 0–29.5 days).

Conclusion

AR-GNB infections preceded by a SC2+ test were rare but more severe and associated with more healthcare risk factors. This underscores the need for continued infection prevention and control practices and monitoring of these infections during the COVID-19 pandemic.

Disclosures

Ghinwa Dumyati, MD, Pfizer: Grant/Research Support.

1666. Sources and Preventability of Hospital-onset Bacteremia and Fungemia in the United States: Evaluation of a Potential Healthcare Quality Measure

Background

Hospital-onset bacteremia and fungemia (HOB) is being proposed as a potential healthcare quality measure due to its clinical significance, objectivity, and ease of detection. However, information is lacking on sources of HOB and the proportion and types of cases considered preventable.

Methods

We evaluated sources and potential preventability of HOB cases at 12 hospitals using retrospective chart review. HOB was defined as a positive blood culture &gt;= day 4 (admission date=day 1) for one or more organisms. Stratified sampling of cases by commensal and noncommensal organisms was used. Infectious disease physicians determined the source of HOB and rated preventability from 1-6 (1=definitely preventable to 6=definitely not preventable) using a previously validated guide. Ratings of 1–3 were collectively considered potentially preventable and 4–6 likely not preventable.

Results

We evaluated sources and potential preventability of HOB cases at 12 hospitals using retrospective chart review. HOB was defined as a positive blood culture &gt;= day 4 (admission date=day 1) for one or more organisms. Stratified sampling of cases by commensal and noncommensal organisms was used. Infectious disease physicians determined the source of HOB and rated preventability from 1–6 (1=definitely preventable to 6=definitely not preventable) using a previously validated guide. Ratings of 1–3 were collectively considered potentially preventable and 4–6 likely not preventable.

Conclusion

Gastrointestinal and endovascular sources account for a large majority of noncommensal HOB cases. A high proportion of noncommensal HOB cases are likely not preventable. The presence of non-preventable events should be considered when using HOB as a quality measure. Approaches to identifying the subset of preventable noncommensal HOB events should be explored.

Disclosures

Scott Fridkin, MD, Pfizer: Grant/Research Support Andi L. Shane, MD, MPH, MSc, International Scientific Association for Probiotics and Prebiotics (ISAPP): travel and lodging to attend international meeting to deliver a presentation, June 2022 Aaron Milstone, MD, Merck: Grant/Research Support Rajeshwari Nair, MBBS, PhD, Vertex Pharmaceuticals: Salary.

1215. Variation in Hand Hygiene Improvement After Implementation of an Electronic Hand Hygiene System During the COVID-19 Pandemic

Background

Electronic hand hygiene (HH) monitoring systems have many potential advantages but there are limited data on wide-scale implementation of these systems. Table

Hand Hygiene Observations, Improvement in Adherence Rates and SIR Trends by Hospital

Methods

We deployed an electronic HH monitoring system in over 2,100 acute and critical care rooms across 9 hospitals in an academic health system. Badges with a Bluetooth beacon were issued to over 7,000 healthcare workers. Deployment began in early 2020 and was interrupted by the pandemic. The rollout of interventions to improve HH adherence was managed at the hospital level. Healthcare-associated infections (HAIs) were determined by the infection prevention team using standard CDC definitions. Hospital-level HH adherence rates were compared to a composite SIR including SIRs for CLABSI, CAUTI, hospital-onset MRSA bloodstream infections and hospital-onset Clostridiodes difficile infections.

Results

Between January 2020 and April 2022, there were over 36 million hand hygiene opportunities with an average of 19 observations per staffed room per day. Overall HH adherence improved from 46% to 60%, with significant variation by hospital (4 improving by >25% and 3 by < 5%). Hospitals whose implementation was most delayed showed the least improvement. Preliminary analysis found no relationship between hand hygiene improvement and the SIR composite aggregated by calendar year.

Conclusion

Despite the challenges of large-scale implementation of an electronic HH system during a pandemic, we demonstrated an overall improvement in HH adherence. The wide variation in improvement among hospitals was due to timing of implementation, variation in the dedicated hospital-specific project management resources and leadership engagement. In addition to technology, successful implementation of electronic HH systems requires dedicated resources and culture change. Pandemic-related staffing challenges, disruption of standard HAI prevention efforts and intensive device utilization confounded our ability to show a relationship between HH adherence and HAI rates.

Disclosures

All Authors: No reported disclosures.

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Poor outcomes in both infection and colonization with carbapenem-resistant Enterobacterales

OBJECTIVES

To describe the epidemiology of patients with nonintestinal carbapenem-resistant Enterobacterales (CRE) colonization and to compare clinical outcomes of these patients to those with CRE infection.

DESIGN

A secondary analysis of Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae 2 (CRACKLE-2), a prospective observational cohort.

SETTING

A total of 49 US short-term acute-care hospitals.

PATIENTS

Patients hospitalized with CRE isolated from clinical cultures, April, 30, 2016, through August 31, 2017.

METHODS

We described characteristics of patients in CRACKLE-2 with nonintestinal CRE colonization and assessed the impact of site of colonization on clinical outcomes. We then compared outcomes of patients defined as having nonintestinal CRE colonization to all those defined as having infection. The primary outcome was a desirability of outcome ranking (DOOR) at 30 days. Secondary outcomes were 30-day mortality and 90-day readmission.

RESULTS

Of 547 patients with nonintestinal CRE colonization, 275 (50%) were from the urinary tract, 201 (37%) were from the respiratory tract, and 71 (13%) were from a wound. Patients with urinary tract colonization were more likely to have a more desirable clinical outcome at 30 days than those with respiratory tract colonization, with a DOOR probability of better outcome of 61% (95% confidence interval [CI], 53%-71%). When compared to 255 patients with CRE infection, patients with CRE colonization had a similar overall clinical outcome, as well as 30-day mortality and 90-day readmission rates when analyzed in aggregate or by culture site. Sensitivity analyses demonstrated similar results using different definitions of infection.

CONCLUSIONS

Patients with nonintestinal CRE colonization had outcomes similar to those with CRE infection. Clinical outcomes may be influenced more by culture site than classification as "colonized" or "infected."

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

Background

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

Methods

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

Results

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

Conclusions

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

Development and evaluation of a structured guide to assess the preventability of hospital-onset bacteremia and fungemia

OBJECTIVE

To assess preventability of hospital-onset bacteremia and fungemia (HOB), we developed and evaluated a structured rating guide accounting for intrinsic patient and extrinsic healthcare-related risks.

DESIGN

HOB preventability rating guide was compared against a reference standard expert panel.

PARTICIPANTS

A 10-member panel of clinical experts was assembled as the standard of preventability assessment, and 2 physician reviewers applied the rating guide for comparison.

METHODS

The expert panel independently rated 82 hypothetical HOB scenarios using a 6-point Likert scale collapsed into 3 categories: preventable, uncertain, or not preventable. Consensus was defined as concurrence on the same category among ≥70% experts. Scenarios without consensus were deliberated and followed by a second round of rating.Two reviewers independently applied the rating guide to adjudicate the same 82 scenarios in 2 rounds, with interim revisions. Interrater reliability was evaluated using the κ (kappa) statistic.

RESULTS

Expert panel consensus criteria were met for 52 scenarios (63%) after 2 rounds.After 2 rounds, guide-based rating matched expert panel consensus in 40 of 52 (77%) and 39 of 52 (75%) cases for reviewers 1 and 2, respectively. Agreement rates between the 2 reviewers were 84% overall (κ, 0.76; 95% confidence interval [CI], 0.64-0.88]) and 87% (κ, 0.79; 95% CI, 0.65-0.94) for the 52 scenarios with expert consensus.

CONCLUSIONS

Preventability ratings of HOB scenarios by 2 reviewers using a rating guide matched expert consensus in most cases with moderately high interreviewer reliability. Although diversity of expert opinions and uncertainty of preventability merit further exploration, this is a step toward standardized assessment of HOB preventability.

Characteristics of community-acquired carbapenem-resistant Enterobacterales

BACKGROUND

Community-acquired carbapenem-resistant Enterobacterales (CA-CRE) are an important threat.

