Antimicrobial Use in US Hospitals: Comparison of Results From Emerging Infections Program Prevalence Surveys, 2015 and 2011

BACKGROUND

In the 2011 US hospital prevalence survey of healthcare-associated infections and antimicrobial use 50% of patients received antimicrobial medications on the survey date or day before. More hospitals have since established antimicrobial stewardship programs. We repeated the survey in 2015 to determine antimicrobial use prevalence and describe changes since 2011.

METHODS

The Centers for Disease Control and Prevention's Emerging Infections Program sites in 10 states each recruited ≤25 general and women's and children's hospitals. Hospitals selected a survey date from May-September 2015. Medical records for a random patient sample on the survey date were reviewed to collect data on antimicrobial medications administered on the survey date or day before. Percentages of patients on antimicrobial medications were compared; multivariable log-binomial regression modeling was used to evaluate factors associated with antimicrobial use.

RESULTS

Of 12 299 patients in 199 hospitals, 6084 (49.5%; 95% CI, 48.6-50.4%) received antimicrobials. Among 148 hospitals in both surveys, overall antimicrobial use prevalence was similar in 2011 and 2015, although the percentage of neonatal critical care patients on antimicrobials was lower in 2015 (22.8% vs 32.0% [2011]; P = .006). Fluoroquinolone use was lower in 2015 (10.1% of patients vs 11.9% [2011]; P < .001). Third- or fourth-generation cephalosporin use was higher (12.2% vs 10.7% [2011]; P = .002), as was carbapenem use (3.7% vs 2.7% [2011]; P < .001).

CONCLUSIONS

Overall hospital antimicrobial use prevalence was not different in 2011 and 2015; however, differences observed in selected patient or antimicrobial groups may provide evidence of stewardship impact.

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.

Antimicrobial Use in a Cohort of US Nursing Homes, 2017

IMPORTANCE

Controlling antimicrobial resistance in health care is a public health priority, although data describing antimicrobial use in US nursing homes are limited.

OBJECTIVE

To measure the prevalence of antimicrobial use and describe antimicrobial classes and common indications among nursing home residents.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional, 1-day point-prevalence surveys of antimicrobial use performed between April 2017 and October 2017, last survey date October 31, 2017, and including 15 276 residents present on the survey date in 161 randomly selected nursing homes from selected counties of 10 Emerging Infections Program (EIP) states. EIP staff reviewed nursing home records to collect data on characteristics of residents and antimicrobials administered at the time of the survey. Nursing home characteristics were obtained from nursing home staff and the Nursing Home Compare website.

EXPOSURES

Residence in one of the participating nursing homes at the time of the survey.

MAIN OUTCOMES AND MEASURES

Prevalence of antimicrobial use per 100 residents, defined as the number of residents receiving antimicrobial drugs at the time of the survey divided by the total number of surveyed residents. Multivariable logistic regression modeling of antimicrobial use and percentages of drugs within various classifications.

RESULTS

Among 15 276 nursing home residents included in the study (mean [SD] age, 77.6 [13.7] years; 9475 [62%] women), complete prevalence data were available for 96.8%. The overall antimicrobial use prevalence was 8.2 per 100 residents (95% CI, 7.8-8.8). Antimicrobial use was more prevalent in residents admitted to the nursing home within 30 days before the survey date (18.8 per 100 residents; 95% CI, 17.4-20.3), with central venous catheters (62.8 per 100 residents; 95% CI, 56.9-68.3) or with indwelling urinary catheters (19.1 per 100 residents; 95% CI, 16.4-22.0). Antimicrobials were most often used to treat active infections (77% [95% CI, 74.8%-79.2%]) and primarily for urinary tract infections (28.1% [95% CI, 15.5%-30.7%]). While 18.2% (95% CI, 16.1%-20.1%) were for medical prophylaxis, most often use was for the urinary tract (40.8% [95% CI, 34.8%-47.1%]). Fluoroquinolones were the most common antimicrobial class (12.9% [95% CI, 11.3%-14.8%]), and 33.1% (95% CI, 30.7%-35.6%) of antimicrobials used were broad-spectrum antibiotics.

