Oncoplastic Surgery Outcomes in the Older Breast Cancer Population: A Matched-Cohort Comparison Study.

BACKGROUND: Oncoplastic breast surgery (OBS) is a form of breast conservation surgery (BCS) that involves a partial mastectomy followed by immediate volume displacement or volume replacement surgical techniques. To date, there are few studies evaluating OBS in older patients. Therefore, we sought to determine if outcomes differed between patients 65 years and older versus younger patients who underwent oncoplastic surgical procedures. METHODS: A retrospective chart review was performed for all oncoplastic breast operations within a single health system from 2015 to 2021. Patients were stratified by age, with patients 65 years and older (OBS65+) identified and then matched with younger patients (OBS <65) based on BMI. Primary outcomes were positive margin rates and overall complication rates; secondary outcomes were locoregional recurrence (LR), distant recurrence (DR), disease-free survival (DFS), overall survival (OS), and long-term breast asymmetry. RESULTS: A total of 217 patients underwent OBS over the 6-year period, with 22% being OBS65+. Preoperatively, older patients experienced higher American Anesthesia (ASA) scores, Charlson Co-morbidity index (CCI) scores, and higher rates of diabetes mellitus, hypertension, and grade 3 breast ptosis. Despite this, no significant differences were found between primary or secondary outcomes compared to younger patients undergoing the same procedures. CONCLUSIONS: Oncoplastic breast reconstruction is a safe option in patients 65 years and older, with overall similar recurrence rates, positive margin rates, and survival when compared to younger patients. Although the older cohort of patients had greater preoperative risk, there was no difference in overall surgical complication rates or outcomes. Supporting the argument that all oncoplastic breast reconstruction techniques should be offered to eligible patients, irrespective of age.

Application of Pathogen Genomics to Outbreak Investigation.

Outbreaks are a risk to public health particularly when pathogenic, hypervirulent, and/or multidrug-resistant organisms (MDROs) are involved. In a hospital setting, vulnerable populations such as the immunosuppressed, intensive care patients, and neonates are most at risk. Rapid and accurate outbreak detection is essential to implement effective interventions in clinical areas to control and stop further transmission. Advances in the field of whole genome sequencing (WGS) have resulted in lowered costs, increased capacity, and improved reproducibility of results. WGS now has the potential to revolutionize the investigation and management of outbreaks replacing conventional genotyping and other discrimination systems. Here, we outline specific procedures and protocols to implement WGS into investigation of outbreaks in healthcare settings.

In patients with the kidney-dysfunction triad, facilitated evidence-based care did not reduce hospitalizations at 1 y.

SOURCE CITATION: Vazquez MA, Oliver G, Amarasingham R, et al; ICD-Pieces Study Group. Pragmatic trial of hospitalization rate in chronic kidney disease. N Engl J Med. 2024;390:1196-1206. 38598574.

Substantia Nigra Pathology, Contact Sports Play, and Parkinsonism in Chronic Traumatic Encephalopathy.

