A prospective study of symptomatic bacteremia following platelet transfusion and of its management

RND Pump-Mediated Efflux of Amotosalen, a Compound Used in Pathogen Inactivation Technology to Enhance Safety of Blood Transfusion Products, May Compromise Its Gram-Negative Anti-Bacterial Activity

Pathogen inactivation is a strategy to improve the safety of transfusion products. The only pathogen reduction technology for blood products currently approved in the US utilizes a psoralen compound, called amotosalen, in combination with UVA light to inactivate bacteria, viruses, and protozoa. Psoralens have structural similarity to bacterial multidrug efflux pump substrates. As these efflux pumps are often overexpressed in multidrug-resistant pathogens, we tested whether contemporary drug-resistant pathogens might show resistance to amotosalen and other psoralens based on multidrug efflux mechanisms through genetic, biophysical, and molecular modeling analysis. The main efflux systems in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa are tripartite resistance-nodulation-cell division (RND) systems, which span the inner and outer membranes of Gram-negative pathogens, and expel antibiotics from the bacterial cytoplasm into the extracellular space. We provide evidence that amotosalen is an efflux substrate for the E. coli AcrAB, Acinetobacter baumannii AdeABC, and P. aeruginosa MexXY RND efflux pumps. Furthermore, we show that the MICs for contemporary Gram-negative bacterial isolates for these species and others in vitro approached and exceeded the concentration of amotosalen used in the approved platelet and plasma inactivation procedures. These findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens. IMPORTANCE Pathogen inactivation is a strategy to enhance the safety of transfused blood products. We identify the compound, amotosalen, widely used for pathogen inactivation, as a bacterial multidrug efflux substrate. Specifically, experiments suggest that amotosalen is pumped out of bacteria by major efflux pumps in E. coli, Acinetobacter baumannii, and Pseudomonas aeruginosa. Such efflux pumps are often overexpressed in multidrug-resistant pathogens. Importantly, the MICs for contemporary multidrug-resistant Enterobacterales, Acinetobacter baumannii, Pseudomonas aeruginosa, Burkholderia spp., and Stenotrophomonas maltophilia isolates approached or exceeded the amotosalen concentration used in approved platelet and plasma inactivation procedures, potentially as a result of efflux pump activity. Although there are important differences in methodology between our experiments and blood product pathogen inactivation, these findings suggest that otherwise safe and effective inactivation methods should be further studied to identify possible gaps in their ability to inactivate contemporary, multidrug-resistant bacterial pathogens.

Variability in the Use of Platelet Transfusion in Patients with Intracerebral Hemorrhage: Observations from the Ethnic/Racial Variations of Intracerebral Hemorrhage Study

BACKGROUND

We examined platelet transfusion (PTx) in the Ethnic/Racial Variations of Intracerebral Hemorrhage (ERICH) study, hypothesizing that rates of PTx would vary among hospitals and depend on whether patients were on an antiplatelet therapy or underwent intracerebral hemorrhage (ICH) surgical treatment.

METHODS

The ERICH study is a prospective observational study evaluating risk factors for ICH among whites, blacks, and Hispanics. We identified factors associated with PTx, examined practice patterns of PTx across the United States, and explored the association of PTx with mortality and poor outcome (modified Rankin Scale score 4-6).

RESULTS

Nineteen centers enrolled 2572 ICH cases; 11.7% received PTx. Factors significantly associated with PTx were antiplatelet use before onset (odds ratio [OR], 5.02; 95% confidence interval [CI], 3.81-6.61, P < .0001), thrombocytopenia (OR, 13.53; 95% CI, 8.43-21.72, P < .0001), and ventriculostomy placement (OR, 1.85; 95% CI, 1.36-2.52, P < .0001). Blacks were less likely (OR, .57; 95% CI, .41-0.80) to receive PTx. Among patients who received PTx, 42.4% were not on an antiplatelet therapy before onset. Twenty-three percent of patients on antiplatelet therapy received PTx, but percentages varied from 0% to 71% across centers. There was no difference in mortality or poor outcome at 3 months between patients receiving PTx and those who did not.

CONCLUSIONS

The frequency of PTx for ICH varies across academic centers. Thrombocytopenia, antiplatelet use, vascular risk factors, and ventriculostomy placement were associated with PTx. PTx was not associated with improved outcomes. We anticipate reduced PTx use over time given recent clinical trial data suggesting its use could be harmful; however, the issue of whether surgical management warrants PTx remains.

A prospective study to determine the frequency of bacterial contamination of platelets

Bacterial contamination of transfusion products is a long standing problem which includes donor bacteremia, contamination during the whole blood collection procedure, contamination of the collection pack and contamination during the blood processing procedure. The purpose of this study is to know the incidence of bacterial contamination of platelets and how to overcome it. During January 2009 to December 2010, 5,000 units of platelets concentrate were collected and 5 ml of platelet concentrate was sent for sterility test. A total of 8 units were reported as bacterially contaminated. Bacterial contamination can be reduced by better skin disinfection, collection of blood with a diversion pouch set, testing for bacteria and potentially the use of safe & effective pathogen reduction technologies and when available.

Impact on patient outcome following transfusion of bacterially contaminated platelets: the M.D. Anderson Cancer Center experience

This study examined the clinical outcome of every patient who received a bacterially contaminated unit of platelets at The University of Texas M.D. Anderson Cancer Center, Houston, during 2007. Samples of platelets were aerobically cultured and read for 1 day at 35 degrees C. Positive bottles were subcultured in the appropriate media. The effect of independent variables in the clinical outcome of patients infused with bacterially contaminated platelet units was analyzed. A total of 23,199 platelet units were transfused, 71 of which were bacterially contaminated units; 8 were apheresis platelets and 63 were whole blood platelets. Of the 71 units, 70 were contaminated with gram-positive bacteria and 1 with gram-negative bacteria. Only 1 patient developed fever, and coagulase-negative staphylococci were isolated from the transfused unit. Transfusion of fresh units and antibiotic therapy possibly explain the lack of clinical consequences in our patients.