CONCLUSIONS AND RELEVANCE

In this cross-sectional survey of a cohort of US nursing homes in 2017, prevalence of antimicrobial use was 8.2 per 100 residents. This study provides information on the patterns of antimicrobial use among these nursing home residents.

Assessment of the Appropriateness of Antimicrobial Use in US Hospitals

IMPORTANCE

Hospital antimicrobial consumption data are widely available; however, large-scale assessments of the quality of antimicrobial use in US hospitals are limited.

OBJECTIVE

To evaluate the appropriateness of antimicrobial use for hospitalized patients treated for community-acquired pneumonia (CAP) or urinary tract infection (UTI) present at admission or for patients who had received fluoroquinolone or intravenous vancomycin treatment.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included data from a prevalence survey of hospitalized patients in 10 Emerging Infections Program sites. Random samples of inpatients on hospital survey dates from May 1 to September 30, 2015, were identified. Medical record data were collected for eligible patients with 1 or more of 4 treatment events (CAP, UTI, fluoroquinolone treatment, or vancomycin treatment), which were selected on the basis of common infection types reported and antimicrobials given to patients in the prevalence survey. Data were analyzed from August 1, 2017, to May 31, 2020.

EXPOSURE

Antimicrobial treatment for CAP or UTI or with fluoroquinolones or vancomycin.

MAIN OUTCOMES AND MEASURES

The percentage of antimicrobial use that was supported by medical record data (including infection signs and symptoms, microbiology test results, and antimicrobial treatment duration) or for which some aspect of use was unsupported. Unsupported antimicrobial use was defined as (1) use of antimicrobials to which the pathogen was not susceptible, use in the absence of documented infection signs or symptoms, or use without supporting microbiologic data; (2) use of antimicrobials that deviated from recommended guidelines; or (3) use that exceeded the recommended duration.

RESULTS

Of 12 299 patients, 1566 patients (12.7%) in 192 hospitals were included; the median age was 67 years (interquartile range, 53-79 years), and 864 (55.2%) were female. A total of 219 patients (14.0%) were included in the CAP analysis, 452 (28.9%) in the UTI analysis, 550 (35.1%) in the fluoroquinolone analysis, and 403 (25.7%) in the vancomycin analysis; 58 patients (3.7%) were included in both fluoroquinolone and vancomycin analyses. Overall, treatment was unsupported for 876 of 1566 patients (55.9%; 95% CI, 53.5%-58.4%): 110 of 403 (27.3%) who received vancomycin, 256 of 550 (46.6%) who received fluoroquinolones, 347 of 452 (76.8%) with a diagnosis of UTI, and 174 of 219 (79.5%) with a diagnosis of CAP. Among patients with unsupported treatment, common reasons included excessive duration (103 of 174 patients with CAP [59.2%]) and lack of documented infection signs or symptoms (174 of 347 patients with UTI [50.1%]).

CONCLUSIONS AND RELEVANCE

The findings suggest that standardized assessments of hospital antimicrobial prescribing quality can be used to estimate the appropriateness of antimicrobial use in large groups of hospitals. These assessments, performed over time, may inform evaluations of the effects of antimicrobial stewardship initiatives nationally.

Epidemiology of Antibiotic Use for Urinary Tract Infection in Nursing Home Residents

OBJECTIVES

Describe antibiotic use for urinary tract infection (UTI) among a large cohort of US nursing home residents.

DESIGN

Analysis of data from a multistate, 1-day point prevalence survey of antimicrobial use performed between April and October 2017.

SETTING AND PARTICIPANTS

Residents of 161 nursing homes in 10 US states of the Emerging Infections Program (EIP).

METHODS

EIP staff reviewed nursing home medical records to collect data on systemic antimicrobial drugs received by residents, including therapeutic site, rationale for use, and planned duration. For drugs with the therapeutic site documented as urinary tract, pooled mean and nursing home-specific prevalence rates were calculated per 100 nursing home residents, and proportion of drugs by selected characteristics were reported. Data were analyzed in SAS, version 9.4.

RESULTS

Among 15,276 residents, 407 received 424 antibiotics for UTI. The pooled mean prevalence rate of antibiotic use for UTI was 2.66 per 100 residents; nursing home-specific rates ranged from 0 to 13.6. One-quarter of antibiotics were prescribed for UTI prophylaxis, with a median planned duration of 111 days compared with 7 days when prescribed for UTI treatment (P < .001). Fluoroquinolones were the most common (18%) drug class used.

