Carbapenem-resistant Acinetobacter baumannii complex in the United States - an epidemiological and molecular description of isolates collected through the Emerging Infections Program, 2019

BACKGROUND

Understanding the epidemiology of carbapenem-resistant A. baumannii complex (CRAB) and the patients impacted is an important step towards informing better infection prevention and control practices and improving public health response.

METHODS

Active, population-based surveillance was conducted for CRAB in 9 U.S. sites from January 1-December 31, 2019. Medical records were reviewed, isolates were collected and characterized including antimicrobial susceptibility testing and whole genome sequencing.

RESULTS

Among 136 incident cases in 2019, 66 isolates were collected and characterized; 56.5% were from cases who were male, 54.5% were from persons of Black or African American race with non-Hispanic ethnicity, and the median age was 63.5 years. Most isolates, 77.2%, were isolated from urine, and 50.0% were collected in the outpatient setting; 72.7% of isolates harbored an acquired carbapenemase gene (aCP), predominantly blaOXA-23 or blaOXA-24/40; however, an isolate with blaNDM was identified. The antimicrobial agent with the most in vitro activity was cefiderocol (96.9% of isolates were susceptible).

CONCLUSIONS

Our surveillance found that CRAB isolates in the U.S. commonly harbor an aCP, have an antimicrobial susceptibility profile that is defined as difficult-to-treat resistance, and epidemiologically are similar regardless of the presence of an aCP.

Characteristics of Patients With Initial Clostridioides difficile Infection (CDI) That Are Associated With Increased Risk of Multiple CDI Recurrences

Background

Because interventions are available to prevent further recurrence in patients with recurrent Clostridioides difficile infection (rCDI), we identified predictors of multiple rCDI (mrCDI) in adults at the time of presentation with initial CDI (iCDI).

Methods

iCDI was defined as a positive C difficile test in any clinical setting during January 2018-August 2019 in a person aged ≥18 years with no known prior positive test. rCDI was defined as a positive test ≥14 days from the previous positive test within 180 days after iCDI; mrCDI was defined as ≥2 rCDI. We performed multivariable logistic regression analysis.

Results

Of 18 829 patients with iCDI, 882 (4.7%) had mrCDI; 437 with mrCDI and 7484 without mrCDI had full chart reviews. A higher proportion of patients with mrCDI than without mrCDI were aged ≥65 years (57.2% vs 40.7%; P < .0001) and had healthcare (59.1% vs 46.9%; P < .0001) and antibiotic (77.3% vs 67.3%; P < .0001) exposures in the 12 weeks preceding iCDI. In multivariable analysis, age ≥65 years (adjusted odds ratio [aOR], 1.91; 95% confidence interval [CI], 1.55-2.35), chronic hemodialysis (aOR, 2.28; 95% CI, 1.48-3.51), hospitalization (aOR, 1.64; 95% CI, 1.33-2.01), and nitrofurantoin use (aOR, 1.95; 95% CI, 1.18-3.23) in the 12 weeks preceding iCDI were associated with mrCDI.

Conclusions

Patients with iCDI who are older, on hemodialysis, or had recent hospitalization or nitrofurantoin use had increased risk of mrCDI and may benefit from early use of adjunctive therapy to prevent mrCDI. If confirmed, these findings could aid in clinical decision making and interventional study designs.

Residential social vulnerability among healthcare personnel with and without severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection in Five US states, May-December 2020

OBJECTIVE

To characterize residential social vulnerability among healthcare personnel (HCP) and evaluate its association with severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection.

DESIGN

Case-control study.

SETTING

This study analyzed data collected in May-December 2020 through sentinel and population-based surveillance in healthcare facilities in Colorado, Minnesota, New Mexico, New York, and Oregon.

PARTICIPANTS

Data from 2,168 HCP (1,571 cases and 597 controls from the same facilities) were analyzed.

METHODS

HCP residential addresses were linked to the social vulnerability index (SVI) at the census tract level, which represents a ranking of community vulnerability to emergencies based on 15 US Census variables. The primary outcome was SARS-CoV-2 infection, confirmed by positive antigen or real-time reverse-transcriptase- polymerase chain reaction (RT-PCR) test on nasopharyngeal swab. Significant differences by SVI in participant characteristics were assessed using the Fisher exact test. Adjusted odds ratios (aOR) with 95% confidence intervals (CIs) for associations between case status and SVI, controlling for HCP role and patient care activities, were estimated using logistic regression.

RESULTS

Significantly higher proportions of certified nursing assistants (48.0%) and medical assistants (44.1%) resided in high SVI census tracts, compared to registered nurses (15.9%) and physicians (11.6%). HCP cases were more likely than controls to live in high SVI census tracts (aOR, 1.76; 95% CI, 1.37-2.26).

CONCLUSIONS

These findings suggest that residing in more socially vulnerable census tracts may be associated with SARS-CoV-2 infection risk among HCP and that residential vulnerability differs by HCP role. Efforts to safeguard the US healthcare workforce and advance health equity should address the social determinants that drive racial, ethnic, and socioeconomic health disparities.

Effectiveness of a Messenger RNA Vaccine Booster Dose Against Coronavirus Disease 2019 Among US Healthcare Personnel, October 2021-July 2022

Background

Protection against symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (coronavirus disease 2019 [COVID-19]) can limit transmission and the risk of post-COVID conditions, and is particularly important among healthcare personnel. However, lower vaccine effectiveness (VE) has been reported since predominance of the Omicron SARS-CoV-2 variant.

Methods

We evaluated the VE of a monovalent messenger RNA (mRNA) booster dose against COVID-19 from October 2021 to June 2022 among US healthcare personnel. After matching case-participants with COVID-19 to control-participants by 2-week period and site, we used conditional logistic regression to estimate the VE of a booster dose compared with completing only 2 mRNA doses >150 days previously, adjusted for multiple covariates.

Results

Among 3279 case-participants and 3998 control-participants who had completed 2 mRNA doses, we estimated that the VE of a booster dose against COVID-19 declined from 86% (95% confidence interval, 81%-90%) during Delta predominance to 65% (58%-70%) during Omicron predominance. During Omicron predominance, VE declined from 73% (95% confidence interval, 67%-79%) 14-60 days after the booster dose, to 32% (4%-52%) ≥120 days after a booster dose. We found that VE was similar by age group, presence of underlying health conditions, and pregnancy status on the test date, as well as among immunocompromised participants.

Conclusions

A booster dose conferred substantial protection against COVID-19 among healthcare personnel. However, VE was lower during Omicron predominance, and waning effectiveness was observed 4 months after booster dose receipt during this period. Our findings support recommendations to stay up to date on recommended doses of COVID-19 vaccines for all those eligible.

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.

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.

2040. Healthcare-Associated Infection Surveillance During the COVID-19 Pandemic in New Mexico

Background

The COVID-19 pandemic changed accessibility of care and practices within healthcare environments. This period has been associated with healthcare-associated infection outbreaks and shifts in healthcare-associated infectious disease epidemiology. This study’s objective is to describe changes in rates and characteristics of antimicrobial-resistant gram negative and Clostridioides difficile (CD) infections during the COVID-19 pandemic in Bernalillo County, New Mexico.

Methods

The NM EIP, a collaboration between University of New Mexico and the NM DOH, conducts ongoing laboratory- and population-based surveillance of infectious disease including Clostridium difficile, extended-spectrum beta lactamase (ESBL-E) and carbapenemase-producing gram negative bacteria (CRE). Stata statistical software was used for retrospective analysis of rates and characteristics on NM EIP data from Bernalillo county, NM between 2016 and 2021.

Results

Reported C. difficile rates decreased from 76 to 49 cases/month and ESBL-producing Enterobacterales decreased from 145 to 86 cases/month during the pandemic period from March-December 2020 compared with the prior 14 months. Monthly case counts for 2020 are lowest during initial public health orders for the state of New Mexico. Rates of CRE remained constant between 2018-2021.

The proportion of CDI cases originating from long-term care facilities decreased significantly from 17.2% to 10.4% (p=0.006) while the proportion attributable to hospital inpatient and community populations remained constant. The proportion of ESBL-E cases from sterile sample sites increased from 3.1% to 4.9% (p=0.05) and the proportion of patients who died within 30 days or prior to discharge increased from 2.2% to 3.2% (p=0.019).

Conclusion

Rates and characteristics of CD and ESBL-E infections in Bernalillo county NM changed significantly during the COVID-19 pandemic, while rates of CRE remained constant. It is still unclear whether this is related to changes in actual disease rates due to risk factor exposure (healthcare), or if this trend reflects changes in care-seeking behavior and/or reporting of cases.

Disclosures

All Authors: No reported disclosures.

Low sensitivity of ICD-10 coding for culture-confirmed candidemia cases in an active surveillance system—United States, 2019–2020

We evaluated healthcare facility use of ICD-10 codes for culture-confirmed candidemia cases detected by active public health surveillance during 2019–2020. Most cases (56%) did not receive a candidiasis code, suggesting that studies relying on ICD-10 codes likely underestimate disease burden.