Analysis of bacterial detection in whole blood-derived platelets by quantitative glucose testing at a university medical center

After the March 2004 implementation of American Association of Blood Banks standards regarding platelet bacterial detection, we began quantitative glucose screening of whole blood-derived platelets (WB-P). The glucose level was measured immediately before component release--often storage day 4 or 5--using the Glucometer SureStep Flexx Meter (LifeScan, Milpitas, CA), with a positive cutoff of less than 500 mg/dL; failing units were cultured and not transfused. During 29 months (March 1, 2004-July 31, 2006) 93,073 units of WB-P were tested. Initially, 929 units (0.998%) screened positively. Bacterial growth was culture-confirmed in 6 units, for a bacterial contamination incidence of 0.006% and a true-positive rate of 6.4/100,000. Three additional culture-confirmed contamination cases were detected in transfused units causing febrile nonhemolytic reactions, for a false-negative rate of 3.2/100,000. Our overall contamination prevalence was 9.6/100,000 units of platelets transfused, lower than ordinarily cited, and showed a false-negative rate remarkably congruent to that of culture: 3.2/100,000. A low-sensitivity screening test applied late in platelet shelf-life can be comparable to culture in preventing bacterial-related morbidity.

Screening platelet concentrates for bacterial contamination: low numbers of bacteria and slow growth in contaminated units mandate an alternative approach to product safety

BACKGROUND AND OBJECTIVES

We introduced 100% screening of platelets for bacterial contamination in 2005 to reduce the risk of clinical sepsis from platelet transfusion. We test all outdating units again at expiry to assess the sensitivity of the initial test.

MATERIALS AND METHODS

We test all platelet concentrates prior to release for clinical use using a large volume automated culture technique on the day after manufacture. All units that expire unused are retested. Platelets still in stock on day 4 of storage may have a repeat culture performed, and are returned to stock with two extra days of shelf life.

RESULTS

Of 43,230 platelet units screened, 35 (0.08%) were positive; of 8282 expired unused, 18 (0.22%) were positive; and of 3310 day-4 retests, four (0.12%) were positive. Overall sensitivity of the initial screening test was 29.2% (95% confidence interval 19.4 to 39.1%). Thirteen of the 35 positive screening tests would have been expected to grow in both aerobic and anaerobic bottles; eight grew in aerobic culture only and five grew in anaerobic culture only, indicating that the likely number of bacteria in the contaminated platelet units at the time of sampling was less than 60 colony-forming unit per platelet unit.

CONCLUSIONS

Screening platelet concentrates for bacterial contamination using the most sensitive method available has a sensitivity of less than 40% because of the low numbers of bacteria in the initial contamination. Effective resolution of this problem will require a pathogen-inactivation technique.

Prevention of transfusion of platelet components contaminated with low levels of bacteria: a comparison of bacteria culture and pathogen inactivation methods

BACKGROUND

This study compared the efficacy of bacterial detection with inactivation for reducing the risk associated with transfusion of platelet (PLT) components contaminated with low levels of bacteria.

STUDY DESIGN AND METHODS

Twenty-one double-dose PLTs were spiked with seven species of bacteria at three levels (0.003-0.03, 0.03-0.3, 0.3-3 colony-forming units [CFUs]/mL). After split, each PLT unit contained 1 to 10, 10 to 100, and 100 to 1000 CFUs. One unit was photochemically treated (PCT; 150 micromol/L amotosalen and 3 J/cm(2) ultraviolet A). The other unit was untreated. All units were stored and sampled on Days 1, 2, and 5 of storage for aerobic and anaerobic culture in the BacT/ALERT system (bioMérieux). PLTs were classified as sterile when no bacterial growth was detected after 120 hours of culture.

RESULTS

In all PCT PLTs, no bacteria were detected throughout 5 days of storage regardless of species, level of contamination, and sampling time. In untreated PLTs, Staphylococcus aureus was consistently detected by culturing. Growth of 1 to 10 CFUs per unit Staphylococcus epidermidis, 1 to 100 CFUs per unit of Klebsiella pneumoniae, and 1 to 1000 CFUs per unit Propionibacterium acnes was delayed and only detectable after 5, 2, and 5 days of storage, respectively. Low levels of Streptococcus agalactiae (1-10 CFUs/unit), Escherichia coli (1-100 CFUs/unit), and Clostridium perfringens (1-100 CFUs/unit) were not detected during 5 days of storage, although bacterial outgrowth was detected at higher levels of contamination.

CONCLUSIONS

For the seven bacterial species examined, contaminated PLTs may be released for transfusion on test-negative-to-date status. In contrast, bacterial inactivation by PCT could reduce the risk associated with transfusion of PLTs contaminated with low levels of these bacteria.

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.

[New container of sample: role in the reduction of bacterial contamination of standard platelet units]

BACKGROUND

Bacterial contamination of unstable blood products constitutes today the most frequent infectious risk transmitted by blood transfusion. Platelet concentrates are often incrimineted. As responsible germs are in general of cutaneous origin, a sample procedure with diversion of the first 20 ml during blood donation is studied. The aim of this study is to evaluate the results of this technique on bacterial contamination rate of standard platelet units prepared at the regional blood transfusion center in Casablanca.