Importance: Parkinsonism is associated with traumatic brain injury and chronic traumatic encephalopathy (CTE), a neurodegenerative disease associated with repetitive head impact (RHI) exposure, but the neuropathologic substrates that underlie parkinsonism in individuals with CTE are yet to be defined. Objective: To evaluate the frequency of parkinsonism in individuals with CTE and the association of RHI and neuropathologic substrates with parkinsonism in these individuals. Design, Setting, and Participants: This cross-sectional study included brain donors with neuropathologically diagnosed CTE without other significant neurodegenerative disease and with information on parkinsonism from the Understanding Neurologic Injury and Traumatic Encephalopathy brain bank between July 2015 and May 2022. Exposure: Years of contact sports participation as a proxy for RHI. Main Outcomes and Measures: The main outcomes were frequency of parkinsonism in individuals with CTE and associations between (1) RHI with substantia nigra (SN) Lewy bodies (LBs) and neurofibrillary tangles (NFTs); (2) LBs, NFTs, and arteriolosclerosis with SN neuronal loss; and (3) SN neuronal loss, LBs, NFTs, and arteriolosclerosis with parkinsonism, tested by age-adjusted logistic regressions. Results: Of 481 male brain donors with neuropathologically diagnosed CTE, parkinsonism occurred frequently in individuals with CTE (119 [24.7%]; 362 [75.3%] did not have parkinsonism). Participants with parkinsonism had a higher mean (SD) age at death (71.5 [13.0] years) than participants without parkinsonism (54.1 [19.3] years) (P < .001) and higher rates of dementia (104 [87.4%] vs 105 [29.0%]), visual hallucinations (45 [37.8%] vs 51 [14.1%]), and probable rapid eye movement sleep behavior disorder (52 [43.7%] vs 58 [16.0%]) (P < .001 for all). Participants with parkinsonism had a more severe CTE stage (eg, stage IV: 35 [29.4%] vs 39 [10.8%]) and nigral pathology than those without parkinsonism (NFTs: 50 of 117 [42.7%] vs 103 of 344 [29.9%]; P = .01; neuronal loss: 61 of 117 [52.1%] vs 59 of 344 [17.1%]; P < .001; and LBs: 28 of 116 [24.1%] vs 20 of 342 [5.8%]; P < .001). Years of contact sports participation were associated with SN NFTs (adjusted odds ratio [AOR], 1.04; 95% CI, 1.00-1.07; P = .03) and neuronal loss (AOR, 1.05; 95% CI, 1.01-1.08; P = .02). Nigral neuronal loss (AOR, 2.61; 95% CI, 1.52-4.47; P < .001) and LBs (AOR, 2.29; 95% CI, 1.15-4.57; P = .02) were associated with parkinsonism. However, SN neuronal loss was associated with SN LBs (AOR, 4.48; 95% CI, 2.25-8.92; P < .001), SN NFTs (AOR, 2.51; 95% CI, 1.52-4.15; P < .001), and arteriolosclerosis (AOR, 2.27; 95% CI, 1.33-3.85; P = .002). In American football players, regression analysis demonstrated that SN NFTs and neuronal loss mediated the association between years of play and parkinsonism in the context of CTE (ß, 0.012; 95% CI, 0.001-0.038). Conclusions and Relevance: In this cross-sectional study of contact sports athletes with CTE, years of contact sports participation were associated with SN tau pathology and neuronal loss, and these pathologies were associated with parkinsonism. Repetitive head impacts may incite neuropathologic processes that lead to symptoms of parkinsonism in individuals with CTE.

Addressing food insecurity in the inpatient setting: Results of a postdischarge pilot study.

BACKGROUND AND OBJECTIVES: With a growing interest in screening for food insecurity (FI) during pediatric hospitalization, there is a parallel need to develop interventions. With input from caregivers experiencing FI, we sought to identify interventions to assist with short-term FI after discharge and evaluate their feasibility, acceptability, and appropriateness. METHODS: We first employed qualitative methods to identify potential interventions. Next, we conducted a pilot study of selected interventions for families experiencing FI. Seven days postdischarge, caregivers rated the intervention's feasibility, acceptability, and appropriateness. We also assessed for ongoing FI. We summarized the median and proportion of "completely agree" responses to feasibility, acceptability, and appropriateness questions, and we compared in-hospital and postdischarge FI using McNemar's test. RESULTS: In the qualitative stage, 14 caregivers prioritized three interventions: grocery store gift cards, grocery delivery/pick-up, and frozen meals. In the pilot study, 53 caregivers (25% of those screened) endorsed FI during their child's hospitalization and received one or more of the interventions. Every caregiver selected the grocery gift card option; 37 families (69.8%) also received frozen meals. Seven days after discharge, most caregivers rated the intervention as "completely" feasible (76%), acceptable (90%), and appropriate (88%). There was a significant decrease in caregivers who reported FI after discharge compared to during the hospitalization (p < .001). CONCLUSIONS: This study demonstrates the feasibility, acceptability, and appropriateness of inpatient interventions to address FI, particularly at the time of pediatric hospital discharge and transition home. Randomized trials are needed to further evaluate the efficacy of interventions employed during hospitalization.

Quantitative microbial risk assessment (QMRA) tool for modelling pathogen infection risk to wastewater treatment plant workers.