METHODS

In CRACKLE-2, we defined patients with CA-CRE as admitted from home, without pre-existing conditions, and a positive culture within 48 h of admission. Healthcare-associated CRE (HA-CRE) were those with the lowest likelihood of community acquisition, not admitted from home and cultured >48 h after admission. Specific genetic markers in carbapenemase-producing Klebsiella pneumoniae were evaluated through random forest modelling.

RESULTS

CA-CRE and HA-CRE were detected in 83 (10%) and 208 (26%) of 807 patients. No significant differences were observed in bacterial species or strain type distribution. K. pneumoniae (204/291, 70%) was the most common CRE species, of these 184/204 (90%) were carbapenemase producers (CPKP). The top three genetic markers in random forest models were kpi_SA15, fimE, and kpfC. Of these, kpi_SA15 (which encodes a chaperone/usher system) was positively associated (OR 3.14, 95% CI 1.13-8.87, P = 0.026), and kpfC negatively associated (OR 0.21, 95% CI 0.05-0.72, P = 0.015) with CA-CPKP.

CONCLUSIONS

Ten percent of CDC-defined CRE were CA. The true proportion of CA-CRE in hospitalized patients is likely lower as patients may have had unrecorded prior healthcare exposure. The kpi_SA15 operon was associated with the CA phenotype.

Healthcare worker mental models of patient care tasks in the context of infection prevention and control

OBJECTIVE

Understanding the cognitive determinants of healthcare worker (HCW) behavior is important for improving the use of infection prevention and control (IPC) practices. Given a patient requiring only standard precautions, we examined the dimensions along which different populations of HCWs cognitively organize patient care tasks (ie, their mental models).

DESIGN

HCWs read a description of a patient and then rated the similarities of 25 patient care tasks from an infection prevention perspective. Using multidimensional scaling, we identified the dimensions (ie, characteristics of tasks) underlying these ratings and the salience of each dimension to HCWs.

SETTING

Adult inpatient hospitals across an academic hospital network.

PARTICIPANTS

In total, 40 HCWs, comprising infection preventionists and nurses from intensive care units, emergency departments, and medical-surgical floors rated the similarity of tasks. To identify the meaning of each dimension, another 6 nurses rated each task in terms of specific characteristics of tasks.

RESULTS

Each HCW population perceived patient care tasks to vary along 3 common dimensions; most salient was the perceived magnitude of infection risk to the patient in a task, followed by the perceived dirtiness and risk of HCW exposure to body fluids, and lastly, the relative importance of a task for preventing versus controlling an infection in a patient.

CONCLUSIONS

For a patient requiring only standard precautions, different populations of HCWs have similar mental models of how various patient care tasks relate to IPC. Techniques for eliciting mental models open new avenues for understanding and ultimately modifying the cognitive determinants of IPC behaviors.

Clinical and Genomic Epidemiology of mcr-9-Carrying Carbapenem-Resistant Enterobacterales Isolates in Metropolitan Atlanta, 2012 to 2017

Colistin is a last-resort antibiotic for multidrug-resistant Gram-negative infections. Recently, the ninth allele of the mobile colistin resistance (mcr) gene family, designated mcr-9, was reported. However, its clinical and public health significance remains unclear. We queried genomes of carbapenem-resistant Enterobacterales (CRE) for mcr-9 from a convenience sample of clinical isolates collected between 2012 and 2017 through the Georgia Emerging Infections Program, a population- and laboratory-based surveillance program. Isolates underwent phenotypic characterization and whole-genome sequencing. Phenotypic characteristics, genomic features, and clinical outcomes of mcr-9-positive and -negative CRE cases were then compared. Among 235 sequenced CRE genomes, 13 (6%) were found to harbor mcr-9, all of which were Enterobacter cloacae complex. The median MIC and rates of heteroresistance and inducible resistance to colistin were similar between mcr-9-positive and -negative isolates. However, rates of resistance were higher among mcr-9-positive isolates across most antibiotic classes. All cases had significant health care exposures. The 90-day mortality was similarly high in both mcr-9-positive (31%) and -negative (7%) CRE cases. Nucleotide identity and phylogenetic analysis did not reveal geotemporal clustering. mcr-9-positive isolates had a significantly higher number of median [range] antimicrobial resistance (AMR) genes (16 [4 to 22] versus 6 [2 to 15]; P < 0.001) than did mcr-9-negative isolates. Pangenome tests confirmed a significant association of mcr-9 detection with mobile genetic element and heavy metal resistance genes. Overall, the presence of mcr-9 was not associated with significant changes in colistin resistance or clinical outcomes, but continued genomic surveillance to monitor for emergence of AMR genes is warranted. IMPORTANCE Colistin is a last-resort antibiotic for multidrug-resistant Gram-negative infections. A recently described allele of the mobile colistin resistance (mcr) gene family, designated mcr-9, has been widely reported among Enterobacterales species. However, its clinical and public health significance remains unclear. We compared characteristics and outcomes of mcr-9-positive and -negative CRE cases. All cases were acquired in the health care setting and associated with a high rate of mortality. The presence of mcr-9 was not associated with significant changes in colistin resistance, heteroresistance, or inducible resistance but was associated with resistance to other antimicrobials and antimicrobial resistance (AMR), virulence, and heavy metal resistance (HMR) genes. Overall, the presence of mcr-9 was not associated with significant phenotypic changes or clinical outcomes. However, given the increase in AMR and HMR gene content and potential clinical impact, continued genomic surveillance of multidrug-resistant organisms to monitor for emergence of AMR genes is warranted.

Carbapenem-Resistant Acinetobacter baumannii in U.S. Hospitals: Diversification of Circulating Lineages and Antimicrobial Resistance

Carbapenem-resistant Acinetobacter baumannii (CRAb) is a major cause of health care-associated infections. CRAb is typically multidrug resistant, and infection is difficult to treat. Despite the urgent threat that CRAb poses, few systematic studies of CRAb clinical and molecular epidemiology have been conducted. The Study Network of Acinetobacter as a Carbapenem-Resistant Pathogen (SNAP) is designed to investigate the clinical characteristics and contemporary population structure of CRAb circulating in U.S. hospital systems using whole-genome sequencing (WGS). Analysis of the initial 120 SNAP patients from four U.S. centers revealed that CRAb remains a significant threat to hospitalized patients, affecting the most vulnerable patients and resulting in 24% all-cause 30-day mortality. The majority of currently circulating isolates belonged to ST2Pas, a part of clonal complex 2 (CC2), which is the dominant drug-resistant lineage in the United States and Europe. We identified three distinct sublineages within CC2, which differed in their antibiotic resistance phenotypes and geographic distribution. Most concerning, colistin resistance (38%) and cefiderocol resistance (10%) were common within CC2 sublineage C (CC2C), where the majority of isolates belonged to ST2Pas/ST281Ox. Additionally, we identified ST499Pas as the most common non-CC2 lineage in our study. Our findings suggest a shift within the CRAb population in the United States during the past 10 years and emphasize the importance of real-time surveillance and molecular epidemiology in studying CRAb dissemination and clinical impact. IMPORTANCE Carbapenem-resistant Acinetobacter baumannii (CRAb) constitutes a major threat to public health. To elucidate the molecular and clinical epidemiology of CRAb in the United States, clinical CRAb isolates were collected along with data on patient characteristics and outcomes, and bacterial isolates underwent whole-genome sequencing and antibiotic susceptibility phenotyping. Key findings included emergence of new sublineages within the globally predominant clonal complex 2 (CC2), increased colistin and cefiderocol resistance within one of the CC2 sublineages, and emergence of ST499Pas as the dominant non-CC2 CRAb lineage in U.S. hospitals.

Antimicrobial Resistance Through the Lens of One Health in Ethiopia: A Review of the Literature Among Humans, Animals, and the Environment

OBJECTIVES

We aimed to review and describe antimicrobial resistance (AMR) prevalence in humans, animals, and the environment in Ethiopia.

METHODS

We conducted a structured review of the literature on AMR in humans, animals, and the environment in Ethiopia from 2016 to 2020. We reported the pooled prevalence of AMR of bacterial pathogens in all three sectors.

