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. 2022 Mar;43(3):291-297.
doi: 10.1017/ice.2021.111. Epub 2021 Apr 26.

Risk factors and clinical outcomes associated with blood culture contamination

Justin M Klucher  1 , Kevin Davis  2 , Mrinmayee Lakkad  3 , Jacob T Painter  3 , Ryan K Dare  4
Affiliations

Risk factors and clinical outcomes associated with blood culture contamination

Justin M Klucher et al. Infect Control Hosp Epidemiol. 2022 Mar.

Abstract

Objective: To determine patient-specific risk factors and clinical outcomes associated with contaminated blood cultures.

Design: A single-center, retrospective case-control risk factor and clinical outcome analysis performed on inpatients with blood cultures collected in the emergency department, 2014-2018. Patients with contaminated blood cultures (cases) were compared to patients with negative blood cultures (controls).

Setting: A 509-bed tertiary-care university hospital.

Methods: Risk factors independently associated with blood-culture contamination were determined using multivariable logistic regression. The impacts of contamination on clinical outcomes were assessed using linear regression, logistic regression, and generalized linear model with γ log link.

Results: Of 13,782 blood cultures, 1,504 (10.9%) true positives were excluded, leaving 1,012 (7.3%) cases and 11,266 (81.7%) controls. The following factors were independently associated with blood-culture contamination: increasing age (adjusted odds ratio [aOR], 1.01; 95% confidence interval [CI], 1.01-1.01), black race (aOR, 1.32; 95% CI, 1.15-1.51), increased body mass index (BMI; aOR, 1.01; 95% CI, 1.00-1.02), chronic obstructive pulmonary disease (aOR, 1.16; 95% CI, 1.02-1.33), paralysis (aOR 1.64; 95% CI, 1.26-2.14) and sepsis plus shock (aOR, 1.26; 95% CI, 1.07-1.49). After controlling for age, race, BMI, and sepsis, blood-culture contamination increased length of stay (LOS; β = 1.24 ± 0.24; P < .0001), length of antibiotic treatment (LOT; β = 1.01 ± 0.20; P < .001), hospital charges (β = 0.22 ± 0.03; P < .0001), acute kidney injury (AKI; aOR, 1.60; 95% CI, 1.40-1.83), echocardiogram orders (aOR, 1.51; 95% CI, 1.30-1.75) and in-hospital mortality (aOR, 1.69; 95% CI, 1.31-2.16).

Conclusions: These unique risk factors identify high-risk individuals for blood-culture contamination. After controlling for confounders, contamination significantly increased LOS, LOT, hospital charges, AKI, echocardiograms, and in-hospital mortality.

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