STUDY DESIGN AND METHODS

A comparative study of two types of sample pockets is made: 500 Standard Platelet concentrates (CPS) are prepared after collection using standard triple bags (Baxter) (group 1) and 560 pockets of CPS were prepared after collection using triple bags with Sample Diversion Pouch sampling system for elimination of the first 20 ml of donation (Macopharma and Terumo) (group 2). The skin was disinfected in two times with alcohol 70%. The bacteriological study was made in the two groups at the third day of conservation.

RESULTS

Six CPS of group 1 were contaminated, of which five were staphylococci coagulase negative and one bacillus sp. Six CPS of group 2 were contaminated, of which five were staphylococci coagulase negative and one staphylococcus aureus. The bacteria isolated were those of cutaneous flora at 100%. Diversion of first 20 ml of blood donation results in a 16.6% reduction in bacterial contamination of CPS (P>0.05).

CONCLUSION

The non-significant reduction in the prevalence of the bacterial infection of CP formulates the problem of the indication of the sampling devices with derivation of first 20 ml during blood collection.

Comparison of the BACTEC 9240 and BacT/Alert blood culture systems for detection of bacterial contamination in platelet concentrates

The BACTEC 9240 blood culture system with a standard aerobic medium, Plus Aerobic/F, was compared to the BacT/Alert system with a platelet-specific medium, BPA, as a means for detecting bacterial contamination of platelet preparations. One hundred thirteen platelet units seeded with low levels of different bacteria were examined with both systems. In 93 instances, growth was detected first in the BACTEC system; in 12 cases, growth registered first in the BacT/Alert system. Among all comparisons, growth was detected, on average, 1.7 h sooner with the BACTEC system. The differences in length of time to detection were statistically significant.

Transfusion of 7-day-old amotosalen photochemically treated buffy-coat platelets to patients with thrombocytopenia: a pilot study

BACKGROUND

Photochemical treatment (PCT) of platelets (PLTs) with amotosalen and ultraviolet A light to inactivate bacteria may facilitate extension of storage from 5 to 7 days.

STUDY DESIGN AND METHODS

A randomized, double-blinded, crossover, noninferiority, single-site pilot study utilizing pooled buffy-coat PLTs was conducted. The primary endpoint was the 1-hour corrected count increment (CCI) after one transfusion each of 7-day-old PCT and reference (R) PLT components. Secondary endpoints included 1-hour count increment, time to next transfusion, hemostasis, transfusion reactions, and serious adverse events.

RESULTS

Twenty patients with thrombocytopenia were randomly assigned: 9 to the PCT-R sequence and 11 to the R-PCT sequence. A significant treatment-by-period interaction was observed. Therefore, the first period only was also analyzed for the primary endpoint. Including both treatment periods, mean 1-hour CCI was 6587 +/- 4531 for PCT versus 8935 +/- 5478 for R-PLTs. For the first period only, mean 1-hour CCI was 8739 +/- 3785 for PCT versus 7433 +/- 5408 for R-PLTs. The upper bound of the one-sided 95 percent confidence interval of 2400 for the mean difference was higher than the specified noninferiority margin of 2200 for both analyses. Overall median time to next transfusion was 22 hours for PCT versus 27 hours for R-PLTs. Hemostasis was adequate and no transfusion reactions or serious adverse events were reported.

CONCLUSIONS

Although this pilot study of a limited number of patients failed to show noninferiority within the specified noninferiority margin, 7-day-old PCT PLTs showed acceptable efficacy and safety for support of thrombocytopenia. The results, however, warrant evaluation in a larger trial of 7-day-old PCT PLTs.

Infectious complications after cardiac surgery: lack of association with fresh frozen plasma or platelet transfusions

OBJECTIVE

The purpose of this study was to examine the effect of perioperative transfusion of platelets and fresh frozen plasma (FFP) on infection rates after cardiac surgery.

DESIGN

Retrospective study comparing infection rates after cardiac surgery among patients receiving combinations of packed red blood cells (PRBCs), platelets, and FFP.

SETTING

Tertiary care university teaching hospital.

PARTICIPANTS

All elective primary coronary artery bypass (CABG) surgery patients from July 1995 to January 1998 before introduction of leukocyte-reduced blood products.

INTERVENTIONS

Multivariate logistic and linear regression models were applied to identify clinical risk factors for postoperative infection and to determine the relationship between perioperative administration of PRBCs, platelets, and FFP with postoperative infection.

MEASUREMENTS AND MAIN RESULTS

Transfusion of PRBCs, diabetes, age, preoperative hematocrit, and the duration of cardiopulmonary bypass were significantly associated with postoperative infection; platelet or FFP transfusion added no additional risk to PRBC transfusion alone.

CONCLUSIONS

Infectious complications in a population of adult primary CABG surgery patients were not increased by transfusion of platelets or FFP. It is PRBC transfusion that confers an increased risk of postoperative infection in this population.

In vitro function of platelet concentrates prepared after filtration of whole blood or buffy coat pools

BACKGROUND/METHOD

Data on the quality of platelet concentrates (PC) produced by the buffy coat method and stored beyond 5 days in plasma are limited. We therefore evaluated the quality of PCs prepared by leucocyte depletion of whole blood (Terumo WBSP, n = 10) or a buffy coat pool (Pall Autostop, n = 10), and stored for 7 days in plasma by assessing platelet parameters and markers of platelet activation.

