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.

Monitoring bacterial contamination of blood components in Germany: effect of contamination reduction measures.

BACKGROUND AND OBJECTIVES: National guidelines for monitoring bacterial contamination of blood components were introduced in Germany in 1997. Between 1998 and 2002, numerous measures were implemented to prevent bacterial contamination. This study investigates their impact on contamination rates. MATERIALS AND METHODS: Culture-based testing for bacterial detection on a random sample of blood components is part of routine quality control in German blood establishments. Using standardized questionnaires, data from the production periods 1998, 2001 and 2005/2006 were collected and analysed. RESULTS: The bacterial contamination rate of RBCs was reduced from 0·157% in 1998 to 0·029% in 2005/2006 (P<0·001). While the contamination rate of apheresis PCs remained nearly unchanged over the years, it dramatically decreased for pooled PCs by 70% to a contamination rate of 0·158% (P=0·001) within the last observation period, similar to that of apheresis PCs. The contamination rate of plasma decreased from 0·100% in 1998 to 0·019% in 2005/2006 (P=0·002). CONCLUSIONS: Precautionary measures significantly reduced bacterial contamination rates of blood components. Long-term monitoring with standardized methods is appropriate to evaluate the cumulative effect of contamination-preventing measures.

Inventory management.

A critical aspect of blood transfusion is the timely provision of high quality blood products. This task remains a significant challenge for many blood services and blood systems reflecting the difficulty of balancing the recruitment of sufficient donors, the optimal utilization of the donor's gift, the increasing safety related restrictions on blood donation, a growing menu of specialized blood products and an ever-growing imperative to increase the efficiency of blood product provision from a cost perspective. As our industry now faces questions about our standard practices including whether or not the age of blood has a negative impact on recipients, it is timely to take a look at our collective inventory management practices. This International Forum represents an effort to get a snap shot of inventory management practices around the world, and to understand the range of different products provided for patients. In addition to sharing current inventory management practices, this Forum is intended to foster an exchange of ideas around where we see our field moving with respect to various issues including specialty products, new technologies, and reducing recipient risk from blood transfusion products.

Comparison of three bacterial detection methods under routine conditions.

BACKGROUND AND OBJECTIVES: Since 2004, bacterial screening of platelets has been required in the USA and is also done on a voluntary basis in many European countries. The German Red Cross blood donor services conducted a prospective multicentre study in order to investigate the prevalence of bacterially contaminated pool platelet concentrates and apheresis platelet concentrates. This substudy compares three different bacterial detection systems. STUDY DESIGN AND METHODS: Platelet concentrates were tested in parallel with BacT/ALERT, Scansystem and Pall eBDS (n = 6307) in pool platelets. Apheresis platelets were tested in parallel with BacT/ALERT and Pall eBDS (n = 4730). All initially positive results were evaluated by a standardized procedure including evaluation by a microbiology reference laboratory. RESULTS: One in 6307 pool platelets were confirmed positive by BacT/ALERT, whereas Pall eBDS and Scansystem failed to detect these samples. Only three samples were initially reactive with Pall eBDS without proof of any bacteria strains. The rate of false-positive results was substantially higher for BacT/ALERT (0.25%, 28 in 11,037 tested samples) than for eBDS (0.03%, 3 in 11 037 tested samples) or Scansystem (0.0%, 0 in 6307 tested samples). Three of 4730 apheresis platelets were confirmed positive by BacT/ALERT. These were negative with Pall eBDS. CONCLUSION: Sensitivity was best for BacT/ALERT, whereas specificity was enhanced for Pall eBDS and Scansystem. Scansystem required specially trained staff, whereas BacT/ALERT and Pall eBDS were easy, quick, user-friendly and objective methods.

Bacterial contamination of platelet concentrates prepared by different methods: results of standardized sterility testing in Germany.

