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Background: We examined whether disparities existed in hospital-onset (HO) Staphylococcus aureus bloodstream infections (BSIs) and used whole-genome sequencing (WGS) to identify factors associated with USA300 transmission networks., Methods: We evaluated HO methicillin-susceptible S. aureus (MSSA) and HO methicillin-resistant S. aureus (MRSA) BSIs for 2009-2013 at 2 hospitals and used an adjusted incidence for modeling. WGS and phylogenetic analyses were performed on a sample of USA300 BSI isolates. Epidemiologic data were analyzed in the context of phylogenetic reconstructions., Results: On multivariate analysis, male sex, African-American race, and non-Hispanic white race/ethnicity were significantly associated with HO-MRSA BSIs whereas Hispanic ethnicity was negatively associated (rate ratio, 0.41; P = .002). Intermixing of community-onset and HO-USA300 strains on the phylogenetic tree indicates that these strains derive from a common pool. African-American race was the only factor associated with genomic clustering of isolates., Conclusions: In a multicenter assessment of HO-S. aureus BSIs, African-American race was significantly associated with HO-MRSA but not MSSA BSIs. There appears to be a nexus of USA300 community and hospital transmission networks, with a community factor being the primary driver. Our data suggest that HO-USA300 BSIs likely are due to colonizing strains acquired in the community before hospitalization. Therefore, prevention efforts may need to extend to the community for maximal benefit., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Objective: To develop a probabilistic method for measuring central line-associated bloodstream infection (CLABSI) rates that reduces the variability associated with traditional, manual methods of applying CLABSI surveillance definitions., Design: Multicenter retrospective cohort study of bacteremia episodes among patients hospitalized in adult patient-care units; the study evaluated presence of CLABSI., Setting: Hospitals that used SafetySurveillor software system (Premier) and who also reported to the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN)., Patients: Patients were identified from a stratified sample from all eligible blood culture isolates from all eligible hospital units to generate a final set with an equal distribution (ie, 20%) from each unit type. Units were divided a priori into 5 major groups: medical intensive care unit, surgical intensive care unit, medical-surgical intensive care unit, hematology unit, or general medical wards., Interventions: Episodes were reviewed by 2 experts, and a selection of discordant reviews were re-reviewed. Data were joined with NHSN data for hospitals for in-plan months. A predictive model was created; model performance was assessed using the c statistic in a validation set and comparison with NHSN reported rates for in-plan months., Results: A final model was created with predictors of CLABSI. The c statistic for the final model was 0.75 (0.68-0.80). Rates from regression modeling correlated better with expert review than NHSN-reported rates., Conclusions: The use of a regression model based on the clinical characteristics of the bacteremia outperformed traditional infection preventionist surveillance compared with an expert-derived reference standard. Infect.

Background: 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., Objective: To examine the epidemiology of S. aureus BSIs, including USA300 and non-USA300 MRSA strains., Design: Retrospective observational study with molecular analysis., Setting: Large urban public hospital., Patients: Individuals with S. aureus BSIs from January 1, 2007 through December 31, 2013., Methods: 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., Results: 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., Conclusions: 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.

Objective: Central line-associated bloodstream infection (BSI) rates are a key quality metric for comparing hospital quality and safety. Traditional BSI surveillance may be limited by interrater variability. We assessed whether a computer-automated method of central line-associated BSI detection can improve the validity of surveillance., Design: Retrospective cohort study., Setting: Eight medical and surgical intensive care units (ICUs) in 4 academic medical centers., Methods: Traditional surveillance (by hospital staff) and computer algorithm surveillance were each compared against a retrospective audit review using a random sample of blood culture episodes during the period 2004-2007 from which an organism was recovered. Episode-level agreement with audit review was measured with κ statistics, and differences were assessed using the test of equal κ coefficients. Linear regression was used to assess the relationship between surveillance performance (κ) and surveillance-reported BSI rates (BSIs per 1,000 central line-days)., Results: We evaluated 664 blood culture episodes. Agreement with audit review was significantly lower for traditional surveillance (κ [95% confidence interval (CI) = 0.44 [0.37-0.51]) than computer algorithm surveillance (κ [95% CI] = 0.58; P = .001). Agreement between traditional surveillance and audit review was heterogeneous across ICUs (P = .01); furthermore, traditional surveillance performed worse among ICUs reporting lower (better) BSI rates (P = .001). In contrast, computer algorithm performance was consistent across ICUs and across the range of computer-reported central line-associated BSI rates. Conclusions: Compared with traditional surveillance of bloodstream infections, computer automated surveillance improves accuracy and reliability, making interfacility performance comparisons more valid.