RESULTS

In both types of PC, levels of glucose decreased during storage but were not totally depleted (> 11 mM on day 7). In contrast, lactate levels increased on storage and was consistently < 20 mM throughout, with pH maintained at > 6.8 in all units. Hypotonic shock response scores were > 47% in all units at day 7. On day 1, markers of platelet activation were significantly higher in WBSP PC, but by day 7 were similar for percentage CD63+ and CD62P + (40%) with levels of platelet microparticles and annexin V binding two-fold higher in WBSP. The expression of CD61 did not alter during storage and the percentage of platelets expressing CD42b was > 88% in all units on day 7. RANTES (Regulated on activation, normal, T-cell expressed and secreted) and TGFbeta released from platelets by day 7 was < 800 ng/ml and 90 ng/ml, respectively. C3a(desarg) increased throughout storage in both types of PC, but without a commensurate increase in the terminal complex SC5b-9 or activation of factor XII.

CONCLUSION

Our data indicates that the in vitro characteristics of PCs prepared using these methods is maintained over storage for 7 days in plasma and is not associated with significant deterioration of platelet function. ONE SENTENCE SUMMARY: In vitro function of platelet concentrates prepared by either filtration of whole blood, or pooled buffy coats.

Bacterial contamination of blood components

Blood for transfusion is a potential source of infection by a variety of known and unknown transmissible agents. Over the last 20 years, astounding reductions in the risk of viral infection via allogeneic blood have been achieved. As a result of this success, bacterial contamination of blood products has emerged as the greatest residual source of transfusion-transmitted disease. This paper summarizes the current status of detection, prevention, and elimination of bacteria in blood products for transfusion.

Photochemical treatment of platelet concentrates with amotosalen and long-wavelength ultraviolet light inactivates a broad spectrum of pathogenic bacteria

BACKGROUND

Bacterial contamination of platelet (PLT) concentrates can result in transfusion-transmitted sepsis. A photochemical treatment (PCT) process with amotosalen HCl and long-wavelength ultraviolet light (UVA), which cross-links nucleic acids, was developed to inactivate bacteria and other pathogens in PLT concentrates.

STUDY DESIGN AND METHODS

High titers of pathogenic aerobic and anaerobic Gram-positive bacteria (10 species), aerobic Gram-negative bacteria (7 species), and spirochetes (2 species) were added to single-donor PLT concentrates containing 3.0 x 10(11) to 6.0 x 10(11) PLTs in approximately 300 mL of 35 percent plasma and 65 percent PLT additive solution (InterSol, Baxter Healthcare) or saline. After PCT with 150 micro mol per L amotosalen and 3 J per cm(2) UVA, residual bacterial levels were detected by sensitive microbiologic methods.

RESULTS

The level of inactivation of viable bacteria was expressed as log reduction. Log reduction of Gram-positive bacteria for Staphylococcus epidermidis was > 6.6; for Staphylococcus aureus, 6.6; for Streptococcus pyogenes, > 6.8; for Listeria monocytogenes, > 6.3; for Corynebacterium minutissimum, > 6.3; for Bacillus cereus (vegetative), > 5.5; for Lactobacillus sp., > 6.4; for Bifidobacterium adolescentis, > 6.0; for Propionibacterium acnes, > 6.2; and for Clostridium perfringens, > 6.5. Log reduction of Gram-negative bacteria for Escherichia coli was > 6.4; for Serratia marcescens, > 6.7; for Klebsiella pneumoniae, > 5.6; for Pseudomonas aeruginosa, 4.5; for Salmonella choleraesuis, > 6.2; for Yersinia enterocolitica, > 5.9; and for Enterobacter cloacae, 5.9. Log reduction of spirochetes for Treponema pallidum was 6.8 to 7.0, and for Borrelia burgdorferi, > 6.9.

CONCLUSION

PCT inactivates high levels of a broad spectrum of pathogenic bacteria. The inactivation of bacteria in PLT concentrates offers the potential to prospectively prevent PLT-transfusion-associated bacteremia.

Rapid screening method for detection of bacteria in platelet concentrates

Public awareness has long focused on the risks of the transmission of viral agents through blood product transfusion. This risk, however, pales in comparison to the less publicized danger associated with the transfusion of blood products contaminated with bacteria, in particular, platelet concentrates. Up to 1,000 cases of clinical sepsis after the transfusion of platelet concentrates are reported annually in the United States. The condition is characterized by acute reaction symptoms and the rapid onset of septicemia and carries a 20 to 40% mortality rate. The urgent need for a method for the routine screening of platelet concentrates to improve patient safety has long been recognized. We describe the development of a rapid and highly sensitive method for screening for bacteria in platelet concentrates for transfusion. No culture period is required; and the entire procedure, from the time of sampling to the time that the final result is obtained, takes less than 90 min. The method involves three basic stages: the selective removal of platelets by filtration following activation with a monoclonal antibody, DNA-specific fluorescent labeling of bacteria, and concentration of the bacteria on a membrane surface for enumeration by solid-phase cytometry. The method offers a universal means of detection of live, nondividing, or dead gram-negative and gram-positive bacteria in complex cellular blood products. The sensitivity is higher than those of the culture-based methods available at present, with a detection limit of 10 to 10(2) CFU/ml, depending upon the bacterial strain.

