To devise a local strategy for eradication of a hospital-wide outbreak caused by carbapenem-resistant Klebsiella pneumoniae (CRKP).

Quasi-experimental, before-and-after, interrupted time-series study.

A 1,000-bed tertiary-care university teaching hospital.

Retrospectively, all relevant data were collected from the medical records of patients with CRKP infections from May 2006 through April 2007, the preintervention period. From May 1, 2007, through May 1, 2010, the postintervention period, the intervention was applied and prospectively followed. The 5 key elements of this strategy were an emergency department flagging system, the building of a cohort ward, the eradication of clusters, environmental and personnel hand cultures, and a carbapenem-restriction policy. The demographic and clinical parameters of patients colonized by and/or infected with CRKP were collected from medical records.

A total of 10,680 rectal cultures were performed for 8,376 patients; 433 (5.16%) and 370 (4.4%) were CRKP-colonized and CRKP-infected patients, respectively, and 789 (98%) of 803 patients were admitted to the CRKP cohort ward. The CRKP infection density was reduced from 5.26 to 0.18 per 10,000 patient-days (P<.001), and no nosocomial CRKP infections were diagnosed. Twenty-three percent of environmental cultures were found to be positive. Meropenem use was reduced from 283 ± 70.92 to 118 ± 74.32 defined daily doses per 1,000 patient-days (P<.001).

This intervention produced an enormous impact on patient location, surveillance cultures, and antibiotic policies and a massive investment in infection control resources.

To compare an interventional protocol with a standard protocol for preventing the acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in the intensive care unit (ICU).

Prospective, randomized, controlled, parallel-group, nonblinded clinical trial.

Medical ICUs of 2 French university hospitals.

Five hundred adults with an expected length of stay in the ICU greater than 48 hours.

For the intervention group, the protocol required repeated MRSA screening, contact and droplet isolation precautions for patients at risk for MRSA at ICU admission and for MRSA-positive patients, and decontamination with nasal mupirocin and chlorhexidine body wash for MRSA-positive patients. For the standard group, the standard precautions protocol was used, and the results of repeated MRSA screening in the standard group were not communicated to investigators.

MRSA acquisition rate in the ICU. An audit was conducted to assess compliance with hygiene and isolation precautions.

In the intent-to-treat analysis (n = 488), the MRSA acquisition rate in the ICU was similar in the standard (13 [5.3%] of 243) and intervention (16 [6.5%] of 245) groups (P =.58). The audit showed that the overall compliance rate was 85.5% in the standard group and 84.1% in the intervention group (P =.63), although compliance was higher when isolation precautions were absent than when they were in place (88.2% vs 79.1%; P<.001). MRSA incidence rates were higher without isolation precautions (7.57‰) than with isolation precautions (2.36‰; P =.01).

Individual allocation to MRSA screening, isolation precautions, and decontamination do not provide individual benefit in reducing MRSA acquisition, compared with standard precautions, although the collective risk was lower during the periods of isolation.

Clinicaltrials.gov identifier: NCT00151606.

To describe the rates of several key outcomes and healthcare-associated infections (HAIs) among hospitals that participated in the Duke Infection Control Outreach Network (DICON).

Prospective, observational cohort study of patients admitted to 24 community hospitals from 2003 through 2009.

The following data were collected and analyzed: incidence of central line-associated bloodstream infections (CLABSIs), ventilator-associated pneumonia (VAP), catheter-associated urinary tract infections (CAUTIs), and HAIs caused by methicillin-resistant Staphylococcus aureus (MRSA); employee exposures to bloodborne pathogens (EBBPs); physician EBBPs; patient-days; central line-days; ventilator-days; and urinary catheter-days. Poisson regression was used to determine whether incidence rates of these HAIs and exposures changed during the first 5 and 7 years of participation in DICON; nonrandom clustering of each outcome was controlled for. Cost saved and lives saved were calculated on the basis of published estimates.

