Evaluation of a new generation of plastic culture bottles with an automated microbial detection system for nine common contaminating organisms found in PLT components

BACKGROUND: A microbial detection system (BacT/ALERT 3D, bioMérieux [formerly Organon Teknika]) has previously been validated with a variety of bacterial contaminants in PLTs. The recovery of nine organisms seeded into PLTs with new plastic culture bottles was studied in comparison to the current glass bottles. The use of plastic instead of glass would be expected to reduce the risk of injury. STUDY DESIGN AND METHODS: Isolates of Bacillus cereus, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Streptococcus viridans, and Propionibacterium acnes were inoculated into Day 2 (>24 hr <48 hr) apheresis PLT units to 10 and 100 CFUs per mL. Replicate samples (4 mL) were inoculated into both current- and new-generation standard aerobic and anaerobic bottles. RESULTS: All organisms (with the exception of P. acnes) were detected in a mean time of 9.3 to 18.9 hours (10 CFUs/mL) or 8.7 to 18.2 hours (100 CFUs/mL). In aggregate (with the exception of P. acnes), the plastic and glass aerobic bottles had a mean difference in detection of 1.2 hours (p < 0.0001), and the plastic and glass anaerobic bottles had a mean difference of 3.3 hours (p < 0.0001). In all cases, the mean detection time was superior or clinically comparable (within 0.1 hr) with the new plastic bottles. P. acnes (an anaerobic organism) was detected with the new and current anaerobic bottles in a mean of 72.8 and 90.4 hours (10 CFUs/mL) or 64.0 and 80.8 hours (100 CFUs/mL), respectively. The narrower bottle neck and smaller inoculation septum present with the new-generation plastic bottles were inoculated with comparable ease to that of the glass bottles. CONCLUSIONS: These data demonstrate that the new plastic bottles are clinically comparable or superior to the current glass standard aerobic and anaerobic culture bottles.     

Evaluation of an automated culture system for detecting bacterial contamination of platelets: an analysis with 15 contaminating organisms

BACKGROUND: Approximately 1 in 2000 platelet components are bacterially contaminated. The time to detection of 15 seeded organisms in platelets recovered from an automated culture system was studied. STUDY DESIGN AND METHODS: Isolates of Bacillus cereus, Bacillus subtilis, Candida albicans, Clostridium perfringens, Corynebacterium species, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Propionibacterium acnes, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens, Streptococcus pyogenes, and Streptococcus viridans were inoculated into Day 2 apheresis platelet components to obtain a final concentration of approximately 10 and 100 CFU per mL (2 units/organism). Each bag was sampled 10 times (20 mL/sample). Four mL of each sample was inoculated into standard aerobic and anaerobic bottles and into aerobic and anaerobic bottles containing charcoal; 2 mL was inoculated into pediatric aerobic bottles (so as to maintain a 1:10 ratio of sample to media) and 1 mL into thioglycollate broth. RESULTS: With the exception of P. acnes, all organisms were detected in a mean of 9.2 to 25.6 hours. A range of 10 serial dilutions in inoculating concentrations was associated with an overall 10.1-percent difference in detection time. A mean of 74.4 and 86.2 hours (100 and 10 CFU/mL inocula, respectively) was required for the detection of P. acnes in anaerobic bottles. CONCLUSION: Bacteria thought to be clinically significant platelet contaminants can be detected in 9.2 to 25.6 hours when the starting concentration is approximately 10 to 100 CFU per mL. P. acnes required considerably longer incubation times for detection (in either aerobic or anaerobic bottles). However, P. acnes is of questionable clinical significance. Such a detection system could be used in either a blood collection center or a transfusion service to screen platelet concentrates for bacterial contamination. Such testing (with sterile sampling performed so as to maintain a closed-bag system) would be expected to save lives and might allow an extension of platelet storage.     