Optimizing platelet transfusion therapy

Platelet transfusions are widely used. Prophylactic transfusions are employed in severely thrombocytopenic patients without evidence of bleeding, but no randomized trial data prove the safety or efficacy of this approach. Randomized trials have demonstrated the equivalence of transfusion triggers of 10,000 and 20,000/microl for prophylactic transfusions. The former threshold is potentially safer for the patient, conservative of donor resources and leads to lower costs, with perhaps a slightly greater risk of minor hemorrhage. Randomized trials have demonstrated the equivalence of pheresis or whole blood-derived platelet transfusions. The former present a lower risk for infectious agents, and the latter are less expensive and a more efficient use of limited donor resources. Randomized trials prove that leukoreduced and ABO identical platelet transfusions reduce the risks of HLA alloimmunization and platelet transfusion refractoriness (both leukoreduction and ABO matching), transfusion reactions (leukoreduction) and CMV transmission (leukoreduction). Leukoreduction and ABO matching of platelet transfusions also have been associated in preliminary observational studies with reduced morbidity and mortality in surgical patients and reduced infections in patients with leukemia. These results require further investigation. Future challenges include (1) determining the best approach to bacterial contamination of platelets, whether by detection methods or pathogen inactivation and (2) determining the threshold for prophylactic platelet transfusions in thrombocytopenic patients undergoing surgery or invasive procedures.

Association of Laribacter hongkongensis in community-acquired gastroenteritis with travel and eating fish: a multicentre case-control study

BACKGROUND

Laribacter hongkongensis has been recovered from several patients with gastroenteritis. However, the causative role of this organism in human gastroenteritis is still unproven, and sources of the bacterium are unknown. We undertook a multicentre case-control study to investigate the association of L hongkongensis with gastroenteritis.

METHODS

Faecal samples from patients with community-acquired gastroenteritis and controls were cultured for L hongkongensis. Targeted food surveillance was done to identify potential sources of this bacterium. All isolates of this organism from patients and food items were characterised by pulsed-field gel electrophoresis and ribotyping.

FINDINGS

During a 4-month period, L hongkongensis was recovered from 17 of 3788 patients with community-acquired gastroenteritis, but was absent in 1894 controls (p=0.001). Those who were culture-positive for this bacterium had a recent history of travel (ten [59%] patients vs two [6%] of 34 matched controls, p<0.0001), of fish consumption (16 [94%] vs 19 [56%], p=0.009), and of eating minced freshwater fish meat (five [29%] vs one [3%], p=0.012). We recovered 25 L hongkongensis isolates from intestinal samples of freshwater fish and two from minced freshwater fish meat. Bacteria with the same pulsed-field gel electrophoretic pattern and ribotype were recovered from one patient and a sample of minced freshwater fish meat, which was from the same retail market recently visited by the patient. We did not see this particular combination of electrophoretic pattern and ribotype in any other isolates.

INTERPRETATION

L hongkongensis is associated with community-acquired gastroenteritis and traveller's diarrhoea. However, its causative role has not been shown. Freshwater fish is one source of this bacterium.

Effect of thrombopoietin alone and a combination of cytochalasin B and ethylene glycol bis(β-aminoethyl ether) N,N′-tetraacetic acid-AM on the survival and function of autologous baboon platelets stored at 4°C for as long as 5 days

BACKGROUND

PLTs stored at 22 degrees C have the potential for bacterial contamination, a problem that could be reduced by 4 degrees C storage. Nevertheless, PLTs stored at 4 degrees C exhibit a significantly reduced life span. This study was performed to determine whether treatment of PLTs with thrombopoietin or cytochalasin B plus ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA)-AM could prevent exponential loss of PLTs stored at 4 degrees C.

STUDY DESIGN AND METHODS

Autologous baboon PLTs were stored at 22 or 4 degrees C. The 4 degrees C stored PLTs were treated with 1.5 ng per mL thrombopoietin, with 1 micro mol per L cytochalasin B, and 80 micromol per L EGTA-AM (cyto-EGTA) or not treated and labeled with (111)In-oxine to study their in vivo recovery and life span. PLT function was assessed by correction of an aspirin-induced prolonged bleeding time. Aggregation responses and morphology were also assessed.

RESULTS

PLTs stored at 22 degrees C had normal in vivo recovery and linear survival. PLTs stored at 4 degrees C, whether or not they were treated with thrombopoietin, had normal recovery and exponential survival. Aggregation of cyto-EGTA-treated PLTs was similar for PLTs stored at 4 degrees C and fresh PLTs, but decreased in PLTs stored at 22 degrees C for 5 days. The addition of cyto-EGTA to PLTs before 4 degrees C storage inhibited morphologic changes that occurred in PLTs stored at 22 degrees C and cold-induced PLT clumping, but did not prevent exponential disappearance of the PLTs.

CONCLUSION

Addition of thrombopoietin or cyto-chalasin B and EGTA-AM to PLTs before 4 degrees C storage did not prevent exponential loss of PLTs.

Transfusion-transmitted bacterial infection: risks, sources and interventions

Records of the transmission of bacterial infections by transfusion date back to the beginning of organized blood banking. Despite tremendous strides in preventing viral infection through careful donor screening and viral testing, there has been little improvement in reducing the risk of bacterial sepsis since the introduction of closed collection systems. Based on the French Haemovigilance study, the British Serious Hazards of Transmission (SHOT) study and fatality reports to the United States Food and Drug Administration, the risk of clinically apparent sepsis exceeds the risk of HIV, HBV, and HCV transmission. Sources of contamination include the skin, blood, disposables, and the environment. Potential interventions to reduce transfusion-associated bacterial sepsis include improvements to donor arm preparation, diversion of the first aliquot of whole blood, introduction of bacterial testing and/or implementation of pathogen reduction methods.

Estimation of bacterial risk in extending the shelf life of PLT concentrates from 5 to 7 days

BACKGROUND

The use of bacterial culture to prevent bacterial contamination of blood components has renewed interest for extending the shelf life of PLT concentrates to 7 days after collection.