Context: Central line-associated bloodstream infection (BSI) rates, determined by infection preventionists using the Centers for Disease Control and Prevention (CDC) surveillance definitions, are increasingly published to compare the quality of patient care delivered by hospitals. However, such comparisons are valid only if surveillance is performed consistently across institutions., Objective: To assess institutional variation in performance of traditional central line-associated BSI surveillance., Design, Setting, and Participants: We performed a retrospective cohort study of 20 intensive care units among 4 medical centers (2004-2007). Unit-specific central line-associated BSI rates were calculated for 12-month periods. Infection preventionists, blinded to study participation, performed routine prospective surveillance using CDC definitions. A computer algorithm reference standard was applied retrospectively using criteria that adapted the same CDC surveillance definitions., Main Outcome Measures: Correlation of central line-associated BSI rates as determined by infection preventionist vs the computer algorithm reference standard. Variation in performance was assessed by testing for institution-dependent heterogeneity in a linear regression model., Results: Forty-one unit-periods among 20 intensive care units were analyzed, representing 241,518 patient-days and 165,963 central line-days. The median infection preventionist and computer algorithm central line-associated BSI rates were 3.3 (interquartile range [IQR], 2.0-4.5) and 9.0 (IQR, 6.3-11.3) infections per 1000 central line-days, respectively. Overall correlation between computer algorithm and infection preventionist rates was weak (ρ = 0.34), and when stratified by medical center, point estimates for institution-specific correlations ranged widely: medical center A: 0.83; 95% confidence interval (CI), 0.05 to 0.98; P = .04; medical center B: 0.76; 95% CI, 0.32 to 0.93; P = .003; medical center C: 0.50, 95% CI, -0.11 to 0.83; P = .10; and medical center D: 0.10; 95% CI -0.53 to 0.66; P = .77. Regression modeling demonstrated significant heterogeneity among medical centers in the relationship between computer algorithm and expected infection preventionist rates (P < .001). The medical center that had the lowest rate by traditional surveillance (2.4 infections per 1000 central line-days) had the highest rate by computer algorithm (12.6 infections per 1000 central line-days)., Conclusions: Institutional variability of infection preventionist rates relative to a computer algorithm reference standard suggests that there is significant variation in the application of standard central line-associated BSI surveillance definitions across medical centers. Variation in central line-associated BSI surveillance practice may complicate interinstitutional comparisons of publicly reported central line-associated BSI rates.

Background: When Staphylococcus aureus is isolated in urine, it is thought to usually represent hematogenous spread. Because such spread might have special clinical significance, we evaluated predictors and outcomes of S. aureus bacteriuria among patients with S. aureus bacteremia., Methods: A case-control study was performed at John H. Stroger Jr. Hospital of Cook County among adult inpatients during January 2002-December 2006. Cases and controls had positive and negative urine cultures, respectively, for S. aureus, within 72 hours of positive blood culture for S. aureus. Controls were sampled randomly in a 1:4 ratio. Univariate and multivariable logistic regression analyses were done., Results: Overall, 59% of patients were African-American, 12% died, 56% of infections had community-onset infections, and 58% were infected with methicillin-susceptible S. aureus (MSSA). Among 61 cases and 247 controls, predictors of S. aureus bacteriuria on multivariate analysis were urological surgery (OR = 3.4, p = 0.06) and genitourinary infection (OR = 9.2, p = 0.002). Among patients who died, there were significantly more patients with bacteriuria than among patients who survived (39% vs. 17%; p = 0.002). In multiple Cox regression analysis, death risks in bacteremic patients were bacteriuria (hazard ratio 2.9, CI 1.4-5.9, p = 0.004), bladder catheter use (2.0, 1.0-4.0, p = 0.06), and Charlson score (1.1, 1.1-1.3, p = 0.02). Neither length of stay nor methicillin-resistant Staphylococcus aureus (MRSA) infection was a predictor of S. aureus bacteriuria or death., Conclusions: Among patients with S. aureus bacteremia, those with S. aureus bacteriuria had 3-fold higher mortality than those without bacteriuria, even after adjustment for comorbidities. Bacteriuria may identify patients with more severe bacteremia, who are at risk of worse outcomes.

Purpose: Cleansing the skin of intensive care unit (ICU) patients daily with chlorhexidine gluconate (CHG) has been associated with beneficial effects, including a reduction in central-line-associated bacteremias (CLABSIs). Most studies have been done in medical ICUs. In this study, we evaluated the effectiveness of daily chlorhexidine skin cleansing on CLABSI rates in a surgical ICU., Methods: In Fall 2005, the 30-bed surgical ICU at Rush University Medical Center discontinued daily soap-and-water bathing of patients and substituted skin cleansing with no-rinse, 2% CHG-impregnated cloths. This change was made without research investigator input or oversight. Using administrative, microbiological and infection control practitioner databases, we compared rates of CLABSIs and blood culture contamination during soap-and-water bathing (September 2004-October 2005) and CHG cleansing (November 2005-October 2006) periods. Rates of other nosocomial infections that were not expected to be affected by CHG bathing (secondary bacteremia, Clostridium difficile-associated diarrhea, ventilator-associated pneumonia, urinary tract infection) were included as control variables., Results: There was no significant difference in the CLABSI rate between soap-and-water and CHG bathing periods (3.81/1,000 central line days vs. 4.6/1,000 central line days; p = 0.57). Blood culture contamination declined during CHG bathing (5.97/1,000 to 2.41/1,000 patient days; p = 0.003). Rates of other nosocomial infections did not change significantly., Conclusions: In this real-world effectiveness trial, daily cleansing of surgical ICU patients' skin with CHG had no effect on CLABSI rates, but was associated with half the rate of blood culture contamination. Controlled trials in surgical ICUs are needed to determine whether CHG bathing can prevent infections in this setting.