Evaluation of an automated microbiologic blood culture device for detection of bacteria in platelet components

BACKGROUND: Automated culture methods have been used by several investigators to detect bacterial contamination of cellular blood components. We investigated several factors affecting detection by automated culture of bacteria in platelet concentrates (PCs).These factors included the initial contamination level in PCs, the PC sample volume, the PC sample time, and the white cell level in relation to bacteria levels in the PCs. STUDY DESIGN AND METHODS: Staphylococcus epidermidis or Escherichia coli was inoculated into freshly prepared PCs or white cell-reduced PCs to yield colony-forming unit (CFU) levels of 10, 1, or 0.1 per mL. At the time of inoculation (t=0) and at t=6, t=24, and t=48 hours, 0.5, 1.0, and 2.0 mL samples of the contaminated PCs were transferred into culture bottles. The presence of bacteria in the culture bottles was subsequently monitored by an automated blood culturing instrument. Bacteria levels in the PC at the time of first automated culture detection were determined by quantitative plating. RESULTS: E. coli was detected in 92 percent of experiments when 1.0- or 2.0-mL samples were taken at t=6 hours. At t=24 hours, 100-percent detection was observed with all tested inoculation volumes; however, by that time,>10(7) CFU per mL of bacteria were present in every PC. For S. epidermidis, 89 percent and 83 percent of contaminated PCs were detected with a t=24 hour sampling time and 2.0- or 1.0-mL sampling volume. Seven of 36 PCs with a 2.0-mL sampling volume and 10 of 36 PCs with a 1.0-mL sampling volume contained>10(6) CFU per mL of S. epidermidis at the time of first detection. CONCLUSION: Data from this preliminary evaluation suggest that sampling times of 24 hours or more would be necessary to provide confidence in detection of E. coli or S. epidermidis in PCs using this culture method.     

Monitoring of apheresis platelet bacterial contamination with an automated liquid culture system: a university experience

BACKGROUND: With 4 million platelet units transfused per year in the United States and with the current estimate of bacteria contamination rate in PLT units, it would be expected that 2000 to 4000 bacterially contaminated units are transfused and associated with 333 to 1000 cases of clinical sepsis. STUDY DESIGN AND METHODS: Apheresis platelets were sampled on Day 2 of storage (collection day=Day 0) and issue (or following outdate, Days 6-8) using a sterile connection device (SCD) to attach a sampling bag. Using aseptic technique and a laminar flow hood, bottles were inoculated and placed onto an automated liquid culture system (BacT/ALERT 3D Microbial Detection System) for 7 days. RESULTS: A total of 2397 apheresis PLT units were sampled. A triple apheresis collection was reactive within 14 hours of the Day 2 sampling (aerobic bottles) and the bags were removed from inventory. Staphylococcus epidermidis was identified in all three contaminated bags. Two double-apheresis collections were found to be contaminated with Proprionibacterium sp. after 6 days of incubation but had been transfused to four patients without discernible clinical sequelae. There was one false-positive aerobic bottle and one false-positive anaerobic result due to inadvertent contamination of a bottle. Thus, the overall true-positive rate was 7 of 2397 apheresis units (0.29%) with a true-positive rate for aerobic organisms of 0.13% and an anaerobic true-positive rate of 0.17%. The false-positive rate was 2 out of 4794 samplings (0.04%) or 2 out of 9588 bottles (0.02%). CONCLUSION: This preliminary data suggests that the use of a SCD, aseptic technique, and a laminar flow hood is associated with a low rate of contamination. In no case did an issue (or outdate) detect contamination that was not detected by the Day 2 culture. Additional surveillance is necessary before we can conclude that a Day 2 sterile culture is truly predictive of an issue (or outdate) sterile culture. Bacterial culture surveillance of PLTs would be expected to save lives and may facilitate an extension in PLT storage.     

