Investigation of an isolate of Staphylococcus lugdunensis implicated in a platelet fatality: a possible advantage of the use of an anaerobic bottle

The incremental benefit of anaerobic culture for controlling bacterial risk in platelets: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Septic transfusion reactions are a principal cause of transfusion-related mortality. The frequency of detectable bacterial contamination is greater in platelets compared to other blood components because platelets are stored at room temperature. Most strategies outlined in the September 2019 FDA guidance require both aerobic culture (AC) and anaerobic culture (AnC) testing. We performed a systematic review and meta-analysis in an effort to provide the best available estimate of the effectiveness of AnC.

MATERIALS AND METHODS

Our analysis was performed according to published guidelines. Broad and context-specific meta-analyses of bacterial detection rates in platelets by AnC were performed to assess the practical effectiveness of AnC as a risk control measure.

RESULTS

Seven studies with a total of 1 767 014 tested platelet components were included for analysis. With exclusion of positives due to Cutibacterium/Propionibacterium species and redundancy due to AC results, AnC detected 0·06 contamination events per thousand (EPT) components tested, twofold lower than the AC (0·12 EPT).

CONCLUSION

Excluding Cutibacterium/Propionibacterium species, AnC detects occasional bacterial contamination events that are not detected by AC (~1 in 17 000 platelet components).

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

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

Survey of methods used to detect bacterial contamination of platelet products in the United States in 2011

BACKGROUND

Testing of platelets (PLTs) for bacterial contamination is required by the AABB Standards but is not fully standardized. On January 31, 2011, a new AABB Standard, 5.1.5.1.1, specified that bacterial detection methods for PLT components shall use assays either approved by the Food and Drug Administration (FDA) or validated to provide sensitivity equivalent to these FDA-approved methods.

METHODS

An Internet-based survey of AABB member institutions was conducted from May to June 2012, to document current practices used in 2011 for bacterial detection in different PLT products and to assess the impact of the new standard.

RESULTS

Of 1053 AABB member institutions surveyed, 40 of 99 blood centers (40.4%) and 184 of 954 hospital blood banks or transfusion services (19.3%) responded. Sixty-four respondents manufactured PLTs. Apheresis PLTs (APs) were predominantly screened with the BacT/ALERT system (89.5%); the majority (95.2%) were cultured with at least 8 mL of product. There was substantial variation in the minimum incubation time of cultures before release of PLTs (range, 0 to >24 hr). Recalls of released AP for possible bacterial contamination were largely successful (67.3%); successful interdiction before transfusion was associated with incubation for more than 12 hours before release (p < 0.01). After Standard 5.1.5.1.1 took effect, there was a decrease in production of whole blood-derived PLT concentrates (WBPCs). Point-of-issue ("rapid") immunoassays were used to screen a substantial proportion of WBPC PLTs, but were rarely used as secondary tests for previously cultured APs.

CONCLUSION

The survey identified variability in culture methods and release times with AP, while use of WBPC decreased after AABB Standard 5.1.5.1.1 became effective.

Screening of platelets for bacterial contamination at the Welsh Blood Service

BACKGROUND AND OBJECTIVE

This report details the results of the implementation of a bacterial screening system at the Welsh Blood Service and provides an estimate of the levels of bacterial contamination at the time of sampling.

MATERIALS AND METHODS

Apheresis (Caridian BCT) and buffy coat-derived pooled platelet components were sampled on day 1 for bacterial contamination and the sample was monitored throughout the lifespan of the platelet component. Unused platelet components were re-tested to determine the effectiveness of the screening. Results from the BacT/ALERT are uploaded to the in-house Blood Establishment Computer System (BECS) every 12 min. Positive alerts are automatically sent to staff, facilitating a timely intervention.

RESULTS

Between February 2003 and March 2010 the screening system tested 54 828 platelets and detected 257 (1 in 213) initial positives of which 35 (1 in 1567, 0·06%) were confirmed [95% confidence interval (CI), 0·04-0·08%]. Additionally, screening of 6438 unused platelet components detected another 6 (1 in 1073, 0·09%) confirmed positives not detected during initial testing (95% CI, 0·02-0·16%). Analysis of the data suggests that on day 1 the number of bacteria in such platelet component packs was between 5 and 62 cfus total. Day 1 culture has a sensitivity of 40%.

CONCLUSIONS

The bacterial screening system has removed a significant number, but not all bacterially contaminated platelet components from the supply. The sample volume is an important factor in sensitivity due to the low number of bacteria in a platelet component pack on day 1. An effective notification and recall system is a critical part of the bacterial screening system.

Propionibacterium acnes lacks the capability to proliferate in platelet concentrates

BACKGROUND AND OBJECTIVES

Propionibacterium acnes is considered to be one of the most frequent contaminants of platelet concentrates (PCs) when anaerobic culture-based detection methods are used. But Propionibacteria are often detected too late when blood products have already been transfused. Therefore, its transfusion relevance is still demanding clarification because studies of the outcome of patients transfused with P. acnes-contaminated PCs are still uncommon. In this study, we monitored clinical effects in patients after transfusion of PCs, which were detected too late in sterility testing. Furthermore, we assessed the bacterial proliferation of Propionibacterium species seeded into PCs to clarify their significance for platelet bacteria screening.

MATERIALS AND METHODS

In the look-back process, we followed the route of the putative contaminated PC units from storage to transfusion. In the in vitro study, PCs were inoculated with 1-100 colony-forming unit (CFU)/ml of clinical isolates of Propionibacteria (n = 10). Sampling was performed during 10-day aerobic storage at 22 degrees C. The presence of bacteria was assessed by plating culture and automated BacT/Alert culture system.

RESULTS

Propionibacterium acnes shows slow or no growth under PC storage conditions. Clinical signs of adverse events after transfusion of potentially contaminated PC units were not reported.

CONCLUSION

Propionibacteria do not proliferate under PC storage conditions and therefore may be missed or detected too late when blood products have already been transfused.