Ann Clin Microbiol.  2023 Jun;26(2):37-40. 10.5145/ACM.2023.26.2.2.

False positive cases in automated blood culture systems due to hyperleukocytosis: a case report

• Kim DH
• Ryoo N

• KMID: 2550653
• DOI: http://doi.org/10.5145/ACM.2023.26.2.2

Abstract

Automated blood culture systems are widely used in clinical microbiology laboratories to minimize the workload of laboratory personnel and permit fast turnaround times. However, sometimes false positive signals occur due to leukocytosis, presence of fastidious bacteria, or unexplained causes. We experienced false positive signal in a patient with hyperleukocytosis for the first time since the automated blood culture system was introduced in our hospital over 20 years ago. We present two case reports with literature review and describe the procedure for dealing with false-positive cases in our hospital.

Keyword

Automated blood culture systems; False positive; Hyperleukocytosis

Figure

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  Fig. 1. Gram stain of initial blood culture of positive signal showed no bacteria, but with many WBCs (×1,000, left-first case; right-second case). WBC, white blood cell.

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  Fig. 2. Reading graphs of blood culture bottle of the first patient (A) showed positive flag within less than a day after starting to incubate in the automated blood culture system. Additional incubation of blood cultures revealed no change of peaks in reading graphs until 5 days. (B) Normal positive flag within a day showed abrupt peak at 13 hours after incubation.

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