Comparison of the Risk of Recurrent Clostridioides Difficile Infections Among Patients in 2018 Versus 2013

Among persons with an initial Clostridioides difficile infection (CDI) across 10 US sites in 2018 compared with 2013, 18.3% versus 21.1% had ≥1 recurrent CDI (rCDI) within 180 days. We observed a 16% lower adjusted risk of rCDI in 2018 versus 2013 (P < .0001).

Molecular Characterization of Carbapenem-Resistant Enterobacterales Collected in the United States

Carbapenem-resistant Enterobacterales (CRE) are a growing public health concern due to resistance to multiple antibiotics and potential to cause health care-associated infections with high mortality. Carbapenemase-producing CRE are of particular concern given that carbapenemase-encoding genes often are located on mobile genetic elements that may spread between different organisms and species. In this study, we performed phenotypic and genotypic characterization of CRE collected at eight U.S. sites participating in active population- and laboratory-based surveillance of carbapenem-resistant organisms. Among 421 CRE tested, the majority were isolated from urine (n = 349, 83%). Klebsiella pneumoniae was the most common organism (n = 265, 63%), followed by Enterobacter cloacae complex (n = 77, 18%) and Escherichia coli (n = 50, 12%). Of 419 isolates analyzed by whole genome sequencing, 307 (73%) harbored a carbapenemase gene; variants of bla_KPC predominated (n = 299, 97%). The occurrence of carbapenemase-producing K. pneumoniae, E. cloacae complex, and E. coli varied by region; the predominant sequence type within each genus was ST258, ST171, and ST131, respectively. None of the carbapenemase-producing CRE isolates displayed resistance to all antimicrobials tested; susceptibility to amikacin and tigecycline was generally retained.

Risk Factors for SARS-CoV-2 Infection Among US Healthcare Personnel, May-December 2020

To determine risk factors for coronavirus disease (COVID-19) among US healthcare personnel (HCP), we conducted a case-control analysis. We collected data about activities outside the workplace and COVID-19 patient care activities from HCP with positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test results (cases) and from HCP with negative test results (controls) in healthcare facilities in 5 US states. We used conditional logistic regression to calculate adjusted matched odds ratios and 95% CIs for exposures. Among 345 cases and 622 controls, factors associated with risk were having close contact with persons with COVID-19 outside the workplace, having close contact with COVID-19 patients in the workplace, and assisting COVID-19 patients with activities of daily living. Protecting HCP from COVID-19 may require interventions that reduce their exposures outside the workplace and improve their ability to more safely assist COVID-19 patients with activities of daily living.

Effectiveness of mRNA Covid-19 Vaccine among U.S. Health Care Personnel

BACKGROUND

The prioritization of U.S. health care personnel for early receipt of messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19), allowed for the evaluation of the effectiveness of these new vaccines in a real-world setting.

METHODS

We conducted a test-negative case-control study involving health care personnel across 25 U.S. states. Cases were defined on the basis of a positive polymerase-chain-reaction (PCR) or antigen-based test for SARS-CoV-2 and at least one Covid-19-like symptom. Controls were defined on the basis of a negative PCR test for SARS-CoV-2, regardless of symptoms, and were matched to cases according to the week of the test date and site. Using conditional logistic regression with adjustment for age, race and ethnic group, underlying conditions, and exposures to persons with Covid-19, we estimated vaccine effectiveness for partial vaccination (assessed 14 days after receipt of the first dose through 6 days after receipt of the second dose) and complete vaccination (assessed ≥7 days after receipt of the second dose).

RESULTS

The study included 1482 case participants and 3449 control participants. Vaccine effectiveness for partial vaccination was 77.6% (95% confidence interval [CI], 70.9 to 82.7) with the BNT162b2 vaccine (Pfizer-BioNTech) and 88.9% (95% CI, 78.7 to 94.2) with the mRNA-1273 vaccine (Moderna); for complete vaccination, vaccine effectiveness was 88.8% (95% CI, 84.6 to 91.8) and 96.3% (95% CI, 91.3 to 98.4), respectively. Vaccine effectiveness was similar in subgroups defined according to age (<50 years or ≥50 years), race and ethnic group, presence of underlying conditions, and level of patient contact. Estimates of vaccine effectiveness were lower during weeks 9 through 14 than during weeks 3 through 8 after receipt of the second dose, but confidence intervals overlapped widely.

CONCLUSIONS

The BNT162b2 and mRNA-1273 vaccines were highly effective under real-world conditions in preventing symptomatic Covid-19 in health care personnel, including those at risk for severe Covid-19 and those in racial and ethnic groups that have been disproportionately affected by the pandemic. (Funded by the Centers for Disease Control and Prevention.).

Association between Socioeconomic Status and Incidence of Community-Associated Clostridioides difficile Infection - United States, 2014-2015

We evaluated the association between socioeconomic status (SES) and community-associated Clostridioides difficile infection (CA-CDI) incidence across 2474 census tracts in 10 states. Highly correlated community-level SES variables were transformed into distinct factors using factor analysis. We found low SES communities were associated with higher CA-CDI incidence.

The landscape of candidemia during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has resulted in unprecedented healthcare challenges, and COVID-19 has been linked to secondary infections. Candidemia, a fungal healthcare-associated infection, has been described in patients hospitalized with severe COVID-19. However, studies of candidemia and COVID-19 co-infection have been limited in sample size and geographic scope. We assessed differences in patients with candidemia with and without a COVID-19 diagnosis.

METHODS

We conducted a case-level analysis using population-based candidemia surveillance data collected through the Centers for Disease Control and Prevention's Emerging Infections Program during April-August 2020 to compare characteristics of candidemia patients with and without a positive test for COVID-19 in the 30 days before their Candida culture using chi-square or Fisher exact tests.

RESULTS

Of the 251 candidemia patients included, 64 (25.5%) were positive for SARS-CoV-2. Liver disease, solid organ malignancies, and prior surgeries were each >3 times more common in patients without COVID-19 co-infection, whereas intensive care unit-level care, mechanical ventilation, having a central venous catheter, and receipt of corticosteroids and immunosuppressants were each >1.3 times more common in patients with COVID-19. All cause in-hospital fatality was two times higher among those with COVID-19 (62.5%) than without (32.1%).

CONCLUSIONS

One quarter of candidemia patients had COVID-19. These patients were less likely to have certain underlying conditions and recent surgery commonly associated with candidemia and more likely to have acute risk factors linked to COVID-19 care, including immunosuppressive medications. Given the high mortality, it is important for clinicians to remain vigilant and take proactive measures to prevent candidemia in patients with COVID-19.

Treatment Practices for Adults with Candidemia at Nine Active Surveillance Sites - United States, 2017-2018

BACKGROUND

Candidemia is a common opportunistic infection causing substantial morbidity and mortality. Because of an increasing proportion of non-albicans Candida species and rising antifungal drug resistance, the Infectious Diseases Society of America (IDSA) changed treatment guidelines in 2016 to recommend echinocandins over fluconazole as first-line treatment for adults with candidemia. We describe candidemia treatment practices and adherence to the updated guidelines.

METHODS

During 2017-2018, the Emerging Infections Program conducted active population-based candidemia surveillance at nine U.S. sites using a standardized case definition. We assessed factors associated with initial antifungal treatment for the first candidemia case among adults using multivariable logistic regression models. To identify instances of potentially inappropriate treatment, we compared the first antifungal drug received with species and antifungal susceptibility testing (AFST) results from initial blood cultures.

RESULTS

Among 1,835 patients who received antifungal treatment, 1,258 (68.6%) received an echinocandin and 543 (29.6%) received fluconazole as initial treatment. Cirrhosis (adjusted odds ratio = 2.06, 95% confidence interval: 1.29-3.29) was the only underlying medical condition significantly associated with initial receipt of an echinocandin (versus fluconazole). Over half (n = 304, 56.0%) of patients initially treated with fluconazole grew a non-albicans species. Among 265 patients initially treated with fluconazole and with fluconazole AFST results, 28 (10.6%) had a fluconazole-resistant isolate.

CONCLUSIONS

A substantial proportion of patients with candidemia were initially treated with fluconazole, resulting in potentially inappropriate treatment for those involving non-albicans or fluconazole-resistant species. Reasons for non-adherence to IDSA guidelines should be evaluated, and clinician education is needed.

Burden of Candidemia in the United States, 2017

BACKGROUND

Candidemia is a common healthcare-associated bloodstream infection with high morbidity and mortality. There are no current estimates of candidemia burden in the United States (US).

METHODS

In 2017, the Centers for Disease Control and Prevention conducted active population-based surveillance for candidemia through the Emerging Infections Program in 45 counties in 9 states encompassing approximately 17 million persons (5% of the national population). Laboratories serving the catchment area population reported all blood cultures with Candida, and a standard case definition was applied to identify cases that occurred in surveillance area residents. Burden of cases and mortality were estimated by extrapolating surveillance area cases to national numbers using 2017 national census data.

RESULTS

We identified 1226 candidemia cases across 9 surveillance sites in 2017. Based on this, we estimated that 22 660 (95% confidence interval [CI], 20 210-25 110) cases of candidemia occurred in the US in 2017. Overall estimated incidence was 7.0 cases per 100 000 persons, with highest rates in adults aged ≥ 65 years (20.1/100 000), males (7.9/100 000), and those of black race (12.3/100 000). An estimated 3380 (95% CI, 1318-5442) deaths occurred within 7 days of a positive Candida blood culture, and 5628 (95% CI, 2465-8791) deaths occurred during the hospitalization with candidemia.