Wastewater treatment plants (WWTPs) provide vital services to the public by removing contaminants from wastewater prior to environmental discharge or reuse for beneficial purposes. WWTP workers occupationally exposed to wastewater can be at risk of respiratory or gastrointestinal diseases. The study objectives were to: (1) quantify pathogens and pathogen indicators in wastewater aerosols near different WWTP processes/unit operations, (2) develop a QMRA model for multi-pathogen and multi-exposure pathway risks, and (3) create a web-based application to perform and communicate risk calculations for wastewater workers. Case studies for seven different WWTP job tasks were performed investigating infection risk across nine different enteric and respiratory pathogens. It was observed that the ingestion risk among job tasks was highest for "walking the WWTP," which involved exposure from splashing, bioaerosols, and hand-to-mouth contact from touching contaminated surfaces. There was also a notable difference in exposure risk during peak (5:00am-9:00am) and non-peak hours (9:00am- 5:00am), with risks during the peak flow hours of the early morning assumed to be 5 times greater than non-peak hours. N95 respirator usage reduced median respiratory risks by 77 %. The developed tool performs multiple QMRA calculations to estimate WWTP workers' infection risks from accidental ingestion or inhalation of wastewater from multiple pathogens and exposure scenarios, which can inform risk management strategies to protect occupational health. However, more data are needed to reduce uncertainty in model estimates, including comparative data for pathogen concentrations in wastewater during peak and non-peak hours. QMRA tools will increase accessibility of risk models for utilization in decision-making.

A Natural History Study of Timothy Syndrome.

Timothy syndrome (OMIM #601005) is a rare disease caused by variants in the gene CACNA1C . Timothy syndrome patients were first identified as having a cardiac presentation of Long QT and syndactyly of the fingers and/or toes, and an identical variant in CACNA1C , Gly406Arg. However, since this original identification, more individuals harboring diverse variants in CACNA1C have been identified and have presented with various cardiac and extra-cardiac symptoms. Furthermore, it has remained underexplored whether individuals harboring canonical Gly406Arg variants in mutually exclusive exon 8A (Timothy syndrome 1) or exon 8 (Timothy syndrome 2) have additional symptoms. Here, we describe the first Natural History Study for Timothy syndrome, providing a thorough resource describing the current understanding of disease manifestation in Timothy syndrome patients. Parents of Timothy syndrome children were queried regarding a wide-ranging set of symptoms and features via a survey. Importantly, we find that in addition to cardiac concerns, Timothy syndrome patients commonly share extra-cardiac features including neurodevelopmental impairments, hypoglycemia, and respiratory problems. Our work expands the current understanding of the disorder to better inform the care of Timothy syndrome patients.

Genome-wide association analysis of the resistance to infectious hematopoietic necrosis virus in two rainbow trout aquaculture lines confirms oligogenic architecture with several moderate effect quantitative trait loci.

Infectious hematopoietic necrosis (IHN) is a disease of salmonid fish that is caused by the IHN virus (IHNV), which can cause substantial mortality and economic losses in rainbow trout aquaculture and fisheries enhancement hatchery programs. In a previous study on a commercial rainbow trout breeding line that has undergone selection, we found that genetic resistance to IHNV is controlled by the oligogenic inheritance of several moderate and many small effect quantitative trait loci (QTL). Here we used genome wide association analyses in two different commercial aquaculture lines that were naïve to previous exposure to IHNV to determine whether QTL were shared across lines, and to investigate whether there were major effect loci that were still segregating in the naïve lines. A total of 1,859 and 1,768 offspring from two commercial aquaculture strains were phenotyped for resistance to IHNV and genotyped with the rainbow trout Axiom 57K SNP array. Moderate heritability values (0.15-0.25) were estimated. Two statistical methods were used for genome wide association analyses in the two populations. No major QTL were detected despite the naïve status of the two lines. Further, our analyses confirmed an oligogenic architecture for genetic resistance to IHNV in rainbow trout. Overall, 17 QTL with notable effect (≥1.9% of the additive genetic variance) were detected in at least one of the two rainbow trout lines with at least one of the two statistical methods. Five of those QTL were mapped to overlapping or adjacent chromosomal regions in both lines, suggesting that some loci may be shared across commercial lines. Although some of the loci detected in this GWAS merit further investigation to better understand the biological basis of IHNV disease resistance across populations, the overall genetic architecture of IHNV resistance in the two rainbow trout lines suggests that genomic selection may be a more effective strategy for genetic improvement in this trait.

Association of Timing With Postoperative Complications in the Management of Open Distal Radius Fractures.