一种新的实时荧光定量PCR方法对血小板制品细菌污染检测效果的评价

目的建立一种自主研发的针对细菌16 S r DNA基因的实时荧光定量PCR(Real-time PCR)方法并评价该方法对浓缩血小板制品中细菌污染检测的效果。方法设计16S r DNA基因保守区引物,构建SYBR Green Real-time PCR反应体系;然后分别将大肠杆菌、金黄色葡萄球菌、表皮葡萄球菌、蜡样芽孢杆菌和绿脓杆菌以初始浓度为1CFU/m L、10 CFU/m L和100 CFU/m L接种到浓缩血小板中,经22℃保存7 d后,用实时定量荧光PCR方法进行细菌检测。结果细菌污染后的血小板在常规保存条件下,最长保存期7 d,不同接种浓度的细菌生长情况的变化趋势基本一致,所有种类的细菌均在d 1、2表现出迅猛的增殖高峰,d 3以后增殖趋于平缓。结论该Real-time PCR检测体系可定量地检测出血小板的细菌污染的情况,可适用于血小板输注前的快速细菌污染检测。     

The utility of platelet washing using an automated procedure for severe platelet allergic reactions

Increased use of platelets in patients requiring chronic platelet support has increased platelet transfusion reactions. The authors reviewed more than 300 platelet transfusion reactions, evaluated an automated platelet washing technique, and studied the effectiveness of washing platelets to reduce reactions. Febrile reactions (66%) were most frequently reported, followed by moderate and severe allergic reactions (15%), and urticaria alone (19%). Washed platelets were prepared by an automated technique (IBM/COBE 2991). In vitro studies indicated no apparent adverse effects to the platelets due to the wash procedure, and in vivo studies demonstrated good platelet increments in 10 thrombocytopenic patients. Twenty-two patients with histories of platelet transfusion reactions received a total of 554 washed platelet transfusions. Washed platelets were not effective in reducing febrile transfusion reactions in 16 patients receiving 347 washed products. The efficacy of washed platelets in reducing transfusion reactions was demonstrated in six patients with histories of severe allergic reactions who received 207 washed products. Severe allergic reactions were completely alleviated in this group. In conclusion, automated platelet washing is simple and efficacious in preventing or reducing the severity of allergic reactions to platelet transfusions.     

Evaluation of a new automated system for the determination of ck-mb isoforms

We evaluated a new analyzer (Cardio REP) specifically designed for cardiac CK-MB isoenzyme and isoforms activity, with a performance time of 24 minutes. Ten AMI patients, with times elapsed between the onset of chest pain and admission to hospital ranging from 30 minutes to 4 hours, were monitored every 3–4 hours until the 16th hour of hospitalization. In each serum sample, in addition to total CK-MB and CK-MB isoforms measured by the Cardio REP analyzer, we also assayed total CK activity, CK-MB activity by immunoinhibition method, CK-MB mass concentration, CK-MB isoforms by REP method, troponin T, and myoglobin. The precision study demonstrated acceptable within assay and between assay CVs% for total CK-MB (8.1 and 10.4), MB₁ (9.1 and 14.2), and MB₂ (9.1 and 8.2) isoforms. The method was found to be linear up to 371 U/L for MB₂ isoform fraction and up to 516 U/L for total CK-MB. Results for CK-MB obtained with the Cardio REP correlated well with those for CK-MB activity obtained with the immunoinhibition method (r = 0.869) and those of CK-MB mass concentration (r = 0.923). The sensitivity of the Cardio REP CK isoforms method was found to be greater than that of the REP CK isoforms method. Time to first increased value of MB₂/MB₁ ratio and MB₂ isoform was earlier in comparison to that for CK-MB mass concentrations and similar to that for myoglobin, a marker that, however, lacks specificity. The diagnostic efficiency of CK-MB isoforms and the availability of a real-time, fully automated method for their measurement suggest the utilization of this biochemical marker in emergency for the early diagnosis of AMI.     

