Kari Peterson

Performance of the Cepheid Xpert® SA Nasal Complete PCR assay compared to culture for detection of methicillin-sensitive and methicillin-resistant Staphylococcus aureus colonization

Sensitivity, specificity, positive predictive value, and negative predictive value for the Cepheid Xpert® SA Nasal Complete detection (N = 971) of methicillin-sensitive Staphylococcus aureus was 86.5%, 98.5%, 94.6%, and 96.1%; detection of methicillin-resistant S. aureus was 89.3%, 97.9%, 79.8%, and 99.0%, respectively. Our results show that testing on long-term care facility patients had lower sensitivity and specificity compared to acute care patient results.

Evaluation of Multiple Real-Time PCR Tests on Nasal Samples in a Large MRSA Surveillance Program

OBJECTIVES We evaluated the LightCycler MRSA Advanced Test (Roche Molecular Diagnostics, Pleasanton, CA), the BD MAX MRSA assay (Becton Dickinson, Franklin Lakes, NJ), and the Xpert MRSA assay (Cepheid, Sunnyvale, CA) on nasal samples using the same population. METHODS Admission and discharge nasal swabs were collected from inpatients using a double-headed swab. One swab was plated onto CHROMagar MRSA (CMA; Becton Dickinson, Sparks, MD) and then broken off into tryptic soy broth (TSB) for enrichment. TSB was incubated for 24 hours and then plated to CMA. The molecular tests were performed on the second swab. We analyzed the cost benefit of testing to evaluate what parameters affect hospital resources. RESULTS A total of 27,647 specimens were enrolled. The sensitivity/specificity was 98.3%/98.9% for the LightCycler MRSA Advanced Test and 95.7%/98.8% for the Xpert MRSA assay, but the difference was not significant. The positive predictive value was 86.7% for the LightCycler MRSA Advanced Test, 82.7% for the Xpert MRSA assay (P > .1), and 72.2% and for the BD MAX MRSA test (P < .001 compared with the LightCycler MRSA Advanced Test). All three assays were cost-effective, with the LightCycler MRSA Advanced Test having the highest economic return. CONCLUSIONS Our results suggest that the performance of the three commercial assays is similar. When assessing economic cost benefit of methicillin-resistant Staphylococcus aureus screening, the two measures with the most impact are the cost of the test and the specificity of the assay results.

Impact of Detection, Education, Research and Decolonization without Isolation in Long-term care (DERAIL) on methicillin-resistant Staphylococcus aureus colonization and transmission at 3 long-term care facilities

We tested infection prevention strategies to limit exposure of long-term care facility residents to drug-resistant pathogens in a prospective, cluster randomized 2-year trial involving 3 long-term care facilities (LTCFs) using methicillin-resistant Staphylococcus aureus (MRSA) as a model. We hypothesized that nasal MRSA surveillance using rapid quantitative polymerase chain reaction and decolonization of carriers would successfully lower overall MRSA colonization. In year 1, randomly assigned intervention units received decolonization with nasal mupirocin and chlorhexidine bathing and enhanced environmental cleaning with bleach every 4 months. Newly admitted MRSA nares-positive residents were decolonized on admission. Control units were screened but not decolonized. All units received periodic bleach environmental cleaning and instruction on hand hygiene. In year 2, all units followed intervention protocol caused by failure of the cluster randomized approach to sufficiently segregate patients. MRSA colonization was monitored using point prevalence testing every 4-6 months. Colonization status at admission and discharge was performed 1 quarter per year to determine acquisition. Fisher exact test was used for statistical analysis. Baseline MRSA colonization rate was 16.64%. In year 1, the colonization rate of intervention units was 11.61% (P = .028) and 17.85% in control units (P = .613) compared with baseline. Intervention unit rate difference compared with the controls was significant (P = .001). In year 2, the colonization rate was 10.55% (P < .001) compared with baseline. The transmission rates were 1.66% and 3.52% in years 1 and 2, respectively (P = .034). The planned interventions of screening and decolonization were successful at lowering MRSA colonization.

Electronic surveillance for infectious disease trend analysis following a quality improvement intervention.