In total, we analyzed 6.5 million patient-days, 4,783 EBPPs, 2,948 HAIs due to MRSA, and 2,076 device-related infections. Rates of employee EBBPs, HAIs due to MRSA, and device-related infections decreased significantly during the first 5 years of participation in DICON (P < .05 for all models; average decrease was approximately 50%); in contrast, physician EBBPs remained unchanged. In aggregate, 210 CLABSIs, 312 cases of VAP, 332 CAUTIs, 1,042 HAIs due to MRSA, and 1,016 employee EBBPs were prevented. Each hospital saved approximately $100,000 per year of participation, and collectively the hospitals may have prevented 52-105 deaths from CLABSI or VAP. The 7-year analysis demonstrated that these trends continued with further participation.

Hospitals with long-term participation in an infection control network decreased rates of significant HAIs by approximately 50%, decreased costs, and saved lives.

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection has been used as a proxy measure for MRSA transmission, but incidence calculations vary depending on whether active surveillance culture (ASC) data are included.

To evaluate the relationship between incidences of MRSA colonization or infection calculated with and without ASCs in intensive care units and non-intensive care units.

A Veterans Affairs medical center.

From microbiology records, incidences of MRSA colonization or infection were calculated with and without ASC data. Correlation coefficients were calculated for the 2 measures, and Poisson regression was used to model temporal trends. A Poisson interaction model was used to test for differences in incidence trends modeled with and without ASCs.

The incidence of MRSA colonization or infection calculated with ASCs was 4.9 times higher than that calculated without ASCs. Correlation coefficients for incidences with and without ASCs were 0.42 for intensive care units, 0.59 for non-intensive care units, and 0.48 hospital-wide. Trends over time for the hospital were similar with and without ASCs (incidence rate ratio with ASCs, 0.95 [95% confidence interval, 0.93-0.97]; incidence rate ratio without ASCs, 0.95 [95% confidence interval, 0.92-0.99]; P = .68). Without ASCs, 35% of prevalent cases were falsely classified as incident.

At 1 Veterans Affairs medical center, the incidence of MRSA colonization or infection calculated solely on the basis of clinical culture results commonly misclassified incident cases and underestimated incidence, compared with measures that included ASCs; however, temporal changes were similar. These findings suggest that incidence measured without ASCs may not accurately reflect the magnitude of MRSA transmission but may be useful for monitoring transmission trends over time, a crucial element for evaluating the impact of prevention activities.

In 1991 the Centers for Disease Control and Prevention issued guidelines to reduce risks for provider-to-patient transmission of bloodborne pathogens. These guidelines, unchanged since 1991, recommend management strategies for hepatitis B e antigen-positive providers and for providers infected with human immunodeficiency virus; they do not address hepatitis C virus (HCV)-infected providers.

We summarized current state practices and surveyed state health departments to determine (1) whether state policies have been modified since 1991; (2) whether state laws require prospective notification of patients and/or expert review panels to manage infected providers; (3) the frequency with which infected-providers issues come to the attention of state health departments; and (4) how state health departments intervene.

We reviewed the 50 states' laws and guidelines to determine current practices and conducted a structured telephone survey of all state health departments.

Whereas only 19 states require infected providers to notify patients of the providers’ bloodborne pathogen infection, these 19 states require notification under highly varied circumstances. Only 10 of 50 state health department officials identified these issues as requiring significant departmental effort. No state law or guideline incorporates information about providers’ viral burdens as part of the risk assessment. Only 3 of 50 states have modified policies or laws since initial passage, and only 1 of 50 discusses the management of HCV-infected providers.

These results identify a need for incorporating contemporary scientific information into guidelines and also suggest that infected-provider issues are not occurring commonly, are not being detected, or are being managed at levels below the state health department.

Over the past 2 decades, multiple interventions have been developed to prevent catheter-associated urinary tract infections (CAUTIs). The CAUTI prevention guidelines of the Healthcare Infection Control Practices Advisory Committee were recently revised.

To examine changes in rates of CAUTI events in adult intensive care units (ICUs) in the United States from 1990 through 2007.