Evaluation of the 3D BacT/ALERT automated culture system for the detection of microbial contamination of platelet concentrates

Bacterial transmission remains the major component of morbidity and mortality associated with transfusion-transmitted infections. Platelet concentrates are the most common cause of bacterial transmission. The BacT/ALERT 3D automated blood culture system has the potential to screen platelet concentrates for the presence of bacteria. Evaluation of this system was performed by spiking day 2 apheresis platelet units with individual bacterial isolates at final concentrations of 10 and 100 colony-forming units (cfu) mL-1. Fifteen organisms were used which had been cited in platelet transmission and monitoring studies. BacT/ALERT times to detection were compared with thioglycollate broth cultures, and the performance of five types of BacT/ALERT culture bottles was evaluated. Sampling was performed immediately after the inoculation of the units, and 10 replicates were performed per organism concentration for each of the five types of BacT/ALERT bottles. The mean times for the detection of these 15 organisms by BacT/ALERT, with the exception of Propionibacterium acnes, ranged from 9.1 to 48.1 h (all 10 replicates were positive). In comparison, the time range found using thioglycollate was 12.0-32.3 h (all 10 replicates were positive). P. acnes' BacT/ALERT mean detection times ranged from 89.0 to 177.6 h compared with 75.6-86.4 h for the thioglycollate broth. BacT/ALERT, with the exception of P. acnes, which has dubious clinical significance, gave equivalent or shorter detection times when compared with the thioglycollate broth system. The BacT/ALERT system detected a range of organisms at levels of 10 and 100 cfu mL-1. This study validates the BacT/ALERT microbial detection system for screening platelets. Currently, the system is the only practically viable option available for routinely screening platelet concentrates to prevent bacterial transmission.     

Determination of the components in erythrocytes using an automated analyzer

Determination of the biochemical components in erythrocytes should provide unique pathophysiological information. We optimized a simple alcohol binding method for the selective removal of hemoglobins from hemolysates, and enabled simultaneous determination of several components in erythrocytes using commercially available assay kits in an automated analyzer. Venous blood was collected in a vacutainer containing lithium heparin. The washed cells were hemolyzed with distilled water, frozen, and then thawed. Nine volumes of the hemolysates were mixed with one volume of Tris-HCl buffer. One volume of n-butanol was then added to nine volumes of the buffered hemolysates. After vigorous mixing, the mixture of n-butanol and hemolysates was left to stand. The butanol-bound hemoglobins were precipitated by centrifugation, and the clear supernatant below the butanol layer was applied directly to an automated analyzer. Using sera, we determined the effects of the hemoglobin removal procedures on the chemical analytes. Sufficient recovery was noted in most analytes, except for several enzyme activities and lipids. Accordingly, we determined five components present in erythrocytes: creatine, potassium, magnesium, and aspartate aminotransferase as well as superoxide dismutase activities in healthy subjects. We suggest that our simple method is applicable to the simultaneous determination of erythrocyte components in routine laboratory tests.     

Evaluation of a reporting system for bacterial contamination of blood components in the United States

BACKGROUND: The transfusion of blood components contaminated with bacteria may have serious clinical consequences, but few data are available on the incidence of these events. A national effort to assess the frequency of blood component bacterial contamination associated with transfusion reaction (the BaCon Study) was initiated to better estimate their occurrence. STUDY DESIGN AND METHODS: Standard reporting criteria, data collection forms, and a standardized reporting protocol were developed in collaboration with the American Red Cross, AABB, and the Department of Defense. Episodes reported to the BaCon Study were compared with those reported to the FDA's national reporting systems to estimate the extent to which all serious reactions associated with bacterial contamination were captured. RESULTS: During the first 2 years, 38 episodes meeting study criteria were reported; 21 were laboratory-confirmed. The estimated proportion of episodes reported to the BaCon Study (i.e., completeness of coverage) was lower than that reported to the FDA during the same period (0.33 vs. 0.68), but the positive predictive value was higher (0.66 vs.0.28). CONCLUSION: Despite the complexity of obtaining reports from a large number of United States hospitals and transfusion centers, the feasibility and usefulness of the BaCon Study were shown. This study was the only national study in the United States to monitor adverse clinical events associated with bacterial contamination of blood components. By building on hospital-based reporting of transfusion-related adverse events, the BaCon Study serves as a model for the study of other complications associated with blood and blood components.     

