Lucy E. Wilson

Multistate Point-Prevalence Survey of Health Care–Associated Infections

BACKGROUND Currently, no single U.S. surveillance system can provide estimates of the burden of all types of health care-associated infections across acute care patient populations. We conducted a prevalence survey in 10 geographically diverse states to determine the prevalence of health care-associated infections in acute care hospitals and generate updated estimates of the national burden of such infections. METHODS We defined health care-associated infections with the use of National Healthcare Safety Network criteria. One-day surveys of randomly selected inpatients were performed in participating hospitals. Hospital personnel collected demographic and limited clinical data. Trained data collectors reviewed medical records retrospectively to identify health care-associated infections active at the time of the survey. Survey data and 2010 Nationwide Inpatient Sample data, stratified according to patient age and length of hospital stay, were used to estimate the total numbers of health care-associated infections and of inpatients with such infections in U.S. acute care hospitals in 2011. RESULTS Surveys were conducted in 183 hospitals. Of 11,282 patients, 452 had 1 or more health care-associated infections (4.0%; 95% confidence interval, 3.7 to 4.4). Of 504 such infections, the most common types were pneumonia (21.8%), surgical-site infections (21.8%), and gastrointestinal infections (17.1%). Clostridium difficile was the most commonly reported pathogen (causing 12.1% of health care-associated infections). Device-associated infections (i.e., central-catheter-associated bloodstream infection, catheter-associated urinary tract infection, and ventilator-associated pneumonia), which have traditionally been the focus of programs to prevent health care-associated infections, accounted for 25.6% of such infections. We estimated that there were 648,000 patients with 721,800 health care-associated infections in U.S. acute care hospitals in 2011. CONCLUSIONS Results of this multistate prevalence survey of health care-associated infections indicate that public health surveillance and prevention activities should continue to address C. difficile infections. As device- and procedure-associated infections decrease, consideration should be given to expanding surveillance and prevention activities to include other health care-associated infections.

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.).

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.

Prospective study of infective endocarditis among injection drug users

To determine the effect of human immunodeficiency virus (HIV) infection and other factors on infective endocarditis (IE) among injection drug users (IDUs), the incidence of IE was determined according to HIV status in a cohort of IDUs. A nested case-control study assessed IE risk factors. IE incidence (117 cases) was higher among HIV-seropositive than HIV-seronegative IDUs (13.8 vs. 3.3 cases/1000 person-years) during 1988-1998. Multivariate analysis of HIV-infected case patients revealed an inverse association between IE and CD4 lymphocyte count (odds ratio [OR] for 200-499 cells/mm(3), 2.01; OR for <200 cells/mm(3), 3.61) and with alcohol intake (OR for 1-21 drinks/week, 0.43; OR for >21 drinks/week, 0.32). Women had an increased risk of IE (OR, 3.26), as did persons with increasing injection drug use frequency (OR for less than daily use, 3.15; OR for at least daily use, 6.07). This study confirms that IE is more common among IDUs with advanced HIV immunosuppression even after accounting for injection drug use behaviors.

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.

Effect of age and HAART regimen on clinical response in an urban cohort of HIV-infected individuals.

Objectives: The prevalence of HIV infection in older patients (≥50 years) is increasing due to HAART, and new HIV infections in older patients. Some earlier studies suggest that older patients respond differently to HAART than younger patients. The objective of this study is to compare the effectiveness of HAART in older and younger HIV patients. Design: Retrospective analysis of an observational clinical cohort. Methods: Virologic and immunologic response, progression to AIDS and mortality were compared between 670 younger patients (<40 years) and 149 older patients (≥50 years) by t-test, Kaplan–Meier methods, and multivariate Cox proportional hazards analysis. Results: Compared with younger patients, older patients were more likely to be on nonnucleoside reverse transcriptase inhibitors based versus protease inhibitor based regimens (42 vs. 29%, P < 0.01). Time to HIV-1 RNA virologic suppression was less in older than in younger patients (3.2 vs. 4.4 months, P < 0.01). Immunologic response did not differ by age. Older patients had fewer AIDS-defining opportunistic infections (22 vs. 31%, P < 0.01), but higher mortality (36 vs. 27%, P = 0.04) and shorter survival (25th percentile survivor function 36.2 vs. 58.5 months, P = 0.02) than younger patients. Older age was associated with more rapid virologic suppression [adjusted hazard ratio = 1.33 (1.09–1.63)] and earlier mortality [adjusted hazard ratio = 1.56 (1.14–2.14)]. Nonnucleoside reverse transcriptase inhibitors based regimens were associated with more rapid virologic suppression [adjusted hazard ratio = 1.22 (1.03–1.44)]. Conclusion: Time to virologic suppression after HAART initiation was shorter in older patients, although CD4 response did not differ by age. Older patients had fewer opportunistic infections, but survival was shorter. Our data suggest a need to better understand causes of mortality in older patients.

