Local audit of empiric antibiotic therapy in bacteremia: A retrospective cohort study

Abstract

Background It is unclear if a local audit would be useful in providing guidance on how to improve local practice of empiric antibiotic therapy. We performed an audit of antibiotic therapy in bacteremia to evaluate the proportion and risk factors for inadequate empiric antibiotic coverage. Methods This retrospective cohort study included patients with positive blood cultures across 3 hospitals in Hamilton, Ontario, Canada during October of 2019. Antibiotic therapy was considered empiric if it was administered within 24 hours after blood culture collection. Adequate coverage was defined as when the isolate from blood culture was tested to be susceptible to the empiric antibiotic. A multivariable logistic regression model was used to predict inadequate empiric coverage. Diagnostic accuracy of a clinical pathway based on patient risk factors was compared to clinician’s decision in predicting which bacteria to empirically cover. Results Of 201 bacteremia cases, empiric coverage was inadequate in 56 (27.9%) cases. Risk factors for inadequate empiric coverage included unknown source at initiation of antibiotic therapy (adjusted odds ratio (aOR) of 2.76 95% CI 1.27–6.01, P = 0.010) and prior antibiotic therapy within 90 days (aOR of 2.46 95% CI 1.30–4.74, P = 0.006). A clinical pathway that considered community-associated infection as low risk for Pseudomonas was better at ruling out Pseudomonas bacteremia with a negative likelihood ratio of 0.17 (95% CI 0.03–1.10) compared to clinician’s decision with negative likelihood ratio of 0.34 (95% CI 0.10–1.22). Conclusions An audit of antibiotic therapy in bacteremia is feasible and may provide useful feedback on how to locally improve empiric antibiotic therapy.

Risk factors associated with inappropriate empirical antimicrobial treatment in bloodstream infections. A cohort study

“…In our study, adherence to local guidelines resulted in a-EAT in 91% of episodes (which was a protective factor for i-EAT, with a OR 0.22 (95% CI 0.13-0.38), p < 0.001). This finding agrees with a recent study, with a smaller sample size, but with similar design (Bai et al, 2021), which reported that adherence to guidelines produced an a-EAT in 72% of cases in their population. The importance of ASP has been largely studied underlying their beneficial impact on clinical outcomes (better use of antimicrobials, reduction of infections caused by MDR microorganisms and mortality rates, etc.)…”

“…The i-EAT rate in our study (24.2%) was similar to previous studies (McDonald et al, 2005;Mettler et al, 2007;Retamar et al, 2012;Bai et al, 2021;Kadri et al, 2021) and even smaller than the pooled estimate of 32% in a systematic review of studies on i-EAT (Carrara et al, 2018). The differences between these rates among the studies are probably related to, on one hand, the heterogenicity of the definitions for appropriate empirical antimicrobial treatment and on the other, the variability of evaluated infections and the different rates of resistant microorganisms in every setting.…”

“…Evidence on the risk factors for i-EAT in adult patients with BSI is scarce. Previous studies have tried to point them out, but they either limited the analysis to the impact of MDR ( Girometti et al, 2014 ; Kadri et al, 2021 ), were small studies ( Bai et al, 2021 ) or identified some predictors to receive i-EAT even though the study was not designed for this purpose ( Retamar et al, 2013 ). Regarding risk factors for i-EAT identified in our study, they could be classified in patient-related (and, therefore, unmodifiable risk factors) and modifiable risk factors.…”

“…Our study has many strengths: 1) It provides a relevant sample size and identifies modifiable related factors for i-EAT in BSI episodes, which leads to opportunities for improvement in the ASP strategies. Other previous studies had smaller sample sizes or have focused on concrete, unmodifiable factors ( McDonald et al, 2005 ; Retamar et al, 2013 ; Girometti et al, 2014 ; Bai et al, 2021 ; Kadri et al, 2021 ). 2) All consecutive adult BSI episodes have been prospectively recorded, and followed for routine clinical practice, so there is no selection bias and there is no patient-loss for the analysis.…”

“…Despite of the relevance of choosing i-EAT, there is much less evidence on the risk factors associated with this practice. Some studies have focused on concrete patient-related factors ( McDonald et al, 2005 ; Retamar et al, 2013 ) while others have analysed heterogeneous clinical syndromes ( Mettler et al, 2007 ), have small sample size ( Bai et al, 2021 ) or have focused on specific populations like neonates ( Hsu et al, 2015 ) or immunosuppressed patients ( Martinez-Nadal et al, 2020 ; Chumbita et al, 2022 ), which makes their findings ungeneralizable to general adult population. More recently, some studies have focused on the impact of isolation of multidrug resistant (MDR) strains on the adequation of empirical antimicrobial treatment choice ( Girometti et al, 2014 ; Carrara et al, 2018 ) showing higher rates of i-EAT when a MDR microorganism was identified and thus, a negative impact on mortality.…”