CONCLUSIONS

Our analysis highlights the substantial burden of candidemia in the US. Because candidemia is only one form of invasive candidiasis, the true burden of invasive infections due to Candida is higher. Ongoing surveillance can support future burden estimates and help assess the impact of prevention interventions.

780. How Much Does Prior Hospitalization Contribute to Readmission with Community-onset Clostridioides difficile Infection?

Background

Interventions to reduce community-onset (CO) Clostridioides difficile Infection (CDI) are not usually hospital-based due to the perception that they are often acquired outside the hospital. We determined the proportion of admitted CO CDI that might be associated with previous hospitalization.

Methods

The CDC’s Emerging Infections Program conducts population-based CDI surveillance in 10 US sites. We defined an incident case as a C. difficile-positive stool collected in 2017 from a person aged ≥ 1 year admitted to a hospital with no positive tests in the prior 8 weeks. Cases were defined as CO if stool was collected within 3 days of hospitalization. CO cases were classified into four categories: long-term care facility (LTCF)-onset if patient was admitted from an LTCF; long-term acute care hospital (LTACH)-onset if patient was admitted from an LTACH; CO-healthcare-facility associated (CO-HCFA) if patient was admitted from a private residence but had a prior healthcare-facility admission in the past 12 weeks; or community-associated (CA) if there was no admission to a healthcare facility in the prior 12 weeks. We excluded hospitals with < 10 cases among admitted catchment-area residents.

Results

Of 4724 cases in 86 hospitals, 2984 (63.2%) were CO (median per hospital: 65.8%; interquartile range [IQR]: 58.3%-70.7%). Among the CO cases, 1424 (47.7%) were CA (median per hospital: 48.1%; IQR: 40.3%-57.7%), 1201 (40.3%) were CO-HCFA (median per hospital: 41.0%; IQR: 32.9%-47.8%), 350 (11.7%) were LTCF-onset (median per hospital: 10.0%; IQR: 0.6%-14.4%), and 9 (0.3%) were LTACH-onset. Of 1201 CO-HCFA cases, 1174 (97.8%) had a prior hospitalization; among these, 978 (83.3%) (median per hospital: 83.3%; IQR: 69.2%-90.6%), which consists of 32.8% of all hospitalized CO cases, had been discharged from the same hospital (Figure), and 84.4% of the 978 cases (median per hospital: 88.2%: IQR: 76.5%-100.0%) had received antibiotics sometime in the prior 12 weeks.

Figure. Frequency of Cases Discharged in the 12 Weeks Prior to Readmission with Clostridioides difficile Infection (N=1138*)

Conclusion

A third of hospitalized CO CDI had been recently discharged from the same hospital, and most had received antibiotics during or soon after the last admission. Hospital-based and post-discharge antibiotic stewardship interventions could help reduce subsequent CDI hospitalizations.

Disclosures

Ghinwa Dumyati, MD, Roche Diagnostics (Consultant)

146. antifungal Susceptibility Patterns of candida Parapsilosis Bloodstream Isolates in the US, 2008–2018

Background

Multidrug resistant Candida is an increasing concern. C. parapsilosis in particular has decreased in vitro susceptibility to echinocandins. As a result, fluconazole had been favored for C. parapsilosis treatment. However, there is growing concern about increasing azole resistance among Candida species. We report on antifungal susceptibility patterns of C. parapsilosis in the US from 2008 through 2018.

Methods

Active, population-based surveillance for candidemia through the Centers for Disease Control and Prevention’s (CDC) Emerging Infections Program was conducted between 2008–2018, eventually encompassing 9 states (GA, MD,OR, TN, NY, CA, CO, MN, NM). Each incident isolate was sent to the CDC for species confirmation and antifungal susceptibility testing (AFST). Frequency of resistance was calculated and stratified by year and state using SAS 9.4

Results

Of the 8,704 incident candidemia isolates identified, 1,471 (15%) were C. parapsilosis; the third most common species after C. albicans and C. glabrata. AFST results were available for 1,340 C. parapsilosis isolates. No resistance was detected to caspofungin (MIC₅₀ 0.25) or micafungin (MIC₅₀ 1.00) with only one (< 1%) isolate resistant to anidulafungin (MIC₅₀ 1.00). In contrast, 84 (6.3%) isolates were resistant to fluconazole and another 44 (3.3%) isolates had dose-dependent susceptibility to fluconazole (MIC₅₀ 1.00). Fluconazole resistance increased sharply from an average of 4% during 2008–2014 to a peak of 14% in 2016 with a subsequent decline to 6% in 2018 (see figure). Regional variation is also observed with fluconazole resistance ranging from 0% (CO, MN, NM) to 42% (NY) of isolates by site.

Conclusion

The recent marked increase in fluconazole resistance among C. parapsilosis highlights this pathogen as an emerging drug resistant pathogen of concern and the need for ongoing antifungal resistance surveillance among Candida species. Our data support the empiric use of echinocandins for C. parapsilosis bloodstream infections and underscore the need to obtain AFST prior to fluconazole treatment. Furthermore, regional variation in fluconazole resistance emphasizes the importance of understanding local Candida susceptibility patterns.

Disclosures

Lee Harrison, MD, GSK (Consultant)Merck (Consultant)Pfizer (Consultant)Sanofi Pasteur (Consultant)

1424. Factors Associated with Failure to Clear Candidemia Infection: Surveillance Data from Eight States, 2017

Background

Candidemia is a bloodstream infection commonly associated with high morbidity and mortality. Failure to clear candidemia can lengthen hospitalization and treatment. Factors associated with candidemia clearance are unknown.

Methods

We analyzed 2017 candidemia surveillance data from the Centers for Disease Control and Prevention’s Emerging Infections Program. Data from eight sites (counties in California, Colorado, Georgia, Minnesota, New Mexico, New York, Oregon, and Tennessee) were included. Clearance was defined as having a blood culture negative for Candida ≤30 days after initial culture date (ICD). Cases with unknown clearance, unknown survival outcome, or death ≤30 days of ICD were excluded. Demographic and clinical factors associated with clearance were assessed with bivariate analysis using chi-square tests and multivariable logistic regression to calculate adjusted odds ratios (aOR) using backward selection (p-value&lt; 0.10).

Results

Of 1,024 candidemia cases, 737 were included and 582 (79%) demonstrated clearance, of which 79% had evidence of clearance ≤5 days after ICD. In bivariate analysis, clearance was associated with central venous catheter (CVC) ≤2 days before ICD, CVC removal ≤7 days after ICD, and systemic antifungal medication within 14 days before ICD. Clearance was inversely associated with black race and admission from another hospital. In multivariable analysis, only race and admission from another hospital were significant predictors; age, sex, and CVC presence and subsequent removal were also retained for their clinical relevance. In the final model, clearance was less likely among black patients (aOR 0.51, 95% confidence interval [CI] 0.29-0.91) and those admitted from another hospital (aOR 0.28, 95% CI 0.11-0.75).

Table 1. Bivariate associations for select variables between individuals with documented candidemia clearance and those without documented clearance in eight Emerging Infections Program surveillance sites, 2017

Conclusion

We found failure to clear candidemia infection to be associated with black race and prior hospital exposure, but not other factors previously shown to be associated (e.g., comorbidities, CVC presence). These associations could reflect illness severity, access to care, or other obstacles to effective treatment. Additional research is needed to investigate these associations further and identify other factors (e.g., treatment type and timing) to improve outcomes.

Disclosures

All Authors: No reported disclosures

Toxin Enzyme Immunoassays Detect Clostridioides difficile Infection With Greater Severity and Higher Recurrence Rates

BACKGROUND

Few data suggest that Clostridioides difficile infections (CDIs) detected by toxin enzyme immunoassay (EIA) are more severe and have worse outcomes than those detected by nucleic acid amplification tests (NAATs) only. We compared toxin- positive and NAAT-positive-only CDI across geographically diverse sites.

METHODS

A case was defined as a positive C. difficile test in a person ≥1 year old with no positive tests in the prior 8 weeks. Cases were detected during 2014-2015 by a testing algorithm (specimens initially tested by glutamate dehydrogenase and toxin EIA; if discordant results, specimens were reflexed to NAAT) and classified as toxin positive or NAAT positive only. Medical charts were reviewed. Multivariable logistic regression models were used to compare CDI-related complications, recurrence, and 30-day mortality between the 2 groups.

RESULTS

Of 4878 cases, 2160 (44.3%) were toxin positive and 2718 (55.7%) were NAAT positive only. More toxin-positive than NAAT-positive-only cases were aged ≥65 years (48.2% vs 38.0%; P < .0001), had ≥3 unformed stools for ≥1 day (43.9% vs 36.6%; P < .0001), and had white blood cell counts ≥15 000 cells/µL (31.4% vs 21.4%; P < .0001). In multivariable analysis, toxin positivity was associated with recurrence (adjusted odds ratio [aOR], 1.89; 95% confidence interval [CI], 1.61-2.23), but not with CDI-related complications (aOR, 0.91; 95% CI, .67-1.23) or 30-day mortality (aOR, 0.95; 95% CI, .73-1.24).

