Enhancement of a culture-based bacterial detection system (eBDS) for platelet products based on measurement of oxygen consumption.

BACKGROUND: An enhanced bacterial detection system (Pall eBDS) was developed that distinguishes itself from its predecessor (Pall BDS) by removal of the platelet (PLT)-retaining filter allowing for optimal bacterial transfer, modification of the culture tablet to reduce the confounding effects of respiring PLTs while enhancing bacterial growth, and facilitation of nutrients and gas exchange by agitating the sample pouch during incubation at 35 degrees C. The objective was to evaluate the performance of the new eBDS. STUDY DESIGN AND METHODS: Leukoreduced whole blood-derived PLT concentrates (LR-PCs) and LR single-donor PLTs (LR-SDPs) were inoculated with 1 to 15 colony-forming units (CFUs) of bacteria per mL in studies of each of 10 bacterial species associated with fatal transfusion-transmitted bacterial infection. Immediately after inoculation and after 24 hours of storage at 22 degrees C, samples of inoculated LR-PCs were aseptically transferred into the eBDS pouches. Pouches were then incubated for 24 hours at 35 degrees C with agitation and oxygen concentration was then measured. RESULTS: Median inoculation levels ranged from 5 to 13 CFUs per mL for each species studied. No significant differences in oxygen concentration were found when comparing LR-PCs with LR-SDPs. When sampling occurred from the PLTs 24 hours after inoculation, all 280 cases (24-33 replicates of each species) were detected as contaminated by the device (100% sensitivity). No false-positives were obtained with 713 uninoculated PLT units. CONCLUSIONS: The eBDS demonstrated improved detection sensitivity in the range of 1 to 15 CFUs per mL with no observed false-positives compared to the original BDS (detection range 100 to 500 CFUs/mL) with no false-positives.

Detection of bacteria in WBC-reduced PLT concentrates using percent oxygen as a marker for bacteria growth.

BACKGROUND: The risk of receiving a PLT concentrate (PC) contaminated with bacteria may be 1000-fold greater than that of pathogenic viral transmission, yet surveillance for this risk is not generally practiced. A novel bacteria detection system (BDS) that overcomes the limitations of current systems is described. The BDS monitors percent oxygen (%O2) in air above aliquots of PCs that have been filtered to remove the confounding effect of respiring PLTs and residual WBCs. STUDY DESIGN AND METHODS: One-day-old WBC-reduced whole-blood-derived PCs (WBPCs) were inoculated with bacteria at 100 to 500 CFU per mL. After 30 minutes, 2- to 3-mL aliquots were processed through a PLT-reducing filter into a sample pouch containing sodium polyanethol sulfonate and entrained air. After incubation at 35 degrees C for at least 24 hours, the %O2 was measured within the pouch. Noninoculated WBC-reduced WBPCs (n = 155), confirmed free of bacteria by routine culture, were tested in a like manner. Results from the latter group of WBC-reduced WBPCs were used to distinguish contaminated from noncontaminated units. RESULTS: After a 24-hour incubation at 35 degrees C, 195 (96.5%) of the 202 sample pouches obtained from inoculated units were detected by the BDS. After an additional 6 hours at room temperature, those that remained and were tested were found positive. None of the noninoculated controls produced a positive reading. CONCLUSION: The BDS is easy to use and provides good levels of sensitivity and specificity.

Wound irrigation in children: saline solution or tap water?

STUDY OBJECTIVE: Irrigation, a critical component of wound management, is commonly performed with sterile normal saline solution. The purpose of this study was to compare the infection rates of wounds irrigated with normal saline solution versus those of wounds irrigated with running tap water. METHODS: A prospective trial was conducted in an urban pediatric emergency department. Tap water pressure and flow rates were measured, and cultures were obtained before the study and at 5 months after study initiation. Patients 1 to 17 years of age presenting to the pediatric ED with a simple laceration were eligible. Exclusion criteria included immunocompromise, complicated lacerations, or current use of or need for antibiotics. Patients were allocated to the running tap water group or the standard normal saline solution irrigation group. Wounds were closed in standard fashion. Patients returned to the pediatric ED in 48 to 72 hours for evaluation. RESULTS: Two hundred seventy-one patients were enrolled in the normal saline solution group and 259 in the tap water group. Tap water and normal saline solution pressures and flow rates differed. The groups did not differ in terms of patient demographic characteristics or wound characteristics. However, more wounds were located on the hand in the tap water group (21.3%; 95% confidence interval [CI] 16.3% to 27.1%) compared with those in the normal saline solution group (9.2%; 95% CI 5.9% to 13.4%). The wound infection rates were similar in the 2 groups (normal saline solution group: 2.8% [95% CI 1.1% to 5.7%] versus running tap water group: 2.9% [95% CI 1.2% to 5.9%]). CONCLUSION: There were no clinically important differences in infection rates between wounds irrigated with tap water or normal saline solution. Tap water might be an effective alternative to normal saline solution for wound irrigation in children.