CONCLUSIONS AND IMPLICATIONS

One in 38 residents was receiving an antibiotic for UTI on a given day, and nursing home-specific prevalence rates varied by more than 10-fold. UTI prophylaxis was common with a long planned duration, despite limited evidence to support this practice among older persons in nursing homes. The planned duration was ≥7 days for half of antibiotics prescribed for treatment of a UTI. Fluoroquinolones were the most commonly used antibiotics, despite their association with significant adverse events, particularly in a frail and older adult population. These findings help to identify priority practices for nursing home antibiotic stewardship.

Racial Disparities in Invasive Methicillin-resistant Staphylococcus aureus Infections, 2005-2014

Background

Despite substantial attention to the individual topics, little is known about the relationship between racial disparities and antimicrobial-resistant and/or healthcare-associated infection trends, such as for methicillin-resistant Staphylococcus aureus (MRSA).

Methods

We analyzed Emerging Infections Program 2005-2014 surveillance data (9 US states) to determine whether reductions in invasive MRSA incidence (isolated from normally sterile body sites) affected racial disparities in rates. Case classification included hospital-onset (HO, culture >3 days after admission), healthcare-associated community onset (HACO, culture ≤3 days after admission and dialysis, hospitalization, surgery, or long-term care residence within 1 year prior), or community-associated (CA, all others). Negative binomial regression models were used to evaluate the adjusted rate ratio (aRR) of MRSA in black patients (vs in white patients) controlling for age, sex, and temporal trends.

Results

During 2005-2014, invasive HO and HACO (but not CA) MRSA rates decreased. Despite this, blacks had higher rates for HO (aRR, 3.20; 95% confidence interval [CI], 2.35-4.35), HACO (aRR, 3.84; 95% CI, 2.94-5.01), and CA (aRR, 2.78; 95% CI, 2.30-3.37) MRSA. Limiting the analysis to chronic dialysis patients reduced, but did not eliminate, the higher HACO MRSA rates among blacks (aRR, 1.83; 95% CI, 1.72-1.96), even though invasive MRSA rates among dialysis patients decreased during 2005-2014. These racial differences did not change over time.

Conclusions

Previous reductions in healthcare-associated MRSA infections have not affected racial disparities in MRSA rates. Improved understanding of the underlying causes of these differences is needed to develop effective prevention interventions that reduce racial disparities in MRSA infections.

111. Pediatric and Adolescent Sepsis Epidemiology and Clinical Characteristics, Emerging Infections Program, 2014–2015

Background

Sepsis is an important contributor to mortality among children and young adults. However, recent studies focused on hospital management and burden estimation do not provide critical data to inform prevention efforts. We conducted detailed medical record reviews to describe the epidemiology and clinical characteristics of children and young adults with sepsis to inform prevention and early recognition targets.

Methods

We utilized the Emerging Infections Program (EIP) to collect comprehensive data via retrospective record review for patients with severe sepsis or septic shock discharge diagnosis codes from a nonrandom sample of hospitals across 10 states. Children and young adults, aged 30 days through 21 years, discharged between September 30, 2014 and October 1, 2015, were randomly selected for inclusion. We performed a descriptive analysis of these data.

Results

Among 734 patients hospitalized with sepsis, 92% were living in a private residence 4 days before admission, 38% had an outpatient medical encounter in the 7 days before admission, 14% had sepsis onset after hospital day 3, and 11% died within 90 days of sepsis diagnosis. The most frequently identified infection was lower respiratory tract infection (14%); for 317 (43%) no infection was documented as a cause of sepsis. The most frequently identified pathogen was Staphylococcus aureus (10%); for 326 (44%) no pathogen was identified as a cause of sepsis. Among 394 (54%) patients with ≥1 chronic underlying medical condition (CUMC), the most common were pulmonary disease (35%), hematologic/oncologic disease (31%), immune compromise (24%), and cardiovascular disease (20%). Patients with CUMC had a higher percentage of their sepsis onset after hospital day 3, death within 90 days of sepsis diagnosis, and Pseudomonas aeruginosa as a cause of sepsis (table). The percentage of patients with no pathogen identified was similar between those with CUMC and those without.

