Abstract
Background
Although studies have shown blood culture rates have remained stable in recent years, understanding the variability in positivity over time and among hospitals may inform diagnostic and antimicrobial stewardship efforts.
Methods
We included all discharges from hospitals participating in the Premier Healthcare Database and Cerner Health Facts from 2012-2017 in months where a hospital reported at least one blood culture with antimicrobial susceptibility results. A blood culture episode was defined as one or more cultures drawn within 1 hour. Episodes on or before day 3 were defined as admission episodes (AE), and those drawn on day 4 or later were defined as post-admission episodes (PAE). Culture episodes yielding any organism were categorized as pathogen+ (i.e., at least 1 non-commensal organism identified) or commensal (i.e., only commensal organisms identified). Positive or commensal episode rates were calculated as the percentage of pathogen+ or commensal episodes among all blood culture episodes for AE and PAE. Logistic regression with generalized estimating equation models accounting for hospital-level clustering were used to measure time trends and facility level associations.
Results
Among 19.6 million discharges in 493 hospitals, 7.5 million blood culture episodes were identified; 336,102 (4.5%) were pathogen+, and 110,236 (1.5%) were commensals. The rate of pathogen+ AEs increased from 4.2% to 4.7% over the study period (p< .0001) and there was no significant temporal trend in the rate of pathogen+ PAEs (p=.7956) (Figure 1). AE commensals decreased significantly in 2016-2017 compared to previous years (1.6% in 2012 to 1.3% in 2017; p=.0092), and PAE commensals decreased significantly over the study period from 2.0% to 1.2% (p< .0001) (Figure 1). We observed substantial inter-hospital variability for each outcome (Figure 2). In addition, differences among hospital characteristics and seasonality were noted for AE and PAE pathogen+ rates and AE commensal rates (Figure 3), but not urbanicity or teaching hospital status.
Monthly Positivity Rate of Blood Culture Episodes, Premier Healthcare Database and Cerner Health Facts, 2012-2017
Adjusted Odds Ratios and 95% Confidence Intervals of Blood Culture Episode Positive (Non-Commensal) and Commensal Rates and Associated Characteristics
Conclusion
While an increase AE pathogen+ rates and decrease in commensal rates could indicate improved culture ordering and collection practices, significant seasonal, regional, and facility-level variability calls for further investigation.
Disclosures
John A. Jernigan, MD, MS, Nothing to disclose