Clinical and in vitro models identify distinct adaptations enhancing Staphylococcus aureus pathogenesis in human macrophages.

Staphylococcus aureus is a facultative intracellular pathogen of human macrophages, which facilitates chronic infection. The genotypes, pathways, and mutations influencing that phenotype remain incompletely explored. Here, we used two distinct strategies to ascertain S. aureus gene mutations affecting pathogenesis in macrophages. First, we analyzed isolates collected serially from chronic cystic fibrosis (CF) respiratory infections. We found that S. aureus strains evolved greater macrophage invasion capacity during chronic human infection. Bacterial genome-wide association studies (GWAS) identified 127 candidate genes for which mutation was significantly associated with macrophage pathogenesis in vivo. In parallel, we passaged laboratory S. aureus strains in vitro to select for increased infection of human THP-1 derived macrophages, which identified 15 candidate genes by whole-genome sequencing. Functional validation of candidate genes using isogenic transposon mutant knockouts and CRISPR interference (CRISPRi) knockdowns confirmed virulence contributions from 37 of 39 tested genes (95%) implicated by in vivo studies and 7 of 10 genes (70%) ascertained from in vitro selection, with one gene in common to the two strategies. Validated genes included 17 known virulence factors (39%) and 27 newly identified by our study (61%), some encoding functions not previously associated with macrophage pathogenesis. Most genes (80%) positively impacted macrophage invasion when disrupted, consistent with the phenotype readily arising from loss-of-function mutations in vivo. This work reveals genes and mechanisms that contribute to S. aureus infection of macrophages, highlights differences in mutations underlying convergent phenotypes arising from in vivo and in vitro systems, and supports the relevance of S. aureus macrophage pathogenesis during chronic respiratory infection in CF. Additional studies will be needed to illuminate the exact mechanisms by which implicated mutations affect their phenotypes.

Population-average mediation analysis for zero-inflated count outcomes.

Mediation analysis is an increasingly popular statistical method for explaining causal pathways to inform intervention. While methods have increased, there is still a dearth of robust mediation methods for count outcomes with excess zeroes. Current mediation methods addressing this issue are computationally intensive, biased, or challenging to interpret. To overcome these limitations, we propose a new mediation methodology for zero-inflated count outcomes using the marginalized zero-inflated Poisson (MZIP) model and the counterfactual approach to mediation. This novel work gives population-average mediation effects whose variance can be estimated rapidly via delta method. This methodology is extended to cases with exposure-mediator interactions. We apply this novel methodology to explore if diabetes diagnosis can explain BMI differences in healthcare utilization and test model performance via simulations comparing the proposed MZIP method to existing zero-inflated and Poisson methods. We find that our proposed method minimizes bias and computation time compared to alternative approaches while allowing for straight-forward interpretations.

A Moderated Mediation Analysis of HIV and Intersectional Stigmas and Antiretroviral Adherence in People Living with HIV in the Dominican Republic.

Experiencing HIV and intersectional stigmas in healthcare settings may affect antiretroviral treatment (ART) adherence among people with HIV (PWH), given their need for frequent interactions with clinical settings and healthcare providers. Considering the importance of reducing stigmas to promote well-being and the need to elucidate how stigma influences health across various settings, we examined how experienced HIV stigma in Dominican Republic healthcare settings impacts ART adherence through internalized HIV stigma and whether race or sexual orientation stigma moderates this relationship. Participants were 471 PWH (aged 17-71) who were recruited from two HIV clinics in the Dominican Republic in 2021-2022. Results revealed a significant mediation effect (B=-0.10, SE = 0.05, CI [-0.234, - 0.014]) after adjusting for effect of age and time since HIV diagnosis, suggesting that experienced HIV stigma in healthcare settings was associated with more internalized HIV stigma (B = 0.39, SE = 0.11, p = .001), subsequently linked to lower ART adherence (B=-0.26, SE = 0.11, p = .016). The indirect effect was significant at low levels of race stigma (B=-0.16, SE = 0.09, CI [-0.369, - 0.001]) but not at high levels of race stigma (B=-0.06, SE = 0.05, CI [-0.175, 0.038]). This indirect effect was also significant at low levels of sexual orientation stigma (B=-0.19, SE = 0.10, CI [-0.401, - 0.023]) but not at high levels of sexual orientation stigma (B=-0.04, SE = 0.06, CI [-0.160, 0.074]). These findings suggest that addressing experienced HIV stigma in Dominican Republic healthcare settings, along with various dimensions of HIV-related stigma (e.g., internalized stigma) and intersecting stigmas (e.g., race, sexual orientation), is vital for improving health outcomes, such as optimal ART adherence.