CONCLUSIONS

Toxin-positive CDI is more severe, but there were no differences in adjusted CDI-related complication and mortality rates between toxin-positive and NAAT-positive-only CDI that were detected by an algorithm that utilized an initial glutamate dehydrogenase screening test.

The AVMA's definitions of antimicrobial uses for prevention, control, and treatment of disease

Recent state and federal legislative actions and current recommendations from the World Health Organization seem to suggest that, when it comes to antimicrobial stewardship, use of antimicrobials for prevention, control, or treatment of disease can be ranked in order of appropriateness, which in turn has led, in some instances, to attempts to limit or specifically oppose the routine use of medically important antimicrobials for prevention of disease. In contrast, the AVMA Committee on Antimicrobials believes that attempts to evaluate the degree of antimicrobial stewardship on the basis of therapeutic intent are misguided and that use of antimicrobials for prevention, control, or treatment of disease may comply with the principles of antimicrobial stewardship. It is important that veterinarians and animal caretakers are clear about the reason they may be administering antimicrobials to animals in their care. Concise definitions of prevention, control, and treatment of individuals and populations are necessary to avoid confusion and to help veterinarians clearly communicate their intentions when prescribing or recommending antimicrobial use.

Trends in U.S. Burden of Clostridioides difficile Infection and Outcomes

BACKGROUND

Efforts to prevent Clostridioides difficile infection continue to expand across the health care spectrum in the United States. Whether these efforts are reducing the national burden of C. difficile infection is unclear.

METHODS

The Emerging Infections Program identified cases of C. difficile infection (stool specimens positive for C. difficile in a person ≥1 year of age with no positive test in the previous 8 weeks) in 10 U.S. sites. We used case and census sampling weights to estimate the national burden of C. difficile infection, first recurrences, hospitalizations, and in-hospital deaths from 2011 through 2017. Health care-associated infections were defined as those with onset in a health care facility or associated with recent admission to a health care facility; all others were classified as community-associated infections. For trend analyses, we used weighted random-intercept models with negative binomial distribution and logistic-regression models to adjust for the higher sensitivity of nucleic acid amplification tests (NAATs) as compared with other test types.

RESULTS

The number of cases of C. difficile infection in the 10 U.S. sites was 15,461 in 2011 (10,177 health care-associated and 5284 community-associated cases) and 15,512 in 2017 (7973 health care-associated and 7539 community-associated cases). The estimated national burden of C. difficile infection was 476,400 cases (95% confidence interval [CI], 419,900 to 532,900) in 2011 and 462,100 cases (95% CI, 428,600 to 495,600) in 2017. With accounting for NAAT use, the adjusted estimate of the total burden of C. difficile infection decreased by 24% (95% CI, 6 to 36) from 2011 through 2017; the adjusted estimate of the national burden of health care-associated C. difficile infection decreased by 36% (95% CI, 24 to 54), whereas the adjusted estimate of the national burden of community-associated C. difficile infection was unchanged. The adjusted estimate of the burden of hospitalizations for C. difficile infection decreased by 24% (95% CI, 0 to 48), whereas the adjusted estimates of the burden of first recurrences and in-hospital deaths did not change significantly.

CONCLUSIONS

The estimated national burden of C. difficile infection and associated hospitalizations decreased from 2011 through 2017, owing to a decline in health care-associated infections. (Funded by the Centers for Disease Control and Prevention.).

Carbapenem-Resistant Pseudomonas aeruginosa at US Emerging Infections Program Sites, 2015

Pseudomonas aeruginosa is intrinsically resistant to many antimicrobial drugs, making carbapenems crucial in clinical management. During July–October 2015 in the United States, we piloted laboratory-based surveillance for carbapenem-resistant P. aeruginosa (CRPA) at sentinel facilities in Georgia, New Mexico, Oregon, and Tennessee, and population-based surveillance in Monroe County, NY. An incident case was the first P. aeruginosa isolate resistant to antipseudomonal carbapenems from a patient in a 30-day period from any source except the nares, rectum or perirectal area, or feces. We found 294 incident cases among 274 patients. Cases were most commonly identified from respiratory sites (120/294; 40.8%) and urine (111/294; 37.8%); most (223/280; 79.6%) occurred in patients with healthcare facility inpatient stays in the prior year. Genes encoding carbapenemases were identified in 3 (2.3%) of 129 isolates tested. The burden of CRPA was high at facilities under surveillance, but carbapenemase-producing CRPA were rare.

507. Epidemiology of Community-Associated Carbapenemase + Producing Carbapenem-Resistant Enterobacteriacae Identified from the Emerging Infections Program, 2012–2017

Background

Carbapenemase-producing (CP-) carbapenem-resistant Enterobacteriaceae (CRE) have been almost exclusively linked to extensive healthcare exposure and are of significant concern due to limited treatment options and potential for plasmid-mediated spread of resistance. We report on CP-CRE in community-dwelling individuals.

Methods

We used 2012–2017 active, laboratory and population-based surveillance data for CRE from CDC’s Emerging Infections Program sites (9 sites by 2017). Cases were the first isolation of Escherichia coli, Klebsiella spp., or Enterobacter spp. from a normally sterile body specimen or urine in a surveillance site resident meeting a CRE phenotype (figure) in a 30 day period. Epidemiologic data were obtained from chart review. Cases were community-associated (CA) if not isolated after the first three days of a hospital stay; without inpatient healthcare, dialysis, or surgery in the year prior; and without indwelling medical devices within two days prior to culture. A convenience sample of isolates was tested at CDC by real-time PCR to detect bla_KPC, bla_NDM, bla_OXA-48-like, bla_VIM, or bla_IMP.

Results

Of 4023 CRE cases, 699 (17%) were CA, from which 297 isolates were tested; 20 (7%) were CP-CRE, from 18 patients (2 had repeat isolation of the same gene/species). The median age was 68 years (range: 33–91), and 14 (78%) were female. Patients were from 7 sites (range: 1–4/site). Their CP-CRE (10 bla_KPC, 6 bla_NDM, and 2 bla_OXA-48-like) were from three species (10 K. pneumoniae, 6 E. coli, 2 E. cloacae) and isolated from urine (n = 16) and blood (n = 2). Among those with CP-CRE from urine, 12 (75%) had clinical diagnoses of urinary tract infections and the rest had no infection documented. Overall, 7 (39%) were admitted to a hospital within 30 days of culture; none died during hospitalization. Most (n = 13; 72%) had underlying medical comorbidities, most commonly urinary tract abnormalities (n = 5; 28%) and diabetes mellitus (n = 5; 28%). Three (17%) had international travel within two months prior to culture.

Conclusion

CA CP-CRE were found in most surveillance sites but are rare, occurring primarily in older patients with underlying medical conditions. Patient interviews are planned to determine whether CA CP-CRE may be associated with distant or undocumented healthcare exposures.

Disclosures

All authors: No reported disclosures.

486. Epidemiology of Carbapenem-Resistant Pseudomonas aeruginosa Identified through the Emerging Infections Program (EIP), United States, 2016–2018

Background

Pseudomonas aeruginosa is intrinsically resistant to many commonly used antimicrobials, and carbapenems are often required to treat infections. We describe the crude incidence, epidemiology, and molecular characteristics of carbapenem-resistant P. aeruginosa (CRPA) in the EIP catchment area.

Methods

From August 1, 2016 through July 31, 2018, we conducted laboratory- and population-based surveillance for CRPA in selected areas in eight sites. We defined a case as the first isolate of P. aeruginosa resistant to imipenem, meropenem, or doripenem from the lower respiratory tract, urine, wounds, or normally sterile sites identified from a resident of the EIP catchment area in a 30-day period. Patient charts were reviewed. Analysis excluded cystic fibrosis patients. A random sample of isolates was collected. Real-time PCR to detect carbapenemase genes and whole-genome sequencing are in progress.

Results

We identified 4,209 cases in 3373 patients. The annual incidence was 14.50 (95% CI, 14.07–14.94) per 100,000 persons and varied among sites from 4.89 in OR to 25.21 in NY. The median age of patients was 66 years (range: < 1–101), 42.1% were female, and nearly all (97.5%) had an underlying condition. Most cases were identified from urine (42.8%) and lower respiratory tract (35.7%) cultures. Nearly all (93.3%) occurred in patients with inpatient healthcare facility stay, surgery, chronic dialysis, or indwelling devices in the prior year; death occurred in 7.2%. Among 937 isolates tested, 847 (90.4%) underwent PCR; six (0.7%) harbored a carbapenemase, from four sites (CO, MD, NY, and OR): bla_VIM (3), bla_KPC (2), and bla_IMP (1). Of 612 (65.3%) isolates sequenced, the most common ST types were ST235 (9.2%) and ST298 (4.9%).

Conclusion

Carbapenemases were rarely the cause of carbapenem resistance but were found at EIP sites with high and low CRPA incidence. The emergence of mobile carbapenemases in P. aeruginosa has the potential to increase the incidence of CRPA. Increased detection and early response to carbapenemase-producing CRPA is key to prevent further emergence.

Disclosures

All authors: No reported disclosures.

