Follow-up blood cultures for gram-negative bacteremia: pause for Pseudomonas

Reviewed by Cynthia T. Nguyen, PharmD, University of Chicago Medicine

A recently published study in ASHE, adds to the growing body of evidence supporting the opportunity for diagnostic stewardship for follow-up blood cultures. This single-center, retrospective cohort study among 159 inpatients with Pseudomonas aeruginosa bacteremia found that many patients received follow-up blood cultures (80%), with only 15% of these cultures being positive. 

The overall mortality rate was 25% (19% in patients who had follow-up cultures versus 50% in patients without follow-up cultures). After risk adjustment for patient characteristics, follow-up blood cultures showed a trend toward association with lower mortality but was not statistically significant (hazard ratio, 0.43; 95% confidence interval, 1.08; p=0.071). The potential mortality reduction was associated with the use of follow-up blood cultures in patients with Pitt bacteremia scores > 0. 

Overall, follow-up blood cultures are commonly collected for P. aeruginosa bacteremia, despite the lack of clear benefit. Still, follow-up blood cultures may be warranted in a subset of patients. When developing guidance to reduce the routine use of follow-up blood cultures, hospitals should consider patients’ underlying infectious syndrome, the pathogen, and the severity of illness.


Green AL, Liang Y, O’Hara LM, et al. Follow-up blood cultures in Pseudomonas aeruginosa bacteremia: A potential target for diagnostic stewardship. Antimicrobial Stewardship & Healthcare Epidemiology. 2021;1(1):e23. 

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