Data were reported to the Centers for Disease Control and Prevention (CDC) through the National Nosocomial Infections Surveillance System from 1990 through 2004 and the National Healthcare Safety Network from 2006 through 2007. Infection preventionists in participating hospitals used standard methods to identify all CAUTI events (categorized as symptomatic urinary tract infection [SUTI] or asymptomatic bacteriuria [ASB]) and urinary catheter–days (UC-days) in months selected for surveillance. Data from all facilities were aggregated to calculate pooled mean annual SUTI and ASB rates (in events per 1,000 UC-days) by ICU type. Poisson regression was used to estimate percent changes in rates over time.

Overall, 36,282 SUTIs and 22,973 ASB episodes were reported from 367 facilities representing 1,223 adult ICUs, including combined medical/surgical (505), medical (212), surgical (224), coronary (173), and cardiothoracic (109) ICUs. All ICU types experienced significant declines of 19%–67% in SUTI rates and 29%–72% in ASB rates from 1990 through 2007. Between 2000 and 2007, significant reductions in SUTI rates occurred in all ICU types except cardiothoracic ICUs.

Since 1990, CAUTI rates have declined significantly in all major adult ICU types in facilities reporting to the CDC. Further efforts are needed to assess prevention strategies that might have led to these decreases and to implement new CAUTI prevention guidelines.

Central line-associated bloodstream infection (CLABSI) rates are gaining importance as they become publicly reported metrics and potential pay-for-performance indicators. However, the current conventional method by which they are calculated may be misleading and unfairly penalize high-acuity care settings, where patients often have multiple consurrent central venous catheters (CVCs).

We compared the conventional method of calculating CLABSI rates, in which the number of catheter-days is used (1 patient with n catheters for 1 day has 1 catheter-day), with a new method that accounts for multiple concurrent catheters (1 patient with n catheters for 1 day has n catheter-days), to determine whether the difference appreciably changes the estimated CLABSI rate.

Cross-sectional survey.

Academic, tertiary care hospital.

Adult patients who were consecutively admitted from June 10 through July 9, 2009, to a cardiac-surgical intensive care unit and a surgical intensive and surgical intermediate care unit.

Using the conventional method, we counted 485 catheter-days throughout the study period, with a daily mean of 18.6 catheter-days (95% confidence interval, 17.2-20.0 catheter-days) in the 2 intensive care units. In contrast, the new method identified 745 catheter-days, with a daily mean of 27.5 catheter-days (95% confidence interval, 25.6-30.3) in the 2 intensive care units. The difference was statistically significant (P < .001). The new method that accounted for multiple concurrent CVCs resulted in a 53.6% increase in the number of catheter-days; this increased denominator decreases the calculated CLABSI rate by 36%.

The undercounting of catheter-days for patients with multiple concurrent CVCs that occurs when the conventional method of calculating CLABSI rates is used inflates the CLABSI rate for care settings that have a high CVC burden and may not adjust for underlying medical illness. Additional research is needed to validate and generalize our findings.

Multidrug-resistant Acinetobacter baumannii (MDRAB) is difficult to treat and eradicate. Several reports describe isolation and environmental cleaning strategies that controlled hospital MDRAB outbreaks. Such interventions were insufficient to interrupt MDRAB transmission in 2 intensive care unit-based outbreaks in our hospital. We describe strategies that were associated with termination of MDRAB outbreaks at the National Institutes of Health Clinical Center.

In response to MDRAB outbreaks in 2007 and 2009, we implemented multiple interventions, including stakeholder meetings, enhanced isolation precautions, active microbial surveillance, cohorting, and extensive environmental cleaning. We conducted a case-control study to analyze risk factors for acquiring MDRAB. In each outbreak, infection control adherence monitors were placed in MDRAB cohort areas to observe and correct staff infection control behavior.

