To develop a method for calculating the number of healthcare-associated infections (HAIs) that must be prevented to reach a HAI reduction goal and identifying and prioritizing healthcare facilities where the largest reductions can be achieved.

Acute care hospitals that report HAI data to the Centers for Disease Control and Prevention’s National Healthcare Safety Network.

The cumulative attributable difference (CAD) is calculated by subtracting a numerical prevention target from an observed number of HAIs. The prevention target is the product of the predicted number of HAIs and a standardized infection ratio goal, which represents a HAI reduction goal. The CAD is a numeric value that if positive is the number of infections to prevent to reach the HAI reduction goal. We calculated the CAD for catheter-associated urinary tract infections for each of the 3,639 hospitals that reported such data to National Healthcare Safety Network in 2013 and ranked the hospitals by their CAD values in descending order.

Of 1,578 hospitals with positive CAD values, preventing 10,040 catheter-associated urinary tract infections at 293 hospitals (19%) with the highest CAD would enable achievement of the national 25% catheter-associated urinary tract infection reduction goal.

The CAD is a new metric that facilitates ranking of facilities, and locations within facilities, to prioritize HAI prevention efforts where the greatest impact can be achieved toward a HAI reduction goal.

Infect. Control Hosp. Epidemiol. 2015;36(12):1379–1384

The Centers for Disease Control and Prevention (CDC) has developed an approach to ventilator-associated events (VAE) surveillance. Using these methods, this study was performed to investigate VAE incidences and to test whether VAEs are associated with poorer outcomes in China.

A 4-month, prospective multicenter surveillance study between April and July 2013.

Our study included 15 adult intensive care units (ICUs) of 15 hospitals in China.

Patients admitted to ICUs during the study period

Patients on mechanical ventilation (MV) were monitored for VAEs: ventilator-associated conditions (VACs), infection-related ventilator-associated complications (IVACs), and possible or probable ventilator-associated pneumonia (VAP). Patients with and without VACs were compared with regard to duration of MV, ICU length of stay (LOS), overall hospital LOS, and mortality rate.

During the study period, 2,356 of the 5,256 patients admitted to ICUs received MV for 8,438 ventilator days. Of these patients, 636 were on MV >2 days. VACs were identified in 94 cases (4.0%; 11.1 cases per 1,000 ventilator days), including 31 patients with IVACs and 16 with possible VAP but none with probable VAP. Compared with patients without VACs, patients with VACs had longer ICU LOS (by 6.2 days), longer duration on MV (by 7.7 days), and higher hospital mortality rate (50.0% vs 27.3%). The mortality rate attributable to VACs was 11.7%. Compared with those with VACs alone, patients with IVACs had longer duration on MV and increased ICU LOS but no higher mortality rates.

In China, surveillance of VACs and IVACs is able to identify MV patients with poorer outcomes. However, surveillance of possible and probable VAP can be problematic.

Infect. Control Hosp. Epidemiol. 2015;36(12):1388–1395

To increase reliability of the algorithm used in our fully automated electronic surveillance system by adding rules to better identify bloodstream infections secondary to other hospital-acquired infections.

Intensive care unit (ICU) patients with positive blood cultures were reviewed. Central line–associated bloodstream infection (CLABSI) determinations were based on 2 sources: routine surveillance by infection preventionists, and fully automated surveillance. Discrepancies between the 2 sources were evaluated to determine root causes. Secondary infection sites were identified in most discrepant cases. New rules to identify secondary sites were added to the algorithm and applied to this ICU population and a non-ICU population. Sensitivity, specificity, predictive values, and kappa were calculated for the new models.

Of 643 positive ICU blood cultures reviewed, 68 (10.6%) were identified as central line–associated bloodstream infections by fully automated electronic surveillance, whereas 38 (5.9%) were confirmed by routine surveillance. New rules were tested to identify organisms as central line–associated bloodstream infections if they did not meet one, or a combination of, the following: (I) matching organisms (by genus and species) cultured from any other site; (II) any organisms cultured from sterile site; (III) any organisms cultured from skin/wound; (IV) any organisms cultured from respiratory tract. The best-fit model included new rules I and II when applied to positive blood cultures in an ICU population. However, they didn’t improve performance of the algorithm when applied to positive blood cultures in a non-ICU population.

Electronic surveillance system algorithms may need adjustment for specific populations.

Infect. Control Hosp. Epidemiol. 2015;36(12):1396–1400

In this study, we examined the impact of routine use of a passive disinfection cap for catheter hub decontamination in hematology–oncology patients.

