In the United States, methicillin-resistant Staphylococcus aureus (MRSA) with the USA300 pulsed-field gel electrophoresis type causes most community-associated MRSA infections and is an increasingly common cause of health care–associated MRSA infections. USA300 probably emerged during the early 1990s. To assess the spatiotemporal diffusion of USA300 MRSA and USA100 MRSA throughout the United States, we systematically reviewed 354 articles for data on 33,543 isolates, of which 8,092 were classified as USA300 and 2,595 as USA100. Using the biomedical literature as a proxy for USA300 prevalence among genotyped MRSA samples, we found that USA300 was isolated during 2000 in several states, including California, Texas, and midwestern states. The geographic mean center of USA300 MRSA then shifted eastward from 2000 to 2013. Analyzing genotyping studies enabled us to track the emergence of a new, successful MRSA type in space and time across the country.

Background: Military Veterans in the United States are more likely than the general population to live in rural areas, and often have limited geographic access to Veterans Health Administration (VHA) facilities. In an effort to improve access for Veterans living far from VHA facilities, the recently-enacted Veterans Choice Act directed VHA to purchase care from non-VHA providers for Veterans who live more than 40 miles from the nearest VHA facility. To explore potential impacts of these reforms on Veterans and healthcare providers, we identified VHA-users who were eligible for purchased care based on distance to VHA facilities, and quantified the availability of various types of non-VHA healthcare providers in counties where these Veterans lived. Methods: We combined 2013 administrative data on VHA-users with county-level data on rurality, non-VHA provider availability, population, household income, and population health status. Results: Most (77.9%) of the 416,338 VHA-users who were eligible for purchased care based on distance lived in rural counties. Approximately 16% of these Veterans lived in primary care shortage areas, while the majority (70.2%) lived in mental health care shortage areas. Most lived in counties that lacked specialized health care providers (e.g. cardiologists, pulmonologists, and neurologists). Counterintuitively, VHA played a greater role in delivering healthcare for the overall adult population in counties that were farther from VHA facilities (30.7 VHA-users / 1000 adults in counties over 40 miles from VHA facilities, vs. 22.4 VHA-users / 1000 adults in counties within 20 miles of VHA facilities, p < 0.01). Conclusions: Initiatives to purchase care for Veterans living more than 40 miles from VHA facilities may not significantly improve their access to care, as these areas are underserved by non-VHA providers. Non-VHA providers in the predominantly rural areas more than 40 miles from VHA facilities may be asked to assume care for relatively large numbers of Veterans, because VHA has recently cared for a greater proportion of the population in these areas, and these Veterans are now eligible for purchased care.

The Democratic Republic of the Congo (DRC) bears a large share of global malaria burden despite efforts to control and eliminate the disease. More detailed understanding of individual and household level characteristics associated with malaria are needed, as is an understanding of how these characteristics vary spatiotemporally and across different community-level malaria endemicities. An ongoing study in Kinshasa Province is designed to address gaps in prior malaria surveillance in the DRC by monitoring malaria across seasons, age groups and in high and low malaria sites. Across seven sites, 242 households and 1591 individuals are participating in the study. Results of the enrollment questionnaire, rapid diagnostic tests and PCR testing of dried blood spots are presented. Overall malaria prevalence in the study cohort is high, 27% by rapid diagnostic test and 31% by polymerase chain reaction, and malaria prevalence is highly varied across very small geographic distances. Malaria prevalence is highest in children aged 6–15. While the majority of households own bed nets, bed net usage is less than 50%. The study cohort will provide an understanding of how malaria persists in populations that have varying environmental exposures, varying community-level malaria, and varying access to malaria control efforts.