STUDY DESIGN AND METHODS

This study was therefore conducted to determine the residual risk of bacterial contamination in PLT concentrates at the end of 5 and 7 days after collection in a center where all PLT concentrates are routinely screened by taking samples on Day 2 for culture. PLT units with no growth after 48 hours were sampled a second time on Day 5 or Day 7 after collection, followed by inoculation into aerobic culture bottles. The inoculated bottles were then monitored for up to 7 days at 35 degrees C in an automatic monitoring and detection system.

RESULTS

During a 16-month study period, a total of 6020 PLT concentrates were tested 5 days (Group A, n=3010) and 7 days (Group B, n=3010) after collection. Four units in each group (0.133%) were found to be contaminated. In 6 units, bacteria were seen on direct Gram stain. In addition, 5 of the associated RBC units grew the same organisms on culture. The organisms include three coagulase-negative staphylococci and five Propionibacterium acnes. The positive rate of routine short-term bacterial culture was 0.035 percent during the same study period.

CONCLUSION

Despite routine short-term bacterial culture, a significant risk of bacterial contamination remains at 5 and 7 days after collection. For now, the shelf life of PLT concentrates should remain 5 days.

Risks associated with transfusion of cellular blood components in Canada

We provide a comprehensive review of risks associated with allogeneic red blood cell and platelet transfusions in Canada. The review focuses on clinically symptomatic noninfectious transfusion risks (acute and delayed hemolytic, febrile nonhemolytic [FNHTR], allergic, volume overload, transfusion-related acute lung injury, graft-versus-host disease, and posttransfusion purpura) and the risk of clinically significant disease from transfusion-transmitted infections. Data sources include information from Canadian Blood Services, Héma-Québec, Health Canada, and the Québec Hemovigilance System as well as published information from research studies and international hemovigilance systems. We estimate that in 2000 the aggregate risk of potentially severe reactions (excluding FNHTR and minor allergic reactions) was 43.2 per 100000 red cell units (95% confidence interval [CI]: 38.7-48.1), affecting 337 recipients, and 125.7 per 100000 platelet pools of 5 units (95% CI: 100.8-154.9), affecting 88 recipients. The most frequent potentially severe outcomes for red cell transfusion were hemolytic reactions and volume overload and for platelet transfusion were major allergic reactions and bacterial contamination. The current risk of human immunodeficiency virus and hepatitis C virus transmission is approximately 1 in 4 million and 1 in 3 million units, respectively. These estimates are useful for decisions concerning transfusion therapy, the informed consent process, and for evaluating efficacy of interventions to reduce risk.

Bacterial Contamination of Blood Components: Risks, Strategies, and Regulation

Bacterial contamination of transfusion products, especially platelets, is a longstanding problem that has been partially controlled through modern phlebotomy practices, refrigeration of red cells, freezing of plasma and improved materials for transfusion product collection and storage. Bacterial contamination of platelet products has been acknowledged as the most frequent infectious risk from transfusion occurring in approximately 1 of 2,000–3,000 whole-blood derived, random donor platelets, and apheresis-derived, single donor platelets. In the US, bacterial contamination is considered the second most common cause of death overall from transfusion (after clerical errors) with mortality rates ranging from 1:20,000 to 1:85,000 donor exposures. Estimates of severe morbidity and mortality range from 100 to 150 transfused individuals each year.

Concern over the magnitude and clinical relevance of this issue culminated in an open letter calling for the “blood collection community to immediately initiate a program for detecting the presence of bacteria in units of platelets.” Thereafter, the American Association of Blood Banks (AABB) proposed new standards to help mitigate transfusion of units that were contaminated with bacteria. Adopted with a final implementation date of March 1, 2004, the AABB Standard reads “The blood bank or transfusion service shall have methods to limit and detect bacterial contamination in all platelet components.”

This Joint ASH and AABB Educational Session reviews the risks, testing strategies, and regulatory approaches regarding bacterial contamination of blood components to aid in preparing practitioners of hematology and transfusion medicine in understanding the background and clinical relevance of this clinically important issue and in considering the approaches currently available for its mitigation, as well as their implementation.

In this chapter, Drs. Hillyer and Josephson review the background and significance of bacterial contamination, as well as address the definitions, conceptions and limitations of the terms risk, safe and safety. They then describe current transfusion risks including non-infectious serious hazards of transfusion, and current and emerging viral risks. In the body of the text, Dr. Blajchman reviews the prevalence of bacterial contamination in cellular blood components in detail with current references to a variety of important studies. He then describes the signs and symptoms of transfusion-associated sepsis and the sources of the bacterial contamination for cellular blood products including donor bacteremia, and contamination during whole blood collection and of the collection pack. This is followed by strategies to decrease the transfusion-associated morbidity/mortality risk of contaminated cellular blood products including improving donor skin disinfection, removal of first aliquot of donor blood, pre-transfusion detection of bacteria, reducing recipient exposure, and pathogen reduction/inactivation. In the final sections, Drs. Vostal, Epstein and Goodman describe the regulations and regulatory approaches critical to the appropriate implementation of a bacterial contamination screening and limitation program including their and/or the FDA’s input on prevention of bacterial contamination, bacterial proliferation, and detection of bacteria in transfusion products. This is followed by a discussion of sampling strategy for detection of bacteria in a transfusion product, as well as the current approval process for bacterial detection devices, trials recommended under “actual clinical use” conditions, pathogen reduction technologies, and bacterial detection and the extension of platelet storage.

