A prospective microbiologic surveillance program to detect and prevent the transfusion of bacterially contaminated platelets

After two patients received bacterially contaminated platelet transfusions, a prospective surveillance program was instituted to perform Gram staining and microbiologic culturing of platelets at the time of transfusion. In 12 months, 3141 random-donor platelet pools (prepared from 14,481 units) and 2476 single-donor apheresis units were cultured. All single-donor apheresis units were sterile, but 6 (0.19%) of the random-donor pools were found to be bacterially contaminated, with 1 unit of 5 in the pool being the source in each case. Contaminants were Staphylococcus epidermidis (4 cases), Bacillus cereus (1), and Staphylococcus aureus (1) at counts of 0.5 × 10(2) to 10(11) colony-forming units per mL in platelet pools and 10(3) to 10(13) colony-forming units per mL in source units. The contamination rate for units transfused at < or = 4 days (1.8/10,000) was significantly lower than that at 5 days (11.9/10,000; p < 0.05), as was the magnitude of contamination (p < 0.05). Use of the pretransfusion Gram stain on 4- and 5-day-old platelet pools was 100 percent sensitive (4/4 true positives) and 99.93 percent specific (1 false positive) in detecting contaminated pools. These data define the extent and magnitude of platelet bacterial contamination and demonstrate the efficacy of the pretransfusion Gram stain on platelet units stored for 4 and 5 days in preventing the transfusion of heavily contaminated units. It is concluded that the risk of platelet contamination is related to the duration of component storage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of bacterial contamination of apheresis platelets in a Chinese Blood Center

Bacterial contamination of platelets is considered as the most frequent infectious risk of transfusion. The prevalence of bacterial contamination has been reported and varied considerably in different countries, but the data for bacterial contamination of platelets in China are rarely reported. Eight thousand apheresis platelet concentrates (PCs) were analysed by aerobic and anaerobic cultures. Ten millilitres of PCs were inoculated into aerobic and anaerobic bottles (5 mL each), followed by the incubation for a maximum of 7 days. A new sample was taken from the unit for reculturing in order to confirm the initial positive reaction. All positive culture bottles were referred for bacterial isolation and identification. Twenty one cultures (0.26%) were flagged as positive in initial culture. Five cultures (0.06%) were confirmed as true positive and nine cultures (0.11%) were confirmed as indeterminate in reculture. A bacterium from skin flora ( Propionibacterium spp.) was the most prevalent contaminant. Mean time to initial positive culture from start of incubation was 22.1 h for confirmed positive units and 97.3 h for indeterminate units. Most PC units had already been issued by the time of initial positive culture with a 'negative-to-date' issued strategy. There is a risk of bacterial contamination of PCs in China. Implementing bacterial screening of platelets could reduce the risk of septic reaction and fatalities due to transfusion of bacterially contaminated platelets. However, bacterial contamination PCs can still be transfused due to the delay until a positive signal in the culture system.     

Detecting bacterial contamination in platelet products

Bacterial contamination of platelets is an important cause of transfusion-associated morbidity and mortality. It is currently the most frequent infectious complication of transfusion therapy, with between 1 in 1,000 and 1 in 3,000 platelet units being bacterially contaminated at time of transfusion. Several factors have contributed to the persistence of this problem including lack of sensitive detection methods, lack of recognition of the frequency of the problem, inadequate recognition of septic reactions by clinicians treating patients receiving platelet transfusions, differences in transfusion reactions between bacterial species and bacterial inocula transfused, and differing methodologies and time of testing for detection of bacteria in platelet units. There are also important correlations between the receipt of bacterially contaminated platelet units and the development of transfusion reactions and bacteremia. In the last few years the recognition of the importance of platelet bacterial contamination prompted the College of American Pathologists (CAP) and the American Association of Blood Banks (AABB) to set new standards requiring the screening of platelets for bacterial contamination. In the wake of these standards, an increasing number of approaches have been and are being developed to deal with this problem. The clinical sensitivity, specificity and predictive value of these detection methods vary considerably and need to be defined for routine laboratory practice. In this review, we focus on the practical aspects and feasibility of implementing FDA-cleared detection methods for identifying bacterially contaminated platelet units. We also present details of a number of methods under development for at-issue use.     