837. Prior Hospitalizations Among Cases of Community-Associated Clostridioides difficile Infection—10 US States, 2014–2015

Background

Despite overall progress in preventing Clostridioides difficile Infection (CDI), community-associated (CA) infections have been steadily increasing. Although the incubation period of CDI is thought to be relatively short, gastrointestinal microbial disruption from remote healthcare exposures (e.g., inpatient antibiotic use) may be associated with CA-CDI. To assess this potential association, we linked CA-CDI infections identified through CDC’s Emerging Infections Program (EIP) to Medicare claims data to describe prior healthcare utilization.

Methods

We defined an EIP CA-CDI case as a positive C. difficile test collected in 2014–2015 from an outpatient or inpatient within 3 days of hospital admission, provided there was no positive test in the prior 8 weeks and no admission to a healthcare facility in the prior 12 weeks. We linked EIP CA-CDI cases aged ≥65 years to a Medicare beneficiary using unique combinations of birthdate, sex, and zip code. Cases were included if they maintained continuous fee-for-service coverage for 1 year prior to the event date. To calculate exposure odds ratios for previous hospitalizations, each case was matched to 5 control beneficiaries on age, sex, and county of residence. We used logistic regression to calculate adjusted matched odds ratios (amOR) that controlled for chronic conditions.

Results

We successfully linked 2,287/3,367 (68%) EIP CA-CDI cases. Of these, 1,236 cases met inclusion criteria; the median age was 77 years and 63% were female. We identified 69 (5.6%) cases with misclassification of prior healthcare exposures, most of whom (48, 70%) were hospitalized in the 12 weeks prior to their event. Among the 1,167 true CA-CDI cases, 33% were hospitalized in the prior 12 weeks to 1 year. The median number of weeks from prior hospitalization to CDI was 27 (IQR 18–38, Figure 1). Cases had a higher risk of hospitalization than matched controls in the prior 3–6 months (amOR: 2.33, 95% CI: 1.87, 2.90) and 6–12 months (amOR: 1.43 95% CI: 1.18, 1.74).

Conclusion

Remote hospitalization in the previous year was a significant risk factor for CA-CDI, especially in the 3–6 months prior to CA-CDI. Long-lasting prevention strategies implemented at hospital discharge and enhanced inpatient antibiotic stewardship may prevent CA-CDI among older adults.

Disclosures

All Authors: No reported Disclosures.

538. Extended-Spectrum β-Lactamase (ESBL): Producing Enterobacteriaceae Surveillance Pilot, New Mexico, 2017

Background

Extended-spectrum β-lactamase – producing (ESBL) Enterobacteriaceae pose a serious antibiotic resistance threat, yet gaps remain in our understanding of their epidemiology. New Mexico was one of five Emerging Infection Program (EIP) sites to participate in a surveillance pilot from October 1 to December 31, 2017.

Methods

A case was defined as a resident of Bernalillo County, NM with E. coli, Klebsiella pneumoniae, or Klebsiella oxytoca cultured from urine or normally sterile body sites resistant to at least one extended-spectrum cephalosporin and nonresistant to all carbapenem antibiotics tested. EIP staff assessed prior healthcare exposures, risk factors, and outcomes through medical record review.

Results

NM EIP identified 309 incident cases among 288 individuals; 263 medical records were reviewed. Cases ranged in age from 3–95 years, with a median age of 63 years. Most isolates were E. coli (n = 270, 87.4%); 35 (11.3%) were K. pneumoniae and 4 (1.3%) were K. oxytoca. The majority of isolates were cultured from urine (297, 96.1%). Blood cultures comprised 11 cases (3.6%). The majority of ESBL cultures were collected in an outpatient setting; 15% were collected from hospital inpatients and fewer than 5% from residents of a long-term care facility (LTCF) or long-term acute care hospital (LTACH). However, 21% of those collected in an outpatient setting, primarily the ED, were hospitalized within 30 days.

Over 60% of the cases had at least one relevant risk factor documented in their medical record. One-third had documented antimicrobial use in the prior month, 39% had been hospitalized in the year prior, and 19% had a urinary catheter in place in the 2 days prior to culture collection. Interestingly, while only 2% had documentation of international travel in the two months prior to culture, 18% had either documented international travel outside of that timeframe, or required the use of language interpretation, possibly indicating extensive time living internationally in the past.

Conclusion

Among residents of Bernalillo County, NM, ESBL isolates were predominantly E. coli, cultured from urine in outpatient settings. Over half had documentation of recognized risk factors, including prior hospitalizations, recent antibiotic use, or presence of indwelling devices.

Disclosures

All authors: No reported disclosures.

Disparities in the incidence of community-acquired Clostridioides difficile infection: An area-based assessment of the role of social determinants in Bernalillo County, New Mexico

BACKGROUND

Community-associated Clostridioides difficile infections (CA-CDIs) share many risk factors with health care-associated cases, although the role of socioeconomic factors is poorly understood. This study estimates the influence of several census tract-level measures of socioeconomic status on CA-CDI incidence rates.

METHODS

CA-CDI case data from the New Mexico Emerging Infections Program were analyzed using quasi-Poisson regression modeling. Geocoded cases were assigned census tract-level socioeconomic measures to explore racial, ethnic and socioeconomic disparities in CA-CDI incidence.

RESULTS

Regression modeling identified census tract-level socioeconomic measures as well as individual and medical measures that together accounted for 57% of the variance in CA-CDI rates. At the census tract level, socioeconomic factors associated with an increase in CA-CDI incidence included a high percentage of individuals lacking health insurance and a low percentage of individuals with low educational attainment. A subanalysis that included racial and ethnic designation revealed that ethnicity had no significant effect, but compared to white race, other races were significantly more likely to acquire CA-CDI.

CONCLUSIONS

Although this work reveals the role of certain socioeconomic and race and ethnicity risk factors in the incidence of CA-CDI, it also underscores the complex relationships that exist between socioeconomic status and access to health care.

Carbapenem-Nonsusceptible Acinetobacter baumannii, 8 US Metropolitan Areas, 2012-2015

In healthcare settings, Acinetobacter spp. bacteria commonly demonstrate antimicrobial resistance, making them a major treatment challenge. Nearly half of Acinetobacter organisms from clinical cultures in the United States are nonsusceptible to carbapenem antimicrobial drugs. During 2012–2015, we conducted laboratory- and population-based surveillance in selected metropolitan areas in Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee to determine the incidence of carbapenem-nonsusceptible A. baumannii cultured from urine or normally sterile sites and to describe the demographic and clinical characteristics of patients and cases. We identified 621 cases in 537 patients; crude annual incidence was 1.2 cases/100,000 persons. Among 598 cases for which complete data were available, 528 (88.3%) occurred among patients with exposure to a healthcare facility during the preceding year; 506 (84.6%) patients had an indwelling device. Although incidence was lower than for other healthcare-associated pathogens, cases were associated with substantial illness and death.

482. Association between Socioeconomic Status Factors and Incidence of Community-Associated Clostridium difficile Infection Utilizing Factor Analysis—United States, 2014–2015

Background

Traditionally a healthcare-associated infection, Clostridium difficile infection (CDI) is increasingly emerging in communities. Health disparities in CDI exist, but the social determinants of health that influence community-associated (CA) CDI are unknown. We used factor analysis and disparate data sources to identify area-based socioeconomic status (SES) factors associated with CA-CDI incidence.

Methods

CDC’s Emerging Infections Program conducts population-based CDI surveillance in 35 US counties. A CA-CDI case is defined as a positive C. difficile specimen collected as an outpatient or within 3 days of hospitalization in a person aged ≥1 year without a positive test in the prior 8 weeks or an overnight stay in a healthcare facility in the prior 12 weeks. 2014–2015 CA-CDI case addresses were geocoded to a 2010 census tract (CT) and incidence rates were calculated. CT-level SES variables were obtained from the 2011–2015 American Community Survey. The Health Resources and Services Administration provided medically underserved area (MUA) designations. Exploratory factor analysis transformed 15 highly correlated SES variables into threefactors using scree plot and Kaiser criteria: “Low Income,” “Foreign-born,” and “High Income.” To account for CT-level clustering, a negative binomial generalized linear mixed model was used to evaluate the associations of these factors and MUA with CA-CDI incidence, adjusting for age, sex, race and diagnostic test.

Results

Of 13,903 CA-CDI geocoded cases, 63% were female, 80% were white, and 36% were aged ≥65 years. Annual CA-CDI incidence was 63.4/100,000 persons. In multivariable analysis, “Low Income” (rate ratio [RR]: 1.09; 95% confidence interval [CI]: 1.05–1.13) and “High Income” (RR: 0.90; CI: 0.87–0.93) were significantly associated with CA-CDI incidence.

Conclusion

Factor analysis was instrumental in identifying key drivers of disparities among interrelated SES variables. Low-income areas were surprisingly associated with higher CA-CDI incidence, given that known CDI risk factors include increased access to healthcare. Understanding how SES factors might impact CA-CDI incidence can inform prevention strategies in low-income areas.