Transfusion medicine for the pediatrician

In the next decade, many of the methodologies and research reviewed in this article will become clinical practice, making the transfusion of blood products safer and more universally available than they are today. NAT will be standard and will surely be performed on each unit of product, PCR testing for pathogens will evolve, and the pathophysiology and immunology of transfusion-related events such as TRALI and immunomodulation will be elucidated. New methods of preservation and early detection of contamination will extend the life of blood products. Red blood cell antigens may be attenuated, making safe products available to more patients. Clinical vigilance at the bedside and in the blood bank will remain key areas for transfusion safety. As I have told many a resident and patient, blood is not saline; there are and will remain risks inherent in this commonly used medical therapy.

Recombinant human thrombopoietin: basic biology and evaluation of clinical studies

Thrombocytopenia is a common medical problem for which the main treatment is platelet transfusion. Given the increasing use of platelets and the declining donor population, identification of a safe and effective platelet growth factor could improve the management of thrombocytopenia. Thrombopoietin (TPO), the c-Mpl ligand, is the primary physiologic regulator of megakaryocyte and platelet development. Since the purification of TPO in 1994, 2 recombinant forms of the c-Mpl ligand--recombinant human thrombopoietin (rhTPO) and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF)--have undergone extensive clinical investigation. Both have been shown to be potent stimulators of megakaryocyte growth and platelet production and are biologically active in reducing the thrombocytopenia of nonmyeloablative chemotherapy. However, neither TPO has demonstrated benefit in stem cell transplantation or leukemia chemotherapy. Other clinical studies have investigated the use of TPO in treating chronic nonchemotherapy-induced thrombocytopenia associated with myelodysplastic syndromes, idiopathic thrombocytopenic purpura, thrombocytopenia due to human immunodeficiency virus, and liver disease. Based solely on animal studies, TPO may be effective in reducing surgical thrombocytopenia and bleeding, ex vivo expansion of pluripotent stem cells, and as a radioprotectant. Ongoing and future studies will help define the clinical role of recombinant TPO and TPO mimetics in the treatment of chemotherapy- and nonchemotherapy-induced thrombocytopenia.

Impact of donor arm skin disinfection on the bacterial contamination rate of platelet concentrates

BACKGROUND AND OBJECTIVES

Despite improved methods for detecting bacterial contamination of blood products, bacterial sepsis remains a significant risk in blood transfusion. This study was undertaken to investigate whether adopting a different skin disinfection protocol could reduce the rate of bacterial contamination of platelet concentrates.

MATERIALS AND METHODS

Two skin disinfection protocols were consecutively used in the routine blood collection setting during two 10-month periods: 0.5% cetrimide/0.05% chlorhexidine solution followed by 70% isopropyl alcohol (first 10-month time-period); and 10% povidone-iodine followed by 70% isopropyl alcohol (second 10-month time-period). The rates of bacterial contamination of platelet concentrates were monitored by using a surveillance programme described previously.

RESULTS

The overall bacterial contamination rate in the first time-period was 0.072%. After introduction of the povidone-iodine and isopropyl alcohol protocol, the bacterial contamination rate decreased to 0.042% (relative risk reduction: -0.42; 95% confidence interval, -0.12 to -0.61, P= 0.009). There were no differences in the types of micro-organisms identified (P = 0.7).

CONCLUSIONS

Skin disinfection by povidone-iodine and isopropyl alcohol is more effective than that by cetrimide/chorhexidine and isopropyl alcohol in reducing venepuncture-associated contamination of platelet concentrates by skin flora. Our data indicate that the disinfection protocol should be used on a routine basis and such implementation should translate into a significant improvement in blood safety to patients receiving platelet transfusion.

Bacterial contamination of blood products: factors, options, and insights

Transfusion of bacterially contaminated blood products remains an overlooked problem. However, the risk of receiving a bacterially contaminated unit is greater than the combined risk of HIV-1/2, HCV, HBV, and HTLV I/II [American Association of Blood Banks Bulletin, no. 294, 1996]. Topics covered in this article include: the current incidence, clinical presentation and outcome, effective methods of detection, and ways to reduce bacterial contamination of blood products. There is no one existing strategy that can completely eliminate the risk of bacterial contamination. It is inevitable that partial solutions or combinations of methods will be implemented in the near future.

Electrochemiluminescent detection of bacteria in blood components

Transfusion-transmitted bacterial infections cause significant patient morbidity and mortality. This study aimed to improve the sensitivity of a nucleic acid-based electrochemiluminescence (ECL) assay for pretransfusion bacterial testing of cellular blood components. The approach is dependent on the detection of bacterial 16S ribosomal RNA (rRNA). The modifications studied included the use of a chaotrope-based lysis buffer with high-energy mechanical cell disruption by RiboLysis, increased ruthenium (Ru2+) labelling per 16S rRNA molecule and concomitant use of fluorescent nucleic acid dyes (CyQUANT, Syto 17 red and Syto 61 red). The methodological changes made did lead to more effective bacterial cell disruption and enhanced ECL signal generation. Nevertheless, assay sensitivity was only slightly improved at approximately 10(4)-10(5) colony forming units per mL (CFU mL(-1)) and the results were highly inconsistent. The method is still not sensitive to the required 10(2) CFU mL(-1) and remains impractical for routine use in blood centres.

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.

Transfusion-transmitted bacterial infection in the United States, 1998 through 2000

BACKGROUND

Bacterial contamination of blood components can result in transfusion-transmitted infection, but the risk is not established.

STUDY DESIGN AND METHODS

Suspected cases of transfusion-transmitted bacteremia were reported to the CDC by participating blood collection facilities and transfusion services affiliated with the American Red Cross, AABB, or Department of Defense blood programs from 1998 through 2000. A case was defined as any transfusion reaction meeting clinical criteria in which the same organism species was cultured from a blood component and from recipient blood, with the organism pair confirmed as identical by molecular typing.