RESULTS

We included 43 articles in our review. Only five studies evaluated AMR across multiple sectors. The most common bacteria in humans were Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. High prevalence of resistance to third-generation cephalosporins, fluoroquinolones, and sulfamethoxazole-trimethoprim were seen in gram-negative organisms, often with >50% prevalence of resistance. Highest resistance rates were seen in humans, followed by environmental isolates. Salmonella spp. exhibited higher rates of resistance than previously reported in the literature. We found methicillin-resistant S. aureus (MRSA) in approximately half of S. aureus from the environment and a third from human isolates. Few studies evaluated AMR across all three sectors.

CONCLUSION

Our review demonstrated high prevalence of AMR among bacteria in humans, animals, and the environment in Ethiopia. Integrating a One Health approach into AMR surveillance as part of Ethiopia's national surveillance program will inform future implementation of One Health interventions.

Efficacy of Noncarbapenem β-Lactams Compared to Carbapenems for Extended-Spectrum β-Lactamase-Producing Enterobacterales Urinary Tract Infections

Background

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are frequent causes of urinary tract infections (UTIs). Severe infections caused by ESBL Enterobacterales are often treated with carbapenems, but optimal treatment for less severe infections such as UTIs is unclear.

Methods

This retrospective cohort study included patients admitted to 4 hospitals in an academic healthcare system with an ESBL UTI treated with either a noncarbapenem β-lactam (NCBL) or a carbapenem for at least 48 hours from 1 April 2014 to 30 April 2018. Those who received an NCBL were compared to those receiving a carbapenem, with a primary outcome of hospital length of stay (LOS) and secondary outcomes of clinical and microbiological response, days until transition to oral therapy, rate of relapsed infection, and rate of secondary infections with a multidrug-resistant organism.

Results

Characteristics were similar among patients who received carbapenems (n = 321) and NCBLs (n = 171). There was no difference in LOS for the NCBL group compared to the carbapenem group (13 days vs 15 days, P = .66). The NCBL group had higher rates of microbiologic eradication (98% vs 92%, P = .002), shorter time to transition to oral therapy (5 days vs 9 days, P < .001), shorter overall durations of therapy (7 days vs 10 days, P < .001), and lower rates of relapsed infections (5% vs 42%, P = .0003).

Conclusions

Patients treated with NCBLs had similar LOS, higher rates of culture clearance, and shorter durations of antibiotic therapy compared to patients treated with carbapenems, suggesting that treatment for ESBL UTIs should not be selected solely based on phenotypic resistance.

Age, Comorbid Conditions, and Racial Disparities in COVID-19 Outcomes

BACKGROUND

Black patients are disproportionately affected by COVID-19. The purpose of this study was to compare risks of hospitalization of Black and non-Black COVID-19 patients presenting to the emergency department and, of those hospitalized, to compare mortality and acute kidney injury.

METHODS

A retrospective cohort of 831 adult COVID-19 patients (68.5% Black) who presented to the emergency departments of four academic hospitals, March 1, 2020-May 31, 2020. The primary outcome was risk of hospitalization among Blacks vs. non-Blacks. Secondary outcomes were mortality and acute kidney injury, among hospitalized patients.

RESULTS

The crude odds of hospitalization were not different in Black vs. non-Black patients; however, with adjustment for age, Blacks had 55% higher odds of hospitalization. Mortality differed most in the model adjusted for age alone. Acute kidney injury was more common in the Black hospitalized patients, regardless of adjustment. Stratified analyses suggested that disparities in the risk of hospitalization and of in-hospital acute kidney injury were highest in the youngest patients.

CONCLUSIONS

Our report shows that Black and non-Black patients presenting to the emergency department with COVID-19 had similar risks of hospitalization and, of those who were hospitalized, similar mortality when adjusted for multiple factors. Blacks had higher risk of acute kidney injury. Our results suggest that examination of disparities without exploration of the individual effects of age and comorbidities may mask important patterns. While stratified analyses suggest that disparities in outcomes may differ substantially by age and comorbid conditions, further exploration among these important subgroups is needed to better target interventions to reduce disparities in COVID-19 clinical outcomes.

Clinical Decision Support Systems to Reduce Unnecessary Clostridoides difficile Testing Across Multiple Hospitals

BACKGROUND

Inappropriate C. difficile testing has adverse consequences for the patient, hospital, and public health. Computerized Clinical Decision Supports (CCDS) in the Electronic Health Record (EHR) may reduce C. difficile test ordering; however, effectiveness of different approaches, ease of use, and best fit into the healthcare providers' (HCP) workflow, are not well understood.

METHODS

Nine academic and 6 community U.S. hospitals participated in this 2-year cohort study. CCDS (hard- or soft-stop) triggered when duplicate C. difficile test order attempted, or if laxatives were recently received. The primary outcome was the difference in testing rates pre- and post-CCDS interventions, using incident rate ratios (IRR) and mixed effect Poisson regression models. We performed qualitative evaluation (contextual inquiry, interviews, focus groups) based on a human factors model. We identified themes using a codebook with primary- and sub-nodes.

RESULTS

In 9 hospitals implementing hard-stop CCDS and 4 hospitals implementing soft-stop CCDS, C. difficile testing IRR reduction was 33% (95% CI, 30-36%), and 23% (95% CI 21-25%), respectively. Two hospitals implemented a non-EMR based human intervention with IRR reduction of 21% (95% CI 15-28%). HCPs reported generally favorable experiences, and highlighted time efficiencies such as inclusion of the patients most recent laxative administration on the CCDS. Organizational factors including hierarchical cultures, and communication between HCPs caring for the same patient, impact CCDS acceptance and integration.

CONCLUSIONS

CCDS reduced unnecessary C. difficile testing and were perceived positively by HCPs when integrated into their workflow, and when displayed relevant patient specific information needed for decision-making.

Distinctive Features of Ertapenem-Mono-Resistant Carbapenem-Resistant Enterobacterales in the United States: A Cohort Study

Background

Carbapenem-resistant Enterobacterales (CRE) are highly antibiotic-resistant bacteria. Whether CRE resistant only to ertapenem among carbapenems (ertapenem “mono-resistant”) represent a unique CRE subset with regards to risk factors, carbapenemase genes, and outcomes is unknown.

Methods

We analyzed surveillance data from 9 CDC Emerging Infections Program (EIP) sites. A case was the first isolation of a carbapenem-resistant Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, K. oxytoca, K. pneumoniae, or K. variicola from a normally sterile site or urine in an EIP catchment area resident in 2016–2017. We compared risk factors, carbapenemase genes, antibiotic susceptibility, and mortality of ertapenem “mono-resistant” cases to “other” CRE cases (resistant to ≥1 carbapenem other than ertapenem) and analyzed risk factors for mortality.

Results

Of 2009 cases, 1249 (62.2%) were ertapenem-mono-resistant and 760 (37.8%) were other CRE. Ertapenem-mono-resistant CRE cases were more frequently ≥80 years old (29.1% vs 19.5%; P < .0001) and female (67.9% vs 59.0%; P < .0001). Ertapenem-mono-resistant isolates were more likely to be Enterobacter cloacae complex (48.4% vs 15.4%; P < .0001) but less likely to be isolated from a normally sterile site (7.1% vs 11.7%; P < .01) or to have a carbapenemase gene (2.4% vs 47.4%; P < .0001). Ertapenem-mono-resistance was not associated with 90-day mortality in logistic regression models. Carbapenemase-positive isolates were associated with mortality (odds ratio, 1.93; 95% CI, 1.30–2.86).

Conclusions

Ertapenem-mono-resistant CRE rarely have carbapenemase genes and have distinct clinical and microbiologic characteristics from other CRE. These findings may inform antibiotic choice and infection prevention practices, particularly when carbapenemase testing is not available.

Risk factors for isolation of carbapenem-resistant Enterobacterales from normally sterile sites and urine

BACKGROUND

Invasive infections caused by carbapenem-resistant Enterobacterales (CRE) are of significant concern in health care settings. We assessed risk factors for a positive CRE culture from a sterile site (invasive infection) compared to isolation from urine in a large patient cohort in Atlanta from August 2011 to December 2015.

