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

BACKGROUND: Cases have been reported in which detection with an early culture failed to interdict the transfusion of a bacterially contaminated platelet. One fatal case involved Staphylococcus lugdunensis, missed with a 4-mL aerobic (BPA) bottle (BacT/ALERT, bioMerieux). This report noted "deviation from culture methods that meet manufacturer's recommendations (e.g., decreased blood volume) can result in reduced sensitivity and produce false negatives." The manufacturer's package insert "strongly" recommends that more than one type of culture bottle be utilized. The utility of an anaerobic (BPN) bottle compared to a BPA bottle was investigated for the detection of S. lugdunensis. STUDY DESIGN AND METHODS: This isolate was subjected to a series of spiking experiments designed to assess the effect of sample volume and recovery of BPA and/or BPN bottles over a range of concentrations (0.1-6 colony-forming units/mL). RESULTS: With low levels of contamination, larger volumes cultured were associated with higher recovery. With the lowest inoculation, such that only one to two organisms were present in a bottle, reactivity was accelerated in the BPN bottle compared to the BPA bottle. At higher concentrations, 10 mL in the BPA bottle yielded equivalent time to reactivity as 4 mL in the BPN bottles. CONCLUSION: These data support the use of larger inocula; however, when only one to two organisms were present in a bottle, time to reactivity was accelerated in a BPN bottle compared to a BPA bottle. The accelerated growth was not observable with higher inoculum (e.g., more than six organisms per bottle). Quicker time to reactivity might make the difference between interdiction or transfusion of the product.