Between May 2007 and December 2009, 63 patients acquired nosocomial MDRAB; 57 (90%) acquired 1 or more of 4 outbreak strains. Of 347 environmental cultures, only 2 grew outbreak strains of MDRAB from areas other than MDRAB patient rooms. Adherence monitors recorded 1,330 isolation room entries in 2007, of which 8% required interventions. In 2009, around-the-clock monitors recorded 4,892 staff observations, including 127 (2.6%) instances of nonadherence with precautions, requiring 68 interventions (1.4%). Physicians were responsible for more violations than other staff (58% of hand hygiene violations and 37% of violations relating to gown and glove use). Each outbreak terminated in temporal association with initiation of adherence monitoring.

Although labor intensive, adherence monitoring may be useful as part of a multifaceted strategy to limit nosocomial transmission of MDRAB.

The effect of patient movement between hospitals and long-term care facilities (LTCFs) on methicillin-resistant Staphylococcus aureus (MRSA) prevalence levels is unknown. We investigated these effects to identify scenarios that may lead to increased prevalence in either facility type.

We used a hybrid simulation model to simulate MRSA transmission among hospitals and LTCFs. Transmission within each facility was determined by mathematical model equations. The model predicted the long-term prevalence of each facility and was used to assess the effects of facility size, patient turnover, and decolonization.

Analyses of various healthcare networks suggest that the effect of patients moving from a LTCF to a hospital is negligible unless the patients are consistently admitted to the same unit. In such cases, MRSA prevalence can increase significantly regardless of the endemic level. Hospitals can cause sustained increases in prevalence when transferring patients to LTCFs, where the population size is smaller and patient turnover is less frequent. For 1 particular scenario, the steady-state prevalence of a LTCF increased from 6.9% to 9.4% to 13.8% when the transmission rate of the hospital increased from a low to a high transmission rate.

These results suggest that the relative facility size and the patient discharge rate are 2 key factors that can lead to sustained increases in MRSA prevalence. Consequendy, small facilities or those with low turnover rates are especially susceptible to sustaining increased prevalence levels, and they become more so when receiving patients from larger, high-prevalence facilities. Decolonization is an infection-control strategy that can mitigate these effects.

To report a large outbreak of Clostridium difficile infection (CDI; ribotype 027) between June 2007 and August 2008, describe infection control measures, and evaluate the impact of restricting the use of fluoroquinolones in controlling the outbreak.

Outbreak investigation in 3 acute care hospitals of the Northern Health and Social Care Trust in Northern Ireland.

Implementation of a series of CDI control measures that targeted high-risk antibiotic agents (ie, restriction of fluoroquinolones), infection control practices, and environmental hygiene.

A total of 318 cases of CDI were identified during the outbreak, which was the result of the interaction between C. difficile ribotype 027 being introduced into the affected hospitals for the first time and other predisposing risk factors (ranging from host factors to suboptimal compliance with antibiotic guidelines and infection control policies). The 30-day all-cause mortality rate was 24.5%; however, CDI was the attributable cause of death for only 2.5% of the infected patients. Time series analysis showed that restricting the use of fluoroquinolones was associated with a significant reduction in the incidence of CDI (coefficient, —0.054; lag time, 4 months; P = .003).

These findings provide additional evidence to support the value of antimicrobial stewardship as an essential element of multifaceted interventions to control CDI outbreaks. The present CDI outbreak was ended following the implementation of an action plan improving communication, antibiotic stewardship, infection control practices, environmental hygiene, and surveillance.

To investigate potential sources of gram-negative multidrug-resistant organisms (MDROs) in a deployed US military healthcare facility.

Active surveillance.

Swab sampling of patients, hospital personnel, and environmental surfaces was performed before the opening of a new medical treatment facility in Iraq and then serially for the next 6 months. Multidrug resistant isolates were genotypically characterized using pulsed-field gel electrophoresis (PFGE). Univariate and multivariate analysis were performed to evaluate associations between patient characteristics and MDRO carriage.

Deployed US military medical facility.

