Routine bacterial screening of platelet concentrates by flow cytometry and its impact on product safety and supply

BACKGROUND AND OBJECTIVES

Bacterial contamination represents the major infectious hazard associated with transfusion of platelet concentrates (PCs). As bacterial screening of PCs is not mandatory in Germany, the BactiFlow flow cytometry test has been introduced as a rapid detection method to increase product safety.

MATERIALS AND METHODS

During a period of 25 months, a total of 34 631 PCs (26 411 pooled and 8220 apheresis-derived PCs) were tested at the end of day 3 of their shelf life using the BactiFlow system. PCs initially reactive in BactiFlow testing and expired PCs not reactive in BactiFlow on day 3 were also investigated by the BacT/ALERT system and by microbiological cultivation in order to identify the contaminating bacterial species and to confirm reactive BactiFlow results.

RESULTS

Two hundred and twenty-eight PCs (0.7%) had an initially reactive result, 24 of them remained reactive in a second test run. Out of these reproducible reactive BactiFlow results, 12 could not be verified by parallel BacT/ALERT culturing, resulting in a confirmed false-positive rate of 0.03%. The bacterial species were identified as S. aureus, S. epidermidis, S. dysgalactiae ssp. equisimilis and B. cereus. In 10 out of 9017 expired PCs (0.11%), a confirmed-positive result was obtained in the BacT/ALERT system which had a negative result in the BactiFlow system.

CONCLUSION

Testing of PCs by BactiFlow was successfully implemented in our blood donation service and proved sufficient as a rapid and reliable screening method. False reactive results are in an acceptable range since the transfusion of 12 bacterially contaminated PCs was prevented.

Structure of Dibromo(1,2-diaminoethane)palladium(IV)-bis(1,2-diaminoethane)- palladium(II) Tetrakisperchlorate, [Pd(en)2Br2][Pd(en)2](ClO4)4

Orthorhombic [Pd(C2H8N2)2Br2][Pd(C2H8N2)][ClO4]4, C8H32Br2Cl4N8O16Pd2, Mr = 890.42, crystallizes in space group Iba2, a = 9.651(2), b = 13.951(8), c = 10.771(2) Å, Z = 2, V = 1412.80 Å3, dc = 2.05 g cm-3, R = 0.0564 for 1545 unique reflections. Data collection: MoKα, λ = 0.71069 Å, room temperature.

The structure is a typical Wolffram’s Salt Analogue (WSA) with infinite stacks of planar [Pd(en)2]2+,4+ complex cations bridged by bromides. The ligands are three-dimensionally ordered. Intra-chain and inter-chain hydrogen bridges link the ligands with the perchlorate counter ions which occupy statistically two different orientations. Diffuse sheets appear together with Bragg reflections for 1 odd layers indicating a thermally activated motion of the bromides in chain direction. This model was confirmed with temperature dependent Weissenberg work

[The Rostock Headache Questionnaire ("Rokoko")--validation of a tool to screen and to qualify primary headaches]

Primary headache disorders should be diagnosed based on the detailed history of the patient. However, only few questions are necessary to allocate the symptoms to migraine, tension-type headache or other primary headaches in most cases. The "Rostock Headache Questionnaire" (Rokoko) is suitable for being completed by the investigator or the patient him/herself within a few minutes. Validation parameters of a sample of n = 87 patients (median: 44 years), diagnosed by headache experts in a personal interview ("gold standard"), are presented. Sensitivity and specificity for migraine without aura (0.87/0.51), migraine with aura (0.71/0.95), tension-type headache (0.57/0.93), or a combination of both (0.22/0.93) are based on the parameters pain frequency (recurrent vs. permanent), and the presence or absence of aura symptoms. To differentiate tension-type headache into episodic or chronic forms, the questionnaire can be analysed individually based on the frequency of headache days. The questionnaire enables the fast acquisition of relevant data in headache diagnosis and headache research with sufficient sensitivity and specificity. In addition, further information about triggering and symptoms of headaches can be assessed. The questionnaire can be used both by neurologists or psychiatrists and by general practitioners. The questionnaire does not replace the physical examination.

Inhomogeneous thermalization in strongly coupled field theories

To describe theoretically the creation and evolution of the quark-gluon plasma, one typically employs three ingredients: a model for the initial state, nonhydrodynamic early time evolution, and hydrodynamics. In this Letter we study the nonhydrodynamic early time evolution using the AdS/CFT correspondence in the presence of inhomogeneities. We find that the AdS description of the early time evolution is well matched by free streaming. Near the end of the early time interval where our analytic computations are reliable, the stress tensor agrees with the second order hydrodynamic stress tensor computed from the local energy density and fluid velocity. Our techniques may also be useful for the study of far-from-equilibrium strongly coupled systems in other areas of physics.

[Childhood retinal detachment: ROP and myopia]

This article reviews the cause and treatment options for retinopathy of prematurity (ROP)-related tractional detachment and detachments in ROP residuals during childhood and early adulthood. Retinal vascularisation is incomplete after premature birth. Phase I of ROP consists of a delayed retinal vascular growth and vessel loss after premature birth resulting in hypoxia, phase II results in hypoxia-induced vascular proliferation and as a consequence to vitreoretinal traction. The anatomic and functional outcome of tractional detachment in ROP is determined by the previous treatment (e.g., laser to the avascular periphery or anti-VEGF). While the literature reports re-attachment rates > 70 % in ROP IV a, functional and anatomic outcome in the later stages is limited. ROP residuals may cause rhegmatogenous rather than tractional detachments in childhood or early adulthood. Myopia is associated with ROP and may further complicate the retinal situation and the risk for rhegmatogenous detachment. The retinal changes due to ROP warrant lifelong controls.

[Retinal exudative disease in childhood: Coats' disease and familial exudative vitreoretinopathy (FEVR)]

This article reviews the pathophysiology of retinal vascular disease with emphasis on Coats' disease and familial exudative vitreoretinopathy (FEVR). Both Coats' disease and FEVR demonstrate vascular abnormalities and associated exudation. Coats' disease manifests as teleangiectasia and aneurysms. Exudative subretinal lipid deposits can be extensive. Coats' disease is in 90 % unilateral and affects predominantly otherwise healthy young males. If the retina is attached, laser and cryocoagulation are the method of choice. Vitreoretinal surgery is only rarely indicated in advanced cases after a retinoblastoma has been excluded prior to surgery. FEVR inheritance is 56 % dominant (FZD4 und TSPAN12) and 44 % recessive (LRP5 und NDP). Temporal dragging of the vascular arcades and heterotopia of the macula are characteristic for FEVR. Subretinal exudates are indicators for progression of the disease with visual loss due to subsequent exudative or tractive retinal detachment. Exudative forms require treatment and reduction of peripheral ischaemia with laser photocoagulation and cryopexia. In cases of tractive detachments vitreoretinal surgery is necessary. Coats' disease and FEVR are both progressive diseases requiring lifelong follow-up and therapy.