OBJECTIVE Interventions for reducing methicillin-resistant Staphylococcus aureus (MRSA) healthcare-associated disease require outcome assessment; this is typically done by manual chart review to determine infection, which can be labor intensive. The purpose of this study was to validate electronic tools for MRSA healthcare-associated infection (HAI) trending that can replace manual medical record review. DESIGN AND SETTING This was an observational study comparing manual medical record review with 3 electronic methods: raw culture data from the laboratory information system (LIS) in use by our healthcare organization, LIS data combined with admission-discharge-transfer (ADT) data to determine which cultures were healthcare associated (LIS + ADT), and the CareFusion MedMined Nosocomial Infection Marker (NIM). Each method was used for the same 7-year period from August 2003 through July 2010. PATIENTS The data set was from a 3-hospital organization covering 342,492 admissions. RESULTS Correlation coefficients for raw LIS, LIS + ADT, and NIM were 0.976, 0.957, and 0.953, respectively, when assessed on an annual basis. Quarterly performance for disease trending was also good, with R(2) values exceeding 0.7 for all methods. CONCLUSIONS The electronic tools accurately identified trends in MRSA HAI incidence density when all infections were combined as quarterly or annual data; the performance is excellent when annual assessment is done. These electronic surveillance systems can significantly reduce (93% [in-house-developed program] to more than 99.9999% [commercially available systems]) the personnel resources needed to monitor the impact of a disease control program.

Reduction of methicillin-resistant Staphylococcus aureus infection in long-term care is possible while maintaining patient socialization: A prospective randomized clinical trial

BACKGROUND Antibiotic resistance is a challenge in long-term care facilities (LTCFs). The objective of this study was to demonstrate that a novel, minimally invasive program not interfering with activities of daily living or socialization could lower methicillin-resistant Staphylococcus aureus (MRSA) disease. METHODS This was a prospective, cluster-randomized, nonblinded trial initiated at 3 LTCFs. During year 1, units were stratified by type of care and randomized to intervention or control. In year 2, all units were converted to intervention consisting of universal decolonization using intranasal mupirocin and a chlorhexidine bath performed twice (2 decolonization-bathing cycles 1 month apart) at the start of the intervention period. Subsequently, after initial decolonization, all admissions were screened on site using real-time polymerase chain reaction, and those MRSA positive were decolonized, but not isolated. Units received annual instruction on hand hygiene. Enhanced bleach wipe cleaning of flat surfaces was done every 4 months. RESULTS There were 16,773 tests performed. The MRSA infection rate decreased 65% between baseline (44 infections during 365,809 patient days) and year 2 (12 infections during 287,847 patient days; P <.001); a significant reduction was observed at each of the LTCFs (P <.03). CONCLUSIONS On-site MRSA surveillance with targeted decolonization resulted in a significant decrease in clinical MRSA infection among LTCF residents.

Prospective observational study on central line-associated bloodstream infections and central venous catheter occlusions using a negative displacement connector with an alcohol disinfecting cap

Background: Major complications of central venous catheter (CVC) use include bloodstream infection and occlusion. We performed a prospective, observational study to determine the rate of central line–associated bloodstream infection (CLABSI) and CVC occlusion using a negative displacement connector with an alcohol disinfecting cap. Methods: Patients were followed from the time of CVC insertion through 2 days after removal, at the time of hospital discharge if there was no documentation of removal, or 90 days after the insertion of the CVC if it was not removed. CLABSI was defined using National Healthcare Safety Network criteria. Data for evidence of lumen occlusions were extracted from the electronic health record. Direct observations were performed to assess adherence to hospital policy regarding CVC insertion practice. Results: A total of 2,512 catheters from 2,264 patients were enrolled for this study. There were 21 CLABSIs (0.84%; 95% confidence interval [CI], 0.48%‐1.19%; 0.62 per 1,000 line days) and 378 occlusions (15.05%; 95% CI, 13.65%‐16.45%; 11.23 per 1,000 line days). Eighty‐five direct observations demonstrated insertion protocol adherence in 881 of 925 (95.24%; 95% CI, 93.87%‐96.61%) measured criteria. Conclusions: Lines placed following a standardized protocol using a negative displacement connector with an alcohol cap have low rates of infection compared with historically published findings. We also established that the occlusion rate is >15‐fold the CLABSI rate.

637Control of Methicillin-Resistant Staphylococcus aureus (MRSA) in Long Term Care is Possible While Maintaining Patient Socialization without Isolation

637. Control of Methicillin-Resistant Staphylococcus aureus (MRSA) in Long Term Care is Possible While Maintaining Patient Socialization without Isolation Becky Smith, MD; Susan Boehm, RN, BSN; Jennifer Beaumont, MS; Ari Robicsek, MD; Parul Patel, BS MT(ASCP), CCRP; Donna Schora, MT(ASCP); Deborah Burdsall, RN-BC, CIC; Kari Peterson, BA; Maureen Fausone, BA; Lance Peterson, MD; Infectious Diseases, Pritzker School of Medicine, University of Chicago, Chicago, IL; NorthShore University HealthSystem, Evanston, IL; Department of Medical Social Sciences, Northwestern University, Chicago, IL; Infection Control, Lutheran Home/Lutheran Life Communities, Arlington Heights, IL; Research, NorthShore University HealthSystem, Evanston, IL; Pritzker School of Medicine, University of Chicago, Chicago, IL