title: Evaluation of a rapid colorimetric assay for detection of bacterial contamination in apheresis and pooled random-donor platelet units.
abstract: BACKGROUND
  Despite existing strategies, bacterial contamination of platelets (PLTs) remains a problem, and reliable testing near the time of use is needed. We evaluated the BacTx assay (Immunetics, Inc.), a rapid colorimetric assay for detection of bacterial peptidoglycan, for this purpose.
  
  
  METHODS
  Apheresis- and whole blood-derived PLT units, the latter tested in 6-unit pools, inoculated with 10 representative bacterial species (eight aerobic, two anaerobic), were tested with the BacTx assay at two sites to determine analytic sensitivity and time to detection. Specificity on sterile PLTs and reproducibility across different PLT units and assay kit lots was also determined.
  
  
  RESULTS
  Analytical sensitivity for the 10 bacterial species ranged from 6.3 × 10(2) to 7.6 × 10(4) colony-forming units (CFUs)/mL. In time-to-detection studies after inoculation of PLTs with 0.7 to 5.3 CFUs/mL, 10 replicates of all eight aerobic species were positive when bacterial titers were above the analytic sensitivity detection limit, which occurred at 48 hours for 60 PLT units and at 72 hours for the remaining 4 units, as well as at 7 days for all units. Specificity was 99.8% and reproducibility was 100%.
  
  
  CONCLUSIONS
  The BacTx assay had an analytical sensitivity below the 10(5) CFUs/mL threshold of clinical significance, detected all eight aerobic bacterial species 48 to 72 hours after inoculation as well as at 7 days, and had high specificity and reproducibility. These findings suggest that the BacTx assay will be a valuable test for detection of clinically relevant levels of bacterial contaminants in PLT units and pools near time of use.
authors.affiliation: Blood Component Research Laboratory, Feinstein Institute for Medical Research, Manhasset, New York.
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Heaton
authors.forename: Caryn E
authors.initials: CE
authors.lastname: Good
authors.forename: Rakijah
authors.initials: R
authors.lastname: Galloway-Haskins
authors.forename: Roslyn A
authors.initials: RA
authors.lastname: Yomtovian
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jacobs
mesh_terms: D001409:Bacillus cereus / Q000302:isolation & purification; D001781:Blood Component Removal; D001792:Blood Platelets / Q000382:microbiology*; D003016:Clostridium perfringens / Q000302:isolation & purification; D003124:Colorimetry / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification; D006801:Humans; D041121:Klebsiella oxytoca / Q000302:isolation & purification; D011424:Propionibacterium / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013212:Staphylococcus epidermidis / Q000302:isolation & purification; D013234:Stem Cells