A tertiary care cancer center in New York City

In this multiphase prospective study, we used 2 preintervention phases (P1 and P2) to establish surveillance and baseline rates followed by sequential introduction of disinfection caps on high-risk units (HRUs: hematologic malignancy wards, hematopoietic stem cell transplant units and intensive care units) (P3) and general oncology units (P4). Unit-specific and hospital-wide hospital-acquired central-line–associated bloodstream infection (HA-CLABSI) rates and blood culture contamination (BCC) with coagulase negative staphylococci (CONS) were measured.

Implementation of a passive disinfection cap resulted in a 34% decrease in hospital-wide HA-CLABSI rates (combined P1 and P2 baseline rate of 2.66–1.75 per 1,000 catheter days at the end of the study period). This reduction occurred only among high-risk patients and not among general oncology patients. In addition, the use of the passive disinfection cap resulted in decreases of 63% (HRUs) and 51% (general oncology units) in blood culture contamination, with an estimated reduction of 242 BCCs with CONS. The reductions in HA-CLABSI and BCC correspond to an estimated annual savings of $3.2 million in direct medical costs.

Routine use of disinfection caps is associated with decreased HA-CLABSI rates among high-risk hematology oncology patients and a reduction in blood culture contamination among all oncology patients.

Infect. Control Hosp. Epidemiol. 2015;36(12):1401–1408

Limitations in sample size, overly inclusive antibiotic classes, lack of adjustment of key risk variables, and inadequate assessment of cases contribute to widely ranging estimates of risk factors for Clostridium difficile infection (CDI).

To incorporate all key CDI risk factors in addition to 27 antibiotic classes into a single comprehensive model.

Retrospective cohort study.

Kaiser Permanente Southern California.

Members of Kaiser Permanente Southern California at least 18 years old admitted to any of its 14 hospitals from January 1, 2011, through December 31, 2012.

Hospital-acquired CDI cases were identified by polymerase chain reaction assay. Exposure to major outpatient antibiotics (10 classes) and those administered during inpatient stays (27 classes) was assessed. Age, sex, self-identified race/ethnicity, Charlson Comorbidity Score, previous hospitalization, transfer from a skilled nursing facility, number of different antibiotic classes, statin use, and proton pump inhibitor use were also assessed. Poisson regression estimated adjusted risk of CDI.

A total of 401,234 patients with 2,638 cases of incident CDI (0.7%) were detected. The final model demonstrated highest CDI risk associated with increasing age, exposure to multiple antibiotic classes, and skilled nursing facility transfer. Factors conferring the most reduced CDI risk were inpatient exposure to tetracyclines and first-generation cephalosporins, and outpatient macrolides.

Although type and aggregate antibiotic exposure are important, the factors that increase the likelihood of environmental spore acquisition should not be underestimated. Operationally, our findings have implications for antibiotic stewardship efforts and can inform empirical and culture-driven treatment approaches.

Infect. Control Hosp. Epidemiol. 2015;36(12):1409–1416

Methicillin-resistant Staphylococcus aureus (MRSA) infections due to USA300 have become widespread in community and healthcare settings. It is unclear whether risk factors for bloodstream infections (BSIs) differ by strain type.

To examine the epidemiology of S. aureus BSIs, including USA300 and non-USA300 MRSA strains.

Retrospective observational study with molecular analysis.

Large urban public hospital.

Individuals with S. aureus BSIs from January 1, 2007 through December 31, 2013.

We used electronic surveillance data to identify cases of S. aureus BSI. Available MRSA isolates were analyzed by pulsed-field gel electrophoresis. Poisson regression was used to evaluate changes in BSI incidence over time. Risk factor data were collected by medical chart review and logistic regression was used for multivariate analysis of risk factors.

A total of 1,015 cases of S. aureus BSIs were identified during the study period; 36% were due to MRSA. The incidence of hospital-onset (HO) MRSA BSIs decreased while that of community-onset (CO) MRSA BSIs remained stable. The rate of CO– and HO– methicillin-susceptible S. aureus infections both decreased over time. More than half of HO-MRSA BSIs were due to the USA300 strain type and for 4 years, the proportion of HO-MRSA BSIs due to USA300 exceeded 60%. On multivariate analysis, current or former drug use was the only epidemiologic risk factor for CO- or HO-MRSA BSIs due to USA300 strains.

USA300 MRSA is endemic in communities and hospitals and certain populations (eg, those who use illicit drugs) may benefit from enhanced prevention efforts in the community.

Infect. Control Hosp. Epidemiol. 2015;36(12):1417–1422

To determine whether real-time availability of rapid molecular results of Staphylococcus aureus would impact emergency department clinician antimicrobial selection for adults with cutaneous abscesses.

