Risk factors for positive follow-up blood cultures in critically ill adults with Gram-negative bacteraemia

Rebecca A Mayes; Emily A Siegrist; Julia Mathew; Stephen B Neely; Cindy B McCloskey; Bryan P White

doi:10.1093/jacamr/dlae144

Risk factors for positive follow-up blood cultures in critically ill adults with Gram-negative bacteraemia

JAC Antimicrob Resist. 2024 Sep 10;6(5):dlae144. doi: 10.1093/jacamr/dlae144. eCollection 2024 Oct.

Authors

Rebecca A Mayes¹, Emily A Siegrist¹, Julia Mathew¹, Stephen B Neely², Cindy B McCloskey³, Bryan P White¹

Affiliations

¹ University of Oklahoma Medical Center at OU Health, Department of Pharmacy, Oklahoma City, OK, USA.
² The University of Oklahoma College of Pharmacy, Pharmacy office of the Dean, Oklahoma City, OK, USA.
³ The University of Oklahoma College of Medicine, Department of Pathology, Oklahoma City, OK, USA.

Abstract

Objectives: To evaluate the utility of follow-up blood cultures (FUBCs) for Gram-negative bloodstream infection (BSI) in ICU patients and identify risk factors for repeat positive cultures.

Methods: This was a single-centre, retrospective cohort study of critically ill adults with Gram-negative BSI between 1 January 2015 and 1 January 2020. Critically ill patients with one or more blood cultures positive for a Gram-negative organism were included. Descriptive and inferential statistics were performed with an alpha of 0.05.

Results: A total of 148 critically ill patients with Gram-negative BSI were included, with 42 patients (28.4%) having one or more positive FUBCs. The majority (66.2%) were admitted to a medical ICU. The most common organisms isolated were Escherichia coli (n = 56, 37.8%) and Klebsiella pneumoniae (n = 26, 17.6%). Significant patient risk factors associated with a positive FUBC on univariate regression included: MDR organisms, immunocompromised status, fever, vasopressor use at time of FUBC, lack of source control attainment, and higher quick Pitt bacteraemia score. Multivariable penalized logistic regression indicated that lack of source control containment and less time from index to FUBC remained significantly associated with repeat positive FUBC.

Conclusions: This is the first study to investigate the use of FUBC for Gram-negative BSI in exclusively ICU patients. Risk factors for repeat positive FUBC in this population include lack of source control and less time between index and FUBC. Prospective studies are needed to fully elucidate the role of FUBCs in critically ill patients with Gram-negative BSI.