Beware Cold Agglutinins in Organ Donors! Ex Vivo Lung Perfusion From an Uncontrolled Donation After Circulatory-Determination-of-Death Donor With a Cold Agglutinin: A Case Report.

BACKGROUND: We began to recover lungs from uncontrolled donation after circulatory determination of death to assess for transplant suitability by means of ex vivo lung perfusion (EVLP) and computerized tomographic (CT) scan. Our first case had a cold agglutinin with an interesting outcome. CASE REPORT: A 60-year-old man collapsed at home and was pronounced dead by Emergency Medical Services personnel. Next-of-kin consented to lung retrieval, and the decedent was ventilated and transported. Lungs were flushed with cold Perfadex, removed, and stored cold. The lungs did not flush well. Medical history revealed a recent hemolytic anemia and a known cold agglutinin. Warm nonventilated ischemia time was 51 minutes. O2-ventilated ischemia time was 141 minutes. Total cold ischemia time was 6.5 hours. At cannulation for EVLP, established clots were retrieved from both pulmonary arteries. At initiation of EVLP with Steen solution, tiny red aggregates were observed initially. With warming, the aggregates disappeared and the perfusate became red. After 1 hour, EVLP was stopped because of florid pulmonary edema. The lungs were cooled to 20°C; tiny red aggregates formed again in the perfusate. Ex vivo CT scan showed areas of pulmonary edema and a pyramidal right middle lobe opacity. Dissection showed multiple pulmonary emboli-the likely cause of death. However, histology showed agglutinated red blood cells in the microvasculature in pre- and post-EVLP biopsies, which may have contributed to inadequate parenchymal preservation. CONCLUSIONS: Organ donors with cold agglutinins may not be suitable owing to the impact of hypothermic preservation.

The effect of using citric or acetic acid on survival of Listeria monocytogenes during fish protein recovery by isoelectric solubilization and precipitation process.

Isoelectric solubilization and precipitation (ISP) is a protein recovery process effective at reducing Listeria innocua, a nonpathogenic bacterium typically used as a surrogate for L. monocytogenes in recovered trout protein. The response of L. monocytogenes to ISP processing was determined and compared to the response of L. innocua. Headed and gutted rainbow trout were inoculated with L. monocytogenes (10.16 log CFU/g), homogenized, and pH-adjusted with granular citric acid (pH 2.0 and 2.5) or glacial acetic acid (pH 3.0 and 3.5). Proteins were solubilized and centrifugation was used to remove insoluble components (skin, insoluble protein, so on). The supernatant was returned to the protein isoelectric point (pH 5.5) with NaOH and centrifuged to remove precipitated protein. Microbial load was enumerated on both growth and selective media; recovery was not significantly different (P > 0.05). Surviving cells from each component (protein, insoluble, and water) were compared to initial inoculum numbers. Significant reductions were detected at all pH (P < 0.05). The greatest reductions were at pH 3.0 with acetic acid, with a mean log reduction of 3.03 in the combined components, and a 3.53 log reduction in the protein portion. Data were compared to results from a previous study using L. innocua. Significant differences (P < 0.05) in recovery were found between the 2 species at pH 2.0 and 3.0 with greater recovery of L. monocytogenes, regardless of processing pH or acid type. These results demonstrate the variability in resistance between species and indicate that L. innocua is not an appropriate surrogate for L. monocytogenes for ISP processing with organic acids.

Survival of Listeria innocua in rainbow trout protein recovered by isoelectric solubilization and precipitation with acetic and citric acids.

During mechanical fish processing, a substantial amount of protein is discarded as by-products. Isoelectric solubilization and precipitation (ISP) is a process that uses extreme pH shifts to solubilize and precipitate protein from by-products to recover previously discarded protein. Typically, strong acids are used for pH reduction, but these acids do not have a pasteurization effect (6 log reduction) on bacterial load; therefore, organic acids were used during ISP processing to test the impact on Listeria innocua concentrations. Headed and gutted rainbow trout (Oncorhynchus mykiss) were inoculated with L. innocua, homogenized, and brought to the target pH with granular citric acid (pH 2.0 and 2.5) or glacial acetic acid (pH 3.0 and 3.5). Proteins were solubilized for 10 min at 4°C, and insoluble components (e.g., skin and insoluble protein) were removed by centrifugation. The remaining solution was pH shifted to the protein isoelectric point (pH 5.5) with sodium hydroxide, and precipitated protein was separated from the water. Microbial cells for each component (proteins, insolubles, and water) were enumerated on modified Oxford agar (MOX) and tryptic soy agar with 6% yeast extract (TSAYE). The sums of the surviving cells from each component were compared with the initial inoculum levels. No significant differences were observed between results obtained from TSAYE and from MOX (P > 0.05). Significant reductions in microbial populations were detected, regardless of pH or acid type (P < 0.05). The greatest reduction was at pH 3.0 with glacial acetic acid, resulting in a mean reduction of 6.41 log CFU/g in the recovered protein and 5.88 log CFU/g in the combined components. These results demonstrate the antimicrobial potential of organic acids in ISP processing.

Use of electron beam radiation for the reduction of Salmonella enterica serovars typhimurium and Tennessee in peanut butter.

