Evaluation of a rapid colorimetric assay for detection of bacterial contamination in apheresis and pooled random-donor platelet units.

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. STUDY DESIGN AND 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.

Genetic analysis of a duck circovirus detected in commercial Pekin ducks in New York.

The genetic organization of the duck circovirus (DuCV) 33753-52 detected in commercial Pekin duck flocks from Long Island, NY, is described. The nucleotide sequence of virus 33753-52 exhibited high similarity with DuCVs previously detected in Germany and Hungary. It is possible that this DuCV from New York shares the same ancestor with the European counterparts. The virus 33753-52 exhibited genetic features characteristic of other circoviruses, such as the presence of two major open reading frames (rep and cap), two intergenic regions, one stem-loop structure, four intergenic direct repeats, and the conserved motifs for the rolling circle replication and for the dNTP binding domain in the Rep protein. This report is the first report of the presence of DuCV in commercial Pekin duck farms in the United States. The clinical and pathologic significance of DuCV in the duck farms located on Long Island needs to be clarified. DuCv was detected in culled birds, due to low body development, leg deformities, or arthritis. Staphylococcus aureus and Riemerella anatipestifer serotype 4 were isolated from some of the DuCV-positive birds. The apparent low prevalence of the virus suggests that at this time, this infection is not a significant problem for the duck industry in New York. However, the immunosuppressive properties of this virus need to be clarified as well as its role as a predisposing agent for other diseases.