BACKGROUND: This study investigates whether open distal radius fractures (ODRFs) treated after 24 hours from time of injury have an increased risk of infection or overall complication profile compared with those treated within 24 hours. METHODS: Retrospective review was performed of all patients treated for ODRF over a 6-year period at a single large academic institution. Postoperative complications included surgical site infections, need for revision irrigation and debridement, delayed soft tissue healing, loss of reduction, nonunion, and malunion. RESULTS: One-hundred twenty patients were treated for ODRF. Mean (SD) age at time of injury was 59.92 (17.68) years. Twenty patients (16.7%) had postoperative complications. Regarding mechanism of injury, 78 (65.0%) had a low-energy and 42 (35.0%) had a high-energy injury. Age and fracture grade were not significant factors. Mean (SD) open wound size was 1.18 (1.57) cm. Mean (SD) time from injury presentation to the emergency department (ED) and first dose of intravenous antibiotics was 3.07 (4.05) hours and mean (SD) time from presentation to the ED and operative treatment was 11.90 (6.59) hours, which did not show a significant association with postoperative complications. Twenty-four patients (20.0%) were treated greater than 24 hours after presentation to the ED, which was not significantly distinct from those treated within 24 hours. CONCLUSION: Patients with ODRFs treated after 24 hours were not associated with a greater risk of postoperative complications. Factors including age, energy and mechanism of injury, and fracture grade did not alter outcome in any statistically significant manner. LEVEL OF EVIDENCE: Level IV.

Investigating Unconscious Race Bias and Bias Awareness Among Vascular Surgeons.

Background: Implicit bias can influence behavior and decision-making. In clinical settings, implicit bias may influence treatment decisions and contribute to health disparities. Given documented Black-White disparities in vascular care, the purpose of this study was to examine the prevalence and degree of unconscious bias and awareness of bias among vascular surgeons treating peripheral artery disease (PAD). Methods: The sampling frame included all vascular surgeons who participate in the Vascular Quality Initiative (VQI). Participants completed a survey which included demographic questions, the race implicit association test (IAT) to measure magnitude of unconscious bias, and six bias awareness questions to measure conscious bias. The magnitude of unconscious bias was no preference; or slight, moderate, or strong in the direction of pro-White or pro-Black. Data from participants were weighted to account for nonresponse bias and known differences in the characteristics of surgeons who chose to participate compared to the full registry. We stratified unconscious and conscious findings by physician race/ethnicity, physician sex, and years of experience. Finally, we examined the relationship between unconscious and conscious bias. Results: There were 2,512 surgeons in the VQI registry, 304 of whom completed the survey, including getting IAT results. Most participants (71.6%) showed a pro-White bias with 73.0% of this group in the moderate and strong categories. While 77.5% of respondents showed conscious awareness of bias, of those whose conscious results showed lack of awareness, 67.8% had moderate or strong bias, compared to 55.7% for those with awareness. Bias magnitude varied based on physician race/ethnicity and years of experience. Women were more likely than men to report awareness of biases and potential impact of bias on decision-making. Conclusions: Most people have some level of unconscious bias, developed from early life reinforcements, social stereotypes, and learned experiences. Regarding health disparities, however, these are important findings in a profession that takes care of patients with PAD due to heavy burden of comorbid conditions and high proportion of individuals from structurally vulnerable groups. Given the lack of association between unconscious and conscious awareness of biases, awareness may be an important first step in mitigation to minimize racial disparities in healthcare.

Removing Persistent Barriers to Systematic Searching.

This is the third article in a new series designed to provide readers with insight into educating nurses about evidence-based decision-making (EBDM). It builds on AJN's award-winning previous series-Evidence-Based Practice, Step by Step and EBP 2.0: Implementing and Sustaining Change (to access both series, go to http://links.lww.com/AJN/A133). This follow-up series on EBDM will address how to teach and facilitate learning about the evidence-based practice (EBP) and quality improvement (QI) processes and how they impact health care quality. This series is relevant for all nurses interested in EBP and QI, especially DNP faculty and students. The brief case scenario included in each article describes one DNP student's journey. To access previous articles in this EBDM series, go to http://links.lww.com/AJN/A256.

Recognising the importance and impact of Imaging Scientists: Global guidelines for establishing career paths within core facilities.

In the dynamic landscape of scientific research, imaging core facilities are vital hubs propelling collaboration and innovation at the technology development and dissemination frontier. Here, we present a collaborative effort led by Global BioImaging (GBI), introducing international recommendations geared towards elevating the careers of Imaging Scientists in core facilities. Despite the critical role of Imaging Scientists in modern research ecosystems, challenges persist in recognising their value, aligning performance metrics and providing avenues for career progression and job security. The challenges encompass a mismatch between classic academic career paths and service-oriented roles, resulting in a lack of understanding regarding the value and impact of Imaging Scientists and core facilities and how to evaluate them properly. They further include challenges around sustainability, dedicated training opportunities and the recruitment and retention of talent. Structured across these interrelated sections, the recommendations within this publication aim to propose globally applicable solutions to navigate these challenges. These recommendations apply equally to colleagues working in other core facilities and research institutions through which access to technologies is facilitated and supported. This publication emphasises the pivotal role of Imaging Scientists in advancing research programs and presents a blueprint for fostering their career progression within institutions all around the world.