Detection of micro-organisms using a two bottle blood culture system: a twelve month study.

Over a twelve month period the isolation rate of pathogens, frequency of isolation of non-significant organisms, and time taken to detect positive cultures from a two-bottle blood culture system were analysed. Of 6916 blood cultures collected, 978 organisms were isolated from 863 cultures, 540 organisms being considered clinically significant and the majority (81%) being isolated within 48 h. Our results showed that use of more than one bottle increased the general isolation rate, with both bottles facilitating growth independently. This situation was particularly apparent in the cases of Haemophilus influenzae and Neisseria meningitidis, which showed that using the system alone only 76% and 33% (respectively) of the total number of strains would have been isolated. The results of this study reinforce the need for a second bottle containing a suitable culture medium.     

Evaluation of an automated immunoassay method for cytokine measurement using the Immulite Immunoassay system.

Cytokines are key mediators in cell regulation and communication. The concentration of these proteins can rapidly and importantly increase during severe clinical situations. However, current techniques are not adapted to stat measurement, thus making their clinical use limited. In this context, the commercialization of five new kits for cytokine measurement interleukin ((IL)-1, IL-6, IL-8, tumor necrosis factor (TNF)-alpha and IL-2R) on an automated immunoanalyzer, the Immulite, seems to be a new approach for the determination of these markers. We report here the evaluation of the performance of these tests. The technique is based on a solid phase (bead) two site chemiluminescent enzyme immunometric assay. The analysis is performed within 60 to 90 minutes and the calibration is stable for 15 days. The values of the between-run imprecision study were similar to those from the within-run study with coefficients of variation (CV) ranging from 2% (low values of IL-8) to 11.5% for intermediate concentrations of IL-6 (500 pg/ml). CVs were usually around 5%. The accuracy was determined by a linearity study using standards (except for IL-2R) provided by the National Institute for Biological Standards and Control (NIBSC). Slopes obtained during this study were close to 1 (r2 = 0.99), except for IL-6, for which the slope was 1.55. TNF-alpha values were close to those expected. IL-1 results were about 20% higher. IL-6 values were over estimated above 100 pg/ml and under estimated below this value. IL-8 study seemed to be impaired by the poor stability of this molecule in the NIBSC preparation. Correlation study with standard laboratory techniques gave variable results: for IL-1 (n = 43) the slope was 0.77 (study carried out using cell culture media), for IL-6 (n = 54) the slope was 0.78, for IL-8 (n = 37) the slope was 1.64, for TNF-alpha (n = 40) the slope was 0.33 and the slope for IL-2R (n = 51) was 5.1. For the last cytokine, the unit in Immulite assay was different from the one used in our comparison technique. Cross-calibration results were consistent with these data and show that the bias is probably linked to a calibration problem. The study demonstrated excellent practicality of the system, and good stability of the calibration curve (15 days). However, the sample volume required (350 microl for the IL-6 and the TNF-alpha) could constitute a limitation for pediatric measurements.     

Determination of the degree of bacterial contamination of whole-blood collections using an automated microbe-detection system

BACKGROUND: The prevalence of bacterial contamination in whole-blood collections, either with immediate sampling or sampling after overnight storage as whole blood at 20 degrees C, is determined. STUDY DESIGN AND METHODS: Whole blood was collected under blood bank conditions in special five-bag systems, allowing sampling in a closed system for culture bottles. Samples were taken within 2 hours after collection (Group 1) or after overnight storage of the whole blood at 20 degrees C (Group 2). Culture bottles were incubated for 7 days, and positive samples were entered on agar plates for confirmation and determination. RESULTS: In Group 1, 9219 units were tested; 27 units were positive with positive subculture, that is, 0.29 percent with a 95% CI of 0.19 to 0.42 percent. In Group 2, 9038 units were tested; 36 units were positive with positive subculture, that is, 0.39 percent with a 95% CI of 0.28 to 0.55 percent. No significant difference could be found between the two test groups. The majority of bacteria were either Staphylococcus (all coagulase-negative) or Propionibacterium species. CONCLUSION: For a total of 18,257 units, 0.34 percent (CI, 0.25-0.44) of whole-blood collections appeared to have bacterial contamination (mainly skin-derived). Overnight storage of whole blood at 20 degrees C did not have a significant effect on the prevalence of bacterial contamination.     