Conclusion

In our large cohort of children and young adults with sepsis, most had sepsis onset outside of the hospital and over half had chronic conditions. Our data suggest that distinct approaches may be needed to develop effective prevention and early recognition strategies for children and young adults depending on the presence of chronic conditions.

Disclosures

All authors: No reported disclosures.

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.

1891. Invasive Group A Streptococcus Infections Among Residents of Multiple Nursing Homes—Denver, Colorado, 2017–2018

Background

Older adults residing in nursing homes (NH) are at increased risk for invasive group A Streptococcus (GAS) infections due to advanced age, presence of wounds, and comorbidities; approximately one-third of infected patients die. Beginning in 2015, increasing numbers of GAS infections in NH residents and several NH clusters were reported from the Denver metropolitan area. Colorado Department of Public Health and Environment (CDPHE) and CDC investigated to characterize cases and assess if outbreaks resulted from interfacility transmission.

Methods

We reviewed data from Active Bacterial Core surveillance (ABCs) in the 5-county Denver area from January 2017 to June 2018. We defined a case as isolation of GAS from a normally sterile site in an NH resident. GAS isolates underwent whole-genome sequencing (WGS) at CDC’s Streptococcus Laboratory to determine emm types for genotyping. Among isolates with the same emm type, pairwise single-nucleotide polymorphism (SNP) distances were calculated using Nucmer software. In October 2018, a CDPHE-CDC team assessed infection control at NHs with cases of the most common emm type.

Results

Over 18 months, among >100 NHs in the Denver area, ≥1 GAS case was identified in 29 NHs, with 6 having ≥3 cases. During this period, 68 cases in NH residents were identified. WGS identified 17 emm types among isolates from these cases; most common was emm11.10 (34%, n = 22), a rare subtype in ABCs. All emm11.10 isolates had nearly identical genomes (average pairwise SNP distance: 3.2), and were isolated from 10 NHs, with 2 NHs having ≥ 4 cases. Multiple infection control lapses were noted during site visits to 8 NHs.

Conclusion

Multiple outbreaks due to GAS were noted in 5-county Denver area NHs in 2017–2018. WGS of surveillance isolates identified a rarely seen emm subtype 11.10 from multiple facilities with temporal and genomic clustering suggesting interfacility GAS transmission.

Disclosures

All Authors: No reported Disclosures.

Candida Bloodstream Infections Among Persons Who Inject Drugs - Denver Metropolitan Area, Colorado, 2017-2018

Candidemia, a bloodstream infection caused by Candida species, is typically considered a health care-associated infection, with known risk factors including the presence of a central venous catheter, receipt of total parenteral nutrition or broad-spectrum antibiotics, recent abdominal surgery, admission to an intensive care unit, and prolonged hospitalization (1,2). Injection drug use (IDU) is not a common risk factor for candidemia; however, in the context of the ongoing opioid epidemic and corresponding IDU increases, IDU has been reported as an increasingly common condition associated with candidemia (3) and methicillin-resistant Staphylococcus aureus bacteremia (4). Little is known about the epidemiology of candidemia among persons who inject drugs. The Colorado Department of Public Health and Environment (CDPHE) conducts population-based surveillance for candidemia in the five-county Denver metropolitan area, encompassing 2.7 million persons, through CDC's Emerging Infections Program (EIP). As part of candidemia surveillance, CDPHE collected demographic, clinical, and IDU behavior information for persons with Candida-positive blood cultures during May 2017-August 2018. Among 203 candidemia cases reported, 23 (11%) occurred in 22 patients with a history of IDU in the year preceding their candidemia episode. Ten (43%) of the 23 cases were considered community-onset infections, and four (17%) cases were considered community-onset infections with recent health care exposures. Seven (32%) of the 22 patients had disseminated candidiasis with end-organ dysfunctions; four (18%) died during their hospitalization. In-hospital IDU was reported among six (27%) patients, revealing that IDU can be a risk factor in the hospital setting as well as in the community. In addition to community interventions, opportunities to intervene during health care encounters to decrease IDU and unsafe injection practices might prevent infections, including candidemia, among persons who inject drugs.

