Pseudo-NRBC in the Mindray BC-6800Plus analyzer: A clue for diagnostic anticipation of fungemia. Experimental and preliminary clinical reports.

INTRODUCTION: Candidemia can be a significant cause of death in immunosuppressed or debilitated patients particularly. Abnormalities of the instrumental cytograms of some hematological analyzers, such as Mindray BC-6800Plus, can be related to circulating Candida. We studied the possible diagnostic usefulness of this information. METHODS: A fungal bloodstream infection has been simulated by adding aliquots of Candida albicans, Candida parapsilosis, and Candida glabrata to 75 leftovers and anonymized peripheral blood samples. Cytographic abnormalities like those of experimental samples were used to select patients with possible fungemia. The microscopic review of peripheral blood smears constituted the confirmatory method. RESULTS: In all experimental samples, the various Candida types caused pseudo-NRBC and morphological abnormalities of WNB and DIFF cytograms. Circulating blastospores, free or engulfed by neutrophils, were the microscopic findings in the peripheral blood smears. In the clinical verification, 72 patients were recruited based on the presence of an evocative cluster in the WNB and DIFF cytograms. The microscopic review of 39 out of 72 samples was positive for NRBC. According to blood cultures, light microscopy revealed fungal forms of several Candida or non-Candida types in the remaining 33 samples. Nine of these cases were not yet known to suffer from bloodstream infection. CONCLUSIONS: Although further confirmatory clinical studies are required for these diagnostic abilities, the BC 6800Plus cytographic abnormalities related to fungemia have proven helpful in rapidly monitoring persistent fungemia in already diagnosed patients. In unknown or undiagnosed cases, they could be the trigger point for the subsequent diagnostic-therapeutic pathway.

COVID-19: Black Swan or clumsy use?

"Black Swan" is an unexpected and catastrophic event characterized by three conditions: the anomalous and exceptional value, the extreme impact, and predictability a posteriori. On many sides - by politicians, commentators, scientists - there have been attempts to give the COVID-19 pandemic event the meaning of Black Swan. In reality, one should wonder if the Black Swan was not, instead (or even), the way the epidemic was handled. In Italy, an unreasonable use of a two-step protocol - IgM/IgG anti-COVID followed by RT-PCR in the serologically positive only has caused considerable uncertainty, particularly relevant in measures for maintenance or readmission to work of health personnel. This protocol could be affected by serious uncertainties arising from the analytical limitations of the tests used. To quantify this defect, we evaluated the analytical specifications of serological tests under different prevalence conditions. In conclusion, although laboratory diagnostics represent a useful tool, it can only be used for epidemiological purposes and not to provide healthy pass.

Mindray BC-6800 haematological analyser: 3D-DIFF scattergram usefulness in infectious mononucleosis diagnosis.

INTRODUCTION: 3D-DIFF scattergram of the Mindray BC-6800 haematological analyser shows morphological abnormalities and lymphocyte cluster splitting related to the presence of reactive lymphocytes. This study aims to assess whether these cytographic changes are useful in detecting both activated and apoptotic lymphocytes, leading to an improvement in the laboratory diagnostic process of infectious mononucleosis. METHODS: Two hundred three samples with modified shape and doubled lymphocyte cluster of DIFF scattergram (study group) were divided into two different subgroups: with and, respectively, without serological evidence of ongoing IM. Activated and apoptotic cells in peripheral blood were counted by light microscopy or gating in the instrumental dot plots. Values of apoptotic cells counted by microscopy were compared with those resulting from gating. RESULTS: Samples with both shape change and doubled lymphocyte cluster had serological profiles according to the diagnosis of ongoing infectious mononucleosis. Blood smears review was positive for reactive lymphocytes in all 112 samples (100%). An underestimation of apoptotic cell count by light microscopy compared with the gating in the instrumental scatterplot was also observed (96 out of 112, 85.7%). CONCLUSION: The additional lymphocyte cluster was significantly associated with activated and apoptotic lymphocytes in samples with serology suggesting ongoing infectious mononucleosis. Considering the significance of clue for infectious mononucleosis assigned to the apoptotic lymphocytes, a specific flag such as "apoptotic cells?" could be associate with the related cluster. Such a flag could be used for dedicated rules for smears review, thus increasing infectious mononucleosis detection in laboratories that do not usually practise instrumental cytograms observation.

Short preheating at 41°C leads to a red blood cells count comparable to that in RET channel of Sysmex analysers in samples showing cold agglutination.