RESUMEN: Experimentar estigmas relacionados con el VIH e interseccionales en entornos de atención médica puede afectar la adherencia al tratamiento antirretroviral (TAR) entre las personas que viven con VIH (PVVIH), dado que necesitan interacciones frecuentes con entornos clínicos y proveedores de atención médica. Considerando la importancia de reducir los estigmas para promover el bienestar y la necesidad de esclarecer cómo el estigma influye en la salud en diversos contextos, examinamos cómo el estigma del VIH experimentado en entornos de atención médica en la República Dominicana impacta la adherencia al TAR a través del estigma internalizado del VIH y si el estigma racial o de orientación sexual modera esta relación. Los participantes fueron 471 PVVIH (de 17 a 71 años) que fueron reclutados de dos clínicas de VIH en la República Dominicana en 2021­2022. Los resultados revelaron un efecto de mediación significativo (B=-0.10, SE = 0.05, CI [-0.234, − 0.014]) después de ajustar por el efecto de la edad y el tiempo desde el diagnóstico de VIH, sugiriendo que el estigma del VIH experimentado en entornos de atención médica estaba asociado con un mayor estigma internalizado del VIH (B = 0.39, SE = 0.11, p = .001), vinculado posteriormente a una menor adherencia al TAR (B=-0.26, SE = 0.11, p = .016). El efecto indirecto fue significativo en niveles bajos de estigma racial (B=-0.16, SE = 0.09, CI [-0.369, − 0.001]) pero no en niveles altos de estigma racial (B=-0.06, SE = 0.05, CI [-0.175, 0.038]). Este efecto indirecto también fue significativo en niveles bajos de estigma por orientación sexual (B=-0.19, SE = 0.10, CI [-0.401, − 0.023]) pero no en niveles altos de estigma por orientación sexual (B=-0.04, SE = 0.06, CI [-0.160, 0.074]). Estos hallazgos sugieren que abordar el estigma del VIH experimentado en entornos de atención médica en la República Dominicana, junto con diversas dimensiones del estigma relacionado con el VIH (por ejemplo, estigma internalizado) y estigmas interseccionales (por ejemplo, raza, orientación sexual), es vital para mejorar los resultados de salud, como la adherencia óptima al TAR.

Acceptability, feasibility and potential of an intervention using secret Facebook groups to complement existing HIV prevention strategies among female sex workers in Cameroon, a randomized pilot study.

This randomized pilot project evaluated an intervention promoting health care literacy around HIV, pre-exposure prophylaxis (PrEP), and stigma reduction using private social media groups that complemented existing HIV prevention services among female sex workers (FSWs) in Cameroon. The intervention was 12 HIV and sexual health videos tailored to FSWs that were released over 8 weeks through a secret Facebook group platform. In-person surveys were administered before, after the intervention, and three months later. No HIV seroconversions were detected; all participants completed follow-up and agreed to recommend the intervention to a coworker. Although the intervention was assessed to be acceptable and feasible to implement, poor internet connectivity was a key barrier. In time-series analysis, the intervention group participants reported improved PrEP interest, PrEP knowledge, and condom use along with reduced PrEP and HIV-related stigma, but no impact on sex-work related stigma or social cohesion. Similar results occurred in the control group. Cross-contamination and small pilot study size might have hindered the ability to detect the differential impact of this intervention. As communications technology increases in Cameroon, it is essential to learn more about FSWs preferences on the use of social media platforms for HIV prevention strategies.

2023 Neer Award for Basic Science: Genetics of Cutibacterium acnes in revision shoulder arthroplasty: a large-scale bacterial whole-genome sequencing study.