A total of 1,348 samples were obtained, yielding 654 isolates, 42 of which were MDROs. One hundred fifty-eight patients were sampled; swabs from 18 patients yielded 29 MDR isolates. Host nation patients comprised 89% of patients with MDROs and 37% of patients without MDROs (P < .001 ). Host nation patient status was also significantly associated with MDRO carriage in multivariate logistic regression analysis (adjusted odds ratio, 2.9; confidence interval, 1.3-6.3; P = .009). Bacteria with PFGE patterns matching those recovered from host nation patients were later isolated from environmental surfaces including recovery room patient monitors and the trauma bay floor.

At this facility, MDRO isolation was predominantly obtained from newly admitted host nation patients,,which may reflect baseline colonization with MDROs in the community. Patient MDRO carriage was linked to subsequent environmental contamination. These findings support intensive infection control efforts in forward deployed facilities.

Asymptomatic bacteriuria/candidiuria (ASB) and culture-negative pyuria (CNP) are common and often result in inappropriate antibiotic use. We aimed to evaluate whether a standardized educational memorandum could reduce antimicrobial utilization for ASB/CNP.

Quasi-experimental study with a control group, from a convenience sample of inpatients with abnormal urinalysis or urine culture results in a Veterans Affairs hospital.

An educational memorandum outlining guidelines for diagnosis and treatment of ASB was placed in the chart of patients with ASB/CNP who were receiving antimicrobials.

The records of patients meeting inclusion criteria were abstracted for demographics, comorbidities, antimicrobials, and symptoms suggestive of possible urinary tract infection (UTI). Patients were categorized as having ASB, CNP, or UTI. The number of antimicrobial-days attributed to ASB/CNP was compared between the control group and the intervention group.

Charts of 301 patients with abnormal urine results were reviewed. Thirty of 117 (26%) patients in the control group received antimicrobials for ASB/CNP for an average of 6.3 days. In the intervention group, 24 of 92 (26%) patients received antimicrobials for ASB/CNP for an average of 2.2 days (t-test: P<.001). Adverse events from antimicrobials for ASB/CNP occurred in 3 of the 30 (10%) patients in the control group. There were no adverse events from untreated ASB/CNP in the intervention group.

ASB and CNP resulted in antimicrobial exposure in more than one-quarter of our study patients. Placing a standardized memorandum in the electronic record was associated with a 65% relative reduction in antimicrobial-days for ASB and CNP.

To assess the prevalence of and risk factors for carbapenem-resistant Klebsiella pneumoniae (CRKP) carriage among patients in post-acute-care facilities (PACFs) in Israel.

A cross-sectional prevalence survey was conducted in 12 PACFs. Rectal swab samples were obtained from 1,144 patients in 33 wards. Risk factors for CRKP carriage were assessed among the cohort. Next, a nested, matched case-control study was conducted to define individual risk factors for colonization. Finally, the cohort of patients with a history of CRKP carriage was characterized to determine risk factors for continuous carriage.

The prevalence of rectal carriage of CRKP among 1,004 patients without a history of CRKP carriage was 12.0%. Independent risk factors for CRKP carriage were prolonged length of stay (odds ratio [OR], 1.001; P < .001), sharing a room with a known carrier (OR, 3.09; P = .02), and increased prevalence of known carriers on the ward (OR, 1.02; P = .013). A policy of screening for carriage on admission was protective (OR, 0.41; P = .03). Risk factors identified in the nested case-control study were antibiotic exposure during the prior 3 months (OR, 1.66; P = .03) and colonization with other resistant pathogens (OR, 1.64; P = .03). Among 140 patients with a history of CRKP carriage, 47% were colonized. Independent risk factors for continued CRKP carriage were antibiotic exposure during the prior 3 months (OR, 3.05; P = .04), receipt of amoxicillin-clavulanate (OR, 4.18; P = .007), and screening within 90 days of the first culture growing CRKP (OR, 2.9; P = .012).

We found a large reservoir of CRKP in PACFs. Infection-control polices and antibiotic exposure were associated with patient colonization.