METHODS

CRE cases required isolation, from urine or a normally-sterile site, of E. coli, Klebsiella spp., or Enterobacter spp. that were carbapenem-nonsusceptible (excluding ertapenem) and resistant to all third-generation cephalosporins tested. Risk factors were compared between patients with invasive and urinary infections using multivariable logistic regression.

RESULTS

A total of 576 patients had at least 1 incident case of CRE, with 91 (16%) having an invasive infection. In multivariable analysis, the presence of a central venous catheter (OR 3.58; 95% CI: 2.06-6.23) or other indwelling device (OR 2.34; 95% CI: 1.35-4.06), and recent surgery within the last year (OR 1.81; 95% CI: 1.08-3.05) were associated with invasive infection when compared to urinary infection.

DISCUSSION

Health care exposures and devices were associated with invasive infections in patients with CRE, suggesting that targeting indwelling catheters, including preventing unwarranted insertion or encouraging rapid removal, may be a potential infection control intervention.

CONCLUSIONS

Future infection prevention efforts to decrease CRE cases in health care settings should focus on minimizing unnecessary devices.

Mycobacterium bovis Bacillus Calmette-Guérin Cross-Contamination in the Operating Room: A Case Report

Mycobacterium tuberculosis complex (MTBC) false-positive cultures are commonly attributed to laboratory cross-contamination, but cross-contamination in the operating room (OR) is seldom reported. We report an investigation of cross-contamination in the OR for our case patient, who underwent surgical intervention for a chronic, left-sided breast lesion. Although the case patient had never received Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine or chemotherapy, a subsequent surgical sample culture was identified as MTBC by high-performance liquid chromatography and M. bovis BCG-type by genotyping. A collaborative false-positive investigation was initiated, and we discovered a cross-contamination event in the OR from a source case who received BCG intravesical instillation. Clinicians, public health, and infection control staff should be aware that MTBC cross-contamination in the OR is rare, but possible, and should recognize the importance of conducting thorough false-positive investigations.

Mortality in patients with carbapenem-resistant Pseudomonas aeruginosa with and without susceptibility to traditional antipseudomonal β-lactams

Background

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates can frequently retain susceptibility to traditional antipseudomonal β-lactams including cefepime, ceftazidime and piperacillin/tazobactam.

Objectives

This observational study aimed to determine the proportion of CRPA isolates that were susceptible to all tested other traditional antipseudomonal β-lactams (S-CRPA) and assess whether patients with S-CRPA had improved 30 day mortality compared with patients with NS-CRPA (non-susceptible to cefepime, ceftazidime or piperacillin/tazobactam).

Methods

Patients with CRPA isolated from normally sterile sites, urine, lower respiratory tracts and wounds were identified using active population- and laboratory-based surveillance through the Georgia Emerging Infections Program from August 2016 to July 2018 in Atlanta, GA, USA. Only unique patients who were hospitalized at the time of, or within 1 week of, culture were included. We excluded patients with cystic fibrosis. Multivariable logistic regression estimated the association between S-CRPA and 30 day mortality.

Results

Among 635 adults hospitalized with CRPA, 219 (34%) had S-CRPA. Patients with S-CRPA were more likely to be white (50% versus 38%, P = 0.01) and live in a private residence prior to culture (44% versus 28%, P < 0.01), and less likely to have required ICU care within the prior week (23% versus 36%, P < 0.01) compared with patients with NS-CRPA. Compared with those with NS-CRPA, patients with S-CRPA had an increased 30 day mortality (18% versus 15%, adjusted OR 1.9; 95% CI 1.2–3.1).

Conclusions

S-CRPA was associated with higher 30 day mortality than NS-CRPA in hospitalized patients. The reason for this observed increase in mortality deserves further investigation.

Prevalence of colistin heteroresistance in carbapenem-resistant Pseudomonas aeruginosa and association with clinical outcomes in patients: an observational study

OBJECTIVES

To describe the prevalence of colistin heteroresistance in carbapenem-resistant Pseudomonas aeruginosa (CRPA) and evaluate the association with clinical outcomes.

METHODS

Colistin heteroresistance was evaluated in CRPA isolates collected from patients without cystic fibrosis in Atlanta, Georgia, USA using two definitions: HR1, growth at 4 and 8 mg/L of colistin at a frequency ≥1 × 10-6 the main population; and HR2, growth at a colistin concentration ≥8× the MIC of the main population at a frequency ≥1 × 10-7. A modified population analysis profile (mPAP) technique was compared with reference PAP for detecting heteroresistance. For adults hospitalized at the time of or within 1 week of CRPA culture, multivariable logistic regression estimated the association between heteroresistance and 90 day mortality.

RESULTS

Of 143 colistin-susceptible CRPA isolates, 8 (6%) met the HR1 definition and 37 (26%) met the HR2 definition. Compared with the reference PAP, mPAP had a sensitivity and specificity of 50% and 100% for HR1 and 32% and 99% for HR2. Of 82 hospitalized patients, 45 (56%) were male and the median age was 63 years (IQR 49-73). Heteroresistance was not associated with 90 day mortality using HR1 (0% in heteroresistant versus 22% in non-heteroresistant group; P = 0.6) or HR2 (12% in heteroresistant versus 24% in non-heteroresistant group; P = 0.4; adjusted OR 0.8; 95% CI 0.2-3.4).

CONCLUSIONS

Colistin heteroresistance was identified in up to 26% of patients with CRPA in our sample, although the prevalence varied depending on the definition. We did not observe an apparent association between colistin heteroresistance and 90 day mortality.

1219. Unfavorable Clinical Outcomes with Polymyxins Compared to Ceftolozane/Tazobactam for the Treatment of Carbapenem-Resistant Pseudomonas aeruginosa

Background

Patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) have high in-hospital mortality rates. It is unknown if patients with CRPA treated with ceftolozane/tazobactam (C/T) have improved clinical outcomes compared to those treated with polymyxins.

Methods

The CDC-funded, Georgia Emerging Infections Program performed active population- and laboratory-based surveillance for CRPA isolated from sterile sites, urine, lower respiratory tract and wounds in metropolitan Atlanta, GA from 8/1/2016–7/31/2018. We reviewed charts of adults without cystic fibrosis who were hospitalized within 1 week of CRPA culture. Using a desirability of outcome ranking (DOOR) analysis which incorporates both benefits and risks into a single outcome, we estimated the probability that a patient treated first with C/T would have a more desirable clinical outcome at 30-days than a patient treated with polymyxins (polymyxin B or colistin). We adjusted for confounding using inverse probability of treatment weighting (IPTW) based on culture source and need for dialysis at baseline. A partial credit analysis allowed for variable weighting of DOOR ranks and calculation of differences in mean partial credit scores.

Results

Among 710 cases from 18 different hospitals, we identified 73 patients treated for CRPA infections with polymyxins (n=31) or C/T (n=42). Most patients were male (64%) and Black (80%), and those receiving polymyxins were more likely to have required dialysis at baseline (35% vs. 14%, p=0.03) (Table 1). At 30 days after culture, 34 (47%) were alive with no adverse events, 21 (29%) were alive with ≥ 1 adverse event, and 18 (25%) had died. Patients first treated with C/T had a lower 30-day mortality rate than those treated with polymyxins (14% vs 39%, p=0.03). Additionally, those receiving C/T had better overall clinical outcomes, with an adjusted DOOR probability of having an improved outcome of 67% (95% CI 53%–80%) compared to those receiving polymyxins (Figure 1). Partial credit analyses indicated consistent results across different patient values of survival with adverse events (Figure 2).

Figure 1: Inverse probability of treatment weighting-adjusted desirability of outcome ranking (DOOR) distributions by treatment group, accounting for adverse events and survival status that occurred up to 30 days after CRPA culture.

1. Percentages are adjusted using inverse probability of treatment weighting, controlling for culture source and need for dialysis at baseline 2. Adverse events measured included: acute kidney injury, discharge to higher acuity location than previous residence, or being hospitalized 30 days after culture

Figure 2: Inverse probability of treatment weighting-adjusted partial credit analysis.

This displays the difference (ceftolozane/tazobactam minus polymyxin) in mean partial credit scores (black line) and associated 95% confidence bands (gray lines) as a function of the partial credit score assigned to an individual having at least one adverse event (range 0 – 100%). A score of 100% is assigned to patients alive with no adverse events and a score of 0% is assigned to patients who die. A difference in mean partial credit scores of approximately zero suggests there was no difference observed between treatment groups.