Outbreak of group A Streptococcus infections in an outpatient wound clinic-Colorado, 2014

BACKGROUND

In September 2014, wound clinic A reported a cluster of group A Streptococcus (GAS) infections to public health authorities. Although clinic providers were individually licensed, the clinic, affiliated with hospital A, was not licensed or subject to regulation. We investigated to identify cases, determine risk factors, and implement control measures.

METHODS

A case was defined as GAS isolation from a wound or blood specimen during March 28-November 19, 2014, from a patient treated at wound clinic A or by a wound clinic A provider within the previous 7 days. All wound clinic A staff were screened for GAS carriage. Wound care procedures were assessed for adherence to infection control principles and possible GAS transmission routes.

RESULTS

We identified 16 patients with 19 unique infections: 9 (56%) patients required hospitalization, and 7 (44%) required surgical debridement procedures. One patient died. Six (37%) patients received negative pressure wound therapy at GAS onset. Staff self-screening found no GAS carriers. Breaches in infection control and poor wound care practices were widespread.

CONCLUSIONS

This GAS outbreak was associated with a wound care clinic not subject to state or federal regulation. Lapses in infection control practices and inadequate oversight contributed to the outbreak.

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.

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.

Burden of Clostridium difficile infection in the United States

BACKGROUND

The magnitude and scope of Clostridium difficile infection in the United States continue to evolve.

METHODS

In 2011, we performed active population- and laboratory-based surveillance across 10 geographic areas in the United States to identify cases of C. difficile infection (stool specimens positive for C. difficile on either toxin or molecular assay in residents ≥ 1 year of age). Cases were classified as community-associated or health care-associated. In a sample of cases of C. difficile infection, specimens were cultured and isolates underwent molecular typing. We used regression models to calculate estimates of national incidence and total number of infections, first recurrences, and deaths within 30 days after the diagnosis of C. difficile infection.

RESULTS

A total of 15,461 cases of C. difficile infection were identified in the 10 geographic areas; 65.8% were health care-associated, but only 24.2% had onset during hospitalization. After adjustment for predictors of disease incidence, the estimated number of incident C. difficile infections in the United States was 453,000 (95% confidence interval [CI], 397,100 to 508,500). The incidence was estimated to be higher among females (rate ratio, 1.26; 95% CI, 1.25 to 1.27), whites (rate ratio, 1.72; 95% CI, 1.56 to 2.0), and persons 65 years of age or older (rate ratio, 8.65; 95% CI, 8.16 to 9.31). The estimated number of first recurrences of C. difficile infection was 83,000 (95% CI, 57,000 to 108,900), and the estimated number of deaths was 29,300 (95% CI, 16,500 to 42,100). The North American pulsed-field gel electrophoresis type 1 (NAP1) strain was more prevalent among health care-associated infections than among community-associated infections (30.7% vs. 18.8%, P<0.001).

CONCLUSIONS

C. difficile was responsible for almost half a million infections and was associated with approximately 29,000 deaths in 2011. (Funded by the Centers for Disease Control and Prevention.).

Carbapenem-resistant Klebsiella pneumoniae producing New Delhi metallo-β-lactamase at an acute care hospital, Colorado, 2012

OBJECTIVE

To investigate an outbreak of New Delhi metallo-β-lactamase (NDM)-producing carbapenem-resistant Enterobacteriaceae (CRE) and determine interventions to interrupt transmission.

DESIGN, SETTING, AND PATIENTS

Epidemiologic investigation of an outbreak of NDM-producing CRE among patients at a Colorado acute care hospital.

METHODS

Case patients had NDM-producing CRE isolated from clinical or rectal surveillance cultures (SCs) collected during the period January 1, 2012, through October 20, 2012. Case patients were identified through microbiology records and 6 rounds of SCs in hospital units where they had resided. CRE isolates were tested by real-time polymerase chain reaction for blaNDM. Medical records were reviewed for epidemiologic links; relatedness of isolates was evaluated by pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). Infection control (IC) was assessed through staff interviews and direct observations.