Canadian experience with detection of bacterial contamination in apheresis platelets

BACKGROUND: In Canada, both blood suppliers, Héma-Québec (HQ) and Canadian Blood Services (CBS), implemented bacterial testing in apheresis platelets (PLTs) with an automated microbial detection system (BacT/ALERT, bioMérieux). STUDY DESIGN AND METHODS: Validation of the BacT/ALERT Classic and 3D systems involved apheresis PLT spiking with different bacteria at concentrations of 10 and 10(2) colony-forming units per mL. As of February 2006, more than 95 percent of apheresis PLTs were screened for bacterial contamination at HQ and CBS. Between 3.5 and 10 mL of PLTs is inoculated into BacT/ALERT aerobic culture bottles followed by incubation for a maximum of 7 days. RESULTS: During the validation studies, all bacteria were detected at all concentrations and volumes tested. Upon implementation of bacterial screening, the percentage of initial positive samples at CBS and HQ was 0.09 and 0.07 percent, respectively. The rate of indeterminate cultures was significantly higher at CBS than at HQ, whereas the rates for true-positive, false-positive, and false-negative results did not differ significantly. Six confirmed-positive cultures, including three coagulase-negative staphylococci and three Enterobacteriaceae species, were detected and PLT units contaminated with these bacteria were not transfused. The rate of true-positive cultures was significantly lower than that reported by other blood operators. Unfortunately, failed detection of two contaminated units resulted in septic transfusion reactions. CONCLUSION: Bacterial screening of apheresis PLTs in Canada was successfully implemented, and transfusion of contaminated units was prevented. Rapid bacterial detection systems that could be used before transfusion, however, may further reduce the risk of transfusion reactions.     

Factors that influence platelet recovery after transfusion: resolving donor quality from ABO compatibility

BACKGROUND: A system was established to examine the extent to which the apheresis donor determines platelet recovery after transfusion, to measure the impact of ABO identity, and to predict outcome by evaluating the donor. STUDY DESIGN AND METHODS: The percentage of platelet recovery was measured after prophylactic transfusion of apheresis units divided from single donors to paired recipients with uncomplicated thrombocytopenia secondary to leukemia chemotherapy. Platelet microaggregation induced by citrate was measured at the time of apheresis. RESULTS: Platelet recoveries in paired recipients correlated strongly when both transfusions were ABO- identical. When one recipient was ABO-identical and the other was ABO-nonidentical, nonidentical transfusions yielded one-third the recovery of ABO-identical transfusions. In ABO-identical transfusions, platelet recovery in donors having microaggregates in the before-apheresis ACD sample was one-third that in donors without microaggregates. This difference was observed at 1 and 24 hours. Expression of P-selectin in the apheresis units at the time of transfusion correlated well with ACD microaggregates in the before-apheresis sample. CONCLUSION: When transfusions of platelets are ABO-identical, donor quality dominates recovery in circulation. Donor quality is predicted by a rapid and simple assay of citrate-induced microaggregation performed at the time of apheresis. When donor quality is factored out, ABO identity prevails.     

10 Years Experience with Bacterial Screening of Platelet Concentrates in the Netherlands

SUMMARY: BACKGROUND: Contamination of platelets with bacteria is the major microbiological risk of blood transfusion. Screening for bacterial contamination can reduce the frequency of bacterial transmission considerably. In the present paper, the results of 10-year screening in the Netherlands are described. METHODS: All platelet concentrates were cultured with the BacT/Alert culturing system with large volume (7.5 ml) cultures in either an aerobic or an anaerobic bottle. Products were released on a 'negative-to-date' basis. RESULTS: After introduction of the diversion of the first milliliters of collected blood, the number of positive screening cultures decreased significantly from 0.85% to 0.37%. The frequency of transfusion-transmitted bacterial infections by platelet concentrates is currently less than 1 per 2 years in the Netherlands. CONCLUSION: Over a period of 10 years the bacterial screening system for platelet concentrates proved to result in a safe system with respect to microbiological infection as a result of platelet transfusions.     