Conclusion

These findings support the recent Infectious Diseases Society of America guidance favoring C/T over polymyxins for treatment of CRPA infections.

Disclosures

David van Duin, MD, PhD, Entasis (Advisor or Review Panel member)genentech (Advisor or Review Panel member)Karius (Advisor or Review Panel member)Merck (Grant/Research Support, Advisor or Review Panel member)Pfizer (Consultant, Advisor or Review Panel member)Qpex (Advisor or Review Panel member)Shionogi (Grant/Research Support, Scientific Research Study Investigator, Advisor or Review Panel member)Utility (Advisor or Review Panel member) Scott R. Evans, PhD, Abbvie (Consultant)Advantagene (Consultant)Alexion (Consultant)Amgen (Consultant)AstraZeneca (Consultant)Atricure (Consultant)Breast International Group (Consultant)Cardinal Health (Consultant)Clover (Consultant)FHI Clinical (Consultant)Genentech (Consultant)Gilead (Consultant)Horizon (Consultant)International Drug Development Institute (Consultant)Lung Biotech (Consultant)Microbiotix (Consultant)Neovasc (Consultant)Nobel Pharma (Consultant)Novartis (Consultant)Nuvelution (Consultant)Pfizer (Consultant)Rakuten (Consultant)Roche (Consultant)Roivant (Consultant)SAB Biopharm (Consultant)Shire (Consultant)Stryker (Consultant)SVB Leerink (Consultant)Takeda (Consultant)Teva (Consultant)Tracon (Consultant)Vir (Consultant)

LB16. Surveillance Rates of Cefiderocol Heteroresistance Correlate With All-cause Mortality in the APEKS-NP and CREDIBLE-CR Trials

Background

Cefiderocol is a recently FDA approved, novel siderophore beta-lactam antibiotic. Conventional antimicrobial susceptibility testing (AST) suggests that a variety of Gram-negative pathogens, including carbapenem-resistant (CR) isolates, are overwhelmingly susceptible to cefiderocol.. This antibiotic performed well in the APEKS-NP trial for the treatment of nosocomial pneumonia caused largely by carbapenem susceptible isolates. However, in the CREDIBLE-CR trial involving exclusively CR Gram-negative bacteria, cefiderocol was associated with a higher rate of all-cause mortality. We hypothesized one explanation for these discrepant data might be undetected cefiderocol heteroresistance (HR).

HR is a form of antibiotic resistance in which an isolate harbors a minority resistant subpopulation of cells co-existing with a majority susceptible population, and is often undetected by standard AST. Isolates exhibiting undetected HR, with as low as 1 in 1 million resistant cells, can cause treatment failure in in vivo models.

Methods

We quantified HR to cefiderocol by population analysis profile (PAP) of 161 Acinetobacter, 180 Klebsiella, and 108 Pseudomonas isolates collected in Georgia, USA.

Results

We observed CR isolates exhibited a high frequency of HR, which was largely undetected by standard AST, and correlated with all-cause mortality in the CREDIBLE-CR study (Table). Carbapenem-susceptible isolates exhibited no or low rates of cefiderocol HR (Table). Cephalosporin-resistant bacteria mostly exhibited increased rates of cefiderocol HR, but below those of CR strains. These differences in rates of cefiderocol HR correlated with the mortality data from the APEKS-NP and CREDIBLE-CR trials, across the bacterial species tested (Table).

Table: Surveillance rates of cefiderocol heteroresistance correlate with all-cause mortality in the APEKS-NP and CREDIBLE-CR trials

Conclusion

These data suggest that the lower rates of cefiderocol HR in carbapenem-susceptible isolates that predominated the APEKS-NP trial may explain the enhanced efficacy of the drug in that study as compared to the CREDIBLE-CR trial. Importantly, the widespread, undetected cefiderocol HR observed among CR pathogens may explain the discordance between this drug’s excellent in vitro susceptibility profile and increased patient mortality in the CREDIBLE-CR trial.

Disclosures

All Authors: No reported disclosures

787. Clinical and Genomic Epidemiology of mcr-9 Containing Carbapenem-resistant Enterobacterales Isolates in Metropolitan Atlanta, 2012-2017

Background

Colistin is a last-resort antibiotic for multidrug resistant gram-negative infections. Recently, a new allele of the mobile colistin resistance (mcr) gene family designated mcr-9, has been reported. However, its clinical and phenotypic significance remains unclear.

Methods

The Centers for Diseases Control and Prevention-funded Georgia Emerging Infections Program (EIP) performs population- and laboratory- based surveillance for CRE isolated from sterile sites or urine in metropolitan Atlanta, GA including standardized chart abstraction. We queried genomes of carbapenem-resistant Enterobacterales (CRE) for mcr-9 from a convenience sample of Georgia EIP clinical isolates between 2012-2017. Isolates underwent phenotypic characterization by broth microdilution and population analysis profiling. Nine available E. cloacae (two mcr-9 positive, seven mcr-9 negative) genomes from the National Institutes of Health were included in downstream genomic analysis. Fastq files underwent de novo assembly, annotation and AMR and virulence gene prediction, pan-genome association analysis, pairwise comparisons of average nucleotide identity and phylogenetic tree construction based on core genes. We compared characteristics and outcomes of mcr-9 positive and negative CRE cases.

Results

Among 449 sequenced CRE genomes, thirteen (2.9%) were found to harbor mcr-9, all of which were E. cloacae. Fourteen mcr-9 negative E. cloacae (n=14) were included as a comparative group. E. cloacae was most commonly isolated from the urine (22/24, 86%), and none were community associated. The median colistin MIC, rates of heteroresistance and inducible resistance were similar between mcr-9 positive and negative isolates (Table 1). 90-day mortality was high in both mcr-9 positive (31%) and negative (7% cases (p=0.28, Table 1). Phylogenetic analysis revealed no geo-temporal clustering (Figure 1). Plasmid-associated genes were significantly associated with the presence of mcr-9 (p&lt; 0.001). Phylogeny and average nucleotide identity heatmap of mcr-9 positive and mcr-9 negative E. cloacae.

Conclusion

The presence of mcr-9 was not associated with significant changes in colistin resistance or clinical outcomes.

Disclosures

All Authors: No reported disclosures

177. Distinctive Features of Ertapenem Mono-Resistant Carbapenem-Resistant Enterobacterales in the United States: A Cohort Study

Background

Carbapenem-resistant Enterobacterales (CRE) are highly antibiotic-resistant bacteria. Whether CRE resistant only to ertapenem among carbapenems (ertapenem mono-resistant) represent a unique CRE subset with regards to risk factors, carbapenemase genes, and outcomes is unknown.

Methods

We analyzed laboratory- and population-based surveillance data from nine sites participating in CDC’s Emerging Infections Program (EIP). We defined an incident case as the first isolation of Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, K. oxytoca, K. pneumoniae, or K. variicola resistant to doripenem, ertapenem, imipenem, or meropenem (determined at clinical laboratory) from a normally sterile site or urine identified from a resident of the EIP catchment area in 2016-2017. We compared risk factors, carbapenemase genes (determined via polymerase chain reaction at CDC), and mortality of cases with ertapenem “mono-resistant” to “other” CRE (resistant to ≥ 1 carbapenem other than ertapenem). We additionally conducted survival analysis to determine the effect of ertapenem mono-resistant status and isolate source (sterile vs. urine) on survival.

Results

Of 2009 cases, 1249 (62.2%) were ertapenem mono-resistant and 760 (37.8%) were other CRE (Figure 1). Ertapenem mono-resistant CRE cases were more frequently ≥ 80 years old (29.1% vs. 19.5%, p< 0.0001), female (67.9% vs 59.0%, p< 0.0001), and white (62.6% vs. 45.1%, p< 0.0001). Ertapenem mono-resistant isolates were more likely than other CRE to be Enterobacter cloacae complex (48.4% vs. 15.4%, p< 0.0001) but less likely to be isolated from a normally sterile site (7.1% vs. 11.7%, p< 0.01) or have a carbapenemase gene (2.4% vs. 47.4%, p< 0.0001) (Figure 2). Ertapenem mono-resistance was not associated with difference in 90-day mortality (unadjusted odds ratio [OR] 0.82, 95% confidence interval [CI] 0.63-1.06) in logistic models or survival analysis (Figure 3).

