Reduction of bacterial load by predonation sampling

Bacterial contamination rates in extracorporeal photopheresis

BACKGROUND

Extracorporeal photopheresis (ECP) is an immunosuppressive treatment that involves leukocyte apheresis, psoralen and UV light treatment, and subsequent reinfusion. Patients treated with ECP are usually immunosuppressed. Bacterial contamination therefore poses a much unwanted risk, but incidence data are lacking.

PATIENTS AND METHODS

We screened all 1922 consecutive ECP procedures scheduled within a roughly 3-year period for eligibility. Those with missing data on ECP method (inline or offline) or type of venous access (peripheral or central) were excluded. ECPs with complete aerobic and anaerobic microbial testing of baseline patient blood samples (n = 1637) and of ECP cell concentrates (n = 1814) were included in the analysis.

RESULTS

A test for microbial contamination was positive for 1.82% of the cell concentrates, with central venous access was the most significant risk factor for the contamination (odds ratio = 19). Patient blood samples were positive in 3.85% of cases, but no patients became septic. Staphylococcus spp. were most abundant, and products with bacterial contamination did not cause side effects after reinfusion. There were no significant differences in contamination rates between inline and offline ECP.

CONCLUSION

These findings stress the importance of sterile procedures and the benefits of using peripheral over central venous access for reducing the risk of bacterial contamination in ECP.

Gewinnung, Herstellung und Lagerung von Blut und Blutkomponenten

Blutspender leisten einen wertvollen Dienst für die Gemeinschaft: Die ständige Verfügbarkeit von Blutkomponenten ist zur unverzichtbaren Voraussetzung für viele Bereiche der Medizin geworden. Nicht nur die Gewinnung und Aufarbeitung von Blut und Blutbestandteilen zur Sicherstellung einer qualitativ wie quantitativ guten Versorgung, sondern auch die kompetente Betreuung der Spender ist eine der großen Aufgaben der Transfusionsmedizin.

Real-time RT-PCR for automated detection of HIV-1 RNA during blood donor screening

Real-time RT-PCR has become the method of choice for automated detection of viral RNA target sequences in the clinical laboratory. Besides commercially available certified test systems, a variety of so-called in-house methods have been described in the literature. Generally, appropriate validation and continuous quality control are mandatory if these in-house-developed assays are used in clinical diagnostics. In this chapter, an in-house HIV-1 real-time RT-PCR assay for blood donor screening is described. The procedure includes the pooling of plasma samples, viral RNA isolation, and subsequent detection of amplification in real-time one-step RT-PCR. The validation considers the specificity, the sensitivity on HIV-1 genomic variants, and the robustness of the assay.

Transfusion-transmitted infections

Although the risk of transfusion-transmitted infections today is lower than ever, the supply of safe blood products remains subject to contamination with known and yet to be identified human pathogens. Only continuous improvement and implementation of donor selection, sensitive screening tests and effective inactivation procedures can ensure the elimination, or at least reduction, of the risk of acquiring transfusion transmitted infections. In addition, ongoing education and up-to-date information regarding infectious agents that are potentially transmitted via blood components is necessary to promote the reporting of adverse events, an important component of transfusion transmitted disease surveillance. Thus, the collaboration of all parties involved in transfusion medicine, including national haemovigilance systems, is crucial for protecting a secure blood product supply from known and emerging blood-borne pathogens.

[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.

Optimized Scansystemtm platelet kit for bacterial detection with enhanced sensitivity: detection within 24 h after spiking

BACKGROUND AND OBJECTIVES

The prevention and detection of bacterial contamination of platelet concentrates remains a major challenge for transfusion medicine. To be suitable for blood-transfusion services, the contamination detection method must be highly sensitive, easy to perform and preferably of low cost. In this spiking study, we evaluated the new optimized Scansystem Platelet Kit detection method for use on apheresis platelets.

STUDY DESIGN AND METHODS

Apheresis platelet concentrates (APCs) were individually spiked with 10 colony-forming units (CFU)/ml of one of 10 different strains of bacteria. The spiked APCs were analysed at specific time-points during incubation by using the optimized Scansystem Platelet Kit. Bacterial enumeration was performed by plating onto blood agar.

RESULTS

All the bacterial strains tested were detected by using the optimized Scansystem Platelet Kit when sampled 24 h after spiking. Compared to the Scansystem standard kit, sensitivity was increased to < 50 CFU/ml. The identity of the spiked bacteria was confirmed by Gram staining and DNA fingerprinting.

CONCLUSION

The optimized Scansystem Platelet Kit was able to reliably detect, within 70 min, 10 transfusion-relevant bacterial species in APCs when a sample volume was taken 24 h after spiking. This is the first study carried out by using the optimized Scansystem bacterial detection that was found to have an enhanced sensitivity compared to the standard kit.

ORIGINAL PAPER. Relative values of the interventions of diversion and improved donor-arm disinfection to reduce the bacterial risk from blood transfusion

BACKGROUND AND OBJECTIVES

The aim of this study was to demonstrate the efficiency of diverting the initial 20-ml donation from the collection bag and of an improved donor-arm disinfection procedure in reducing bacterial contamination in blood.

MATERIALS AND METHODS

Donations were collected in bags specially manufactured for the study. These bags incorporated two satellite pouches into each of which 20 ml of blood was collected. Blood initially flowed into sample pouch P1, representing a diversion pouch. Pouch P2 was then filled with 20 ml of blood, which allowed us to sample the collection bag after diversion was complete. Blood then flowed into the standard collection bag. The contents of the pouches were aerobically and anaerobically cultured on the BacT/ALERT automated culture system for 7 days. Two procedures were investigated in the study (each involving 1409 blood donations): one analysed the current disinfection procedure; and the other analysed an improved donor-arm disinfection procedure.

RESULTS

The use of diversion alone resulted in a 47% reduction in contamination, and improved donor-arm disinfection alone resulted in a 57% reduction in contamination. Diversion plus improved donor-arm disinfection produced a predicted 77% reduction in contamination.

CONCLUSIONS

The study validates diversion and an improved donor-arm disinfection procedure. In combination, these two interventions produced a substantial reduction in contamination. These procedures are to be introduced by the English National Blood Service to enhance the safety of the blood supply.

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.