PGD血小板细菌污染检测系统效果的评价

目的评价PGD检测系统用于混合血小板制品细菌污染检测的效果。方法分别将配制后经浓缩血小板稀释为101、103和105CFU/ml的大肠埃希菌和表皮葡萄球菌菌悬液进行PGD检测限的评估;将上述菌株分别接种于浓缩血小板中制成菌液浓度为101、103CFU/ml的模拟细菌污染浓缩血小板,经22℃振荡保存24、72、120 h后分别用PGD法和Bact/ALERT法进行细菌检测,比较2种方法的细菌污染检测限和阳性反应时间。结果 PGD法对大肠埃希菌的检测限为105CFU/ml,表皮葡萄球菌为103CFU/ml;将103CFU/ml的大肠埃希菌和表皮葡萄球菌分别接种到浓缩血小板,24 h后PGD检测均为阴性,72 h后均为阳性,而Bact/ALERT法检测在10 h均呈阳性反应;将105CFU/ml的大肠埃希菌和表皮葡萄球菌接种浓缩血小板4 h后PGD检测均为阳性,Bact/ALERT法在3—6 h内均呈阳性反应。结论 PGD检测系统对血小板细菌污染的检测限为(103—105)CFU/ml,适用于医院输血部门在血小板输血前的快速细菌检测。     

Evaluation of LabRespond, a new automated validation system for clinical laboratory test results

BACKGROUND: Manual validation of laboratory test results is time-consuming, creating a demand for expert systems to automate this process. We have started to set up the program "LabRespond", which covers five validation levels: administrative, technical, sample, patient, and clinical validation. We present the evaluation of a prototype of an automated patient validation system based on statistical methods, in contrast to the commercially available program "VALAB", a rule-based automated validation system. METHODS: In the present study, 163 willfully altered, erroneous test results out of 5421 were submitted for validation to LabRespond, VALAB, and to a group of clinical chemists (n = 9) who validated these test results manually. The test results rejected by three or more clinical chemists (n = 281) served as a secondary reference standard. RESULTS: The error recovery rates of clinical chemists ranged from 23.9% to 71.2%. The recovery rates of LabRespond and VALAB were 77.9% and 71.8%, respectively (difference not significant). The false-positive rates were 82.7% for LabRespond, 83.6% for VALAB, and 27.8-86.7% for clinical chemists. Using the consensus of three or more clinical chemists as the secondary reference standard, we found error recovery rates of 64.8% for LabRespond and 72.2% for VALAB (P = 0.06). Compared with VALAB, LabRespond detected more (P = 0.003) erroneous test results of the type that were changed from abnormal to normal. CONCLUSIONS: The statistical plausibility check used by LabRespond offers a promising automated validation method with a higher error recovery rate than the clinical chemists participating in this study, and a performance comparable to VALAB.     

