Di Mario Antonella, Garzia Mariagrazia, Leone Fiammetta, Arcangeli Andrea, Pagano Livio, Zini Gina
Research Center for Clinical Evaluation of Automated Method in Hematology (ReCAMH), Hematology Department, Catholic University of Sacred Heart, L.go A. Gemelli 8, 00168 Rome, Italy.
J Infect. 2009 Sep;59(3):201-6. doi: 10.1016/j.jinf.2009.07.007. Epub 2009 Jul 18.
Neutrophilia is frequently in hospitalized patients, so a screening test for infections would be very useful. The immature platelet fraction (IPF) is provided by the automated blood analyzer XE 2100 (Sysmex, Kobe, Japan) as a proportional value of the total optical platelet count [IPF%; an absolute count of immature platelets can also be obtained (AIPC)] to indicate the rate of platelet production. IPF could help to identify the aetiology of thrombocytopenia and to recognize the increased bone marrow activity as occurred during the course of infectious disease.
We selected from daily routine cell blood counts 535 samples from adult patients (age >14 years) with neutrophilia (> 8 x 10(9)/L) and platelets > or =150 x 10(9)/L, to avoid bias due to physiological increase of IPF. In 153 patients blood cultures (BC) were done the same day of IPF determination because of clinically suspected infection (fever > or =38 degrees C).
Eighty-nine samples (58.2%) had positive BC (75 Gram-positive agents, 14 Gram-negative). Using our IPF reference normal range [IPF% 2.39% (0.8-5.1); AIPC 5.15 x 10(9)/L (2-12.6)], we found a significantly (p<0.0001) higher level of IPF in samples with positive BC [mean IPF% 4.86+/-2.67%, median 3.8 (range 2.4-15.8); mean AIPC 14.74+/-9.26 x 10(9)/L, median 11.7, (range 4.7-44.9)] than in BC negative samples [mean IPF% 1.79+/-0.63%, median 1.7 (range 0.5-4.7); mean AIPC 6.55+/-3.58 x 10(9)/L, median 5.45 (range 1.6-20.4)].
The increased IPF shows a statistically significant correlation with BC positivity. This parameter could therefore be used in the daily laboratory routine in patients with neutrophilia as a low cost screening test for bacterial infection.
嗜中性粒细胞增多在住院患者中很常见，因此一种感染筛查试验将非常有用。未成熟血小板比率（IPF）由自动血液分析仪XE 2100（日本神户Sysmex公司）提供，作为总光学血小板计数的比例值[IPF%；也可获得未成熟血小板的绝对计数（AIPC）]，以指示血小板生成速率。IPF有助于识别血小板减少的病因，并识别传染病过程中出现的骨髓活性增加。
我们从日常细胞血常规中选取了535份成年患者（年龄>14岁）的样本，这些患者嗜中性粒细胞增多（>8×10⁹/L）且血小板≥150×10⁹/L，以避免因IPF的生理性增加导致偏差。在153例患者中，由于临床怀疑感染（体温≥38℃），在测定IPF的同一天进行了血培养（BC）。
89份样本（58.2%）血培养呈阳性（75份革兰氏阳性菌，14份革兰氏阴性菌）。使用我们的IPF参考正常范围[IPF% 2.39%（0.8 - 5.1）；AIPC 5.15×10⁹/L（2 - 12.6）]，我们发现血培养阳性样本中的IPF水平显著（p<0.0001）高于血培养阴性样本[平均IPF% 4.86±2.67%，中位数3.8（范围2.4 - 15.8）；平均AIPC 14.74±9.26×10⁹/L，中位数11.7，（范围4.7 - 44.9）] [平均IPF% 1.79±0.63%，中位数1.7（范围0.5 - 4.7）；平均AIPC 6.55±3.58×10⁹/L，中位数5.45（范围1.6 - 20.4）]。
IPF升高与血培养阳性呈统计学显著相关性。因此，该参数可在嗜中性粒细胞增多患者的日常实验室检查中用作细菌感染的低成本筛查试验。
