Dataset Information

Follow-up blood cultures in Pseudomonas aeruginosa bacteremia: A potential target for diagnostic stewardship.

ABSTRACT:

Objectives

Evidence supporting collection of follow-up blood cultures for Gram-negative bacteremia is mixed. We sought to understand why providers order follow-up blood cultures when managing P. aeruginosa bacteremia and whether follow-up blood cultures in this context are associated with short- and long-term survival.

Methods

We conducted a retrospective cohort study of adult inpatients with P. aeruginosa bacteremia at the University of Maryland Medical Center in 2015-2020. Kaplan-Meier survival curves and Cox regression with time-varying covariates were used to evaluate the association between follow-up blood cultures and time to mortality within 30 days of first positive blood culture. Provider justifications for follow-up blood cultures were identified through chart review.

Results

Of 159 eligible patients, 127 (80%) had follow-up blood cultures, including 9 (7%) that were positive for P. aeruginosa and 10 (8%) that were positive for other organisms. Follow-up blood cultures were typically collected "to ensure clearance" or "to guide antibiotic therapy." Overall, 30-day mortality was 25.2%. After risk adjustment for patient characteristics, follow-up blood cultures were associated with a nonsignificant reduction in mortality risk (hazard ratio, 0.43; 95% confidence interval, 1.08; P = .071). In exploratory analyses, the potential mortality reduction from follow-up blood cultures was driven by their use in patients with Pitt bacteremia scores >0.

Conclusions

Follow-up blood cultures are commonly collected for P. aeruginosa bacteremia but infrequently identify persistent bacteremia. Targeted use of follow-up blood cultures based on severity of illness may reduce unnecessary culturing.

SUBMITTER: Green AL

PROVIDER: S-EPMC9495539 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Publications

Follow-up blood cultures in <i>Pseudomonas aeruginosa</i> bacteremia: A potential target for diagnostic stewardship.

Green Alexis L AL Liang Yuanyuan Y O'Hara Lyndsay M LM Pineles Lisa L Sorongon Scott S Harris Anthony D AD Baghdadi Jonathan D JD

Antimicrobial stewardship & healthcare epidemiology : ASHE 20210827 1

<h4>Objectives</h4>Evidence supporting collection of follow-up blood cultures for Gram-negative bacteremia is mixed. We sought to understand why providers order follow-up blood cultures when managing <i>P. aeruginosa</i> bacteremia and whether follow-up blood cultures in this context are associated with short- and long-term survival.<h4>Methods</h4>We conducted a retrospective cohort study of adult inpatients with <i>P. aeruginosa</i> bacteremia at the University of Maryland Medical Center in 20 ...[more]

PMID: 36168473

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Project description:BackgroundAlthough the risk factors for positive follow-up blood cultures (FUBCs) in gram-negative bacteremia (GNB) have not been investigated extensively, FUBC has been routinely carried out in many acute care hospitals. We attempted to identify the risk factors and develop a predictive scoring model for positive FUBC in GNB cases.MethodsAll adults with GNB in a tertiary care hospital were retrospectively identified during a 2-year period, and GNB cases were assigned to eradicable and non-eradicable groups based on whether removal of the source of infection was possible. We performed multivariate logistic analyses to identify risk factors for positive FUBC and built predictive scoring models accordingly.ResultsOut of 1473 GNB cases, FUBCs were carried out in 1268 cases, and the results were positive in 122 cases. In case of eradicable source of infection, we assigned points according to the coefficients from the multivariate logistic regression analysis: Extended spectrum beta-lactamase-producing microorganism (+ 1 point), catheter-related bloodstream infection (+ 1), unfavorable treatment response (+ 1), quick sequential organ failure assessment score of 2 points or more (+ 1), administration of effective antibiotics (- 1), and adequate source control (- 2). In case of non-eradicable source of infection, the assigned points were end-stage renal disease on hemodialysis (+ 1), unfavorable treatment response (+ 1), and the administration of effective antibiotics (- 2). The areas under the curves were 0.861 (95% confidence interval [95CI] 0.806-0.916) and 0.792 (95CI, 0.724-0.861), respectively. When we applied a cut-off of 0, the specificities and negative predictive values (NPVs) in the eradicable and non-eradicable sources of infection groups were 95.6/92.6% and 95.5/95.0%, respectively.ConclusionsFUBC is commonly carried out in GNB cases, but the rate of positive results is less than 10%. In our simple predictive scoring model, zero scores-which were easily achieved following the administration of effective antibiotics and/or adequate source control in both groups-had high NPVs. We expect that the model reported herein will reduce the necessity for FUBCs in GNB cases.