We performed a prospective, randomized controlled trial comparing a rapid molecular test with standard of care culture-based testing. Follow-up telephone calls were made at between 2 and 7 days, 1 month, and 3 months after discharge.

Two urban, academic emergency departments.

Patients at least 18 years old presenting with a chief complaint of abscess, cellulitis, or insect bite and receiving incision and drainage were eligible. Seven hundred seventy-eight people were assessed for eligibility and 252 met eligibility criteria.

Clinician antibiotic selection and clinical outcomes were evaluated. An ad hoc outcome of test performance was performed.

We enrolled 252 patients and 126 were randomized to receive the rapid test. Methicillin-susceptible S. aureus–positive patients receiving rapid test results were prescribed beta-lactams more often than controls (absolute difference, 14.5% [95% CI, 1.1%–30.1%]) whereas methicillin-resistant S. aureus–positive patients receiving rapid test results were more often prescribed anti–methicillin-resistant S. aureus antibiotics (absolute difference, 21.5% [95% CI, 10.1%–33.0%]). There were no significant differences between the 2 groups in 1-week or 3-month clinical outcomes.

Availability of rapid molecular test results after incision and drainage was associated with more-targeted antibiotic selection.

clinicaltrials.gov Identifier: NCT01523899

Infect. Control Hosp. Epidemiol. 2015;36(12):1423–1430

To determine the association (1) between shorter operative duration and surgical site infection (SSI) and (2) between surgeon median operative duration and SSI risk among first-time hip and knee arthroplasties.

Retrospective cohort study

A total of 43 community hospitals located in the southeastern United States.

Adults who developed SSIs according to National Healthcare Safety Network criteria within 365 days of first-time knee or hip arthroplasties performed between January 1, 2008 and December 31, 2012.

Log-binomial regression models estimated the association (1) between operative duration and SSI outcome and (2) between surgeon median operative duration and SSI outcome. Hip and knee arthroplasties were evaluated in separate models. Each model was adjusted for American Society of Anesthesiology score and patient age.

A total of 25,531 hip arthroplasties and 42,187 knee arthroplasties were included in the study. The risk of SSI in knee arthroplasties with an operative duration shorter than the 25th percentile was 0.40 times the risk of SSI in knee arthroplasties with an operative duration between the 25th and 75th percentile (risk ratio [RR], 0.40; 95% confidence interval [CI], 0.38–0.56; P<.01). Short operative duration did not demonstrate significant association with SSI for hip arthroplasties (RR, 1.04; 95% CI, 0.79–1.37; P=.36). Knee arthroplasty surgeons with shorter median operative durations had a lower risk of SSI than surgeons with typical median operative durations (RR, 0.52; 95% CI, 0.43–0.64; P<.01).

Short operative durations were not associated with a higher SSI risk for knee or hip arthroplasty procedures in our analysis.

Infect. Control Hosp. Epidemiol. 2015;36(12):1431–1436

To assess the diagnostic value of an adenosinetriphosphate bioluminescence assay (ATPmetry) to monitor the effectiveness of the reprocessing of endoscopes compared with microbiologic sampling.

Diagnostic study.

A 2,200-bed teaching hospital performing 5,000 to 6,000 endoscopic procedures annually.

All samples from bronchial or gastrointestinal endoscopes whatever the context.

Samples for microbiologic analysis and ATPmetry measurements were taken when each endoscope was inspected following reprocessing. Sampling was performed by flushing each endoscope with 300 mL Neutralizing Pharmacopeia Diluent thiosulfate rinsing solution divided equally between the endoscope channels. For each endoscope a series of 3 ATPmetry measurements were made on a vial containing the first jet from each channel and a second series on the whole sample.

Of 165 samples from endoscopes, 11 exceeded the acceptability threshold of 25 colony-forming units/endoscope. In the first jet collected, the median (interquartile range) level of ATPmetry was 30.5 (15.3–37.7) relative light units (RLU) for samples with 25 or fewer colony-forming units compared with 37.0 (34.7–39.3) RLU for samples with more than 25 colony-forming units (P=.008). For the whole sample, the median (interquartile range) level of ATPmetry was 24.8 (14.3–36.3) RLU and 36.3 (36.0–38.3) RLU (P=.006), respectively. After adjusting on the batch of cleansing solution used, no difference in ATPmetry values was found between microbiologically acceptable and unacceptable samples.

ATPmetry cannot be used as an alternative or complementary approach to microbiologic tests for monitoring the reprocessing of endoscopes in France

Infect. Control Hosp. Epidemiol. 2015;36(12):1437–1443