Clostridium difficile Infection Among Children Across Diverse US Geographic Locations

OBJECTIVE: Little is known about the epidemiology of Clostridium difficile infection (CDI) among children, particularly children ≤3 years of age in whom colonization is common but pathogenicity uncertain. We sought to describe pediatric CDI incidence, clinical presentation, and outcomes across age groups. METHODS: Data from an active population- and laboratory-based CDI surveillance in 10 US geographic areas during 2010–2011 were used to identify cases (ie, residents with C difficile–positive stool without a positive test in the previous 8 weeks). Community-associated (CA) cases had stool collected as outpatients or ≤3 days after hospital admission and no overnight health care facility stay in the previous 12 weeks. A convenience sample of CA cases were interviewed. Demographic, exposure, and clinical data for cases aged 1 to 17 years were compared across 4 age groups: 1 year, 2 to 3 years, 4 to 9 years, and 10 to 17 years. RESULTS: Of 944 pediatric CDI cases identified, 71% were CA. CDI incidence per 100 000 children was highest among 1-year-old (66.3) and white (23.9) cases. The proportion of cases with documented diarrhea (72%) or severe disease (8%) was similar across age groups; no cases died. Among the 84 cases interviewed who reported diarrhea on the day of stool collection, 73% received antibiotics during the previous 12 weeks. CONCLUSIONS: Similar disease severity across age groups suggests an etiologic role for C difficile in the high rates of CDI observed in younger children. Prevention efforts to reduce unnecessary antimicrobial use among young children in outpatient settings should be prioritized.

Incidence of, risk factors for, clinical presentation, and 1-year outcomes of infective endocarditis in an urban HIV cohort

Background:Previous studies described infective endocarditis (IE) in the era before highly active antiretroviral therapy (HAART); however, IE has not been well studied in the current HAART era. We evaluated the incidence of, risk factors for, clinical presentation, and 1-year outcomes of IE in HIV-infected patients. Methods:We evaluated all cases of IE diagnosed between 1990 and 2002 in patients followed at the Johns Hopkins Hospital outpatient HIV clinic. To identify factors associated with IE in the current era of HAART, a nested case-control analysis was employed for all initial episodes of IE occurring between 1996 and 2002. Logistic regression analyses were used to assess risk factors for IE and factors associated with 1-year mortality. Results:IE incidence decreased from 20.5 to 6.6 per 1000 person-years (PY) between 1990 and 1995 and 1996 and 2002. The majority of IE cases were male (66%), African American (90%), and injection drug users (IDUs) (85%). In multivariate regression, an increased risk of IE occurred in IDUs (AOR, 8.71), those with CD4 counts <50 cells/mm3, and those with HIV-1 RNA >100,000 copies/mL (AOR, 3.88). Common presenting symptoms included fever (62%), chills (31%), and shortness of breath (26%). The most common etiologic organism was Staphylococcus aureus (69%; of these 11 [28%] were methicillin resistant). Within 1 year, 16% had IE recurrence, and 52% died. Age over 40 years was associated with increased mortality. Conclusions:IE rates have decreased in the current HAART era. IDUs and those with advanced immunosuppression are more likely to develop IE. In addition, there is significant morbidity and 1-year mortality in HIV-infected patients with IE, indicating the need for more aggressive follow-up, especially in those over 40 years of age. Future studies investigating the utility of IE prophylaxis in HIV patients with a history of IE may be warranted.

First NDM-Positive Salmonella sp. Strain Identified in the United States

Antimicrobial resistance among Enterobacteriaceae is growing, largely due to β-lactamase production.…

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.