Evaluation of a new automated instrument for pretransfusion testing

BACKGROUND: A number of automated devices for pretransfusion testing have recently become available. This study evaluated a fully automated device based on column agglutination technology (AutoVue System, Ortho, Raritan, NJ). STUDY DESIGN AND METHODS: Some 6747 tests including forward and reverse ABO group, Rh type and phenotype, antibody screen, autocontrol, and crossmatch were performed on random samples from 1069 blood donors, 2063 patients, and 98 newborns and cord blood. Also tested were samples from 168 immunized patients and 53 donors expressing weak or variant A and D antigens. Test results and technician times required for their performance were compared with those obtained by standard methods (manual column agglutination technology, slide, semiautomatic handler). RESULTS: No erroneous conclusions were found in regard to the 5028 ABO group and Rh type or phenotype determinations carried out with the device. The device rejected 1.53 percent of tests for sample inadequacy. Of the remaining 18 tests with discrepant results found with the device and not confirmed with the standard methods, 6 gave such results because of mixed-field reactions, 10 gave negative results with A2 RBCs in reverse ABO grouping, and 2 gave very weak positive reactions in antibody screening and crossmatching. In the samples from immunized patients, the device missed one weak anti-K, whereas standard methods missed five weak antibodies. In addition, 48, 34, and 31 of the 53 weak or variant antigens were detected by the device, the slide method, and the semiautomated handler, respectively. Technician time with the standard methods was 1.6 to 7 times higher than that with the device. CONCLUSION: The technical performance of the device compared favorably with that of standard methods, with a number of advantages, including in particular the saving of technician time. Sample inadequacy was the most common cause of discrepancy, which suggests that standardization of sample collection can further improve the performance of the device.     

Development and evaluation of a shipping system for platelet components

BACKGROUND: Platelet concentrates and apheresis platelets must be maintained at a temperature as close as possible to 20 to 24 degrees C during transport. To improve temperature control, ensure component quality, and meet handling and freight carrier needs, a new insulated shipping container system was developed and evaluated. STUDY DESIGN AND METHODS: Molded polyurethane-insulated shipping containers were loaded with different payloads of simulated platelet components, with or without gel-based temperature stabilizing packs (TSPs). The containers were subjected to constant ambient temperature of 37, 4 or -10 degrees C. Payload temperatures were continuously monitored, in situ, for 24 hours. RESULTS: Temperature data are reported as the mean number of hours needed for components to warm or cool by 1 degree C. The temperature of payloads exposed to a constant 37 degrees C ambient temperature increased by 1 degree C in 2.5 to 3.8 hours when no TSPs were included in the shipment and in 6.1 to 6.9 hours when TSPs were used. Exposure to a constant 4 degrees C ambient temperature resulted in a 1 degree C temperature decrease in 1.8 to 3.4 hours without TSPs and in 4.6 to 5.6 hours with TSPs. At a -10 degrees C ambient temperature, there was a 1 degree C drop within 1.0 to 1.6 hours without TSPs and within 2.7 to 2.9 hours with TSPs. CONCLUSION: The container and packing methods described moderate the rate of change in the temperature of platelet components during their exposure to challenging ambient conditions. The use of TSPs substantially improves the performance of the system. In addition, the system meets freight carrier requirements and is easy to use, environmentally friendly, and durable.     

Value of anaerobic culture in bacterial surveillance program for platelet concentrates

BACKGROUND: Short‐term aerobic bacterial culture (STABC) has been used routinely in Hong Kong since 1998 to reduce bacterial contamination in platelet concentrates (PCs) with good results. With more countries implementing routine aerobic and anaerobic cultures of PCs, a prospective study was conducted to determine the value of anaerobic culture to STABC. STUDY DESIGN AND METHODS: PC tested by STABC was used as control. Twenty milliliters of the PC selected for this study was aliquoted and pooled for 7 days aerobic and anaerobic culture. If the initial culture was positive, samples retrieved from the original PC and their associated components were cultured for confirmation and microbiologic identification. RESULTS: A total of 10,035 PC units (2007 pools) were tested. The confirmed positive rates by aerobic and anaerobic cultures per pool were 3 (0.15%) and 13 (0.65%), respectively, which was equivalent to an increased yield from 0.03 to 0.13 percent of PC if anaerobic culture was added. Of the 10 bacteria detected by anaerobic culture only, 9 were found to be Propionibacterium acnes and the remaining one Peptostreptococcus sp. Their mean detection time from inoculation was 92.16 hours (range, 50.4‐124.8 hr). CONCLUSION: Addition of anaerobic culture to our routine STABC would significantly increase the detection rate of bacterial contaminated PC. However, since only slow‐growing bacteria were detected, and because their clinical significance was uncertain, it is concluded that there was no clear justification to introduce anaerobic culture locally if 5‐day shelf life for PCs was to be maintained.