BACKGROUND: Cutibacterium acnes is the bacterium most commonly responsible for shoulder periprosthetic joint infection (PJI) and is often cultured from samples obtained at the time of revision for failed shoulder arthroplasty. We sought to determine whether these bacteria originate from the patient or from exogenous sources. We also sought to identify which C. acnes genetic traits were associated with the development of shoulder PJI. METHODS: We performed bacterial whole-genome sequencing of C. acnes from a single-institution repository of cultures obtained before or during primary and revision shoulder arthroplasty and correlated the molecular epidemiology and genetic content of strains with clinical features of infection. RESULTS: A total of 341 isolates collected over a 4-year period from 88 patients were sequenced. C. acnes cultured from surgical specimens demonstrated significant similarity to the strains colonizing the skin of the same patient (P < .001). Infrequently, there was evidence of strains shared across unrelated patients, suggesting that exogenous sources of C. acnes culture-positivity were uncommon. Phylotypes IB and II were modestly associated with clinical features of PJI, but all phylotypes appeared inherently capable of causing disease. Chronic shoulder PJI was associated with the absence of common C. acnes genes involved in bacterial quorum-sensing (luxS, tqsA). CONCLUSION: C. acnes strains cultured from deep intraoperative sources during revision shoulder arthroplasty demonstrate strong genetic similarity to the strains colonizing a patient's skin. Some phylotypes of C. acnes commonly colonizing human skin are modestly more virulent than others, but all phylotypes have a capacity for PJI. C. acnes cultured from cases of PJI commonly demonstrated genetic hallmarks associated with adaptation from acute to chronic phases of infection. This is the strongest evidence to date supporting the role of the patient's own, cutaneous C. acnes strains in the pathogenesis of shoulder arthroplasty infection. Our findings support the importance of further research focused on perioperative decolonization and management of endogenous bacteria that are likely to be introduced into the arthroplasty wound at the time of skin incision.

Mendelian randomization in the multivariate general linear model framework.

Mendelian randomization (MR) is an application of instrumental variable (IV) methods to observational data in which the IV is a genetic variant. MR methods applicable to the general exponential family of distributions are currently not well characterized. We adapt a general linear model framework to the IV setting and propose a general MR method applicable to any full-rank distribution from the exponential family. Empirical bias and coverage are estimated via simulations. The proposed method is compared to several existing MR methods. Real data analyses are performed using data from the REGARDS study to estimate the potential causal effect of smoking frequency on stroke risk in African Americans. In simulations with binary variates and very weak instruments the proposed method had the lowest median [Q1 , Q3 ] bias (0.10 [-3.68 to 3.62]); compared with 2SPS (0.27 [-3.74 to 4.26]) and the Wald method (-0.69 [-1.72 to 0.35]). Low bias was observed throughout other simulation scenarios; as well as more than 90% coverage for the proposed method. In simulations with count variates, the proposed method performed comparably to 2SPS; the Wald method maintained the most consistent low bias; and 2SRI was biased towards the null. Real data analyses find no evidence for a causal effect of smoking frequency on stroke risk. The proposed MR method has low bias and acceptable coverage across a wide range of distributional scenarios and instrument strengths; and provides a more parsimonious framework for asymptotic hypothesis testing compared to existing two-stage procedures.

Transposon sequencing identifies genes impacting Staphylococcus aureus invasion in a human macrophage model.

Staphylococcus aureus is a facultative intracellular pathogen in many host cell types, facilitating its persistence in chronic infections. The genes contributing to intracellular pathogenesis have not yet been fully enumerated. Here, we cataloged genes influencing S. aureus invasion and survival within human THP-1 derived macrophages using two laboratory strains (ATCC2913 and JE2). We developed an in vitro transposition method to produce highly saturated transposon mutant libraries in S. aureus and performed transposon insertion sequencing (Tn-Seq) to identify candidate genes with significantly altered abundance following macrophage invasion. While some significant genes were strain-specific, 108 were identified as common across both S. aureus strains, with most (n = 106) being required for optimal macrophage infection. We used CRISPR interference (CRISPRi) to functionally validate phenotypic contributions for a subset of genes. Of the 20 genes passing validation, seven had previously identified roles in S. aureus virulence, and 13 were newly implicated. Validated genes frequently evidenced strain-specific effects, yielding opposing phenotypes when knocked down in the alternative strain. Genomic analysis of de novo mutations occurring in groups (n = 237) of clonally related S. aureus isolates from the airways of chronically infected individuals with cystic fibrosis (CF) revealed significantly greater in vivo purifying selection in conditionally essential candidate genes than those not associated with macrophage invasion. This study implicates a core set of genes necessary to support macrophage invasion by S. aureus, highlights strain-specific differences in phenotypic effects of effector genes, and provides evidence for selection of candidate genes identified by Tn-Seq analyses during chronic airway infection in CF patients in vivo.

In Vitro Selection Identifies Staphylococcus aureus Genes Influencing Biofilm Formation.