Transfusion-Transmitted Infections Reported to the National Healthcare Safety Network Hemovigilance Module

Transfusion-transmitted infections (TTIs) can be severe and result in death. Transfusion-transmitted viral pathogen transmission has been substantially reduced, whereas sepsis due to bacterial contamination of platelets and transfusion-transmitted babesiosis may occur more frequently. Quantifying the burden of TTI is important to develop targeted interventions. From January 1, 2010, to December 31, 2016, health care facilities participating in the National Healthcare Safety Network Hemovigilance Module monitored transfusion recipients for evidence of TTI and recorded the total number of units transfused. Facilities use standard criteria to report TTIs. Incidence rates of TTIs, including for bacterial contamination of platelets and transfusion-transmitted babesiosis, are presented. One hundred ninety-five facilities reported 111 TTIs and 7.9 million transfused components to the National Healthcare Safety Network Hemovigilance Module. Of these 111 reports, 54 met inclusion criteria. The most frequently reported pathogens were Babesia spp in RBCs (16/23, 70%) and Staphylococcus aureus in platelets (12/30, 40%). There were 1.95 (26 apheresis, 4 whole blood derived) TTIs per 100 000 transfused platelet units and 0.53 TTI per 100 000 transfused RBC components, compared to 0.68 TTI per 100 000 all transfused components. Bacterial contamination of platelets and transfusion-transmitted babesiosis were the most frequently reported TTIs. Interventions that reduce the burden of bacterial contamination of platelets, particularly collected by apheresis, and Babesia transmission through RBC transfusion would reduce transfusion recipient morbidity and mortality. These analyses demonstrate the value and importance of facility participation in national recipient hemovigilance using standard reporting criteria.     

Possible implication of sterile connecting device in contamination of pooled platelet concentrates

Considering the possibility that a pooled random donor platelet concentrate could become contaminated by welding with a sterile connecting device, we undertook a study to determine the influence of pooling on the contamination rate. As a control group, apheresis platelets were examined. Bacteriological testing was done with a sensitive CO2 detecting culture system, the BacT/ Alert. Out of 1105 pooled platelet concentrates prepared by the buffy coat method, 15 (1.4%) were confirmed as contaminated, all with Staphylococcus epidermidis and two with a second bacterial species, i.e. Staphylococcus capitis and Propionibacterium acnes, respectively. Median detection time by the BacT/Alert was 23 h. Twelve pools of five units were contaminated, which is significantly more than the three contaminated pools of four units. On the other hand, the reuse of the welding wafers proved not be a risk factor for contamination. One welded tubing segment of a contaminated platelet concentrate failed the air leakage test, an incident which was 73 times more frequent than with the sterile platelet concentrates. We found five pooled platelet concentrates containing Staphylococci from which no bacteria could be grown from the individual buffy coats that had been pooled. We suggest the contamination here to have occurred after separation of the buffy coat from the whole blood, possibly during the welding process. Finally, none out of 378 apheresis platelet concentrates was contaminated. All our observations highlight the potential risk for contamination when making pooled platelet concentrates with a sterile connecting device. For this type of transfusion product, we advocate bacteriological screening of all units before release. The incubation time for the sterility test should, however, be limited to 36 h, if logistical problems with the availability of platelets are to be avoided.     

Platelet transfusions in children: results of a randomized,prospective, crossover trial of plasma removal and a prospective audit of WBC reduction

BACKGROUND: Febrile nonhemolytic transfusion reactions (FNHTRs) complicate 2 to 37 percent of platelet transfusions in adults, but the incidence of such reactions in children is not known. The effectiveness of plasma reduction after storage and WBC reduction of platelet concentrates before storage was studied in pediatric recipients of platelet transfusions. STUDY DESIGN AND METHODS: In the first study, a prospective randomized crossover design was used in which patients received either unmodified whole-blood-derived or apheresis platelets or platelets from which most of the plasma supernatant had been removed just before transfusion. The second study was a prospective audit of recipients of prestorage WBC-reduced platelets. Children between 3 months and 17 years of age were eligible for both studies. Patients were assessed for signs and symptoms that are characteristic of a reaction during, immediately after, and 2 hours following transfusion. RESULTS: There were 226 platelet transfusions administered to 66 children. One hundred and sixty transfusions were given to 35 children enrolled in the randomized study, and 66 transfusions were given to 33 children during the audit. In the randomized study, nine of the 75 transfusions of unmodified platelets (12%) and six of 85 transfusions of poststorage plasma-removed platelets (7%) were associated with an FNHTR (p=0.42). In the audit, three of 66 transfusions of prestorage WBC-reduced platelets (5%) were associated with an FNHTR. Allergic reactions occurred with 5 percent (4 of 75), 6 percent (5 of 85), and 6 percent (4 of 66) of platelet transfusions, respectively. CONCLUSION: FNHTRs appear to be less common among pediatric recipients of platelet transfusions than in adults. In our two studies, there was a trend toward a lower frequency of FNHTRs with poststorage plasma removal and prestorage WBC reduction than with standard platelets, but this was not significant.     