AIMS: The presence of cold agglutinin in blood samples can cause a spontaneous agglutination of red blood cells (RBCs) when low temperature occurs. This phenomenon causes a spurious lowering of RBC count on the automated haematological analysers that are detected by incongruous values (≥370 g/L) of the mean cellular haemoglobi concentration (MCHC). A preheating at 37°C can remove the RBC agglutination generally resulting in a reliable count. It has been reported that the same result can be reached by using the optical reticulocyte (RET) channel of Sysmex analysers where the RBC count is not influenced by the presence of cold agglutinin. This study aims to evaluate these data in a larger population, with regard to environmental conditions on Sysmex analysers. We have also evaluated the influence of different thermal pretreatments on the RBC count. METHODS: This study was performed on 96 remnants of peripheral blood samples (48 with MCHC in normal range and 48 with MCHC>370 g/L) which have been analysed in different preanalytical conditions on the Sysmex analysers. RESULTS: A preheating of samples at 41°C for 1 min leads to a reversibility of the cold agglutination comparable to the one observed in the RET channel and yields better results compared with 37°C for 2 hours. CONCLUSIONS: None of described procedures assure the complete cold agglutination reversibility in every case. Consequently, since the haematological analysers not yet provide reliable parameters to confirm the complete resolution of agglutination, further verification of RBC count accuracy needs to be performed.

Automatic wedge smears preparation may cause traumatic morphological changes in peripheral blood cells.

In recent years, several automated analysers that prepare and stain blood smears have been introduced in clinical laboratories. Despite the use of instrumental settings based on physical characteristic of individual samples, traumatic injuries of neutrophil and lymphocytes can be observed. Some samples present a very high percentage of damaged cells, allowing the speculation that a cellular susceptibility may enhance mechanical traumatism. These artefacts can puzzle morphological evaluation in both traditional and digitised microscopy; in addition, unskilled operators can be misled.

A prolonged microscopic observation improves detection of underpopulated cells in peripheral blood smears.

We evaluated an extended time in the microscopic review in samples in which the potential clinical information could be increased with respect to those that could be achieved with the usual laboratory methodologies. We used samples containing nucleated red blood cells in a small amount and cytopenic samples. For these purposes for each peripheral blood smear, the timing of eye-count differential was increased up to 20 min, regardless of the final number of cells which could be counted. In addition, an automated system for digital analysis of peripheral blood smears was employed and the number of cells counted was brought up to 1000 leukocytes. In both manual and automatic light microscopy extended observation, we obtained more diagnostic information in respect to those with routine or standard methods. Both automated and manual increase systems of the timing for microscopic review are useful tools to find diagnostic information that otherwise would be lost using normal and standard procedures. So, these methods should be used especially when there is a higher pre-test probability for discovery of pathological cells.

Cytographic changes on BC-6800 Haematological Analyzer related to the presence of Candida albicans in peripheral blood. A new tool to suspect candidemia?

BACKGROUND: We studied the quantitative and cytographic changes that the presence of Candida albicans (C. albicans) in peripheral blood (PB) samples causes on the Mindray BC-6800 Haematological Analyzer. METHODS: A simulated in vitro candidemia was obtained by adding a different amount of C. albicans to discarded remnants of PB samples. Quantitative data and cytographic features were evaluated immediately as well as after 120 and 240 min of the yeast addition. A microscopic slides review was even performed at the same time. RESULTS: After yeasts addition, an increase of total leucocytes, neutrophils and basophils have been observed, but these increases are not certainly descriptive of C. albicans presence.Instead, extracellular blastospores cause a false increase in nucleated red blood cells (nRBCs), which appear as a new population in the specific counting channel for erytroblasts (NRBC channel). Regardless of the numbers, C. albicans form a pseudo-erythroblastic cluster in the NRBC channel whose resulting shape is so different than the 'normal' nRBC that it demands a microscopic review. Even cytographic changes related with the neutrophilic phagocytic activity have been observed on leucocyte's differential count citogram (DIFF) of the BC-6800. CONCLUSIONS: Our observations suggest that the results of the BC-6800, which are due to C. albicans' presence, might be useful to speculate earlier diagnosis of sepsis.

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

BACKGROUND: Cellular analysis in cerebrospinal fluid (CSF) provides important diagnostic information in various medical conditions. The aim of this study was to evaluate the application of Mindray BC-6800 body fluid (BF) mode in cytometric analysis of CSF compared to light microscopy (LM). METHODS: One hundred and twenty-nine consecutive CSF samples were analyzed by BC-6800-BF mode as well as by LM. The study also included limits of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ), carryover and linearity. Results White blood cells LoQ was 4.0×106 cells/L. Linearity was good and carryover was negligible. As for the total and white blood cells, the BC-6800-BF parameters vs. LM showed both bias ranged from -10.28 to 0.06×106 cells/L. Polymorphonuclear and mononuclear cells ranged from 6.64 to 10.90%. For white blood cell the diagnostic agreement was 93% at the cut-off >5.0×106 cells/L, and for polymorphonuclear and mononuclear at the cut-off >50% was 91% and 92%, respectively. CONCLUSIONS: BC-6800-BF offers rapid and accurate counts in clinically relevant concentration ranges, replacing LM for most samples. However, in samples with abnormal cell counts or with abnormal white blood cell differential scattergrams the need to microscopic review for a correct clinical outcome remains.