False Positive Cases in Automated Blood Culture Systems Due to Hyperleukocytosis

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.