Figure 1. Flow diagram of carbapenem-resistant Enterobacterales cases included in analysis, 2017-2018. CRE, carbapenem-resistant Enterobacterales; MIC, minimum inhibitory concentration. Ertapenem mono-resistant CRE are only resistant to ertapenem (among carbapenems). Other CRE are resistant to ≥1 carbapenem other than ertapenem. We excluded isolates that (1) had no interpretable MICs for any carbapenem, (2) were only tested against ertapenem, (3) had unknown death status, or (4) were not associated with patient’s first incident case.

Figure 2. Proportion of ertapenem mono-resistant carbapenem-resistant Enterobacterales (CRE) vs. other CRE isolates with specific carbapenemase genes. KPC, Klebsiella pneumoniae carbapenemase; NDM, New Delhi metallo-ß-lactamase; OXA, oxacillinase. Ertapenem mono-resistant carbapenem-resistant Enterobacterales (CRE) are only resistant to ertapenem (among carbapenems). Other CRE are resistant to ≥1 carbapenem other than ertapenem. Testing via reverse transcriptase polymerase chain reaction.

Figure 3. Survival analysis comparing patients with carbapenem-resistant Enterobacterales (CRE) that are ertapenem mono-resistant to other CRE (i.e., resistant to ≥1 carbapenem other than ertapenem), either total (A) or stratified by isolate site (B).

Ertapenem mono-resistant) isolates were not associated with decreased mortality, and sterile isolate source (i.e., non-urinary isolates) was associated with increased mortality regardless of ertapenem mono-resistance.

Conclusion

Ertapenem mono-resistant CRE rarely have carbapenemase genes and have distinct clinical and microbiologic characteristics compared to other CRE. These findings may inform antibiotic choice particularly when testing for carbapenemases is not readily available.

Disclosures

All Authors: No reported disclosures

42. Outbreak of SARS-CoV-2 in Hospitalized Hemodialysis Patients: an Epidemiologic and Genomic Investigation

Background

Healthcare-associated transmission of SARS-CoV-2 is relatively rare and may be difficult to quantify. We performed an epidemiological investigation and SARS-CoV-2 genome sequencing to define the source and scope of a SARS-CoV-2 outbreak in a cluster of hospitalized patients

Methods

We conducted an outbreak investigation after identifying hospital-onset COVID-19 in patients receiving hemodialysis in January 2021. Electronic medical record review, staff interviews, review of employee schedule logs, and contact tracing were used to determine the outbreak timeline and identify exposed healthcare workers (HCW). SARS-CoV-2 genomes were sequenced from residual nasopharyngeal swab samples from 6 individuals in the outbreak investigation and compared to sequences from 14 patients in the same facility, 54 patients in nearby facilities, and 375 publicly available sequences from individuals in the state of Georgia.

Results

Eight patients with hospital-onset COVID-19 were identified (Cases 1-8); all were receiving hemodialysis and 5 were bedded in a single inpatient nursing unit. Among 53 potentially exposed HCW, 29 underwent testing and 5 were positive (Cases 9-13). The suspected index patient (Case 1) was found to have been coughing and inconsistently wearing a mask during a hemodialysis session on the same day that 6 of the 7 other patients and one HCW (Case 10) were in close proximity in the hemodialysis unit (Figure 1A). Further investigation revealed lack of use of curtain barriers in the hemodialysis bays, inconsistent use of personal protective equipment by HCW, and overcrowding of staff breakrooms. Among the 6 samples available for phylogenetic analysis, SARS-CoV-2 sequences from 5 (4 patients and 1 HCW, Case 9) were identical and at least 4 SNPs removed from the next closest sequence in this study, supporting a transmission cluster (Figure 1B). The sequence from the sixth sample (HCW Case 10) was phylogenetically distinct, indicating an independent source of infection.

Figure 1

Exposure and onset of symptoms for the 6 cases in the outbreak with samples available for SARS-CoV-2 sequencing. Four patients with hospital-onset COVID-19 (Cases 1-4) were receiving hemodialysis and bedded in a single inpatient nursing unit, with two exposed healthcare workers (Cases 9-10). (A). Phylogenetic tree of SARS-CoV-2 genomes from individuals in this outbreak investigation (red), as well as 14 patients in the same facility and 54 patients in nearby facilities between 12/12/2020 and 1/13/2021 (blue). These were aligned with 375 publicly available sequences from individuals in the state of Georgia from the same time period using MAFFT. A maximum-likelihood phylogenetic tree was generated under a generalized time-reversible model with 1,000 bootstrap replicates using IQtree v2.0.3 and visualized and annotated using Interactive Tree of Life (iTOL) v4 (B).

Conclusion

Lack of appropriate respiratory hygiene led to SARS-CoV-2 transmission during a single hemodialysis session, based on clinical and genomic epidemiology. Use of appropriate PPE for both patients and HCW and other infection prevention measures are critical to prevent SARS-CoV-2 transmission.

Disclosures

All Authors: No reported disclosures

Reductions in inpatient fluoroquinolone use and postdischarge Clostridioides difficile infection (CDI) from a systemwide antimicrobial stewardship intervention

Objective

To determine the impact of an inpatient stewardship intervention targeting fluoroquinolone use on inpatient and postdischarge Clostridioides difficile infection (CDI).

Design

We used an interrupted time series study design to evaluate the rate of hospital-onset CDI (HO-CDI), postdischarge CDI (PD-CDI) within 12 weeks, and inpatient fluoroquinolone use from 2 years prior to 1 year after a stewardship intervention.

Setting

An academic healthcare system with 4 hospitals.

Patients

All inpatients hospitalized between January 2017 and September 2020, excluding those discharged from locations caring for oncology, bone marrow transplant, or solid-organ transplant patients.

Intervention

Introduction of electronic order sets designed to reduce inpatient fluoroquinolone prescribing.

Results

Among 163,117 admissions, there were 683 cases of HO-CDI and 1,104 cases of PD-CDI. In the context of a 2% month-to-month decline starting in the preintervention period (P < .01), we observed a reduction in fluoroquinolone days of therapy per 1,000 patient days of 21% after the intervention (level change, P < .05). HO-CDI rates were stable throughout the study period. In contrast, we also detected a change in the trend of PD-CDI rates from a stable monthly rate in the preintervention period to a monthly decrease of 2.5% in the postintervention period (P < .01).

Conclusions

Our systemwide intervention reduced inpatient fluoroquinolone use immediately, but not HO-CDI. However, a downward trend in PD-CDI occurred. Relying on outcome measures limited to the inpatient setting may not reflect the full impact of inpatient stewardship efforts.

Quantification of Occupational and Community Risk Factors for SARS-CoV-2 Seropositivity Among Health Care Workers in a Large U.S. Health Care System

BACKGROUND

Identifying occupational risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among health care workers (HCWs) can improve HCW and patient safety.

OBJECTIVE

To quantify demographic, occupational, and community risk factors for SARS-CoV-2 seropositivity among HCWs in a large health care system.

DESIGN

A logistic regression model was fitted to data from a cross-sectional survey conducted in April to June 2020, linking risk factors for occupational and community exposure to coronavirus disease 2019 (COVID-19) with SARS-CoV-2 seropositivity.

SETTING

A large academic health care system in the Atlanta, Georgia, metropolitan area.

PARTICIPANTS

Employees and medical staff members elected to participate in SARS-CoV-2 serology testing offered to all HCWs as part of a quality initiative and completed a survey on exposure to COVID-19 and use of personal protective equipment.

MEASUREMENTS

Demographic risk factors for COVID-19, residential ZIP code incidence of COVID-19, occupational exposure to HCWs or patients who tested positive on polymerase chain reaction test, and use of personal protective equipment as potential risk factors for infection. The outcome was SARS-CoV-2 seropositivity.