Peanut butter and peanut paste products were implicated as the vehicle of contamination in an outbreak of Salmonella Typhimurium, which began in September 2008, and in the November 2006 outbreak of Salmonella Tennessee. Therefore, this study evaluated the effectiveness of electron beam (e-beam) radiation for the reduction of Salmonella serovars Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter. Each strain was studied independently. Peanut butter samples were inoculated with approximately 8.0 log CFU/g of Salmonella, and exposed to e-beam doses ranging from 0 to 3.1 kGy. Doses were confirmed with film dosimetry. Survivors were enumerated by standard spread plating on nonselective tryptic soy agar (TSA) and selective xylose-lysine-desoxycholate agar (XLD) media. Salmonella Tennessee was more susceptible to e-beam radiation, with 5.00- and 6.75-log reduction of cells on TSA and XLD, respectively, at the approximate e-beam dose of 3.0 kGy. Salmonella Typhimurium was reduced by 4.19 and 4.85 log on TSA and XLD, respectively, at the approximate e-beam dose of 3.0 kGy. D(10)-values show that Salmonella Typhimurium was more resistant (0.82 +/- 0.02 and 0.73 +/- 0.01 kGy on TSA and XLD, respectively) than was Salmonella Tennessee (0.72 +/- 0.02 and 0.60 +/- 0.01 kGy on TSA and XLD, respectively) to e-beam radiation (P < 0.05). The recovery on growth and selective media were different (P < 0.05), indicating cell injury. The results of this study demonstrate that e-beam radiation may be an effective processing step for the nonthermal inactivation of Salmonella in peanut butter.

Survival of Escherichia coli after isoelectric solubilization and precipitation of fish protein.

Protein recovery for fish processing by-products utilizes extreme pH shifts for isoelectric solubilization and precipitation. The purpose of this study was to determine if Escherichia coli would survive exposure to the extreme pH shifts during the protein recovery process. Fresh rainbow trout were beheaded, gutted, and minced and then inoculated with approximately 10(9) CFU of E. coli ATCC 25922 per g, homogenized, and brought to the target pH of 2.0, 3.0, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide to solubilize muscle proteins. The homogenate was blended and centrifuged to separate the lipid and insoluble components (bones, skin, insoluble protein, etc.) from the protein solution. The protein solution was subjected to a second pH shift (pH 5.5) resulting in protein precipitation that was recovered with centrifugation. Microbial analysis was conducted on each fraction (i.e., lipid, insoluble components, protein, and water) with selective and nonselective media. The sums of the surviving E. coli in these fractions were compared with the initial inoculum. The greatest total microbial reduction occurred when the pH was shifted to 12.5 (P < 0.05), i.e., a 4.4-log reduction of cells on nonselective media and a 6.0-log reduction of cells on selective media. The use of selective and nonselective media showed that there was significant (P < 0.05) injury sustained by cells exposed to alkaline treatment (pH 11.5 and 12.5) in all fractions except the insoluble fraction at pH 11.5. Increasing the exposure time or the pH may result in greater bacterial reductions in the recovered protein.

Survival of Listeria innocua after isoelectric solubilization and precipitation of fish protein.

Protein wasted by the disposal of fish processing by-products may be recovered using isoelectric solubilization and precipitation. Extreme pH shifts are used to solubilize the protein and then it is recovered by precipitation and centrifugation. Microbial survival after this process is unknown; therefore, the purpose was to see if Listeria innocua would survive extreme pH shifts during the protein recovery process. Fresh rainbow trout fillets were inoculated with L. innocua, homogenized, and brought to the target pH of 2, 3, 11.5, or 12.5 by the addition of concentrated hydrochloric acid or sodium hydroxide. The proteins were allowed to solubilize at 4 degrees C for 10 min, centrifuged, and the lipid and insoluble components (bones, skin, insoluble protein, and so on) were removed. A 2nd pH shift (pH 5.5) and centrifugation was used to separate the precipitating protein and water fractions. Each constituent (lipid, protein, water, insoluble components) was analyzed for bacterial content using growth and selective media. The sums of the surviving L. innocua in these constituents were compared to the initial inoculum. There were no significant differences in recovery on growth or selective media (P > 0.05). The greatest loss occurred when the pH was shifted to 2, with a 3.1-log reduction in the combined fractions of the trout fillets and a 3.8-log reduction in the protein fraction. There were no significant losses when the pH was adjusted to 11.5 (P > 0.05). Future studies will continue to look at the effects of using organic acid, rather than inorganic, for protein solubilization.

Hearing aid benefit in patients with high-frequency hearing loss.

Patients with hearing loss limited to frequencies above 2 kHz are often considered borderline candidates for hearing aids. In this study, we used the Profile of Hearing Aid Benefit to access 134 patients' perceived benefit with a variety of linear hearing aids, some more capable than others at achieving prescribed frequency gain targets. We also sought to explore various audiologic and subject factors that might have led patients to report different degrees of success or failure with their hearing aids. Results demonstrate that subjects with hearing loss limited to frequencies above 2 kHz benefit significantly from amplification. However, the amount of benefit reported is mostly unrelated to the hearing aid gain and frequency response. Of numerous audiologic and demographic factors explored in the present study, the number of hours of hearing aid use per day turned out to be the most important single factor that was significantly related to the amount of reported hearing aid benefit. However, the predictive value of knowing how many hours per day subjects wore their aids, or any other combination of factors explored, was quite limited and only accounted for a small amount of the variability observed in user benefit.