RESULTS

Two patients were initially identified with NDM-producing CRE during July-August 2012. A third case patient, admitted in May, was identified through microbiology records review. SC identified 5 additional case patients. Patients had resided in 11 different units before identification. All isolates were highly related by PFGE. WGS suggested 3 clusters of CRE. Combining WGS with epidemiology identified 4 units as likely transmission sites. NDM-producing CRE positivity in certain patients was not explained by direct epidemiologic overlap, which suggests that undetected colonized patients were involved in transmission.

CONCLUSIONS

A 4-month outbreak of NDM-producing CRE occurred at a single hospital, highlighting the risk for spread of these organisms. Combined WGS and epidemiologic data suggested transmission primarily occurred on 4 units. Timely SC, combined with targeted IC measures, were likely responsible for controlling transmission.

Invasive methicillin-resistant Staphylococcus aureus infections among patients on chronic dialysis in the United States, 2005-2011

BACKGROUND

Approximately 15 700 invasive methicillin-resistant Staphylococcus aureus (MRSA) infections occurred in US dialysis patients in 2010. Frequent hospital visits and prolonged bloodstream access, especially via central venous catheters (CVCs), are risk factors among hemodialysis patients. We describe the epidemiology of and recent trends in invasive MRSA infections among dialysis patients.

METHODS

We analyzed population-based data from 9 US metropolitan areas from 2005 to 2011. Cases were defined as MRSA isolated from a normally sterile body site in a surveillance area resident who received dialysis, and were classified as hospital-onset (HO; culture collected >3 days after hospital admission) or healthcare-associated community-onset (HACO; all others). Incidence was calculated using denominators from the US Renal Data System. Temporal trends in incidence and national estimates were calculated controlling for age, sex, and race.

RESULTS

From 2005 to 2011, 7489 cases were identified; 85.7% were HACO infections, and 93.2% were bloodstream infections. Incidence of invasive MRSA infections decreased from 6.5 to 4.2 per 100 dialysis patients (annual decrease, 7.3%) with annual decreases of 6.7% for HACO and 10.5% for HO cases. Among cases identified during 2009-2011, 70% of patients were hospitalized in the year prior to infection. Among hemodialysis cases, 60.4% of patients were dialyzed through a CVC. The 2011 national estimated number of MRSA infections was 15 169.

CONCLUSIONS

There has been a substantial decrease in invasive MRSA infection incidence among dialysis patients. Most cases had previous hospitalizations, suggesting that efforts to control MRSA in hospitals might have contributed to the declines. Infection prevention measures should include improved vascular access and CVC care.

Effect of nucleic acid amplification testing on population-based incidence rates of Clostridium difficile infection

Nucleic acid amplification testing (NAAT) is increasingly being adopted for diagnosis of Clostridium difficile infection (CDI). Data from 3 states conducting population-based CDI surveillance showed increases ranging from 43% to 67% in CDI incidence attributable to changing from toxin enzyme immunoassays to NAAT. CDI surveillance requires adjustment for testing methods.

Epidemiology of community-associated Clostridium difficile infection, 2009 through 2011

IMPORTANCE

Clostridium difficile infection (CDI) has been increasingly reported among healthy individuals in the community. Recent data suggest that community-associated CDI represents one-third of all C difficile cases. The epidemiology and potential sources of C difficile in the community are not fully understood.

OBJECTIVES

To determine epidemiological and clinical characteristics of community-associated CDI and to explore potential sources of C difficile acquisition in the community.

DESIGN AND SETTING

Active population-based and laboratory-based CDI surveillance in 8 US states.

PARTICIPANTS

Medical records were reviewed and interviews performed to assess outpatient, household, and food exposures among patients with community-associated CDI (ie, toxin or molecular assay positive for C difficile and no overnight stay in a health care facility within 12 weeks). Molecular characterization of C difficile isolates was performed. Outpatient health care exposure in the prior 12 weeks among patients with community-associated CDI was a priori categorized into the following 3 levels: no exposure, low-level exposure (ie, outpatient visit with physician or dentist), or high-level exposure (ie, surgery, dialysis, emergency or urgent care visit, inpatient care with no overnight stay, or health care personnel with direct patient care).

MAIN OUTCOMES AND MEASURES

Prevalence of outpatient health care exposure among patients with community-associated CDI and identification of potential sources of C difficile by level of outpatient health care exposure.

