Introduction/Objective Parenteral therapy for invasive staphylococcal infections often comprises lipo/glycopeptides for methicillin resistant (MR) organisms, with extended spectrum penicillins reserved for those confirmed as methicillin susceptible (MS). While phenotypic antimicrobial susceptibility testing (AST) using cefoxitin has high accuracy for differentiating MR/MS for S. aureus, the same, simple approach does not reliably distinguish resistance among all coagulase negative Staphylococcus species (CoNS). As such, clinicians may work under an assumption that MS CoNS cannot be reliably predicted by laboratories, leading to lipo/glycopeptide therapeutic use for invasive infections caused by both MR and MS isolates. To better inform laboratory practice, this study aimed to establish the accuracy of multiple phenotypic and genotypic tests for differentiation of MR/MS among commonly recovered CoNS species producing invasive infections. Methods/Case Report A convenience sample of 155 unique invasive CoNS isolates with historic Vitek 2 and/or disc diffusion (DD) AST results (~50% MR) were retrieved from frozen storage and tested by: (1) cefoxitin and oxacillin DD, (2) a lateral flow immunoassay for PBP2a without beta-lactam induction, and (3) a lab-developed PCR for mecA. A commercial real-time PCR for mecA/C was also employed for a subset of isolates. Results (if a Case Study enter NA) A total of 144 isolates belonging to 11 taxa were evaluated by all tests after accounting for missing, non-viable, and incorrectly cataloged isolates. Using PCR mecA/C detection as the reference standard, categorical agreement for MR/MS status was 95.5% (127/133) for original Vitek GP75 results, 98.6% (142/144) for DD interpreted using updated, species-specific CLSI guidelines, and 100% (144/144) for the lateral flow PBP2a assay. Six MR isolates from five different taxa that were repeatedly mecA-negative by lab-developed PCR confirmed as mecA/C-positive by a commercial assay. Conclusion Although all methods evaluated distinguish MR/MS CoNS with sufficient accuracy, definitive determination is best achieved using off-label/lab-developed PCR for mec or lateral flow immunoassay for PBP2a.

Introduction/Objective Sarcoidosis is a syndrome of unknown cause that may manifest with clinical, radiographic and pathological findings similar to those seen with histoplasmosis. We present a case of disseminated histoplasmosis in an immunocompetent patient previously diagnosed with sarcoidosis. Methods/Case Report A 69-year-old obese male with a history of hypertension, diabetes mellitus and long-standing sarcoidosis was admitted to the hospital for several months of intermittent fevers and pancytopenia. His sarcoidosis was diagnosed 21 years prior, initially involving the lungs and eventually showing cardiac involvement, requiring a pacemaker. He had been treated with methotrexate and prednisone. His recent medical history was also significant for COVID-19 infection, diagnosed 3 months before admission. His fevers were initially attributed to sarcoidosis and his pancytopenia to methotrexate. However, his symptoms continued despite discontinuation of his medications, and further workup was initiated. Computed tomography showed hepatomegaly, splenomegaly, and lymphadenopathy, concerning for a lymphoproliferative disorder. The patient underwent a bone marrow biopsy that showed noncaseating granulomas and microorganisms consistent with histoplasmosis on fungal stain. Bone marrow cultures were not possible as the marrow was inaspirable. The patient subsequently underwent a lymph node biopsy with both morphology and culture identifying histoplasmosis. Urine and serum histoplasma antigen also returned positive. The patient’s overall clinical picture was consistent with disseminated histoplasmosis and he was administered intravenous Amphotericin B for 3 weeks followed by oral itraconazole for 1 year. One month follow-up after discharge showed significant improvement in the patient’s condition. Results (if a Case Study enter NA) N/A Conclusion Sarcoidosis reduces T-cell activity, and treatment with steroids causes further immunosuppression and vulnerability for development of a disseminated infection. COVID-19 also presumably increases the predisposition to acquire bacterial or fungal co-infections. Clinicians and pathologists should be aware of the overlap in clinical, radiologic and pathological presentations of sarcoidosis and histoplasmosis to make the correct diagnosis and administer the appropriate treatment.

No abstract

Background Bacteremia is a life-threatening illness. Delayed treatment increases patient morbidity and healthcare costs. Accelerate Pheno™ Blood Culture Detection System (AXDX) is a novel diagnostic technology for rapid detection of gram-negative bacteremia. Studies have shown accurate and faster time to speciation and sensitivity (TTSS) by AXDX compared to conventional modality. Our unique study examined the direct impact of AXDX on clinical outcomes and cost. Methods This retrospective study consisted of 213 patients aged 18 years and older admitted to our academic institution with gram-negative bacteremia. The pre-AXDX group had 109 patients admitted in 2019 and the post-AXDX group had 104 patients admitted in 2021. Demographics, microbes, TTSS, time to de-escalation of therapy (TTDeT), length of stay (LOS), readmissions, mortality rates, and Clostridioides difficile infection (CDI) rates were recorded. Results The pre-AXDX group had 51.4% females, mean age of 60.3 years, mean Charlson Comorbidity Index (CCMI) of 2.2, mean LOS of 21.2 days, and mean Pitt Bacteremia Score (PBS) of 2.4. The post-AXDX group had 52.0% females, mean age of 63.7 years, mean CCMI of 3.0, mean LOS of 15.0 days, and mean PBS of 2.7. Both groups’ top 2 sources of bacteremia were urinary and gastrointestinal and top 2 microbes were Escherichia coli and Klebsiella pneumoniae. Pre-AXDX's mean TTSS was 71.9 hours and 23.6 hours for post-AXDX. Pre-AXDX's mean TTDeT was 74.0 hours and 43.9 hours for post-AXDX. The pre-AXDX cohort had 7.4% more related readmissions, 5.5% more CDI, and 0.3% more inpatient mortality than post-AXDX group. Conclusion In addition to faster TTSS with AXDX as seen with previous studies, our study shows clinical advantages with AXDX use. Both groups were comparable in bacteremia sources and microbes. The post-AXDX group had higher CCMI and PBS scores, indicating they were more ill. Despite this, the pre-AXDX group had 30.05 hours longer TTDeT, 6.17 days longer mean LOS, 5.45% more CDI, 7.12% more readmissions, and 0.26% higher mortality. The pre-AXDX group also reported adverse reactions to antibiotics, while post-AXDX did not. Our data shows AXDX use improves clinical outcomes with reduced adverse effects, mortality and CDI rate and lower costs with less LOS and readmission rates. Disclosures All Authors: No reported disclosures.