BACKGROUND:The popularity of Low-Titer O Whole Blood (LTOWB) for treating trauma patients requires that donor centers and transfusion services make decisions on what titer testing capabilities to institute and an appropriate titer level threshold. This study compared the titer results determined by four methods to find a rate of agreement. STUDY DESIGN AND METHODS:Isohemagglutinin titers were tested on 300 plasma samples utilizing various methods, each determining IgM antibody levels by direct hemagglutination with A1 and B reference cells. The methods used were the Beckman Coulter's PK7300, Immucor's NEO Iris microplate technology, Ortho Clinical Diagnostics (OCD) Vision, and manual titrations. RESULTS:Only 42.7% of the samples tested showed agreement across all methods on ABO isohemaglutinin titer levels and only 32.5% demonstrated "High titer" agreement. Sample agreement was close to 90% if the Immucor method was excluded. At a <1:256 titer level threshold, the pass rate was 94.3% for Immucor, 89.7% for the PK7300, 87.3% for manual testing, and 75.7% for OCD's gel method. Sensitivity and specificity rates at a ± 1 titer level were respectively 100% and 95.4% for OCD's gel, 73.7% and 100% for Immucor, and 100% and 99.6% for the PK7300. Overall method accuracy was 91.7% for Immucor, 90.3% for the PK7300, and 86.7% for OCD's gel method as compared to manual titration. CONCLUSION:All three automated methods perform comparably to the manual method at a ± 1 titer tolerance level. Based on these comparisons, a titer level of <1:256 would maximize LTOWB production regardless of the method used.

Background Several large studies have demonstrated that syphilis carries a risk of future sexually transmitted infections (STI), such as human immunodeficiency virus. There are limited data on outcomes of syphilis infections that occur in populations that undergo universal syphilis screening, such as blood donors. Military trainees who donate blood can be followed through their military career to determine the future risk of STIs. Methods Blood donor data were gathered from the Armed Services Blood Bank Center–San Antonio for those with positive Treponema pallidum antibodies between 2014 and 2021. The medical chart of each case was compared with 6 sex- and military accession date–matched controls with negative T. pallidum antibodies to determine the risk of STI in the 3 years after donation. Results A total of 63,375 individuals donated blood during the study period. A total of 23 military trainees (0.36 per 1000 donors) had positive T. pallidum antibodies. A minority (n = 7; 30%) of cases were treated for early syphilis. Only 6 cases (26%) received a follow-up nontreponemal test within 1 year. Donors who tested positive had a significantly higher risk of developing an STI within 3 years after blood donation compared with blood donors who tested negative (relative risk, 3.8; 95% confidence interval, 1.3–10.5; P = 0.01) including gonorrhea (9% vs. 0%, P = 0.02) and syphilis (9% vs. 0%, P = 0.02). Conclusions This study shows the presence of T. pallidum antibodies in blood donors was associated with an increased risk of future STIs. These cases support the need for close follow-up and broad STI testing in blood donors with positive T. pallidum antibodies.

Abstract Background The burden of transfusion-transmitted infections (TTIs) among blood recipients remains low due to strict blood donor selection as well as extensive post-donation screening. However, the military has the unique challenge of providing blood in austere environments with limited testing capabilities. This study evaluates infectious etiologies of deferred blood donors at a large military blood donation center. Methods All blood donors at the Armed Service Blood Bank Center-San Antonio between 2017-2022 with positive post-donation screening tests for hepatitis C (HCV), hepatitis B (HBV), HIV, HTLV-1/2, Zika, West Nile virus (WNV), T. cruzi, T. pallidum, or Babesia were evaluated. Patients were deferred from donating based on FDA criteria including a positive screen with positive confirmatory testing, a positive screen with indeterminate confirmatory testing, and a second occurrence of a positive screen with negative confirmatory testing. Results Of the 89,459 blood donors during the study period, 213 (238 per 100,000 donors) met FDA criteria for deferral. T. pallidum (n=45, 50.3 per 100,000), HCV (n=34, 38.0 per 100,000), and HBV (n=19, 21.2 per 100,000) were the most common infections seen in those with both positive screening and positive confirmatory testing. The majority of HIV (95%), Chagas (78%), HTLV-1/2 (50%) deferrals were due to indeterminate confirmatory tests following initial positive screens. The majority of deferrals for HBV were for a second occurrence of a positive screening test despite negative confirmatory testing. Conclusion The rates of deferral due to positive post-donation screening for infectious diseases were low in this military cohort. In environments with limited resources, donor testing in service members should focus on HBV, HCV, and T. pallidum as the most common pathogens. Our findings also highlight the need for better diagnostics in screening donors for HIV, Chagas, and HTLV-1/2 due to frequent indeterminate confirmatory tests. Disclosures All Authors: No reported disclosures