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Background: Although unnecessary blood component transfusions are costly and pose substantial patient risks, the extent of unnecessary blood use in a community hospital setting has not been systematically measured., Methods: A 15-hospital observational analysis was performed using comprehensive retrospective review. Approximately 100 encounters (x¯ = 103.9, standard deviation [SD] ± 7.6) per hospital (6,696 total component transfusion events) were reviewed between 2012 and 2018. Review was performed by two medical directors. Findings were supported by blind intra- and inter-reviewer double review and blind external review by 10 independent reviewers., Results: Patients received an average of 4.3 (± 1.3) units. Only 8.2% (± 6.7) of patient encounters did not receive unnecessary units. Fifty-five percent (54.6% ± 13.5) could have been managed without at least one component type, while 44.6% (± 14.9) could have been managed completely without transfusion. Forty-five percent (45.4% ± 17.0) of red blood cell, 54.9% (± 19.3) of plasma-cryoprecipitate, and 38.0% (± 15.6) of plateletpheresis encounters could likely have been managed without transfusion. Between 2,713 units (40.5%) and 3,306 units (49.4%) were likely unnecessary. In patients who could have been managed without transfusion of at least one component type, unnecessary blood use was associated with a 0.38 (± 0.11)-day increase in length of hospital stay for each additional unnecessary unit received (p < 0.001)., Conclusion: Substantial unnecessary blood use was identified, all of which was unrecognized by hospitals prior to review. Unnecessary blood use was attributed to overreliance on laboratory transfusion criteria and failure to follow common blood management principles, which resulted in potential harm to patients and avoidable cost., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Molecular mimicry or epitope similarity between group A streptococcal M proteins and myosin may contribute to the presence of heart reactive antibodies in acute rheumatic fever. In our study overlapping synthetic peptides copying the entire sequence of PepM5 protein were used to map the myosin cross-reactive epitopes of streptococcal M protein recognized by mouse and human mAb and affinity purified myosin-specific antibodies from acute rheumatic fever and rheumatic heart disease sera. Overlapping M protein peptides SM5(164-197)C and SM5(184-197)C inhibited the murine mAb reactions with PepM5 protein. The human mAb and affinity purified myosin-specific antibodies reacted exclusively with SM5(184-197)C. However, one of the five different purified myosin-specific antibodies not only reacted with SM5(184-197)C but also reacted with SM5(84-116)C. The synthetic subpeptides SM5(175-184)C and SM5(188-197C) did not react with any of the antibodies to PepM5 and myosin demonstrating a requirement of the 184-188 amino acid sequence for antibody recognition. A heptapeptide containing the sequence SM5(183-189) was also found to inhibit selected human myosin-specific antibodies and a human antimyosin mAb. Therefore, the majority of mouse and human myosin crossreactive antibodies recognized an epitope within the 14 residue carboxy terminus of PepM5 which appeared to involve the GLN-LYS-SER-LYS-GLN sequence.

Tropomyosin is an alpha-helical coiled-coil protein with structural similarities to the streptococcal M protein. In order to show serologic cross-reactivity between streptococcal M proteins and tropomyosin, we selected from a panel of murine mAb those which reacted with M proteins and tropomyosins in the ELISA. Western blots were used to study the reactions of each mAb with human and rabbit cardiac and rabbit skeletal tropomyosins. The antibodies were further characterized for their reactions with the additional autoantigens myosin, actin, keratin, and DNA. Five mAb were found which reacted with either PepM5 or ColiM6 protein and tropomyosin in Western blots or ELISA. Two of the tropomyosin positive mAb were also antinuclear antibodies and were inhibited with DNA. In Western blots of cardiac tropomyosins, the mAb reacted with either the 70-kDa dimer of tropomyosin, the 35-kDa monomer, or both. Some differences were observed in the reactions of the mAb with the different tropomyosins in Western blots. The heart cross-reactive epitopes shared between M proteins and tropomyosin were in most instances shared with cardiac myosin. Differences were observed among the reactions of the mAb with the different tropomyosins. This report constitutes the first evidence of serologic cross-reactivity between streptococcal M proteins and tropomyosins.