Detection of bacterial contamination in prestorage culture-negative apheresis platelets on day of issue with the Pan Genera Detection test

BACKGROUND: Bacterial contamination is currently the most important infectious risk associated with transfusion of platelet (PLT) products. Prestorage culture has reduced but not eliminated this problem. STUDY DESIGN AND METHODS: Eighteen hospitals studied the Pan Genera Detection (PGD) test, a rapid, lateral‐flow immunoassay for the detection of Gram‐positive and Gram‐negative bacteria. The PGD test was performed on day of issue on apheresis PLTs released by collection centers as culture negative. Confirmatory bacterial culture was performed when PGD tests were repeatedly reactive, with three sites performing culture on all doses studied. RESULTS: PGD tests on nine of 27,620 (1:3069, 95% confidence interval [CI] 1:6711 to 1:1617; or 326 per million, 95% CI 149‐618 per million) apheresis PLT doses were repeatedly reactive and verified as bacterially contaminated by confirmatory culture. Bacterial species isolated included coagulase‐negative staphylococci (n = 6), Bacillus sp. (n = 2), and Enterococcus faecalis (n = 1). The ages of these contaminated doses were Day 3 (n = 4), Day 4 (n = 2), and Day 5 (n = 3). Two contaminated doses with nonreactive PGD tests were detected among 10,424 doses at hospitals where concurrent culture was performed, and one other was identified via a transfusion reaction investigation. There were 142 PGD false positives (0.51%). CONCLUSIONS: The PGD test detected bacterial contamination in 1:3069 (9 of 27,620) doses released as negative by prestorage culture in PLTs as young as 3 days old. Three contaminated doses, two clinically insignificant, had nonreactive PGD tests, while 0.51% of tests were false positives. Application of this test on day of issue can interdict contaminated units and prevent transfusion reactions.     

Experience with universal bacterial culturing to detect contamination of apheresis platelet units in a hospital transfusion service

BACKGROUND: Bacterial contamination of platelet units poses one of the greatest risks of morbidity and mortality to platelet transfusion recipients. A routine culture of all units (WBC-reduced apheresis platelet units) was instituted on Day 2 over a 2-year period to reduce this risk. STUDY DESIGN AND METHODS: A sterile connecting device was used to attach a small transfer pack on the morning of Day 2 after collection, and 10 mL of the unit were transferred to the small bag. After disconnection from the unit, about half of this volume was transferred to an aerobic culture bottle of an automated bacterial detection system. Units were maintained in available inventory until and unless a report was received of growth in the sample. When available, the unit or a retained aliquot was recultured if the initial sample was positive. Units were held up to 2 days beyond their 5-day outdate and used for transfusion if no other suitable units were available to meet the clinical need or were evaluated with in vitro testing on Day 8. RESULTS: Of 2678 units cultured, 16 (0.6%) were positive on initial culture. Thirteen could be recultured, and all of these samples were negative. Shortly after the 2-year period of the study, two units (split from the same collection) were documented as growing coagulase-negative Staphylococci 12 hours after sampling. Units transfused on Day 6 or 7 (n = 40) yielded expected clinical responses, and CCI available on 21 cipients 10 to 60 minutes after transfusion demonstrated acceptable results (mean, 14,400 +/- 8800; median, 12,191; 90% > 7500). More than 96 percent of units tested on Day 8 had pH greater than 6.2 and continued to demonstrate swirling. CONCLUSIONS: Routine culturing of apheresis platelet units is feasible, can be accomplished with a low rate of false positivity, and can detect contaminated units. The cost of such a protocol could be mitigated with extension of the storage period, and clinical experience with units held for 6 or 7 days was satisfactory.     

