IMPORTANCEUse of empirical broad-spectrum antibiotics for pneumonia has increased owing to concern for resistant organisms, including methicillin-resistant Staphylococcus aureus (MRSA). The association of empirical anti-MRSA therapy with outcomes among patients with pneumonia is unknown, even for high-risk patients.OBJECTIVE To compare 30-day mortality among patients hospitalized for pneumonia receiving empirical anti-MRSA therapy vs standard empirical antibiotic regimens. DESIGN, SETTING, AND PARTICIPANTSRetrospective multicenter cohort study was conducted of all hospitalizations in which patients received either anti-MRSA or standard therapy for community-onset pneumonia in the Veterans Health Administration health care system from January 1, 2008, to December 31, 2013. Subgroups of patients analyzed were those with initial intensive care unit admission, MRSA risk factors, positive results of a MRSA surveillance test, and positive results of a MRSA admission culture. Primary analysis was an inverse probability of treatment-weighted propensity score analysis using generalized estimating equation regression; secondary analyses included an instrumental variable analysis. Statistical analysis was conducted from June 14 to November 20, 2019.EXPOSURES Empirical anti-MRSA therapy plus standard pneumonia therapy vs standard therapy alone within the first day of hospitalization.MAIN OUTCOMES AND MEASURES Risk of 30-day all-cause mortality after adjustment for patient comorbidities, vital signs, and laboratory results. Secondary outcomes included the development of kidney injury and secondary infections with Clostridioides difficile, vancomycin-resistant Enterococcus species, or gram-negative bacilli. RESULTS Among 88 605 hospitalized patients (86 851 men; median age, 70 years [interquartile range, 62-81 years]), empirical anti-MRSA therapy was administered to 33 632 (38%); 8929 patients (10%) died within 30 days. Compared with standard therapy alone, in weighted propensity score analysis, empirical anti-MRSA therapy plus standard therapy was significantly associated with an increased adjusted risk of death (adjusted risk ratio [aRR], 1.4 [95% CI, 1.3-1.5]), kidney injury (aRR, 1.4 [95% CI, 1.3-1.5]), and secondary C difficile infections (aRR, 1.6 [95% CI, 1.3-1.9]), vancomycin-resistant Enterococcus spp infections (aRR, 1.6 [95% CI, 1.0-2.3]), and secondary gram-negative rod infections (aRR, 1.5 [95% CI, 1.2-1.8]). Similar associations between anti-MRSA therapy use and 30-day mortality were found by instrumental variable analysis (aRR, 1.6 [95% CI, 1.4-1.9]) and among patients admitted to the intensive care unit (aRR, 1.3 [95% CI, 1.2-1.5]), those with a high risk for MRSA (aRR, 1.2 [95% CI, 1.1-1.4]), and those with MRSA detected on surveillance testing (aRR, 1.6 [95% CI, 1.3-1.9]). No significant favorable association was found between empirical anti-MRSA therapy and death among patients with MRSA detected on culture (aRR, 1.1 [95% CI, 0.8-1.4]).CONCLUSIONS AND RELEVANCE This study suggests that empirical anti-MRSA th...

Background The Core Elements of Outpatient Antibiotic Stewardship provide a framework to improve antibiotic use, but evidence supporting safety are limited. We report the impact of Core Elements implementation within Veterans Health Administration sites. Methods A quasi-experimental controlled study assessed the effects of an intervention targeting antibiotic prescription for uncomplicated acute respiratory tract infections (ARI). Outcomes included per-visit antibiotic prescribing, treatment appropriateness, potential benefits and complications of reduced antibiotic treatment, and change in ARI diagnoses over a 3-year pre-implementation and 1-year post implementation period. Logistic regression adjusted for covariates [OR (95% CI)] and a difference-in-differences analysis compared outcomes between intervention and control sites. Results From 2014-2019, there were 16,712 and 51,275 patient-visits in 10 intervention and 40 control sites, respectively. Antibiotic prescribing rates pre-post implementation in intervention sites were 59.7% and 41.5%, respectively; in control sites they were 73.5% and 67.2%, respectively [difference-in-differences p<0.001]. The intervention site pre-post implementation odds ratio to receive appropriate therapy increased [1.67 (1.31, 2.14)] which remained unchanged within control sites [1.04 (0.91, 1.19)]. There was no difference in ARI-related return visits post-implementation [(-1.3% vs. -2.0%; difference-in-differences p=0.76] but all-cause hospitalization was lower within intervention sites [(-0.5% vs. -0.2%); difference-in-differences p=0.02]. The odds ratio to diagnose upper respiratory tract infection not otherwise specified compared to other non-ARI diagnosis increased post-implementation for intervention [1.27(1.21,1.34)] but not control [0.97(0.94,1.01)] sites. Conclusions Implementation of the Core Elements was associated with reduced antibiotic prescribing for uncomplicated ARIs and a reduction in hospitalizations. ARI diagnostic coding changes were observed.

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Key Points Question Are contact precautions for pathogen transmission associated with reductions in person-to-person transmission of methicillin-resistant Staphylococcus aureus (MRSA) in US Veterans Affairs (VA) acute care hospitals? Findings In this cohort study, transmission models were fit to data on 8.4 million surveillance tests from 5.6 million admissions to 108 VA hospitals between 2008 and 2017. The estimated reduction in transmissibility of MRSA associated with contact precautions was 47%. Meaning In this large-scale study, contact precautions were associated with a 2-fold reduction in MRSA transmission, which suggests that the MRSA Prevention Initiative was associated with the decline in acquisition rates in VA hospitals.