RESULTS

Of 984 patients with community-associated CDI, 353 (35.9%) did not receive antibiotics, 177 (18.0%) had no outpatient health care exposure, and 400 (40.7%) had low-level outpatient health care exposure. Thirty-one percent of patients without antibiotic exposure received proton pump inhibitors. Patients having CDI with no or low-level outpatient health care exposure were more likely to be exposed to infants younger than 1 year (P = .04) and to household members with active CDI (P = .05) compared with those having high-level outpatient health care exposure. No association between food exposure or animal exposure and level of outpatient health care exposure was observed. North American pulsed-field gel electrophoresis (NAP) 1 was the most common (21.7%) strain isolated; NAP7 and NAP8 were uncommon (6.7%).

CONCLUSIONS AND RELEVANCE

Most patients with community-associated CDI had recent outpatient health care exposure, and up to 36% would not be prevented by reduction of antibiotic use only. Our data support evaluation of additional strategies, including further examination of C difficile transmission in outpatient and household settings and reduction of proton pump inhibitor use.

Health care-associated outbreak of Salmonella Tennessee in a neonatal intensive care unit

BACKGROUND

In December 2006, we investigated an outbreak of Salmonella serotype Tennessee in a neonatal intensive care unit (NICU) that coincided with a nationwide Salmonella Tennessee outbreak associated with contaminated peanut butter.

METHODS

Salmonellosis was defined as isolation of Salmonella Tennessee from any clinical specimen or more than 1 episode of bloody stool within a 24-hour period. We conducted a cohort study among 13 NICU infants, reviewed medical records, cultured stool from infants and staff, collected environmental samples, and examined infection control practices.

RESULTS

Ten of the 13 infants had salmonellosis (77%). No medical or dietary risk factors were identified. The proportion of days in which the NICU census exceeded its 11-bed design capacity was higher in December compared with the previous 11 months (41.9% vs 0.3%; P < .001). Hand sinks did not meet operational standards. Salmonella Tennessee was isolated from 9 of the 13 infants, 2 of 40 staff members, and 6 of 42 environmental samples; all isolates matched the pulsed-field gel electrophoresis pattern of the nationwide Salmonella Tennessee outbreak.

CONCLUSIONS

Although the source of Salmonella Tennessee was not identified, the high census and limited access to sinks likely facilitated transmission to the NICU infants. Infection control interventions, including halting new NICU admissions, interrupted further transmission.

Outbreak of Q fever associated with a horse-boarding ranch, Colorado, 2005

Coxiella burnetii is a bacterium located worldwide that can cause Q fever when inhaled. We describe an outbreak of Q fever associated with a horse-boarding ranch that had acquired two herds of goats. We conducted case finding and cohort studies among persons who boarded horses on the ranch and ranchers and among residents in the surrounding community, and conducted sampling of the goats and environment, to determine risk factors for infection and guide public health interventions. Sixty-six ranchers and persons who boarded horses on the ranch were interviewed; 62 (94%) were not professional ranchers. Twenty persons (53%) of 38 persons tested had evidence of infection with C. burnetii. Contact with goats was associated with seropositivity, including having helped birth goats (relative risk [RR] 2.4, 95% confidence interval [CI] 1.6-3.6), having had contact with newborn goats (RR 2.3, CI 1.2-4.3), having vaccinated goats (RR 2.1, CI 1.3-3.5), having had contact with stillbirths or newborns that died (RR 2.1, CI 1.2-3.7), and having fed goats (RR 2.1, CI 1.0-4.3). Among 138 tested persons living within 1 mile of the ranch, 11 (8%) demonstrated evidence of C. burnetii infection; eight seropositive persons (73%) had no direct contact with the ranch. Testing of the soil and goats with an IS1111 polymerase chain reaction (PCR) assay confirmed the presence of C. burnetii among the herd and in the environment. This outbreak of Q fever was caused by exposure to infected goats, but exposure to the environment likely played a secondary role. Laypersons should not participate in the birthing process of goats; professionals who come into contact with birthing goats should be educated on reducing their infection risk. This is the first time an IS1111 PCR assay has been used in an outbreak investigation in the United States.