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We report Mycetohabitans rhizoxinica bacteremia in a 65-year-old woman in California, USA, who was undergoing chimeric antigen receptor T-cell therapy for multiple myeloma. Acute brain infarction and pneumonia developed; Rhizopus microsporus mold was isolated from tracheal suction. Whole-genome sequencing confirmed bacteria in blood as genetically identical to endofungal bacteria inside the mold.

In Los Angeles, California, USA, persistent, refractory shigellosis was diagnosed in an immunocompetent man who has sex with men. Whole-genome sequencing augmented phenotypic antimicrobial susceptibility testing to comprehensively profile bacterial drug resistance and appropriately guide therapy and clear the infection.

With blood stream infections (BSIs) representing a major cause of mortality and morbidity worldwide, blood cultures play a crucial role in diagnosis, but their clinical application is dampened by the long turn-around time and the detection of only culturable pathogens. In this study, we developed and validated a shotgun metagenomics next-generation sequencing (mNGS) test directly from positive blood culture fluid, allowing for the identification of fastidious or slow growing microorganisms more rapidly. The test was built based on previously validated next-generation sequencing tests, which rely on several key marker genes for bacterial and fungal identification. The new test utilizes an open-source metagenomics CZ-ID platform for the initial analysis to generate the most likely candidate species, which is then used as a reference genome for downstream, confirmatory analysis. This approach is innovative because it takes advantage of an open-source software’s agnostic taxonomic calling capability while still relying on the more established and previously validated marker gene-based identification scheme, increasing the confidence in the final results. The test showed high accuracy (100%, 30/30) for both bacterial and fungal microorganisms. We further demonstrated its clinical utility especially for anaerobes and mycobacteria that are either fastidious, slow growing, or unusual. Although applicable in only limited settings, the Positive Blood Culture mNGS test provides an incremental improvement in solving the unmet clinical needs for the diagnosis of challenging BSIs.

We describe a case of New Delhi metallo-β-lactamase 1–producing carbapenem-resistant Pseudomonas aeruginosa (CRPA) in a transplant patient with multiple hospitalizations in California, USA. Whole-genome sequencing revealed the isolate was genetically distinctive, despite ≈95% similarity to other global strains. The patient’s lack of international travel suggests this CRPA was acquired domestically.

We describe a case of catheter-related bacteremia caused by Mycolicibacterium iranicum in the United States. The case highlights the value of using next-generation sequencing to identify infrequent and emerging pathogens and the challenges associated with choosing appropriate treatments because of limited knowledge of drug resistance mechanisms in those emerging pathogens.

Objectives: We aimed to analyze the landscape of viral respiratory illnesses (VRIs) in a large metropolitan area in Southern California with a focus on the COVID-19 pandemic. Methods: We conducted a retrospective cohort study within the UCLA Health System, which evaluated children aged 0–5 years who received comprehensive respiratory viral panel (cRVP) testing during August–February of 2018–2023. The patient demographics, disease severity, and clinical course were specifically compared during the pandemic. Predictors of significant VRI were determined by multivariate logistic regression. Results: A total of 1321 children underwent cRVP testing, and 753 positive subjects were identified during the study period. Rhinovirus (RV) was by far the most frequent virus detected across 5 years, even during the COVID-19 pandemic, followed by respiratory syncytial virus (RSV). Along with RSV and human metapneumovirus, RV was identified as an independent risk for significant disease and occurred irrespective of co-infection with other viruses. Conclusions: RV was the most common viral pathogen in young children, even during the height of the COVID-19 pandemic, and was an independent driver of moderate-to-severe disease, particularly in children with comorbidities. Ethnic disparities were also observed as a risk for significant disease, underscoring the need for targeted interventions and heightened clinical vigilance in pediatric populations.

We report an unexpected case of Bartonella quintana endocarditis and pauci-immune glomerulonephritis in a patient without known risk factors in Los Angeles, California, USA, highlighting that infection can occur in the general population without a history of homelessness. The diagnosis was challenging and made definitively through extensive diagnostic tests and multidisciplinary investigation.

Candida auris is an emerging multidrug-resistant yeast. We describe an ongoing C. auris outbreak that began in October 2019 in Los Angeles, California, USA. We used genomic analysis to determine that isolates from 5 of 6 patients belonged to clade III; 4 isolates were closely related.

A rare case of Francisella hispaniensis infection associated with seawater exposure occurred in a deep-sea diving fisherman in Zhejiang, China. He had skin and soft tissue infection that progressed to bacteremia and multiple organ failure. Moxifloxacin treatment cleared the infections, but the patient suffered a sequela of heart damage.

We describe a case of endogenous endophthalmitis caused by sequence type 66-K2 hypervirulent Klebsiella pneumoniae in a diabetic patient with no travel history outside the United States. Genomic analysis showed the pathogen has remained highly conserved, retaining >98% genetic similarity to the original strain described in Indonesia in 1935.