Effects of bacteria and yeast on WBC counting in three automated hematology counters

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.

Evaluation of Mindray BC-6800 body fluid mode for automated cerebrospinal fluid cell counting

“…As the presence of microorganisms in blood and body fluids may often cause interference issues in automated analyzers (overestimation of WCB count and abnormal DIFF-scattergram being the most common ones) [38,39], we were interested also in evaluating BC-6800-BF performance under these conditions. In two case studies the application of BC-6800-BF analysis displayed abnormal DIFF-scattergram, and the presence of bacteria was further revealed by LM and microbiologically confirmed Staphylococcus coagulase negative.…”

Automated haematology analysis to diagnose malaria

“…In 1993, a study analysing 18 samples from patients with malaria ( P. falciparum: 10 and P. vivax : 8) and 52 samples from healthy controls with a Technicon H1 ® analyser (Technicon Instruments Corporation, Tarry Town, NY; now Siemens), found that all malaria-infected patients had ≥3% (range 3.3-20.9%) of so-called 'large-unstained-cells' suggesting their potential use for malaria screening [25]. Unfortunately, changes in WBC populations [26], reticulocytosis, or increase of 'large-unstained-cells' [25] may also appear with other pathologies, giving these changes low accuracy for malaria detection.…”

Cytographic changes on BC-6800 Haematological Analyzer related to the presence ofCandida albicansin peripheral blood. A new tool to suspect candidemia?

“…In this way, we could observe that microscopic features observed in the “in vitro” Candidemia are not different from those reported in case of in ‘in vivo’ BSI regardless of the type of Candida. 4 5 8 17 18 Even the correspondence from CBC and LDC on simulated candidemia as well as on clinical BSI has already been described 6 7 13 14. In addition, in our experimental conditions C. albicans has grown in the BACTEC system just as the clinical materials.…”