Disclosures

G. Dumyati, Seres: Scientific Advisor, Consulting fee.

492. Long-Term Outcomes of Clostridium difficile Infection Among Medicare Beneficiaries

Background

Clostridium difficile infection (CDI) is a common healthcare-associated infection, particularly among older adults. We used laboratory-confirmed CDI surveillance data from 8 states participating in the Centers for Disease Control and Prevention’s Emerging Infections Program linked to claims data for Centers for Medicare and Medicaid Services (CMS) beneficiaries to measure variation in 1-year outcomes associated with CDI.

Methods

A CDI case was defined as a positive C. difficile stool test in 2014 in a person without a positive test in the prior 8 weeks. Cases aged ≥65 years were linked to their CMS beneficiary ID using unique combinations of date of birth, sex, and zip code. Each case was matched to five control beneficiaries who did not link to any case and were residents of the same catchment area. Inclusion criteria were continuous fee-for-service Medicare for the entire study period (1 year before and after event date), and no hospitalization or skilled nursing facility stay with an ICD-9-CM code for CDI in the year prior to their match date. Multivariable logistic regression models were used to compare mortality and hospitalization for 1 year following the event date between beneficiaries with and without CDI, adjusting for age, sex, race, catchment area, chronic conditions, number of hospitalizations in the prior year, and hospitalization status at the time of and 7 days preceding the event date.

Results

Of 5,097 cases aged ≥65, 3,082 (60%) were linked to a CMS ID, and 1,832 (59%) met inclusion criteria. In crude analysis, 34% of beneficiaries with CDI died within 1 year, compared with 5% of beneficiaries without CDI. Beneficiaries with CDI were also more likely to be hospitalized in the subsequent year (54% vs. 17%). Beneficiaries with CDI had a higher adjusted odds of death (adjusted OR 3.01, 95% CI: 2.46, 3.69) and hospitalization within 1 year (adjusted OR 1.93, 95% CI: 1.65, 2.25) than those without CDI.

Conclusion

Older adults with CDI were three times more likely to die in the year following infection and nearly two times more likely to be hospitalized compared with those without CDI, revealing independent long-term risk of poor outcomes. This excess morbidity and mortality supports the need to develop novel CDI prevention strategies for this population.

Disclosures

All authors: No reported disclosures.

490. Comparison of Clostridium difficile Infection Outcomes by Diagnostic Testing Method

Background

US laboratories are increasingly using nucleic acid amplification tests (NAAT) to diagnose Clostridium difficile infection (CDI) due to their increased sensitivity over toxin enzyme immunoassays (EIA), but NAATs may be more likely than toxin EIAs to detect colonization rather than true disease. Limited data indicate patients positive by toxin EIA (toxin+) have worse outcomes than those positive by NAAT (NAAT+) only, suggesting toxin EIA detects true infection more often than NAAT. We used multisite CDI surveillance data from the Centers for Disease Control and Prevention’s Emerging Infections Program to compare clinical course and outcomes between toxin+ and NAAT+ only patients.

Methods

A case was defined as a positive C. difficile test in a person ≥1 year old with no positive tests in the prior 8 weeks. Cases detected during 2014–2015 by a testing algorithm using toxin EIA and NAAT were classified as toxin+ or NAAT+ only. Medical charts were reviewed. Death data were obtained from state death registries. Multivariable logistic regression models were used to compare CDI recurrence and 90-day mortality between the two groups, adjusting for age, sex, race, Charlson comorbidity index, and receipt of oral vancomycin. For the outcome of recurrence, we also adjusted for history of CDI in the prior 6 months.

Results

Of 4,878 cases, 2160 (44%) were toxin+ and 2,718 (56%) were NAAT+ only. Toxin+ cases were more likely than NAAT+ only cases to be ≥65 years old (48% vs. 38%; P < 0.0001), have white blood cells ≥15,000/µL (483/1,539 [31%] vs. 423/1,978 [21%]; P < 0.0001), and have received oral vancomycin ≤3 days of diagnosis (32% vs. 29%; P = 0.03). Comparing toxin+ to NAAT+ only cases, 21% vs. 11% had a recurrence (P < 0.0001), of which 71% vs. 33% had a toxin+ recurrence (P < 0.0001), and 10% vs. 9% died ≤90 days of diagnosis (P = 0.12). In multivariable analysis, a toxin+ result was associated with recurrence (adjusted odds ratio [aOR]: 1.89, 95% CI: 1.61–2.22) but not with 90-day mortality (aOR: 0.99; 95% CI: 0.81–1.22).

Conclusion

Toxin+ CDI is more severe by some markers and more likely to recur as toxin+. However, there was no difference in adjusted mortality, which may reflect an effect on mortality in NAAT+ only cases from mild CDI, receipt of unnecessary CDI treatment, or other factors.

Disclosures

G. Dumyati, Seres: Scientific Advisor, Consulting fee.

1761. Effect of Carbapenem-Resistant Enterobacteriaceae (CRE) Surveillance Case Definition Change on CRE Epidemiology—Selected US Sites, 2015–2016

Background

Carbapenem-resistant Enterobacteriacae (CRE) are an urgent US public health threat. CDC reported CRE incidence to be 2.93/100,000 population in 2012–2013 in selected sites but changed the CRE surveillance case definition in 2016 to improve sensitivity for detecting carbapenemase-producing (CP) CRE. We describe CRE epidemiology before and after the change.

Methods

Eight CDC Emerging Infections Program sites (CO, GA, MD, MN, NM, NY, OR, TN) conducted active, population-based CRE surveillance in selected counties. A case was defined as having an isolate of E. coli, Enterobacter, or Klebsiella meeting a susceptibility phenotype (figure) at a clinical laboratory from urine or a normally sterile body site in a surveillance area resident in a 30-day period. We collected data from medical records and defined cases as community-associated (CA) if no healthcare risk factors were documented. A convenience sample of isolates were tested for carbapenemase genes at CDC by real-time PCR. We calculated incidence rates (per 100,000 population) by using US Census data. Case epidemiology and the proportion of CP-CRE isolates in 2015 versus 2016 were compared.

Results

In total, 442 incident CRE cases were reported in 2015, and 1,149 cases were reported in 2016. Most isolates were cultured from urine: 87% in 2015 and 92% in 2016 (P < .001). The crude overall pooled mean incidence in 2015 was 2.9 (range by site: 0.45–7.19) and in 2016 was 7.48 (range: 3.13–15.95). The most common CRE genus was Klebsiella (51%) in 2015, and in 2016 was Enterobacter (41%, P < 0.001). Of the subset of CRE isolates tested at CDC, 109/227 (48%) were CP-CRE in 2015 and 109/551 (20%) were CP-CRE in 2016. In 2015, 52/442 (12%) of cases were CA CRE, and in 2016, 267/1,149 (23%) were CA CRE (P < 0.001). In 2016, 3/111 (2.7%) of CA CRE isolates tested were CP-CRE.

Conclusion

A large increase in reported CRE incidence was observed after the change in the case definition. The new case definition includes a substantially larger number of Enterobacter cases. A decrease in CP-CRE prevalence appears to be driven by an increase in non-CP-CRE cases. Although CP-CRE in the community still appear to be rare, a substantial proportion of phenotypic CRE appear to be CA, and CDC is undertaking efforts to further investigate CA CRE, including CP-CRE.

Disclosures

G. Dumyati, Seres: Scientific Advisor, Consulting fee.

1162. Epidemiology of Carbapenem-Resistant Pseudomonas aeruginosa Identified Through the Emerging Infections Program (EIP), United States, 2016–2017

Background

Pseudomonas aeruginosa is intrinsically resistant to many commonly used antimicrobials and carbapenems are often required to treat infections. We describe the epidemiology and crude incidence of carbapenem-resistant P. aeruginosa(CRPA) in the EIP catchment area.

Methods

From August 1, 2016 through July 31, 2017, we conducted laboratory- and population-based surveillance for CRPA in selected metropolitan areas in Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee. We defined an incident case as the first isolate of P. aeruginosa-resistant to imipenem, meropenem, or doripenem from the lower respiratory tract, urine, wounds, or normally sterile sites identified from a resident of the EIP catchment area in a 30-day period. Patient charts were reviewed. A random sample of isolates was screened at CDC for carbapenemases using the modified carbapenem inactivation method (mCIM) and real-time PCR.

Results

During the 12-month period, we identified 3,042 incident cases among 2,154 patients. The crude incidence rate was 21.2 (95% CI, 20.4–21.9) per 100,000 persons and varied by site (range: 7.7 in Oregon to 31.1 in Maryland). The median age of patients was 64 years (range: <1–101) and 41.2% were female. Nearly all (97.1%) had at least one underlying condition and 10.2% had cystic fibrosis (CF); 17.8% of cases were from CF patients. For most cases, isolates were from the lower respiratory tract (49.2%) or urine (35.3%) and occurred in patients with recent hospitalization (87.2%) or indwelling devices (70.3%); 8.7% died. At the clinical laboratory, 84.7% of isolates were susceptible to an aminoglycoside and 66.4% to ceftazidime or cefepime. Among the 391 isolates tested, nine (2.3%) were mCIM-positive; one had a carbapenemase detected by PCR (bla_VIM-4).

Conclusion

The burden of CRPA varied by EIP site. Most cases occurred in persons with healthcare exposures and underlying conditions. The majority of isolates were susceptible to at least one first-line antimicrobial. Carbapenemase producers were rare; a more specific phenotypic definition would greatly facilitate surveillance for these isolates.

