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In the United States, fatal transfusion-transmitted infections from red blood cell units are rare. Although this pattern mostly reflects how inhospitable refrigerated red blood cell units are to contaminant growth, fatalities caused by microorganisms that can grow at storage temperature (4°C), but not in standard clinical blood cultures at 37°C, are probably underestimated. We analyzed a fatal red blood cell transfusion in Peoria, Illinois, USA, that occurred in 2017. Samples from the patient's whole blood and the red blood cell unit remained culture-negative during the investigation, despite direct visualization of gram-negative bacilli within the unit immediately after transfusion. We identified the bacteria as Pseudomonas poae, a nonpathogenic pseudomonad carrying multiple cold-shock domain protein genes, and confirmed its cold tolerance and inability to grow at 37°C. Our work indicates transfusion reaction workups need to include testing for psychrophilic organisms, which could explain the cause of other apparently culture-negative transfusion reactions. [ABSTRACT FROM AUTHOR]

Background Infection disease (ID) groups covering inpatient and office, antimicrobial stewardship, and infection prevention duties may welcome an opportunity to streamline diagnostics via metagenomic next-generation sequencing (NGS). But the appropriate patient profile for NGS has yet to be defined. In 2019, we began using the Karius Test (KT), an NGS test that identifies and quantifies microbial cell-free DNA in plasma. Methods On January 10, 2019 our ID group (7 MDs and an APN covering 14 Illinois hospitals) began using the KT (Redwood City, CA). 5 ml of whole blood is collected, spun to plasma, and shipped to Karius for analysis. Following NGS, human sequences are removed and remaining sequences are aligned to a curated pathogen database of >1,000 organisms. Organisms present above a statistical threshold are quantified in DNA molecules per microliter (MPM) and reported. Results Over 90 days 45 KTs were ordered on 42 patients (mean age = 46); including 3 repeat tests. Thirty-six were inpatients (8 in the ICU) with a mean 4.7 days to ID consult and length-of-stay of 16 days. 31% (13/42) were immunocompromised: i.e. transplant, oncology, or HIV/AIDS. Fine needle or open biopsies were performed on 13 patients and 13 patients had bronchoscopy; 30.8% (8/26) were diagnostic of infection. A valid KT result was returned in 44/45 tests (mean 3.5 days from ID consult). 56.8% (25/44) of tests were positive for one or more organisms (a single pathogen was detected on 11 KTs). Among positive tests, 56% (14/25 - 10 bacterial and 4 fungal infections) were confirmed by culture, antigen, or PCR. Mean time to diagnosis for culture, PCR, antigen, and KT was 16.4, 3, 5.5, and 3.5 days, respectively. In 3 cases, the KT was the only positive test but correlated with the clinical scenario resulting in antimicrobial changes (Pneumocystis jirovecii pneumonia in AIDS, pulmonary aspergillosis in AIDS, and Fusobacterium nucleatum septic thrombophlebitis). Conclusion We identified 4 clinical scenarios where the KT provided value: patients with suspected invasive fungal infections, culture-negative endovascular infections/endocarditis, possible discitis or paravertebral infection, and pulmonary disease in AIDS. Future efforts will include outreach for prevention of invasive diagnostic procedures when a KT is pending or positive. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]