Staphylococcus aureus generates biofilms during many chronic human infections, which contributes to its growth and persistence in the host. Multiple genes and pathways necessary for S. aureus biofilm production have been identified, but knowledge is incomplete, and little is known about spontaneous mutations that increase biofilm formation as infection progresses. Here, we performed in vitro selection of four S. aureus laboratory strains (ATCC 29213, JE2, N315, and Newman) to identify mutations associated with enhanced biofilm production. Biofilm formation increased in passaged isolates from all strains, exhibiting from 1.2- to 5-fold the capacity of parental lines. Whole-genome sequencing identified nonsynonymous mutations affecting 23 candidate genes and a genomic duplication encompassing sigB. Six candidate genes significantly impacted biofilm formation as isogenic transposon knockouts: three were previously reported to impact S. aureus biofilm formation (icaR, spdC, and codY), while the remaining three (manA, narH, and fruB) were newly implicated by this study. Plasmid-mediated genetic complementation of manA, narH, and fruB transposon mutants corrected biofilm deficiencies, with high-level expression of manA and fruB further enhancing biofilm formation over basal levels. This work recognizes genes not previously identified as contributing to biofilm formation in S. aureus and reveals genetic changes able to augment biofilm production by that organism.

Role of Visit Modality in the HIV-Related No-Shows During the COVID-19 Pandemic: A Multisite Retrospective Cohort Study.

The emergence of the COVID-19 pandemic necessitated rapid expansion of telehealth as part of healthcare delivery. This study compared HIV-related no-shows by visit type (in-person; video; telephone) during the COVID-19 pandemic (April 2020-September 2021) from the Data for Care Alabama project. Using all primary care provider visits, each visit's outcome was categorized as no-show or arrived. A logistic regression model using generalized estimating equations accounting for repeat measures in individuals and within sites calculated odds ratios (OR) and their accompanying 95% confidence interval (CI) for no-shows by visit modality. The multivariable models adjusted for sociodemographic factors. In-person versus telephone visits [OR (95% CI) 1.64 (1.48-1.82)] and in-person versus video visits [OR (95% CI) 1.53 (1.25-1.85)] had higher odds of being a no-show. In-person versus telephone and video no-shows were significantly higher. This may suggest success of telehealth visits as a method for HIV care delivery even beyond COVID-19.

Assessing the Impact of COVID-19 on Retention in HIV Primary Care: A Longitudinal Multisite Analysis.

We compared retention in care outcomes between a pre-COVID-19 (Apr19-Mar20) and an early-COVID-19 (Apr20-Mar21) period to determine whether the pandemic had a significant impact on these outcomes and assessed the role of patient sociodemographics in both periods in individuals enrolled in the Data for Care Alabama project (n = 6461). Using scheduled HIV primary care provider visits, we calculated a kept-visit measure and a missed-visit measure and compared them among the pre-COVID-19 and early-COVID-19 periods. We used logistic regression models to calculated odds ratios (OR) and accompanying 95% confidence intervals (CI). Overall, individuals had lowers odds of high visit constancy [OR (95% CI): 0.85 (0.79, 0.92)] and higher odds of no-shows [OR (95% CI): 1.27 (1.19, 1.35)] during the early-COVID-19 period. Compared to white patients, Black patients were more likely to miss an appointment and transgender people versus cisgender women had lower visit constancy in the early-COVID-19 period.

Partnership status and retention in care among cisgender heterosexual newly diagnosed people with HIV: a cohort study.

This study examined the role of partnership status (married, unmarried-partnered, and unpartnered) on retention in care among newly diagnosed (2013-2017), cisgender heterosexual people with HIV in Birmingham, Alabama (n = 152). This study evaluated all scheduled HIV primary care provider visits for two years following diagnosis date. A kept-visit measure was calculated such that, if an individual attended ≥1 visit in each of the four 6-month intervals, they were considered to have high visit constancy. A missed-visit measure was categorized as ≥1 no-show vs. 0 no-show for first and second year after diagnosis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression models. Models were adjusted for confounding sociodemographic and clinical characteristics. The study population was 76% Black, 57% male, median age of 37 years. Overall, 65% had high visit consistency and 34.5% had ≥1 no-show in both years. Compared to unpartnered, married individuals had higher visit constancy [AOR (95% CI): 2.88 (1.02, 8.16)]; no differences were observed among unmarried-partnered individuals. No differences in having ≥1 no-show among partnership status groups were observed for either year. These findings suggest potential success of interventions involving a social confidant in optimizing retention in care among newly diagnosed, heterosexual PWH.

Development and implementation of a distributed data network between an academic institution and state health departments to investigate variation in time to HIV viral suppression in the Deep South.