Disclosures

All authors: No reported disclosures.

1722. The Changing Epidemiology of Candidemia in the United States: Injection Drug Use as an Emerging Risk Factor for Candidemia

Background

Known risk factors for candidemia include diabetes, malignancy, antibiotics, total parenteral nutrition (TPN), prolonged hospitalization, abdominal surgery, and central venous catheters. Injection drug use (IDU) is not a common risk factor. We used data from CDC Emerging Infections Program’s candidemia surveillance to assess prevalence of IDU among candidemia cases and compare IDU and non-IDU cases.

Methods

Active, population-based candidemia surveillance was conducted in 45 counties in 9 states during January–December 2017. Data from 2014 to 2016 were available from 4 states and were used to look for trends. A case was defined as blood culture with Candida in a surveillance area resident. We collected clinical information, including IDU in the past 12 months. Differences between IDU and non-IDU cases were tested using logistic regression.

Results

Of 1,018 candidemia cases in 2017, 123 (12%) occurred in the context of recent IDU (1% in Minnesota and 27% in New Mexico) (Figure 1). In the 4 states with pre-2017 data, the proportion of IDU cases increased from 7% in 2014 to 15% in 2017, with the proportion in Tennessee nearly tripling from 7% to 18% (Figure 2). IDU cases were younger than non-IDU cases (median 34 vs. 62 years, P < 0.001). Compared with non-IDU cases, IDU cases were less likely to have diabetes (16% vs. 35%; OR 0.4, CI 0.2–0.6), malignancies (7% vs. 30%; OR 0.2, CI 0.1–0.3), abdominal surgery (6% vs. 19%; OR 0.3, CI 0.1–0.6), receive TPN (6% vs. 27%; OR 0.2, CI 0.1–0.4) and were more likely to have hepatitis C (96% vs. 47%; OR 16.1, CI 10.4–24.9), be homeless (13% vs. 1%; OR 17.8, CI 7.1–44.6), and have polymicrobial blood cultures (33% vs. 17%; OR 2.4, CI 1.6–3.6). Median time from admission to candidemia was 0.5 vs. 3 days and in-hospital mortality was 7% vs. 28% for IDU and non-IDU cases, respectively.

Conclusion

In 2017, 1 in 8 candidemia cases had a history of IDU, including a quarter of cases in some sites. The proportion of such cases increased since 2014. IDU cases lacked many of the typical risk factors for candidemia, suggesting that IDU may be an independent risk factor. Given the growing opioid epidemic, further study is necessary to elucidate how people who inject drugs acquire candidemia and design effective interventions for prevention.

Disclosures

All authors: No reported disclosures.

Trends in incidence of long-term-care facility onset Clostridium difficile infections in 10 US geographic locations during 2011-2015

During 2011-2015, the adjusted long-term-care facility onset Clostridium difficile infection incidence rate in persons aged ≥65 years decreased annually by 17.45% (95% confidence interval, 14.53%-20.43%) across 10 US sites. A concomitant decline in inpatient fluoroquinolone use and the C difficile epidemic strain NAP1/027 among persons aged ≥65 years may have contributed to the decrease in long-term-care facility-onset C difficile infection incidence rate.

Risk Factors for Community-Associated Clostridium difficile Infection in Adults: A Case-Control Study

Background

An increasing proportion of Clostridium difficile infections (CDI) in the United States are community-associated (CA). We conducted a case-control study to identify CA-CDI risk factors.

Methods

We enrolled participants from 10 US sites during October 2014-March 2015. Case patients were defined as persons age ≥18 years with a positive C. difficile specimen collected as an outpatient or within 3 days of hospitalization who had no admission to a health care facility in the prior 12 weeks and no prior CDI diagnosis. Each case patient was matched to one control (persons without CDI). Participants were interviewed about relevant exposures; multivariate conditional logistic regression was performed.

Results

Of 226 pairs, 70.4% were female and 52.2% were ≥60 years old. More case patients than controls had prior outpatient health care (82.1% vs 57.9%; P < .0001) and antibiotic (62.2% vs 10.3%; P < .0001) exposures. In multivariate analysis, antibiotic exposure-that is, cephalosporin (adjusted matched odds ratio [AmOR], 19.02; 95% CI, 1.13-321.39), clindamycin (AmOR, 35.31; 95% CI, 4.01-311.14), fluoroquinolone (AmOR, 30.71; 95% CI, 2.77-340.05) and beta-lactam and/or beta-lactamase inhibitor combination (AmOR, 9.87; 95% CI, 2.76-340.05),-emergency department visit (AmOR, 17.37; 95% CI, 1.99-151.22), white race (AmOR 7.67; 95% CI, 2.34-25.20), cardiac disease (AmOR, 4.87; 95% CI, 1.20-19.80), chronic kidney disease (AmOR, 12.12; 95% CI, 1.24-118.89), and inflammatory bowel disease (AmOR, 5.13; 95% CI, 1.27-20.79) were associated with CA-CDI.

Conclusions

Antibiotics remain an important risk factor for CA-CDI, underscoring the importance of appropriate outpatient prescribing. Emergency departments might be an environmental source of CDI; further investigation of their contribution to CDI transmission is needed.

Socioeconomic Status Factors Associated with Increased Incidence of Community-Associated Clostridium difficile Infection

Background

Traditionally a hospital-acquired pathogen, Clostridium difficile is increasingly recognized as an important cause of diarrhea in community settings. Health disparities in C. difficileinfection (CDI) have been reported, but little is known about the social determinants of health that influence community-associated (CA) CDI incidence. We sought to identify socioeconomic status (SES) factors associated with increased CA-CDI incidence.

Methods

Population-based CDI surveillance is conducted in 35 U.S. counties through the Centers for Disease Control and Prevention’s Emerging Infections Program. A CA-CDI case is defined as a positive C. difficile stool specimen collected as an outpatient or within three days of hospitalization in a person aged ≥ 1 year who did not have a positive test in the prior 8 weeks or an overnight stay in a healthcare facility in the prior 12 weeks. ArcGIS software was used to geocode 2014–2015 CA-CDI case addresses to a 2010 census tract (CT). Incidence rate was calculated using 2010 Census population denominators. CT-level SES factors were obtained from the 2011–2015 American Community Survey 5-year estimates and divided into deciles. To account for CT-level clustering effects, separate generalized linear mixed models with negative binomial distribution were used to evaluate the association between each SES factor and CA-CDI incidence, adjusted by age, sex and race.

Results

Of 9686 CA-CDI cases, 9417 (97%) had addresses geocoded to a CT; of these, 62% were female, 82% were white, and 35% were aged ≥65 years. Annual CA-CDI incidence was 42.9 per 100,000 persons. After adjusting for age, sex and race, CT-level SES factors significantly associated with increased CA-CDI incidence included living under the poverty level (rate ratio [RR] 1.12; 95% confidence interval [CI] 1.09–1.53), crowding in homes (RR 1.11; 95% CI 1.01–1.21), low education (RR 1.11; 95% CI 1.07–1.15), low income (RR 1.15; 95% CI 1.12–1.17), having public health insurance (RR 1.21; 95% CI 1.18–1.24), receiving public assistance income (RR 1.69; 95% CI 1.55–1.84), and unemployment (RR 1.14; 95% CI 1.07–1.22).

Conclusion

Areas with lower SES have modestly increased CA-CDI incidence. Understanding the mechanisms by which SES factors impact CA-CDI incidence could help guide prevention efforts in these higher-risk areas.

Disclosures

All authors: No reported disclosures.

Differences in Clinical Characteristics and Outcomes of Patients with Community-Onset Clostridium difficile Infection who Tested Positive by EIA Compared with NAAT through a Two-Step Algorithm

Background

The low sensitivity of toxin enzyme immunoassay (EIA) for the diagnosis of Clostridium difficile infection (CDI) motivated many laboratories to add nucleic acid amplification tests (NAAT) to their testing protocol. However, NAAT do not distinguish between colonization and infection, and indiscriminant testing could lead to over treatment of CDI.

Methods

Active, population-based CDI surveillance has been conducted through the Emerging Infections Program in Bernalillo County, NM since 2011, with test type collected at the individual level since 2014. Community-onset (CO) CDI cases with a first positive test diagnosed by a two-step algorithm (concurrent EIA/GDH, with discordant results reflexed to NAAT) in 2014–2015 were included. We analyzed clinical characteristics and outcomes of patients EIA positive compared with NAAT positive. Demographics, risk factors, treatment, and outcomes were assessed through medical record review.

Results

Among 1,063 cases, 559 (52.6%) were EIA positive only and 504 (47.4%) were NAAT positive only. Of those with stool collected as a hospital inpatient, 57% were NAAT positive (P &lt; 0.001); this increased from 43.4% if tested the day of admission to 61.4% when tested on day three. Conversely, 38.6% of patients with stool collected in an emergency department were NAAT positive (P = 0.004). Fewer cases with complicated outcomes were NAAT positive (40.7%, P = 0.023). Among those with no documentation of recent antibiotic use, 64.3% were NAAT positive (P &lt; 0.001), and 67.8% of cases with no CDI treatment were NAAT positive (P = 0.005). Only 28.3% percent of cases with recurrent CDI were initially NAAT positive (P &lt; 0.001).

