The following is a summary of “Contamination of Blood Cultures From Arterial Catheters and Peripheral Venipuncture in Critically Ill Patients: A Prospective Multicenter Diagnostic Study,” published in the July 2023 issue of the Chest by Nakayama et al.

When peripheral venipuncture is challenging in critically ill adult patients, collecting blood cultures from indwelling arterial catheters is an attractive option. Inconclusive is whether the contamination rate of blood cultures from arterial catheters is acceptable compared to that from venipuncture. Blood culture contamination from arterial catheters is comparable to venipuncture in critically ill adult patients with suspected bloodstream infections. In this prospective multicenter diagnostic investigation conducted at five hospitals, the researchers enrolled episodes of paired blood culture collection, each consisting of blood drawn from an arterial catheter and another by venipuncture, from critically ill adult patients with a cynical indication. 

The most important metric was the contamination proportion, defined as the ratio of false-positive results to the total number of procedures performed. The benchmark for a genuine bloodstream infection was a blinded evaluation by infectious disease experts. They tested the noninferiority hypothesis that the percentage of contaminated blood cultures from arterial catheters did not exceed the rate from venipuncture by more than 2%. 

From December 2018 to July 2021, 590 paired blood culture episodes were enrolled from a total of 1,655 blood culture episodes; 41 of these 590 episodes (6.9%) produced a genuine bloodstream infection. 33 of 590 (6.0%) arterial catheter blood cultures were positive, and two of 590 (0.3%) were contaminated; 36 of 590 (6.1%) venipuncture blood cultures were positive, and four of 590 (0.7%) were contaminated. 

The estimated difference in contamination proportion was –0.3% (upper limit of one-sided 95% CI, +0.3%). The upper limit of the 95% CI did not exceed the predetermined margin of +2.0%, indicating noninferiority (P for noninferiority <.001). Obtaining blood cultures from arterial catheters is an acceptable alternative to venipuncture in critically ill patients.

Source: sciencedirect.com/science/article/abs/pii/S0012369223001617