Detection and Quantitation of Bacteria in Platelet Products Stored at Ambient Temperature

A study of bacterial contamination in platelet products stored at ambient temperature demonstrated the presence of bacteria in 2.4 per cent of platelets as determined by culturing platelet pools. The recovery of bacteria increased as storage time prior to culture increased, which suggested bacterial proliferation during storage. While many of the bacteria recovered were normal skin flora, i.e ., diphtheroids and Staphylococcus epidermidis , pathogens such as Enterobacter cloacae, Staphylococcus aureus , and Pseudomonas spp. were recovered several times. Quantitative cultures were performed in the present study which demonstrated that most pools contained relatively few microorganisms, although some harbored more than 500 bacteria/ml after ambient temperature storage.
The introduction of microorganisms during the pooling procedure can not be ruled out. Of 3,251 units not subjected to pooling, 45 (1.4%) were found to contain bacteria. Platelets kept at ambient temperature for 11 to 71 days were cultured and 38 of 631 (6.0%) individual units contained bacteria. Four additional severe patient reactions and two deaths have occurred consequent to transfusion of platelets contaminated with bacteria. These observations lead to the conclusion that caution should be exercised in the use of platelets stored at ambient temperature.     

Detection of bacterial contamination in apheresis platelet products: American Red Cross experience, 2004

BACKGROUND: Routine quality control (QC) testing for bacterial contamination in apheresis platelet (PLT) products was implemented in all 36 regional blood centers of the American Red Cross in March 2004. STUDY DESIGN AND METHODS: PLT samples were cultured under aerobic conditions until the end of the product shelf life or when a positive reaction was indicated. To confirm the initial positive reaction, a new sample was taken from the unit for reculturing. All positive culture bottles were referred for bacterial isolation and identification. Bacterial testing data along with apheresis PLT collection information were collected for analysis. Reports and investigations of potential septic reactions to apheresis PLTs were reviewed. RESULTS: In the first 10 months of bacterial testing, 226 of 350,658 collections tested initially positive. Sixty-eight were confirmed on resampling to be bacterially contaminated for an overall confirmed-positive rate of 0.019 percent or 1 in 5157. Staphylococcus spp. (47.1%) and Streptococcus spp. (26.5%) were the most frequently isolated bacteria; Gram-negative bacteria accounted for 17.6 percent of the confirmed-positive products. Of the 354 apheresis PLT products derived from all 226 initial test-positive cases, 38 (10.7%) were transfused by the time the initial positive reaction was indicated. None of these transfused products, however, had a confirmed-positive bacterial screen and no patient who had been transfused with an unconfirmed-positive product had evidence of a septic transfusion reaction. Three high-probability septic transfusion reactions to screened, negative components were identified. In all three cases, a coagulase-negative Staphylococcus was implicated. CONCLUSION: Our experience demonstrates that bacterial testing of apheresis PLT products as a QC measure was efficiently implemented throughout the American Red Cross system and that this new procedure has been effective in identifying and preventing the transfusion of many, although not all, bacterially contaminated PLT units.     

Febrile reactions after platelet transfusion: the effect of single versus multiple donors

Febrile reactions to platelet transfusions are a common problem. The platelet transfusion records from a 30-month period were analyzed to determine 1) when reactions occur in a transfusion sequence; 2) how frequently they recur; and 3) whether the choice of multiple-donor (pooled concentrates) or single-donor components (unmatched apheresis and HLA-compatible apheresis platelets) affected the reaction rate. Overall, 18.7 percent of all patients receiving platelets experienced reactions. A subset of 85 patients, who began platelet support with unmodified components during the study interval, were analyzed in detail. This group received 1204 unmodified transfusions (mean, 14.2/patient), which were associated with 171 reactions (per-transfusion reaction rate, 14.2%). Despite a higher mean white cell content, the transfusion of 438 unmatched single-donor platelets (10.84 x 10(8) white cells, 8.4% reaction rate) resulted in reactions significantly less often than did that of 583 pooled concentrates (8.53 x 10(8) white cells, 21.4% reaction rate) (p less than 0.001). The rate of reaction to HLA-compatible platelets (9/183 transfusions, 4.9%) was not significantly different from that to unmatched single-donor platelets. The use of platelet components from one donor, as opposed to multiple donors, may provide an effective means of reducing the incidence of febrile reactions.     