BACKGROUND AND OBJECTIVES: National guidelines for monitoring the bacterial contamination rate of blood components were introduced in Germany in 1997. The objective of this study was to present and evaluate the results of sterility testing of platelet concentrates (PCs) prepared by different methods. MATERIALS AND METHODS: The analysis of results of sterility testing of blood component production from transfusion medicine centres in Germany in 1998 and 2001 was based on information collected using standardized questionnaires. RESULTS: The bacterial contamination rates for single-donor PCs derived from whole blood and apheresis (0.210% vs. 0.156%) were comparable and showed no significant difference. However, pooled PCs produced from four buffy coats using the sterile docking procedure showed a significantly higher bacterial contamination rate compared with single-donor PCs derived from whole blood and apheresis (0.184% vs. 0.604%). CONCLUSIONS: Use of standardized methods for sterility monitoring is sufficient to assess collection and production processes in terms of hygiene and yields reliable data on bacterial contamination rates of blood components. The methods described are suitable for using to analyse the efficiency of newly introduced methods to reduce bacterial contamination rates of blood components (e.g. diversion, bacteria screening and pathogen inactivation).

[Outcome quality in terms of product safety in preoperative autologous blood donation]. / Ergebnisqualität im Sinne der Produktsicherheit bei der präoperativen Eigenblutspende.

OBJECTIVE OF THE STUDY: The most common form of autologous blood transfusion is where blood is donated in anticipation of elective surgery. The aim of this study is to critically evaluate the product safety of autologous blood units. METHODS: The results are based on an analysis of the documented data and records of 22,630 cases with 21,553 patients and 49,650 autologous blood donations, blood processing and testing protocols, and reported transfusion reactions following autologous transfusions. RESULTS AND CONCLUSIONS: Autologous blood components are prepared individually, and an established system of quality assurance with controls of processes and products is particularly important to meet quality standards. The red cell content of autologous units cannot be standardized as in allogeneic components. Due to the differences between the laboratory screening programmes for patients and donors, the risk of transmission of virus infections is different from that of allogeneic blood components. The quality of stored autologous red cells is comparable to that of allogeneic products. Results of systematic sterility monitoring lead to the conclusion that under the conditions practised the risk of transfusion-associated sepsis is not higher to that of allogeneic products. Soluble biological response modifiers which accumulate during storage, are assumed to be the cause of reactions that occur in one of 4,500 autologous transfusions. Incorrect allocation and handling errors continue to be a serious problem in autologous transfusions.

[Optimized "baby preserves" of transfusion in premature infants]. / Optimierte "Babykonserven" für die Transfusion bei Frühgeborenen.

For transfusion therapy of premature infants special packed red cells '0 rh-negative, anti-CMV-negative, hemolysin-free' are of great value. To optimize the preparations, we examined the influence of leukocyte depletion, suspension in SAGM and irradiation on ATP level, pH, free hemoglobin and potassium level. Results show the advantage of filtration and SAGM solution especially in respect to the ATP level. Irradiation leads to an increase of potassium to a twofold level, but is not of clinical significance in running time.

[Hypotonic shock reaction as quality control marker for platelet concentrates]. / Die hypotone Belastbarkeit als Qualitätskontrollmarker für Thrombozytenkonzentrate.

Ten years of quality control in routine have led to a standardized platelet concentrate (PC). Mean parameters of the preparations are in the range of pH 6.7-7.3, (1.0-1.5) x 10(9)/ml platelet concentration, 80 x 10(9) platelets/PC and 2 x 10(7) leukocytes/PC. To judge the function of PCs, three methods were compared: the morphologic score, platelet aggregation tests, and the hypotonic shock reaction. The result is: The hypotonic shock reaction is a simple, well reproducible and sensitive method to judge the cell integrity.

[The fine structure of baroreceptor's nerve endings in the wall of carotid sinus in cats]. / Die Feinstruktur der barorezeptorischen Nervenendigungen in der Wand des Sinus caroticus der Katze

The baroreceptor endings of the sinus nerve extend into the region of the external media, to the media-adventitia border, and into the adventitia of the wall of the carotid sinus. The size of the receptors, tightly filled with mitochondria, varies between 600 and 5,700 nm in diameter. The endings are accompanied by densely structured Schwann's cells, come into contact with the muscular-elastic system or are surrounded by the collagenous material of the vessel wall. This functional junction makes the reception of the tension in the vessel wall possible. Glycogen granules could be demonstrated in some axon endings. In kittens and older cats, numerous receptors were regularly found with various degrees of structural change: homogeneous and lamellar transformation of mitochondria, lamellar aggregates, lysis of axoplasm matrix, irregularities of tubules and vesicles. These modifications may be evaluated as the morphological expression of degeneration and regeneration processes. Physiological detrition is considered to be the cause for this.