RESULTS

Adjusted SARS-CoV-2 seropositivity was estimated to be 3.8% (95% CI, 3.4% to 4.3%) (positive, n = 582) among the 10 275 HCWs (35% of the Emory Healthcare workforce) who participated in the survey. Community contact with a person known or suspected to have COVID-19 (adjusted odds ratio [aOR], 1.9 [CI, 1.4 to 2.6]; 77 positive persons [10.3%]) and community COVID-19 incidence (aOR, 1.5 [CI, 1.0 to 2.2]) increased the odds of infection. Black individuals were at high risk (aOR, 2.1 [CI, 1.7 to 2.6]; 238 positive persons [8.3%]).

LIMITATIONS

Participation rates were modest and key workplace exposures, including job and infection prevention practices, changed rapidly in the early phases of the pandemic.

CONCLUSION

Demographic and community risk factors, including contact with a COVID-19-positive person and Black race, are more strongly associated with SARS-CoV-2 seropositivity among HCWs than is exposure in the workplace.

PRIMARY FUNDING SOURCE

Emory COVID-19 Response Collaborative.

Risk Factors Associated With SARS-CoV-2 Seropositivity Among US Health Care Personnel

IMPORTANCE

Risks for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among health care personnel (HCP) are unclear.

OBJECTIVE

To evaluate the risk factors associated with SARS-CoV-2 seropositivity among HCP with the a priori hypothesis that community exposure but not health care exposure was associated with seropositivity.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study was conducted among volunteer HCP at 4 large health care systems in 3 US states. Sites shared deidentified data sets, including previously collected serology results, questionnaire results on community and workplace exposures at the time of serology, and 3-digit residential zip code prefix of HCP. Site-specific responses were mapped to a common metadata set. Residential weekly coronavirus disease 2019 (COVID-19) cumulative incidence was calculated from state-based COVID-19 case and census data.

EXPOSURES

Model variables included demographic (age, race, sex, ethnicity), community (known COVID-19 contact, COVID-19 cumulative incidence by 3-digit zip code prefix), and health care (workplace, job role, COVID-19 patient contact) factors.

MAIN OUTCOME AND MEASURES

The main outcome was SARS-CoV-2 seropositivity. Risk factors for seropositivity were estimated using a mixed-effects logistic regression model with a random intercept to account for clustering by site.

RESULTS

Among 24 749 HCP, most were younger than 50 years (17 233 [69.6%]), were women (19 361 [78.2%]), were White individuals (15 157 [61.2%]), and reported workplace contact with patients with COVID-19 (12 413 [50.2%]). Many HCP worked in the inpatient setting (8893 [35.9%]) and were nurses (7830 [31.6%]). Cumulative incidence of COVID-19 per 10 000 in the community up to 1 week prior to serology testing ranged from 8.2 to 275.6; 20 072 HCP (81.1%) reported no COVID-19 contact in the community. Seropositivity was 4.4% (95% CI, 4.1%-4.6%; 1080 HCP) overall. In multivariable analysis, community COVID-19 contact and community COVID-19 cumulative incidence were associated with seropositivity (community contact: adjusted odds ratio [aOR], 3.5; 95% CI, 2.9-4.1; community cumulative incidence: aOR, 1.8; 95% CI, 1.3-2.6). No assessed workplace factors were associated with seropositivity, including nurse job role (aOR, 1.1; 95% CI, 0.9-1.3), working in the emergency department (aOR, 1.0; 95% CI, 0.8-1.3), or workplace contact with patients with COVID-19 (aOR, 1.1; 95% CI, 0.9-1.3).

CONCLUSIONS AND RELEVANCE

In this cross-sectional study of US HCP in 3 states, community exposures were associated with seropositivity to SARS-CoV-2, but workplace factors, including workplace role, environment, or contact with patients with known COVID-19, were not. These findings provide reassurance that current infection prevention practices in diverse health care settings are effective in preventing transmission of SARS-CoV-2 from patients to HCP.

Improving the communication of hand hygiene procedures: Controlled observation, redesign, and randomized group comparisons

OBJECTIVE

To assess the clarity and efficacy of the World Health Organization (WHO) hand-rub diagram, develop a modified version, and compare the 2 diagrams.

DESIGN

Randomized group design preceded by controlled observation and iterative product redesigns.

SETTING

The Cognitive Ergonomics Lab in the School of Psychology at the Georgia Institute of Technology.

PARTICIPANTS

We included participants who were unfamiliar with the WHO hand-rub diagram (convenience sampling) to ensure that performance was based on the diagram and not, for example, on prior experience.

METHODS

We iterated through the steps of a human factors design procedure: (1) Participants simulated hand hygiene using ultraviolet (UV) absorbent lotion and a hand-rub technique diagram (ie, WHO or a redesign). (2) Coverage, confusion judgments, and behavioral videos informed potentially improved diagrams. And (3) the redesigned diagrams were compared with the WHO version in a randomized group design. Coverage was assessed across 72 hand areas from multiple UV photographs.

RESULTS

The WHO diagram led to multiple omissions in hand-surface coverage, including inadequate coverage by up to 75% of participants for the ulnar edge. The redesigns improved coverage significantly overall and often substantially.

CONCLUSIONS

Human factors modification to the WHO diagram reduced inadequate coverage for naïve users. Implementation of an improved diagram should help in the prevention of healthcare-associated infections.

Evaluating Movement of Patients With Carbapenem-resistant Enterobacteriaceae Infections in the Greater Atlanta Metropolitan Area Using Social Network Analysis

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent threat with potential for rapid spread. We evaluated the role of Medicare patient movement between facilities to model the spread of CRE within a region.

METHODS

Through population-based CRE surveillance in the 8-county Atlanta (GA) metropolitan area, all Escherichia coli, Enterobacter spp., or Klebsiella spp. resistant to ≥1 carbapenem were reported from residents. CRE was attributed to a facility based on timing of culture and facility exposures. Centrality metrics were calculated from 2016 Medicare data and compared to CRE-transfer derived centrality metrics by Spearman correlation.

RESULTS

During 2016, 283 incident CRE cases with concurrent or prior year facility stays were identified; cases were attributed mostly to acute care hospitals (ACHs; 141, 50%) and skilled nursing facilities (SNFs; 113, 40%), and less frequently to long-term acute care hospitals (LTACHs; 29, 10%). Attribution was widespread, originating at 17 of 20 ACHs (85%), 7 of 8 (88%) LTACHs, but only 35 of 65 (54%) SNFs. Betweenness of Medicare patient transfers strongly correlated with betweenness of CRE case-transfer data in ACHs (r = 0.75; P < .01) and LTACHs (r = 0.77; P = .03), but not in SNFs (r = 0.02; P = 0.85). We noted 6 SNFs with high CRE-derived betweenness but low Medicare-derived betweenness.

CONCLUSIONS

CRE infections originate from almost all ACHs and half of SNFs. We identified a subset of SNFs central to the CRE transfer network but not the Medicare transfer network; other factors may explain CRE patient movement in these facilities.

Close Patient Follow-up Among Patients Receiving Outpatient Parenteral Antimicrobial Therapy

BACKGROUND

Outpatient parenteral antimicrobial therapy (OPAT) programs allow patients to receive intravenous treatment in the outpatient setting. We developed a predictive model of 30-day readmission among hospitalized patients discharged on OPAT from 2 academic medical centers with a dedicated OPAT clinic for management.

METHODS

A retrospective medical records review was performed and logistic regression was used to assess OPAT and other outpatient clinic follow-up in conjunction with age, sex, pathogen, diagnosis, discharge medication, planned length of therapy, and Charlson comorbidity score. We hypothesized that at least 1 follow-up visit at the Emory OPAT clinic would reduce the risk for hospital readmission within 30 days.

RESULTS

Among 755 patients, 137 (18%) were readmitted within 30 days. Most patients (73%) received outpatient follow-up care at Emory Healthcare within 30 days of discharge or prior to readmission, including 52% of patients visiting the OPAT clinic. The multivariate logistic regression model indicated that a follow-up OPAT clinic visit was associated with lower readmission compared to those who had no follow-up visit (odds ratio, 0.10 [95% confidence interval, .06-.17]) after adjusting for infection with enterococci, Charlson score, discharge location, and county of residence.