RESULTS

There were 34 cases and 9 deaths. The rate of transfusion-transmitted bacteremia (in events/million units) was 9.98 for single-donor platelets, 10.64 for pooled platelets, and 0.21 for RBC units; for fatal reactions, the rates were 1.94, 2.22, and 0.13, respectively. Patients at greatest risk for death received components containing gram-negative organisms (OR, 7.5; 95% CI, 1.3-64.2; p = 0.009).

CONCLUSION

Bacterial contamination of blood is an important cause of transfusion-transmitted infection; infection risk from platelet transfusion is higher compared with that from RBCs, and, overall, the risk of infection from bacterial contamination now may exceed that from viral agents. Recipients of components containing gram-negative organisms are at highest risk for transfusion-related death. The results of this study may help direct efforts to improve transfusion-related patient safety.

Transfusion-related bacterial sepsis

Transfusion-associated bacterial sepsis is a persistent problem in transfusion medicine, posing a greater threat than the combined risks of receiving a blood product contaminated with HIV-1 or 2, hepatitis C virus (HCV), hepatitis B virus (HBV), and human T-cell lymphtrophic virus (HTVL) -I or -II. This article provides a brief overview of the current incidence, clinical presentation, associated blood products and organisms, and the most feasible and effective methods available to reduce the potential risk of transfusion-associated sepsis. Because bacterial contamination of blood products is the most frequent cause of transfusion-transmitted infectious disease, and as no single existing strategy can completely eliminate its risk, it is important that clinical suspicion be high, and any partial solutions additively be implemented.

Methicillin-resistant Staphylococcus aureus sepsis associated with the transfusion of contaminated platelets: a case report

BACKGROUND

Platelet transfusion-associated sepsis is usually due to donor skin flora introduced into the unit during phlebotomy. An unusual case of a platelet component contaminated with methicillin-resistant Staphylococcus aureus (MRSA) is reported.

CASE REPORT

A 54-year-old man, terminally ill with progressive non-Hodgkin's lymphoma, developed fever and hypotension during a platelet transfusion. He was receiving multiple antibiotics, including vancomycin. Blood cultures taken soon after transfusion were negative. An aliquot taken from the platelet pool grew MRSA at a count of 1.6 x 10(8) CFUs per mL. One of the individual bags constituting the pool showed MRSA at a count of 5.1 x 10(8) CFUs per mL. The patient died soon after the platelet transfusion. This case was reported to the FDA and submitted to the BaCon Study. The identity of the isolate and its methicillin resistance were confirmed by the CDC as part of the BaCon Study protocol. The source of contamination of the implicated unit could not be established with certainty.

CONCLUSION

The emergence of antimicrobial-resistant organisms poses additional challenges for the diagnosis and treatment of transfusion-associated sepsis. Measures to prevent or intercept the transfusion of contaminated platelets should be developed.

Bacterial contamination of platelet concentrates: incidence, significance, and prevention

Severe transfusion reactions associated with bacteria and/or their products, during or following a blood transfusion, were one of the earliest recognized complications of allogeneic blood transfusions. Bacterial contamination of blood products has thus been a problem for many decades and at present is likely the most common microbiological cause of transfusion-associated morbidity and mortality. Transfusion-associated sepsis due to contaminated platelet concentrates appears to be much more common than that due to contaminated red blood cells. The overall incidence of contaminated cellular blood products is approximately 1 in 3,000. However, transfusion to a recipient of a contaminated platelet unit may not necessarily be associated with clinically apparent morbidity, because the majority of contaminated platelet units contain relatively few organisms. In a minority of instances, contaminated units contain large numbers of potentially virulent bacteria, as well as endotoxins, and their transfusion is often associated with significant recipient morbidity and mortality. The incidence of severe septic episodes has not been clearly established, but is probably of the order of 1 per 50,000 platelet units transfused. With heightened awareness in recent years of the possibility that platelet transfusion-associated septic episodes can occur, a variety of measures have been proposed, and in some cases implemented, to try to prevent and control this transfusion risk.

Determinants of transfusion-associated bacterial contamination: results of the French BACTHEM Case-Control Study

BACKGROUND

Transfusion-associated bacterial contamination (TABC), probably the most frequent transfusion-transmitted infection, may induce serious adverse events. Systematic information and documentation on determinants are lacking.

STUDY DESIGN AND METHODS

The BACTHEM Study is a French matched case-control study assessing TABC determinants. Included were cases of TABC reported in France in a 2-year period, as determined from uniform definitions. Information on recipient-, blood component-, and donor-related potential determinants was collected on site. ORs were estimated by conditional logistic regression.

RESULTS

Of the 158 cases of suspected TABC reported, 41 that involved transfusion with 25 RBCs and 16 platelet concentrates were included. Gram-negative rods accounted for nearly half of the bacteria species involved and for all six deaths. In comparison with the risk of TABC for patients receiving RBCs for anemia, the risk was higher for patients receiving RBCs for pancytopenia (OR, 7.3; 95% CI, 1.3-41.0) and for those receiving platelets for thrombocytopenia (OR, 5.3; 95% CI, 1.2-24.1). Other potential determinants were platelet transfusion for pancytopenia (OR, 4.5; 95% CI, 0.5-40.0), immunosuppressive treatment (OR, 2.8; 95% CI, 0.7-10.6), shelf-life of more than 1 day for platelets or 8 days for RBCs (OR, 2.6; 95% CI, 0.7-9.6), and more than 20 previous donations by donors (OR, 1.9; 95% CI, 0.7-5.3).

CONCLUSION

This first comparative study revealed TABC determinants that suggest approaches for prevention.