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.