Secondary bacterial culture of platelets to mitigate transfusion-associated sepsis: A 3-year analysis at a large academic institution.

BACKGROUND: In 2019, the United States Food and Drug Administration published its final recommendations to mitigate bacterial contamination of platelets. We sought to evaluate our secondary bacterial culture (SBC) strategy in light of those recommendations. STUDY DESIGN AND METHODS: A retrospective analysis was conducted of SBC data (October 2016-2019) at our institution. SBC was performed upon receipt (Day 3 after collection); 5 mL of platelet product was inoculated aseptically into an aerobic bottle and incubated at 35°C for 3 days. For 8 months, a 10-mL inoculum was trialed. No quarantine was applied. All positive cultures underwent Gram staining and repeat culture of the platelet product (if available). A probable true positive was defined as concordant positive culture between the initial and repeat culture. The incidence of probable true- and false-positive cultures were reported descriptively and differences evaluated by sampling volume. RESULTS: Over 3 years, 55 896 platelet products underwent SBC, yielding 30 initial positive results (approx. 1/1863 platelets); 25 (83.3%) signaled within 24 hours of SBC. The rates of probable true positive, false positive, and indeterminate for 5 mL were 0.027% (1/3771), 0.002% (1/45 251) and 0.018% (1/5656), respectively. The respective rates for 10 mL were 0.018% (1/5323), 0.07% (1/1521), and 0%. Seven of eight (87.5%) false-positive SBCs occurred with a 10-mL inoculum. No septic transfusion reactions were reported. CONCLUSION: SBC continues to interdict bacterially contaminated units of platelets. Our findings suggest higher rates of false positivity using large-volume inocula.

Evaluation of the NG-Test MCR-1 Lateral Flow Assay and EDTA-Colistin Broth Disk Elution Methods To Detect Plasmid-Mediated Colistin Resistance among Gram-Negative Bacterial Isolates.

Plasmid-mediated colistin resistance (PMCR) is a global public health concern, given its ease of transmissibility. The purpose of this study was to evaluate two methods for the detection of PMCR from bacterial colonies: (i) the NG-Test MCR-1 lateral flow immunoassay (LFA; NG Biotech, Guipry, France) and (ii) the EDTA-colistin broth disk elution (EDTA-CBDE) screening test method. These methods were evaluated using a cohort of contemporary, clinical Gram-negative bacillus isolates from 3 U.S. academic medical centers (126 isolates of the Enterobacterales, 50 Pseudomonas aeruginosa isolates, and 50 Acinetobacter species isolates; 1 isolate was mcr positive) and 12 mcr-positive CDC-FDA Antibiotic Resistance (AR) Isolate Bank isolates for which reference broth microdilution colistin susceptibility results were available. Eleven (4.6%) isolates were strongly positive by the MCR-1 LFA, with an additional 8 (3.4%) isolates yielding faintly positive results. The positive percent agreement (PPA) and negative percent agreement (NPA) for MCR-1 detection were 100% and 96.1%, respectively. Upon repeat testing, only a single false-positive MCR-2 producer remained, as the isolates with initially faintly positive results were negative. The EDTA-CBDE screening method had an overall PPA and NPA of 100% and 94.3%, respectively. The NPA for the EDTA-CBDE method was slightly lower at 94.2% with Enterobacterales, whereas it was 96.0% with P. aeruginosa The MCR-1 LFA and EDTA-CBDE methods are both accurate and user-friendly methods for the detection of PMCR. Despite the rarity of PMCR among clinical isolates in the United States, these methods are valuable tools that may be implemented in public health and clinical microbiology laboratories to further discern the mechanism of resistance among colistin-resistant Gram-negative isolates and to detect PMCR for infection prevention and control purposes.

Central Nervous System Blastomycosis With Multiple Brain Abscesses Presenting as Right Upper Extremity Weakness.

Blastomycosis is a mycotic infection that typically affects the lung, but that can have dermatologic, orthopedic, genitourinary, and central nervous system manifestations. Blastomyces dermatitidis is a true human pathogen, which can produce disease in immunocompetent hosts. Risk factors for infection include residence in or travel to endemic areas and outdoor occupation, particularly those activities near open bodies of water and that disrupt soil. Immunosuppressed patients are also at increased risk for severe and disseminated disease. We present a case of a 79-year-old male who presented with a 2-week history of progressive right upper extremity weakness and severe odontogenic disease. He was found to have multiple brain abscesses with positive cultures from a cerebral abscess incision and drainage for B dermatitidis. He underwent an incision and drainage of the largest cerebral abscess and was treated with intravenous liposomal amphotericin B, which he tolerated poorly. He was subsequently switched to voriconazole, which was well tolerated, and his neurological deficits improved throughout his hospitalization.

First Case Report of Human Bacteremia With Malacobacter (Arcobacter) mytili.

Arcobacter spp. are commonly associated with shellfish and have been increasingly implicated in human gastrointestinal disease. We report the first case of human bacteremia with Malacobacter (previously Arcobacter) mytili acquired after exposure to Maryland crab. Arcobacter spp. should be considered in febrile illnesses when the history indicates exposure to seafood.