Objective: To evaluate the effect of bathing patients with 2% chlorhexidine on the rates of central vascular catheter (CVC)-associated bloodstream infection (BSI) at a long-term acute care hospital (LTACH)., Design: Quasi-experimental study., Setting: A 70-bed LTACH in the greater Chicago area., Patients: All consecutive patients admitted to the LTACH during the period from February 2006 to February 2008., Methods: For patients at the LTACH, daily 2% chlorhexidine baths were instituted during the period from September 2006 until May 2007 (ie, the intervention period). A preintervention period (in which patients were given daily soap-and-water baths) and a postintervention period (in which patients were given daily nonmedicated baths and weekly 2% chlorhexidine baths) were also observed. The rates of CVC-associated BSI and ventilator-associated pneumonia were analyzed for the intervention period and for the pre- and postintervention periods., Results: The rates of CVC-associated BSI were 9.5, 3.8, and 6.4 cases per 1,000 CVC-days during the preintervention, intervention, and postintervention periods, respectively. By the end of the intervention period, there was a net reduction of 99% in the CVC-associated BSI rate. No changes were seen in the rates of ventilator-associated pneumonia during the preintervention and intervention periods., Conclusion: Daily chlorhexidine baths appeared to be an effective intervention to reduce rates of CVC-associated BSI in an LTACH.

Background: Controlled studies that took place in medical intensive care units (MICUs) have demonstrated that bathing patients with chlorhexidine gluconate (CHG) can reduce skin colonization with potential pathogens and can lessen the risk of central venous catheter (CVC)-associated bloodstream infection (BSI)., Objective: To examine, without oversight of practice by research study staff, the effectiveness or real-world effect of patient cleansing with CHG on rates of CVC-associated BSI., Design: In the fall of 2005, the MICU at Rush University Medical Center discontinued bathing patients daily with soap and water and substituted skin cleansing with no-rinse, 2% CHG-impregnated cloths. This change was a clinical management decision without research input., Setting: A 21-bed MICU at Rush University Medical Center., Patients: Patients hospitalized in the MICU during the period from September 2004 through October 2006., Methods: In a pre-post study design, we gathered data from administrative and laboratory databases, infection control practitioner logs, and patient medical charts to compare rates of CVC-associated BSI and blood culture contamination between the baseline soap-and-water bathing period (September 2004-October 2005) and the CHG bathing period (November 2005-October 2006). Rates of secondary BSI, Clostridium difficile infection (CDI), ventilator-associated pneumonia (VAP), and urinary tract infection (UTI) served as control variables that were not expected to be affected by CHG bathing., Results: Bathing with CHG was associated with a statistically significant decrease in the rate of CVC-associated BSI (from 5.31 to 0.69 cases per 1,000 CVC-days; P = .006) and in the rate of blood culture contamination (from 6.99 to 4.1 cases per 1,000 patient-days; P = .04). Rates of secondary BSI, CDI, VAP, and UTI did not change significantly., Conclusions: In our analysis of real-world practice, daily bathing of MICU patients with CHG was effective at reducing rates of CVC-associated BSI and blood culture contamination. Controlled studies are needed to determine whether these beneficial effects extend outside the MICU.

Increasing bacterial antimicrobial resistance has prompted physicians to choose broad-spectrum antimicrobials in order to reduce the likelihood of inactive empirical therapy. However, for bacteremic patients already receiving supportive care, it is unclear whether delay of active antimicrobial therapy significantly impacts patient outcomes. We performed a retrospective cohort study of patients with monomicrobial bloodstream infections at a large urban hospital in the United States from 2001 to 2006. We assessed the impact of delay of active antimicrobial therapy on mortality by using multivariable logistic regression modeling with and without propensity score methodology. We evaluated 1,523 episodes of monomicrobial bacterial bloodstream infections at our institution. Nine hundred eighty-three bacteremic episodes (64.5%) were treated with an active antimicrobial agent within 24 h of the index blood culture; the remaining 540 episodes (35.5%) were considered to have delay of active antimicrobial therapy. In adjusted analysis, among patients in the non-intensive-care-unit setting with an absolute neutrophil count (ANC) of <100 cells/microl, delay was associated with increased mortality (odds ratio [OR], 18.0; 95% confidence interval [CI], 2.84 to 114.5; P < 0.01); among intensive-care-unit patients with an ANC of <100 cells/microl, the effect of delay on mortality was nearly significant (OR, 5.56; 95% CI, 0.85 to 36.3; P = 0.07). However, for patients who were nonneutropenic (ANC, >500 cells/microl) or had ANCs of 100 to 500 cells/microl, delay was not associated with increased mortality. While the delay of active antimicrobial therapy was not significantly associated with higher mortality for most patients in this cohort, patients with severe neutropenia appeared to be vulnerable.