To test in a real-world setting the recommendations for measuring infection with multidrug-resistant organisms (MDRO) from the Society for Healthcare Epidemiology of America (SHEA) and the Centers for Disease Control and Prevention's Healthcare Infection Control Practices Advisory Committee (HICPAC).

Using data from 3 hospital settings within a healthcare network, we applied the SHEA/HICPAC recommendations to measure methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization. Data were obtained from the hospitals' electronic surveillance system and were supplemented by manual medical record review as necessary. Additionally, we tested (1) different definitions for nosocomial incidence, (2) the effect of excluding patients not at risk from the denominator for hospital-onset incidence, and (3) the appropriate time period to use when including or excluding patients with a prior history of MRSA infection or colonization from nosocomial rates. Negative binomial regression models were used to test for differences between rate definitions. A rating scale was created for each metric, assessing the extent to which manual or electronic data elements were required.

There was no statistically significant difference between using 72 hours or 3 calendar days as the cutoff to define hospital-onset incidence. Excluding patients not at risk from the denominator when calculating hospital-onset incidence led to statistically significant increases in rates. When excluding patients with a prior history of MRSA infection or colonization from nosocomial incidence rates, rates were similar regardless of whether we looked at 1, 2, or 3 years' worth of prior data.

The SHEA/HICPAC MDRO metrics are useful but can be challenging to implement. We include in our description of the data sources and processes required to calculate these metrics information that may simplify the process for institutions.

To review the experiences at Winnipeg Children's Hospital (WCH) during the 2009 influenza season, with an emphasis on nosocomial transmission and infection prevention and control responses.

A case series of patients admitted to WCH who had laboratory-confirmed cases of influenza between January 1 and July 31, 2009, with a comparison of patients with seasonal influenza and those with pandemic (H1N1) 2009 influenza; a review of the impact of infection prevention and control modifications on nosocomial transmission.

A total of 104 inpatients with influenza, 81 of whom had pandemic (H1N1) 2009 influenza, were reviewed at a large Canadian pediatric tertiary care center.

There were no differences in risk factors, presentation, or outcome between patients with seasonal influenza and those with pandemic (H1N1) 2009 influenza. There were 8 nosocomial cases of pandemic (H1N1) 2009 influenza. Excluding patients with nosocomial cases, mean length of hospital stay was significantly shortened to 3.7 days for individuals who had pandemic (H1N1) 2009 influenza and who received empiric oseltamivir on admission to the hospital, compared with 12.0 days for patients for whom treatment was delayed (P = .02). Treatment with oseltamivir of all patients with suspected cases of influenza and prompt modifications to infection control practices, including playroom closures and enhanced education of visitors and staff, terminated nosocomial transmission.

Infection with pandemic (H1N1) 2009 influenza virus resulted in a substantial number of hospitalizations of pediatric patients in Manitoba, including those with nosocomial cases, thereby stressing the capacity of WCH. Immediate therapy with oseltamivir on admission to the hospital resulted in a significantly reduced length of hospitalization. This, coupled with intensified infection prevention and control practices, halted nosocomial transmission. These strategies should be considered in future pandemic influenza or other respiratory viral outbreaks.

To develop and validate an electronic surveillance tool for catheter-associated urinary tract infections (CAUTIs).

Retrospective cohort study.

413-bed university-affiliated urban teaching hospital.

An electronic surveillance tool was developed for CAUTI and urinary catheter utilization based on the objective components of the National Healthcare Safety Network (NHSN) definitions including fever, urinalysis, and urine culture. Results were compared to manual chart review by an infection preventionist (IP).