Conclusion

EIA negative and NAAT positive CO-CDI cases tended to have a milder clinical presentation than those that were EIA positive. This suggests that some patients positive only by NAAT may have mild CDI or be colonized, rather than infected, with C. difficile. These individuals were less likely to have complicated outcomes, have recent documented antibiotic use, be treated for CDI, or have a recurrent CDI episode than those positive by EIA. Longer hospital stay correlated with increased proportion of testing NAAT positive. Providers may benefit from considering testing protocol and clinical correlation when assessing patients with positive C. difficile test results.

Disclosures

All authors: No reported disclosures.

Wide Range of Carbapenem-resistant Enterobacteriaceae Incidence and Trends in Emerging Infections Program Surveillance, 2012–2015

Background

Carbapenem-resistant Enterobacteriaceae (CRE) are an urgent threat in the United States because of high morbidity and mortality, few treatment options, and potential for rapid spread among patients. To assess for changes in CRE epidemiology and risk among populations, we analyzed CDC Emerging Infections Program (EIP) 2012–2015 surveillance data for CRE.

Methods

Active, population-based CRE surveillance was initiated in January 2012 at 3 EIP sites (GA, MN, OR) and expanded to 5 additional sites (CO, MD, NM, New York, TN) by 2014. An incident case was the first Escherichia coli, Enterobacter, or Klebsiella isolate (non-susceptible to at least one carbapenem and resistant to all third-generation cephalosporins tested) collected from urine or a normally sterile body site from a patient during a 30-day period. Data were collected from patients’ medical records. Cases were hospital-onset (HO) or long-term care facility (LTCF) onset if patients were in the respective facility ≥3 days prior to culture or at the time of culture; and community-onset (CO) otherwise. We calculated incidence rates based on census data for EIP sites and described by type of infection onset.

Results

A total of 1,582 incident CRE cases were reported in 2012–2015. Most cases (88%) were identified through urine cultures; 946 (60%) were female, and median age was 66 years (interquartile range: 55–77). The median incidence by site was 2.95 per 100,000 population (range: 0.35–8.98). Among the three sites with four full years of data, a different trend was seen in each (Figure). Trends in GA and MN were statistically significant, and no significant trend was seen in OR. Overall, 480 cases (30%) were HO, 524 (33%) were LTCF onset, and 578 (37%) were CO. Of CO cases, 308 (53%) had been hospitalized, admitted to a long- term acute care hospital or were a LTCF resident in the prior year.

Conclusion

CRE incidence varied more than 20-fold across surveillance sites, with evidence of continued increases in MN. Measuring impact of programs aimed at reducing CRE transmission in other regions will require obtaining local data to identify cases occurring during and after healthcare facility discharge. Further study of changes in incidence in some settings and areas might offer opportunities to refine and expand effective control strategies.

Disclosures

All authors: No reported disclosures.

Improved Phenotype-Based Definition for Identifying Carbapenemase Producers among Carbapenem-Resistant Enterobacteriaceae

A new, less restrictive definition increases detection of Klebsiella pneumoniae carbapenemase producers.

Preventing transmission of carbapenemase-producing, carbapenem-resistant Enterobacteriaceae (CP-CRE) is a public health priority. A phenotype-based definition that reliably identifies CP-CRE while minimizing misclassification of non–CP-CRE could help prevention efforts. To assess possible definitions, we evaluated enterobacterial isolates that had been tested and deemed nonsusceptible to >1 carbapenem at US Emerging Infections Program sites. We determined the number of non-CP isolates that met (false positives) and CP isolates that did not meet (false negatives) the Centers for Disease Control and Prevention CRE definition in use during our study: 30% (94/312) of CRE had carbapenemase genes, and 21% (14/67) of Klebsiella pneumoniae carbapenemase–producing Klebsiella isolates had been misclassified as non-CP. A new definition requiring resistance to 1 carbapenem rarely missed CP strains, but 55% of results were false positive; adding the modified Hodge test to the definition decreased false positives to 12%. This definition should be considered for use in carbapenemase-producing CRE surveillance and prevention.

Burden of Nursing Home-Onset Clostridium difficile Infection in the United States: Estimates of Incidence and Patient Outcomes

Background.  Approximately 4 million Americans receive nursing home (NH) care annually. Nursing home residents commonly have risk factors for Clostridium difficile infection (CDI), including advanced age and antibiotic exposures. We estimated national incidence of NH-onset (NHO) CDI and patient outcomes. Methods.  We identified NHO-CDI cases from population-based surveillance of 10 geographic areas in the United States. Cases were defined by C difficile-positive stool collected in an NH (or from NH residents in outpatient settings or ≤3 days after hospital admission) without a positive stool in the prior 8 weeks. Medical records were reviewed on a sample of cases. Incidence was estimated using regression models accounting for age and laboratory testing method; sampling weights were applied to estimate hospitalizations, recurrences, and deaths. Results.  A total of 3503 NHO-CDI cases were identified. Among 262 sampled cases, median age was 82 years, 76% received antibiotics in the 12 weeks prior to the C difficile-positive specimen, and 57% were discharged from a hospital in the month before specimen collection. After adjusting for age and testing method, the 2012 national estimate for NHO-CDI incidence was 112 800 cases (95% confidence interval [CI], 93 400-131 800); 31 400 (28%) were hospitalized within 7 days after a positive specimen (95% CI, 25 500-37 300), 20 900 (19%) recurred within 14-60 days (95% CI, 14 600-27 100), and 8700 (8%) died within 30 days (95% CI, 6600-10 700). Conclusions.  Nursing home onset CDI is associated with substantial morbidity and mortality. Strategies focused on infection prevention in NHs and appropriate antibiotic use in both NHs and acute care settings may decrease the burden of NHO CDI.

Epidemiology of Carbapenem-Resistant Enterobacteriaceae in 7 US Communities, 2012-2013

IMPORTANCE

Carbapenem-resistant Enterobacteriaceae (CRE) are increasingly reported worldwide as a cause of infections with high-mortality rates. Assessment of the US epidemiology of CRE is needed to inform national prevention efforts.

OBJECTIVE

To determine the population-based CRE incidence and describe the characteristics and resistance mechanism associated with isolates from 7 US geographical areas.

DESIGN, SETTING, AND PARTICIPANTS

Population- and laboratory-based active surveillance of CRE conducted among individuals living in 1 of 7 US metropolitan areas in Colorado, Georgia, Maryland, Minnesota, New Mexico, New York, and Oregon. Cases of CRE were defined as carbapenem-nonsusceptible (excluding ertapenem) and extended-spectrum cephalosporin-resistant Escherichia coli, Enterobacter aerogenes, Enterobacter cloacae complex, Klebsiella pneumoniae, or Klebsiella oxytoca that were recovered from sterile-site or urine cultures during 2012-2013. Case records were reviewed and molecular typing for common carbapenemases was performed.

EXPOSURES

Demographics, comorbidities, health care exposures, and culture source and location.

MAIN OUTCOMES AND MEASURES

Population-based CRE incidence, site-specific standardized incidence ratios (adjusted for age and race), and clinical and microbiological characteristics.

RESULTS

Among 599 CRE cases in 481 individuals, 520 (86.8%; 95% CI, 84.1%-89.5%) were isolated from urine and 68 (11.4%; 95% CI, 8.8%-13.9%) from blood. The median age was 66 years (95% CI, 62.1-65.4 years) and 284 (59.0%; 95% CI, 54.6%-63.5%) were female. The overall annual CRE incidence rate per 100<000 population was 2.93 (95% CI, 2.65-3.23). The CRE standardized incidence ratio was significantly higher than predicted for the sites in Georgia (1.65 [95% CI, 1.20-2.25]; P < .001), Maryland (1.44 [95% CI, 1.06-1.96]; P = .001), and New York (1.42 [95% CI, 1.05-1.92]; P = .048), and significantly lower than predicted for the sites in Colorado (0.53 [95% CI, 0.39-0.71]; P < .001), New Mexico (0.41 [95% CI, 0.30-0.55]; P = .01), and Oregon (0.28 [95% CI, 0.21-0.38]; P < .001). Most cases occurred in individuals with prior hospitalizations (399/531 [75.1%; 95% CI, 71.4%-78.8%]) or indwelling devices (382/525 [72.8%; 95% CI, 68.9%-76.6%]); 180 of 322 (55.9%; 95% CI, 50.0%-60.8%) admitted cases resulted in a discharge to a long-term care setting. Death occurred in 51 (9.0%; 95% CI, 6.6%-11.4%) cases, including in 25 of 91 cases (27.5%; 95% CI, 18.1%-36.8%) with CRE isolated from normally sterile sites. Of 188 isolates tested, 90 (47.9%; 95% CI, 40.6%-55.1%) produced a carbapenemase.

CONCLUSIONS AND RELEVANCE

In this population- and laboratory-based active surveillance system in 7 states, the incidence of CRE was 2.93 per 100<000 population. Most CRE cases were isolated from a urine source, and were associated with high prevalence of prior hospitalizations or indwelling devices, and discharge to long-term care settings.