Research gaps and priorities for quantitative microbial risk assessment (QMRA).

The coronavirus disease 2019 pandemic highlighted the need for more rapid and routine application of modeling approaches such as quantitative microbial risk assessment (QMRA) for protecting public health. QMRA is a transdisciplinary science dedicated to understanding, predicting, and mitigating infectious disease risks. To better equip QMRA researchers to inform policy and public health management, an Advances in Research for QMRA workshop was held to synthesize a path forward for QMRA research. We summarize insights from 41 QMRA researchers and experts to clarify the role of QMRA in risk analysis by (1) identifying key research needs, (2) highlighting emerging applications of QMRA; and (3) describing data needs and key scientific efforts to improve the science of QMRA. Key identified research priorities included using molecular tools in QMRA, advancing dose-response methodology, addressing needed exposure assessments, harmonizing environmental monitoring for QMRA, unifying a divide between disease transmission and QMRA models, calibrating and/or validating QMRA models, modeling co-exposures and mixtures, and standardizing practices for incorporating variability and uncertainty throughout the source-to-outcome continuum. Cross-cutting needs identified were to: develop a community of research and practice, integrate QMRA with other scientific approaches, increase QMRA translation and impacts, build communication strategies, and encourage sustainable funding mechanisms. Ultimately, a vision for advancing the science of QMRA is outlined for informing national to global health assessments, controls, and policies.

Identification of factors associated with opioid-related and hepatitis C virus-related hospitalisations at the ZIP code area level in the USA: an ecological and modelling study.

BACKGROUND: Opioid overdose and related diseases remain a growing public health crisis in the USA. Identifying sociostructural and other contextual factors associated with adverse health outcomes is needed to improve prediction models to inform policy and interventions. We aimed to identify high-risk communities for targeted delivery of screening and prevention interventions for opioid use disorder and hepatitis C virus (HCV). METHODS: In this ecological and modelling study, we fit mixed-effects negative binomial regression models to identify factors associated with, and predict, opioid-related and HCV-related hospitalisations for ZIP code tabulation areas (ZCTAs) in South Carolina, USA. All individuals aged 18 years or older living in South Carolina from Jan 1, 2016, to Dec 31, 2021, were included. Data on opioid-related and HCV-related hospitalisations, as well as data on additional individual-level variables, were collected from medical claims records, which were obtained from the South Carolina Revenue and Fiscal Affairs Office. Demographic and socioeconomic variables were obtained from the United States Census Bureau (American Community Survey, 2021) with additional structural health-care barrier data obtained from South Carolina's Center for Rural and Primary Health Care, and the American Hospital Directory. FINDINGS: Between Jan 1, 2016, and Dec 31, 2021, 41 691 individuals were hospitalised for opioid misuse and 26 860 were hospitalised for HCV. There were a median of 80 (IQR 24-213) opioid-related hospitalisations and 61 (21-196) HCV-related hospitalisations per ZCTA. A standard deviation increase in ZCTA-level uninsured rate (relative risk 1·24 [95% CI 1·17-1·31]), poverty rate (1·24 [1·17-1·31]), mortality (1·18 [1·12-1·25]), and social vulnerability index (1·17 [1·10-1·24]) was significantly associated with increased combined opioid-related and HCV-related hospitalisation rates. A standard deviation increase in ZCTA-level income (0·79 [0·75-0·84]) and unemployment rate (0·87 [0·82-0·93]) was significantly associated with decreased combined opioid-related and HCV-related hospitalisations. Using 2016-20 hospitalisations as training data, our models predicted ZCTA-level opioid-related hospitalisations in 2021 with a median of 80·4% (IQR 66·8-91·1) accuracy and HCV-related hospitalisations in 2021 with a median of 75·2% (61·2-87·7) accuracy. Several underserved high-risk ZCTAs were identified for delivery of targeted interventions. INTERPRETATION: Our results suggest that individuals from economically disadvantaged and medically under-resourced communities are more likely to have an opioid-related or HCV-related hospitalisation. In conjunction with hospitalisation forecasts, our results could be used to identify and prioritise high-risk, underserved communities for delivery of field-level interventions. FUNDING: South Carolina Center for Rural and Primary Healthcare, National Institute on Drug Abuse, and National Library of Medicine.

