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Updated: Jul 7, 2026
Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes
Published on: March 22, 2022
Effects of bacteria and yeast on WBC counting in three automated hematology counters
Hye Ryoun Kim1, Bo Rae G Park, Mi Kyung Lee
1Department of Laboratory Medicine, Chung-Ang University College of Medicine, 65-207, 3-Ka Hangang-Ro Yongsan-Ku, Seoul, 140-757, South Korea.
Abstract:
Bacteria or yeast may be observed on peripheral blood smears and may lead to spuriously elevated platelet counts. They have been reported to disturb the white blood cell (WBC) differential count if they clumped together, and a large number of such microorganisms have been shown to increase WBC counts. The purpose of this study was to evaluate the spurious rise in WBC counts according to species of microorganisms and automated hematology analyzers. The species we selected were Staphylococcus aureus, Escherichia coli, Candida albicans, C. tropicalis, C. krusei, C. dubliniensis, C. glabrata, and C. parapsilosis. We investigated the effects of bacteria and yeast on peripheral blood samples by the ADVIA 120/2120 Hematology System, Sysmex XE-2100 (TOA Medical Electronics, Kobe, Japan) and Coulter LH 750 (Beckman Coulter, Miami, FL, USA). C. albicans, C. tropicalis, C. krusei, and C. dubliniensis had an overt effect on the WBC count at concentrations of up to 1-5 x 10(7) colony-forming units (CFU)/mL in three automated cell counters, and C. glabrata and C. parapsilosis, when present at concentrations of 1-5 x 10(8) CFU/mL, caused a significant increase in the WBC count obtained by the Sysmex XE-2100 but not by the ADVIA 120/2120 system and Coulter LH 750 (p < 0.05). In conclusion, yeast may influence the results of peripheral blood smears only when the yeast concentration is unusually high. The results differed among analyzers and among species of yeast. Hematologists should be aware that samples containing bacteria and yeast may give erroneously high WBC counts and differential leukocyte counts and should review the peripheral blood smear by microscopy.
Insights
Microorganisms like bacteria and yeast can falsely elevate white blood cell (WBC) counts. The impact varies by microorganism species and the specific automated hematology analyzer used, necessitating microscopic review of blood smears.
Area of Science:
- Clinical Pathology
- Hematology
- Microbiology
Background:
- Bacteria and yeast in peripheral blood smears can cause falsely high platelet counts.
- Microorganisms can interfere with white blood cell (WBC) differential counts, potentially increasing WBC counts.
Purpose of the Study:
- To evaluate how different microorganism species and automated hematology analyzers affect spurious increases in WBC counts.
- To compare the performance of ADVIA 120/2120, Sysmex XE-2100, and Coulter LH 750 analyzers in detecting microorganism-induced WBC count alterations.
Main Methods:
- Investigated the effects of Staphylococcus aureus, Escherichia coli, and several Candida species (C. albicans, C. tropicalis, C. krusei, C. dubliniensis, C. glabrata, C. parapsilosis) on blood samples.
- Tested samples using three automated hematology analyzers: ADVIA 120/2120, Sysmex XE-2100, and Coulter LH 750.
- Determined the concentrations of microorganisms required to cause significant changes in WBC counts.
Main Results:
- Candida albicans, C. tropicalis, C. krusei, and C. dubliniensis overtly affected WBC counts at 1-5 x 10(7) CFU/mL across all three analyzers.
- C. glabrata and C. parapsilosis at 1-5 x 10(8) CFU/mL significantly increased WBC counts on the Sysmex XE-2100, but not on the ADVIA 120/2120 or Coulter LH 750.
- The magnitude of WBC count elevation varied by yeast species and analyzer.
Conclusions:
- Yeast can influence peripheral blood smear results, but typically only at very high concentrations.
- Automated hematology analyzers and yeast species differ in their susceptibility to microorganism-induced interference.
- Clinicians should be aware of potential spurious WBC count elevations due to bacteria and yeast and confirm findings with peripheral blood smear microscopy.
