Antibiotic-labeled probes and microvolume fluorimetry for the rapid detection of bacterial contamination in platelet components: a preliminary report

BACKGROUND: Approximately 1 platelet in 2000 components is bacterially cont aminated. Most commonly, contaminating organisms are gram positive skin sap rophytes (such as Staphylococcus sp. or Bacillus sp.). A novel approach to the rapid diagnosis of gram positive contamination by the use of a fluoresc ence-labeled antibiotic probe with affinity for the gram positive cell was investigated. STUDY DESIGN AND METHODS: Two isolates of Staphylococcus epidermidis were i noculated into bags of Day 0 platelets. Quantitative cultures along with a semiautomated screening assay on a microvolume fluorimeter employing a fluo rescence-conjugated vancomycin probe was performed for each day of storage. In addition, serial dilutions of the bacteria were added to sterile platel ets to achieve a range spanning 10(1) to 10(8) CFUs per mL. RESULTS: All samples with a bacterial contamination of greater than or equa l to 10(5) CFU per mt were detected. Sterile samples were nonreactive. The entire procedure requires three pipetting steps and took less than 1 hour t o perform. CONCLUSION: These preliminary results with the use of fluorescence-labeled antibiotics as probes combined with microvolume fluorimetry for the rapid d etection of bacterial contamination of platelet components suggest that thi s is a promising approach. Further studies with additional organisms and al ternative conjugates, bacteria, and antibiotics are underway.