CONCLUSIONS

These results can inform potential interventions to prevent readmissions through OPAT clinic follow-up and to further assess factors associated with successful care transitions from the inpatient to outpatient setting.

834. Clinical Outcomes with Carbapenem-Resistant Pseudomonas aeruginosa that Retain Susceptibility to Traditional Antipseudomonal β-lactams: Atlanta, 2016-2018

Background

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) often results from multiple mechanisms, creating unique phenotypic patterns of resistance including retaining susceptibility to traditional antipseudomonal β-lactams: cefepime (FEP), ceftazidime (CAZ) and piperacillin-tazobactam (TZP). Outcomes of patients with CRPA susceptible to FEP, CAZ and TZP are unclear.

Methods

The Georgia Emerging Infections Programed performs active, population-based surveillance for CRPA (minimum inhibitory concentration [MIC] ≥ 8 µg/mL for doripenem, imipenem or meropenem) isolated from sterile sites, urine, lower respiratory tracts and wounds in metropolitan Atlanta. We created a retrospective cohort of adults without cystic fibrosis with their first episode of CRPA while hospitalized or hospitalized within 1 week, from 8/2016 – 7/2018. We compared patients with CRPA that remained susceptible to FEP, CAZ and TZP (“susceptible CRPA”) to those that were not (“resistant CRPA”) including multivariable logistic regression for 30-day mortality.

Results

Among 643 patients, 638 had susceptibility results available for FEP, CAZ or TZP. 60% were male, median age was 65 years, and median Charlson comorbidity index was 2 (Table 1). Most (66%) resided in a hospital or long-term care facility 4 days prior to culture. The most common source was urine (38%). Non-susceptibility to multiple antibiotic classes was common: 523 (81%) for 3 classes and 214 (33%) for 5 classes (Table 2). 220 (34%) patients had susceptible CRPA and compared to patients with resistant CRPA, were more likely to have lived in a private residence, have a community-associated infection, and less likely to be in the ICU previously (Table 1). Patients with susceptible CRPA had a similar crude 30-day mortality (16% vs 12%, p = 0.15) to those with resistant CRPA, but in a multivariable analysis had an increased 30-day mortality (OR 1.9; 95% CI 1.1–3.2).

Table 1 (Part 1/2): Characteristics and outcomes of hospitalized patients with carbapenem-resistant Pseudomonas aeruginosa (CRPA) in metropolitan Atlanta, stratified by antipseudomonal β-lactam susceptibility

Conclusion

Over 1/3 of hospitalized patients with CRPA retained susceptibility to other antipseudomonal β-lactams, but had an increased mortality compared to CRPA resistant to other β-lactams. Further research into mechanisms of resistance or antibiotics received might help explain this unexpected finding.

Disclosures

Jessica Howard-Anderson, MD, Antibacterial Resistance Leadership Group (ARLG) (Other Financial or Material Support, The ARLG fellowship provides salary support for ID fellowship and mentored research training)

1425. Impact of Social Determinants on Racial Differences in Carbapenem-Resistant Enterobacteriaceae Incidence, Atlanta, 2012-2018

Background

Public health prioritizes addressing social determinants of health to promote health equity. We hypothesized that social determinants of health, including poverty, are associated with racial disparity in the incidence of carbapenem-resistant Enterobacteriaceae (CRE).

Methods

The Georgia Emerging Infections Program conducted CDC-funded, active population-based CRE surveillance in metropolitan Atlanta (2017 population: 3.9 million) from 2012-2018. CRE cases were defined as Atlanta residents with a urine or normally sterile specimen growing E. coli, Klebsiella spp., or Enterobacter spp. resistant to ≥ 1 carbapenems (excluding ertapenem) and all third generation cephalosporins tested. Poverty, education and insurance levels by census tract of residence were obtained from the US Census Bureau’s 2017 American Community Survey. Race and end-stage renal disease (ESRD) were determined from chart review, and primary care provider (PCP) shortage area was obtained from the Health Resources and Services Administration. Age-adjusted incidence rate ratios were individually calculated using direct age standardization. Covariates were considered for inclusion in a multivariable Poisson regression model for the expected rate of CRE.

Results

Adjusting for age, CRE incidence was three times higher in blacks than whites. Higher CRE incidence was also observed among cases assigned > 40% below poverty level, > 15% below high school education, > 10% uninsured, and in a PCP shortage area (Table 1). CRE incidence was 58 times higher among ESRD cases than non-ESRD cases. In the multivariable model (Figure 1) addition of education, poverty or ESRD (p< 0.001), but not PCP access (p = 0.61) and insurance status (p=0.19), significantly reduced the racial difference in CRE incidence compared to race and age alone. Although controlling for age and either education, poverty level or ESRD reduced CRE among blacks, CRE incidence in blacks remained double that of whites.

Figure 1. Comparison of race CRE incidence rate ratio adjusting for age alone (red line) to adjusting for age and individual social determinants (blue bars)”

Table 1. Social Determinants Distribution and Age-Adjusted CRE Incidence Rate Ratio (N = 378)

Conclusion

Poverty level, ESRD and education only partially account for the racial differences seen in CRE incidence. While ESRD suggests a possible biologic component, persistent racial differences indicate the need for targeted public health interventions to address social determinants of health.

Disclosures

All Authors: No reported disclosures

189. Validating a Hospitalist-Specific Antibiotic Prescribing Metric across Four Acute Care Hospitals

Background

Peer comparison reduces unnecessary outpatient antibiotic prescribing, but no prescribing metric has been validated for inpatient comparison. We aimed to evaluate if an electronically derived antibiotic prescribing metric correlated with indicated antibiotic days in hospitalized patients.

Methods

We previously created a hospitalist-specific adjusted antibiotic use metric (observed:expected [O:E]) for National Healthcare Safety Network-defined broad-spectrum antibiotics. From May-Oct 2019 at four Emory Healthcare hospitals, we identified outlier hospitalists prescribing in the top (high O:E) and bottom (low O:E) 15^th percentile. We randomly selected 10 days of antibiotic administration from each outlier and reviewed days with > 2 days of consecutive days of antibiotics. For pneumonia, chronic obstructive pulmonary disease (COPD), or urinary tract infection (UTI) we determined if each day of antibiotics was indicated, assuming the diagnosis was accurate. We compared high vs. low O:E providers and used regression modeling to determine if the metric predicted indicated days of antibiotics.

Results

Among 997 days, 510 (51%) were from high and 487 (49%) from low O:E providers. High O:E providers had a greater proportion of days with > 2 prior days of antibiotics (60%) compared to low O:E providers (54%, p = 0.03). In the subset of days with > 2 prior days of antibiotics (n = 569), high O:E providers had more patient-days with longer hospital stays, diabetes and Charlson comorbidity index (CCI) >3, and fewer days supervising (resident/advanced practice provider, Table 1). The primary diagnosis was pneumonia, COPD exacerbation or UTI in 260 (25%) days; 91% were indicated based on duration with no difference between high and low O:E providers (88% vs. 94%, p = 0.1). After controlling for days of hospitalization, CCI, immunocompromised status, and supervisory role, a high O:E was not associated with indicated antibiotic use (OR 0.5, 95% CI 0.2 – 1.3).

Description of days with a patient on greater than two days of antibiotics, comparing high- versus low-metric providers

Conclusion

A high hospitalist antibiotic prescribing metric correlated with patients receiving > 2 consecutive days of antibiotics on any given day but did not predict unindicated antibiotic use for a subset of diagnoses. Evaluating indicated use by validating diagnoses may improve metric performance.

Disclosures

Jessica Howard-Anderson, MD, Antibacterial Resistance Leadership Group (ARLG) (Other Financial or Material Support, The ARLG fellowship provides salary support for ID fellowship and mentored research training)

Absence of mgrB Alleviates Negative Growth Effects of Colistin Resistance in Enterobacter cloacae

Colistin is an important last-line antibiotic to treat highly resistant Enterobacter infections. Resistance to colistin has emerged among clinical isolates but has been associated with a significant growth defect. Here, we describe a clinical Enterobacter isolate with a deletion of mgrB, a regulator of colistin resistance, leading to high-level resistance in the absence of a growth defect. The identification of a path to resistance unrestrained by growth defects suggests colistin resistance could become more common in Enterobacter.