Validation of sterility testing of cord blood: challenges and results

Ramírez‐Arcos, Sandra; Kou, Yuntong; Yang, Lin; Perkins, Heather; Taha, Mariam; Halpenny, Mike; Elmoazzen, Heidi

doi:10.1111/trf.13050

Cited by 12 publications

(26 citation statements)

References 20 publications

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“…Herein, we have found that bacterial growth inhibitors present in CB appear to significantly affect microbial survival and detection. These results are consistent with those reported by Ramirez‐Arcos and colleagues, who recently demonstrated that bacteria failed to grow in CB containing antibiotics . The present work also underlines the fact that the volume of plasma in the inoculum used for microbial detection should be minimized to ensure the survival of potential contaminating bacteria and to reduce the risk of false‐negative results.…”

Section: Discussionsupporting

confidence: 92%

“…The small volume of FP samples (0.5 or 1.0 mL) generally used by CBBs might not be sufficient to ensure optimal microbial detection, whereas the use of higher inoculum volumes of stem cell concentrate increases the sensitivity of detection, especially when contamination levels are low . Many CBBs have tried to optimize microbial detection in CB by using plasma only or mixtures of CB by‐products . These methods yielded detection rates ranging from 21% to 79%.…”

Section: Discussionmentioning

confidence: 99%

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Optimization of cord blood unit sterility testing: impact of dilution, analysis delay, and inhibitory substances

et al. 2017

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BACKGROUND: Different methods are used by cord blood banks to prepare samples for sterility testing. Suboptimal methods can result in the release of contaminated products. In our organization, samples are prepared by diluting the final product in RPMI-1640 medium. In this work, we have compared our method with different approaches to verify whether optimization should be sought. STUDY DESIGN AND METHODS:Cord blood units (n 5 6 units per bacterial strain) characterized to contain inhibitory substances or not were inoculated (10 colonyforming units/mL) with Streptococcus agalactiae, Staphylococcus epidermidis, Klebsiella pneumoniae, Escherichia coli, or Bacteroides fragilis. After plasma and red blood cell removal, stem cell concentrates were diluted in RPMI-1640, thioglycollate, or the unit's plasma. These products, as well as final product, plasma, and red blood cell fractions, were held from 0 to 72 hours at 20 to 248C before inoculation in culture bottles and detection using the BacT/ALERT 3D system. RESULTS: Dilution of cell concentrates in RPMI-1640allowed bacterial detection in 93.3% of noninhibitory cord blood samples after a 24-hour storage period. Thioglycollate medium better promoted bacterial growth in inhibitory cord blood samples that were held for 72 hours before testing (66.7%) compared with RPMI-1640 (45.0%). Less than 33% of all spiked plasma samples were detected by the BacT/ALERT 3D system. CONCLUSION:Diluting cord blood samples in culture medium containing bacterial growth promoting substances is a suitable option for sterility testing, whereas the use of plasma should be proscribed, because it might lead to false-negative results. Because inhibitory substances affect bacterial growth, inoculation of culture bottles should be done rapidly after sample preparation. U mbilical cord blood (CB) transplantation is indicated for severely immunocompromised patients. These patients have a high risk of contracting infections associated with the transplant. Given the nonsterile collection environment and the numerous procedures carried out before transplantation, microbial contamination of cord blood units (CBUs) is more frequent than for any other blood product.1-3 Consequently, the efficient microbial screening of CB donations remains a primary safety concern for cord blood banks (CBBs) while also being required by international accreditation organizations, such as the American Association of Blood Banks and the Foundation for the Accreditation of Cellular Therapy. 4,5 The development of standardized procedures for microbial screening of CBUs is still being awaited. The lack of consensus standards led to CBBs developing their own method for microbial screening. Generally, a sample of the final volume-reduced CB product is used for sterility testing; however, postprocessing plasma, red blood cell (RBC) fraction, a mixture of these by-products, or a small volume of the final stem cell concentrate (which includes the cryopreservation solution) are also used for microbial ABBREVIATIONS: ATCC 5 American Ty...

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Optimization of cord blood unit sterility testing: impact of dilution, analysis delay, and inhibitory substances

et al. 2017

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show abstract

“…Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922, purchased from the ATCC, were used as control strains for the minimal inhibitory concentration (MIC) assays described below. Bacterial enumerated frozen stocks were prepared as previously described and stored at −80°C until use …”

Section: Methodsmentioning

confidence: 99%

“…CB units were processed within 48 hours post‐collection using a CB processing system (Sepax, Biosafe) following standard procedures at Canadian Blood Services' Cord Blood Bank. Plasma and RBC fractions were collected, and a 1:1 mix of 4 mL of each of these by‐products was used to inoculate BacT/ALERT BPA culture bottles following sterility testing procedures established at the CB bank . Remaining plasma and RBC fractions were used for the antibiotic neutralization assays described below (Phase 3).…”

Section: Methodsmentioning

confidence: 99%

“…A combination of penicillinase plus resin Lewatit CNP 105 was used to simultaneously neutralize penicillin and gentamicin in a 1:1 mix of CB by‐products RBCs and plasma, which represents CB sterility testing samples used at Canadian Blood Services' Cord Blood Bank . The plasma‐RBC sample was inoculated with both bacteria, each at an approximate concentration of 100 CFU/mL.…”

Section: Methodsmentioning

confidence: 99%

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