During January and February 2010, 204 positive urine cultures (≥103 colony-forming units/mL) were identified in 136 patients with indwelling urinary catheters during their hospitalization. The electronic surveillance tool detected 60 CAUTI cases and 7,098 catheter-days, yielding a CAUTI incidence rate of 8.5 per 1,000 catheter-days. Urinary catheter utilization ratios (Foley-days/patient-days) were: acute care units, 0.27 (3,637 of 13,229); intensive care units, 0.77 (3,461 of 4,469); and overall, 0.40 (7,098 of 17,698). In comparison, the IP identified 59 cases by manual review with a sensitivity of 51 of 59 (86.4%), specificity 136 of 145 (93.8%), and negative predictive value of 136 of 144 (94.4%). Fever was present in 54 of 59 (91.5%) of CAUTI cases identified manually, while subjective criteria were documented in only 6 of 59 (10.2%) infections. Agreement between the electronic surveillance and manual IP review was assessed as very good (k, 0.80; 95% confidence interval, 0.71–0.89).

We report an attempt at automating surveillance for CAUTI. With a high negative predictive value, the electronic tool allows for more efficient CAUTI surveillance and facilitates housewide trending of rates and catheter utilization. This approach should be validated in different patient populations.

To determine the feasibility of using electronic laboratory and admission-discharge-transfer data from BioSense, a national automated surveillance system, to apply new modified Clostridium difficile infection (CDI) surveillance definitions and calculate overall and facility-specific rates of disease.

Retrospective, multicenter cohort study.

Thirty-four hospitals sending inpatient, emergency department, and /or outpatient data to BioSense.

Laboratory codes and text-parsing methods were used to extract C. difficile-positive toxin assay results from laboratory data sent to BioSense during the period from January 1, 2007, through June 30, 2008; these were merged with administrative records to determine whether cases were community associated or healthcare onset, as well as patient-day data for rate calculations. A patient was classified as having hospital-onset CDI if he or she had a C. difficile toxin-positive result on a stool sample collected 3 or more days after admission and community-onset CDI if the specimen was collected less than 3 days after admission or the patient was not hospitalized.

A total of 4,585 patients from 34 hospitals in 12 states had C. difficile-positive assay results. More than half (53.0%) of the cases were community-onset, and 30.8% of these occurred in patients who were recently hospitalized. The overall rate of healthcare-onset CDI was 7.8 cases per 10,000 patient-days, with a range among facilities of 1.5-27.8 cases per 10,000 patient-days.

Electronic laboratory data sent to the BioSense surveillance system were successfully used to produce disease rates of CDI comparable to those of other studies, which shows the feasibility of using electronic laboratory data to track a disease of public health importance.

Expanding hospitalized patients' risk stratification for Clostridium difficile infection (CDI) is important for improving patient safety. We applied definitions for hospital-onset (HO) and community-onset (CO) CDI to electronic data from 85 hospitals between January 2007 and June 2008 to identify factors associated with higher HO CDI rates.

Nonrecurrent CDI cases were identified among adult (≥18-year-old) inpatients by a positive C. difficile toxin assay result more than 8 weeks after any previous positive result. Case categories included HO, CO-hospital associated (CO-HA), CO-indeterminate hospital association (CO-IN), and CO–non–hospital associated (CO-NHA). C. difficile testing intensity (CDTI) was defined as the total number of C. difficile tests performed, normalized to the number of patients with at least 1 C. difficile toxin test recorded. We calculated both the incidence density and the prevalence of CDI where appropriate. We fitted a multivariable Poisson model to identify factors associated with higher HO CDI rates.

Among 1,351,156 unique patients with 2,022,213 admissions, 9,803 cases of CDI were identified; of these, 50.6% were HO, 17.4% were CO-HA, 9.0% were CO-IN, and 23.0% were CO-NHA. The incidence density of HO was 6.3 per 10,000 patient-days. The prevalence of CO CDI on admission was, per 10,000 admissions, 8.4 for CO-HA, 4.4 for CO-IN, and 11.1 for CO-NHA. Factors associated (P< .0001) with higher HO CDI rates included older age, higher CO-NHA prevalence on admission, and increased CDTI.

Electronic health information can be leveraged to risk-stratify HO CDI rates by patient age and CO-NHA prevalence on admission. Hospitals should optimize diagnostic testing to improve patient care and measured CDI rates.