Importance: Oral non–β-lactam antibiotics are commonly used for empirical therapy of Staphylococcus aureus infections, especially in outpatient settings. However, little is known about potential geographic heterogeneity and temporal trends in the prevalence of S aureus resistance to non–β-lactams in the US.Objective: To characterize the spatiotemporal trends of resistance to non–β-lactam antibiotics among community-onset S aureus infections, including regional variation in resistance rates and geographical heterogeneity in multidrug resistance.Design, Setting, and Participants: This cross-sectional study used data from Veterans Health Administration clinics collected from adult outpatients with S aureus infection in the conterminous 48 states and Washington, DC, from January 1, 2010, to December 31, 2019. Data were analyzed from January to November 2023.Exposures: Resistance to lincosamides (clindamycin), tetracyclines, sulfonamides (trimethoprim-sulfamethoxazole [TMP-SMX]), and macrolides.Main Outcomes and Measures: Spatiotemporal variation of S aureus resistance to these 4 classes of non–β-lactam antibiotics, stratified by methicillin-resistant S aureus (MRSA) and methicillin-sensitive S aureus (MSSA), and subdivided by regions of the US (Northeast, Midwest, South, and West). Trend tests and bivariate mapping were used to determine significant changes in resistant proportions over time and identify counties where rates of resistance to multiple non–β-lactams were high.Results: A total of 382 149 S aureus isolates from 268 214 unique outpatients (mean [SD] age, 63.4 [14.8] years; 252 910 males [94.29%]) were analyzed. There was a decrease in the proportion of MRSA nationwide, from 53.6% in 2010 to 38.8% in 2019. Among MRSA isolates, we observed a significant increase in tetracycline resistance (from 3.6% in 2010 to 12.8% in 2019; P for trend < .001) and TMP-SMX resistance (from 2.6% in 2010 to 9.2% in 2019; P for trend < .001), modest and not significant increases in clindamycin resistance (from 24.2% in 2010 to 30.6% in 2019; P for trend = .34), and a significant decrease in macrolide resistance (from 73.5% in 2010 to 60.2% in 2019; P for trend < .001). Among MSSA isolates, significant upward trends in clindamycin, tetracyclines, and TMP-SMX resistance were observed. For example, tetracycline resistance increased from 3.7% in 2010 to 9.1% in 2019 (P for trend < .001). Regional stratification over time showed that the Northeast had slightly higher rates of clindamycin resistance but lower rates of tetracycline resistance, while the South had notably higher rates of resistance to tetracyclines and TMP-SMX, particularly among MRSA isolates. Bivariate mapping at the county scale did not indicate clear regional patterns of shared high levels of resistance to the 4 classes of antimicrobials studied.Conclusions and Relevance: In this study of outpatient S aureus isolates, MRSA became less common over the 10-year period, and MRSA isolates were increasingly resistant to tetracyclines and TMP-SMX. Geographic analysis indicated no spatial overlap in counties with high rates of resistance to both tetracyclines and TMP-SMX. Examining the regional spatial variation of antibiotic resistance can inform empirical therapy recommendations and help to understand the evolution of S aureus antibiotic resistance mechanisms.

BACKGROUND: School vaccination rates in California have fallen as more parents opt for personal belief exemptions (PBEs) for their children. Our goals were to (1) spatially analyze PBE patterns over time, (2) determine correlates of PBEs, and (3) examine their spatial overlap with personal medical exemptions (PMEs). METHODS: PBE and PME data for California kindergarten classes from the 2001/2002 to 2013/2014 school years were matched to the locations of schools. Nonspatial clustering algorithms were implemented to group 5147 schools according to their trends in PBE percentages among kindergartners. Cluster assignments were mapped and hotspot analysis was performed to find areas in California where schools sharing trends in PBEs over time were colocated. Schools were further associated both with school-level data on minority enrollment and free and reduced price lunch participation and with charter/private and rural/urban status. Spatial regression was implemented to determine which school-level variables were correlated with PBE rates in the 2013/2014 school year. RESULTS: Distinct spatial patterns are observed in California when PBE cluster assignments are mapped. Results indicate that schools belonging to the “high PBE” cluster are spatially buffered from those in “low PBE” areas by “medium PBE” schools. Further, PBE rates are positively associated with the percentage of white students, charter status, and private schools. CONCLUSIONS: Hotspots of high PBE schools are in some cases colocated with schools that have elevated PME rates, prompting concern that herd immunity is diminished for school populations where students have no choice but to remain unvaccinated.

Among 1,036 patients, residential proximity within 1 mile of large swine facilities was associated with nearly double the risk of methicillin-resistant Staphylococcus aureus (MRSA) colonization at admission (relative risk, 1.8786 [95% confidence interval, 1.0928-3.2289]; P = .0239) and, after controlling for multiple admissions and age, was associated with 1.2nearly triple the odds of MRSA colonization (odds ratio, 2.76 [95% confidence interval, 1.2728-5.9875]; P = .0101).