Applications of Quantitative Microbial Risk Assessment to Respiratory Pathogens and Implications for Uptake in Policy: A State-of-the-Science Review.

BACKGROUND: Respiratory tract infections are major contributors to the global disease burden. Quantitative microbial risk assessment (QMRA) holds potential as a rapidly deployable framework to understand respiratory pathogen transmission and inform policy on infection control. OBJECTIVES: The goal of this paper was to evaluate, motivate, and inform further development of the use of QMRA as a rapid tool to understand the transmission of respiratory pathogens and improve the evidence base for infection control policies. METHODS: We conducted a literature review to identify peer-reviewed studies of complete QMRA frameworks on aerosol inhalation or contact transmission of respiratory pathogens. From each of the identified studies, we extracted and summarized information on the applied exposure model approaches, dose-response models, and parameter values, including risk characterization. Finally, we reviewed linkages between model outcomes and policy. RESULTS: We identified 93 studies conducted in 16 different countries with complete QMRA frameworks for diverse respiratory pathogens, including SARS-CoV-2, Legionella spp., Staphylococcus aureus, influenza, and Bacillus anthracis. Six distinct exposure models were identified across diverse and complex transmission pathways. In 57 studies, exposure model frameworks were informed by their ability to model the efficacy of potential interventions. Among interventions, masking, ventilation, social distancing, and other environmental source controls were commonly assessed. Pathogen concentration, aerosol concentration, and partitioning coefficient were influential exposure parameters as identified by sensitivity analysis. Most (84%, n=78) studies presented policy-relevant content including a) determining disease burden to call for policy intervention, b) determining risk-based threshold values for regulations, c) informing intervention and control strategies, and d) making recommendations and suggestions for QMRA application in policy. CONCLUSIONS: We identified needs to further the development of QMRA frameworks for respiratory pathogens that prioritize appropriate aerosol exposure modeling approaches, consider trade-offs between model validity and complexity, and incorporate research that strengthens confidence in QMRA results. https://doi.org/10.1289/EHP12695.

Meta-Analysis of Rice Phosphoproteomics Data to Understand Variation in Cell Signaling Across the Rice Pan-Genome.

Phosphorylation is the most studied post-translational modification, and has multiple biological functions. In this study, we have reanalyzed publicly available mass spectrometry proteomics data sets enriched for phosphopeptides from Asian rice (Oryza sativa). In total we identified 15,565 phosphosites on serine, threonine, and tyrosine residues on rice proteins. We identified sequence motifs for phosphosites, and link motifs to enrichment of different biological processes, indicating different downstream regulation likely caused by different kinase groups. We cross-referenced phosphosites against the rice 3,000 genomes, to identify single amino acid variations (SAAVs) within or proximal to phosphosites that could cause loss of a site in a given rice variety and clustered the data to identify groups of sites with similar patterns across rice family groups. The data has been loaded into UniProt Knowledge-Base─enabling researchers to visualize sites alongside other data on rice proteins, e.g., structural models from AlphaFold2, PeptideAtlas, and the PRIDE database─enabling visualization of source evidence, including scores and supporting mass spectra.

Newly Recognized Spotted Fever Group Rickettsia as Cause of Severe Rocky Mountain Spotted Fever-Like Illness, Northern California, USA.

The incidence of spotted fever group (SFG) rickettsioses in the United States has tripled since 2010. Rocky Mountain spotted fever, the most severe SFG rickettsiosis, is caused by Rickettsia rickettsii. The lack of species-specific confirmatory testing obfuscates the relative contribution of R. rickettsii and other SFG Rickettsia to this increase. We report a newly recognized rickettsial pathogen, Rickettsia sp. CA6269, as the cause of severe Rocky Mountain spotted fever-like illness in 2 case-patients residing in northern California. Multilocus sequence typing supported the recognition of this pathogen as a novel Rickettsia genotype most closely related to R. rickettsii. Cross-reactivity observed for an established molecular diagnostic test indicated that Rickettsia sp. CA6269 might be misidentified as R. rickettsii. We developed a Rickettsia sp. CA6269-specific real-time PCR to help resolve this diagnostic challenge and better characterize the spectrum of clinical disease and ecologic epidemiology of this pathogen.