The Pan Genera Detection Immunoassay: a Novel Point-of-Issue Method for Detection of Bacterial Contamination in Platelet Concentrates

Abstract

Bacterial contamination of platelet concentrates (PCs) still represents an ongoing risk in transfusiontransmitted sepsis. Recently the Pan Genera Detection (PGD) system was developed and FDA licensed for screening of bacterial contamination of PCs directly prior to transfusion. The test principle is based on the immunological detection of lipopolysaccharide (for Gram-negative bacteria) or lipoteichoic acid (for Grampositive bacteria). In the present study we analyzed the applicability of this method with regard to detection limit, practicability, implementation, and performance. PCs were spiked with Staphylococcus aureus, Bacillus subtilis, and five different Klebsiella pneumoniae strains, as well as eight different Escherichia coli strains. The presence of bacteria was assessed by the PGD immunoassay, and bacteria were enumerated by plating cultures. Application of the PGD immunoassay showed that it is a rapid test with a short hands-on time for sample processing and no demand for special technical equipment and instrument operation. The lower detection limits of the assay for Gram-positive bacteria showed a good agreement with the manufacturer's specifications (8.2 ؋ 10 3 to 5.5 ؋ 10 4 CFU/ml). For some strains of K. pneumoniae and E. coli, the PGD test showed analytical sensitivities (>10 6 CFU/ml) that were divergent from the designated values (K. pneumoniae, 2.0 ؋ 10 4 CFU/ml; E. coli, 2.8 ؋ 10 4 CFU/ml). Result interpretation is sometimes difficult due to very faint bands. In conclusion, our study demonstrates that the PGD immunoassay is an easy-to-perform bedside test for the detection of bacterial contamination in PCs. However, to date there are some shortcomings in the interpretation of results and in the detection limits for some strains of Gram-negative bacteria.

Late sampling for automated culture to extend the platelet shelf life to 5 days in Germany

“…Several methods for the detection of bacterial contamination in platelet concentrates (PCs) have been developed during the past decades, which can be divided into the different incubation/cultivation methods (BacT/ALERT system, bioMérieux; bactec system; VersaTrek system, Thermo Scientific) and direct detection of bacteria using rapid detection methods . Rapid‐detection methods include nucleic acid amplification techniques (NATs), fluorescence assorted cell sorting (e.g., BactiFlow [BF], bioMérieux), immunologic detection (PGD, Pan Genera Detection system [PGD]), or colorimetric assays (BacTx, Verax Biomedical) . Both methodological concepts were linked to different sampling strategies.…”

Bench Test for the Detection of Bacterial Contamination in Platelet Concentrates Using Rapid and Cultural Detection Methods with a Standardized Proficiency Panel

“…using imaging instruments. However, it was demonstrated that currently used bacterial strains are capable to grow in PCs [8,12,13]. The comparison of results obtained with overnight grown cultures was proven to have no influence on the stability of bacterial cell counts and the result outcome.…”

Diagnostic Methods for Platelet Bacteria Screening: Current Status and Developments

“…However, for some Gram-negative strains the detection limit is greater than 10 6 CFU/ml [42]. Further disadvantages of the PGD assay are the costs, a high rate of false-positive results [23] and, currently, the subjective result interpretation [42]. This assay has been evaluated in various studies for use in quality control of PCs [43,44,45].…”

“…The analytical sensitivity of this assay is specified as 10 3 -10 4 CFU/ml for Gram-positive bacteria and 10 3 -10 5 CFU/ml for Gram-negative bacteria. However, for some Gram-negative strains the detection limit is greater than 10 6 CFU/ml [42]. Further disadvantages of the PGD assay are the costs, a high rate of false-positive results [23] and, currently, the subjective result interpretation [42].…”

“…The short hands-on time and the minimum requirement for laboratory instrumentation provide the opportunity for a point-of-issue bacterial detection test immediately before transfusion of PCs [42]. The analytical sensitivity of this assay is specified as 10 3 -10 4 CFU/ml for Gram-positive bacteria and 10 3 -10 5 CFU/ml for Gram-negative bacteria.…”