Operational feasibility of routine bacterial monitoring of platelets

Bacterial contamination of platelets poses the greatest risk of mortality and morbidity to platelet transfusion recipients. Some European countries have introduced routine bacterial monitoring of platelets to reduce the risk of transmission of bacteria. A pilot study was carried out at the Northern Ireland Blood Transfusion Service, using the BacT/ALERT automated culture system, to assess the operational feasibility of routine bacterial monitoring of platelets. About 4885 platelet concentrates (PCs) were tested in a 1-year period. Of the 28 (0.57%) initial reactive cultures, 13 (46%) were reproducible on repeat culturing. Of these, 10 were detected within 24 h of incubation either in aerobic or both aerobic and anaerobic culture bottles. A sample of time-expired units (423) that had initial negative culture results remained negative when retested on day 8. About 213 time-expired units were subjected to routine quality assessment and more than 85% were found to conform to quality standards specified in the UKBTS guidelines for platelet count (> or =240 x 10(9) per adult dose PC) and pH (6.4-7.4). There was a reduction in the platelet count because of the volume removed (15 mL) for sampling. Routine bacterial testing with day 2 sampling and a negative culture result after 24 h as a mandatory release criterion would improve product safety. Implementation of 100% testing would be operationally feasible but may require extension of the shelf life if unacceptable wastage is to be avoided.     

Effects of nitric oxide on platelet activation during plateletpheresis and in vivo tracking of biotinylated platelets in humans

BACKGROUND: The use of platelet transfusions has risen considerably over the last few years, which leads to the collection and transfusion of a greater number of donor plateletpheresis units. Plateletpheresis activates platelets in platelet concentrates, which determines the degree of the storage lesion subsequently observed. STUDY DESIGN AND METHODS: As nitric oxide (NO) is a potent inhibitor of platelet aggregation and activation, a placebo-controlled crossover trial was performed in healthy young male volunteers to determine whether the NO-donating compound, sodium nitroprusside (SNP), decreases platelet activation during apheresis and whether activated (p-selectin+) platelets circulate in vivo after transfusion. The study also investigated whether nonradioactive biotin labeling of apheresis platelets is feasible for the study of platelet recovery after transfusion in humans. RESULTS: Platelet activation increased after plateletpheresis in the platelet components, but SNP did not inhibit platelet activation during apheresis, as measured by the percentage of p-selectin expression and the secretion of soluble p-selectin and RANTES. Only a minor increase in p-selectin+ platelets was seen in peripheral blood at 60 minutes after transfusion of the platelets, a rise that was considerably less than that calculated in p-selectin+ platelets if they all were recovered as activated platelets after transfusion. Biotin-labeled platelets averaged 1.5 percent at 10 minutes after transfusion and increased slowly to 2.6 and 3.4 percent after 60 minutes and 24 hours, respectively (p<0.05). CONCLUSION: SNP does not decrease platelet activation during apheresis and subsequent storage, and only a minor proportion of activated (p-selectin+) platelets circulate after transfusion in men. Moreover, biotin labeling of PCs can safely be used in humans for the study of platelet recovery after transfusion, and measuring recovery at 1 hour may lead to an underestimation of the true recovery when activated platelets are transfused.     

972例次血液病患者输注机采血小板后回顾性分析

目的探讨机采血小板治疗血液病的效果及临床科学、合理应用血小板的情况。方法收集2007年本院血液科输注血小板136例(972次)的资料,比较输注前后24h内病历中记载的血小板检查结果,以血小板增加值判断血小板输注效果。结果972例次中输注后24h内复查血小板的为661例次(68.00%),输注前后24h内均检查血小板的为475例次(48.86%);所有输注血小板患者的血小板数量与输注前比较显著提高(P<0.01),总有效率为75.74%(103/136);但在输注前后24h内检查血小板的475例次中,血小板输注有效率为58.73%。结论机采血小板对血液病具有较好的治疗作用,但科学合理有效使用血小板的意识仍亟待加强。     

The evaluation of microbial contamination in platelet concentrates prepared by two different methods.

The microbial contamination of platelet concentrates (PCs) prepared by two different methods both with a high risk of bacterial contamination during preparation and storage were evaluated. For apheresis platelets, the concentrates were obtained using the Haemonetics MCS 3P device. For the random method, platelets were obtained by two phase centrifugation, in the Heraeus Cryofuge 8500 I device using the Kansuk 3-way bags which permit storage for five days. 1620 plateletpheresis units prepared by apheresis, and 9838 units prepared by the random method, were included in the study. Of the 11,458 PCs studied. 32 (0.27%) were false positives and 24 (0.2%) were real positives. All of the positive results occurred in platelets prepared by the random method. C. xerosis and S. epidermidis, S. hominis, Alpha-hemolytic streptococci, all flora of the skin, were isolated in the contaminated concentrates. The risk of microbial contamination of PCs, prepared both by apheresis and from whole blood, continues at a low rate although the products were collected into specific bags following rules including appropriate disinfection of the skin, correct centrifugation collection time and optimal storage conditions including temperature and agitation. These results again emphasize the importance of: obeying phlebotomy rules and hand disinfection of the person who collects the blood as well as the need for careful skin decontamination of the donor, during donation.     

Bacterial contamination of blood components: Norwegian strategies in identifying donors with higher risk of inducing septic transfusion reactions in recipients

Bacterial contamination of blood and its cellular components remains the most common microbiological cause of transfusion associated morbidity and mortality, even in developed countries. This yet unresolved complication is seen more often in platelet transfusions, as platelet concentrates are stored at room temperature, in gas permeable containers with constant agitation, which support bacterial proliferation from relatively low undetectable levels, at the beginning of storage time, to relatively high virulent bacteria titers and endotoxin generation, at the end of shelf life. Accordingly, several combined strategies are introduced and implemented to at least reduce the potential risk of bacterial contaminated products for transfusion. These embody: improved donors arms cleaning; bacterial avoidance by diversion of the first portion of collection; reducing bacterial growth through development of newer storage media for longer platelet shelf life; bacterial load reduction by leucoreduction/viral inactivation, in some countries and eliminating the use potentially contaminated units through screening, through current available testing procedures, though none are not yet fully secure. We have not seen the same reduction in bacterial associated transfusion infections as we have observed for the sharp drop in transfusion associated transmission rates of HIV and hepatitis B and C. This great viral reduction is not only caused by the introduction of newer and more sensitive and specific detection methods for different viruses, but also the identification of donor risk groups through questionnaires and personal interviews. While search for more efficient methods for identifying potential blood donors with asymptomatic bacteremia, as well as a better way for detecting bacteria in stored blood components will be continuing, it is necessary to establish more standardized guidelines for the recognition the adverse reactions in recipients of potentially contaminated units. Efforts also should be also directed to identify blood donors with significant risk of bacteremia, at the time of donation in the first place as a high priority. The goal of this review is to highlights strategies for identifying both the sources of bacterial contamination of blood components in Norway and identifying donors with a higher risk of bacteremia at the time of donation. The key to achieving this goal is initiating continual revising and upgrading the Norwegian transfusion guidelines, based on the transfusion legislation and by introducing a relevant specialized donor bacterial questionnaire.     

Evaluation of changes in hemoglobin levels associated with ABO- incompatible plasma in apheresis platelets

BACKGROUND: Hemolytic transfusion reaction is considered a rare complication of platelet transfusion. If minor ABO incompatibility exists (donor antibody directed against recipient's red cells [plasma- incompatible platelets]), however, the antibodies present in the plasma of platelets may cause acute hemolysis. A retrospective study was performed to identify possible hemolysis related to the transfusion of plasma-incompatible apheresis platelets. STUDY DESIGN AND METHODS: Acute hemolysis due to low-titer anti-A present in group O apheresis platelets transfused to a group A patient is reported. Pretransfusion and posttransfusion hemoglobin levels were evaluated in 16 non-group O autologous bone marrow transplant patients receiving apheresis platelets. All patients received, within 24 hours, both ABO-identical and plasma-incompatible platelet transfusions. No red cells were transfused during the time between the collection of the pretransfusion and posttransfusion hemoglobin samples. RESULTS: A total of 24 evaluable paired platelet transfusions in the 16 patients were compared. The mean change in hemoglobin following transfusion of the ABO-identical and plasma-incompatible platelets was -0.50 g per dL and - 0.11 g per dL, respectively (p = 0.193). CONCLUSION: There was no significant change in the hemoglobin concentration associated with the transfusion of plasma-incompatible apheresis platelets (minor ABO incompatibility) in our study group. The case reported here represents the only hemolytic transfusion reaction identified among 46,176 platelet transfusions performed at this hospital, despite approximately 21 percent of all platelet transfusions being plasma incompatible. The risk of such a reaction remains low.