BACKGROUND: Achieving early and sustained viral suppression (VS) following diagnosis of HIV infection is critical to improving outcomes for persons with HIV (PWH). The Deep South of the United States (US) is a region that is disproportionately impacted by the domestic HIV epidemic. Time to VS, defined as time from diagnosis to initial VS, is substantially longer in the South than other regions of the US. We describe the development and implementation of a distributed data network between an academic institution and state health departments to investigate variation in time to VS in the Deep South. METHODS: Representatives of state health departments, the Centers for Disease Control and Prevention (CDC), and the academic partner met to establish core objectives and procedures at the beginning of the project. Importantly, this project used the CDC-developed Enhanced HIV/AIDS Reporting System (eHARS) through a distributed data network model that maintained the confidentiality and integrity of the data. Software programs to build datasets and calculate time to VS were written by the academic partner and shared with each public health partner. To develop spatial elements of the eHARS data, health departments geocoded residential addresses of each newly diagnosed individual in eHARS between 2012-2019, supported by the academic partner. Health departments conducted all analyses within their own systems. Aggregate results were combined across states using meta-analysis techniques. Additionally, we created a synthetic eHARS data set for code development and testing. RESULTS: The collaborative structure and distributed data network have allowed us to refine the study questions and analytic plans to conduct investigations into variation in time to VS for both research and public health practice. Additionally, a synthetic eHARS data set has been created and is publicly available for researchers and public health practitioners. CONCLUSIONS: These efforts have leveraged the practice expertise and surveillance data within state health departments and the analytic and methodologic expertise of the academic partner. This study could serve as an illustrative example of effective collaboration between academic institutions and public health agencies and provides resources to facilitate future use of the US HIV surveillance system for research and public health practice.

Dynamics of Cutibacterium repopulation onto the skin surface of the shoulder after chlorhexidine application.

PURPOSE: The objective of this study was to characterize the temporal dynamics of Cutibacterium repopulation of the skin surface after application of chlorhexidine to the shoulder. METHODS: Ten shoulders in five male subjects were used. A skin swab was taken prior to (0 minutes) and then at three, 30, 60, 120, and 240 minutes after skin preparation with 2% chlorhexidine gluconate and 70% isopropyl alcohol. Semi-quantitative bacterial load was measured for each timepoint. RESULTS: From zero minutes (pre-treatment) to three minutes, chlorhexidine-isopropyl alcohol reduced the skin bacterial load in eight out of ten shoulders. Of these eight shoulders, four (50%) had growth by 30 minutes, seven (88%) had growth by 60 minutes, and all eight (100%) had growth by 240 minutes. Compared to the three minutes after chlorhexidine application, bacterial load had significantly increased by 60 minutes but were still significantly lower than the pre-prep bacterial load (0 minutes). CONCLUSION: Following standard surgical skin preparation with chlorhexidine-isopropyl alcohol, the surface of the shoulder is repopulated with Cutibacterium within one hour, presumably from reservoirs in sebaceous glands not penetrated by topical antiseptic agents. Since these dermal glands are transected by skin incision for shoulder arthroplasty, this study suggests that they may be sources of wound contamination during surgery in spite of skin preparation with chlorhexidine.

A novel Mendelian randomization method with binary risk factor and outcome.

BACKGROUND: Mendelian randomization (MR) applies instrumental variable (IV) methods to observational data using a genetic variant as an IV. Several Monte-Carlo studies investigate the performance of MR methods with binary outcomes, but few consider them in conjunction with binary risk factors. OBJECTIVE: To develop a novel MR estimator for scenarios with a binary risk factor and outcome; and compare to existing MR estimators via simulations and real data analysis. METHODS: A bivariate Bernoulli distribution is adapted to the IV setting. Empirical bias and asymptotic coverage probabilities are estimated via simulations. The proposed method is compared to the Wald method, two-stage predictor substitution (2SPS), two-stage residual inclusion (2SRI), and the generalized method of moments (GMM). An analysis is performed using existing data from the CLEAR study to estimate the potential causal effect of smoking on rheumatoid arthritis risk in African Americans. RESULTS: Bias was low for the proposed method and comparable to 2SPS. The Wald method was often biased towards the null. Coverage was adequate for the proposed method, 2SPS, and 2SRI. Coverage for the Wald and GMM methods was poor in several scenarios. The causal effect of ever smoking on rheumatoid arthritis risk was not statistically significant using a variety of genetic instruments. CONCLUSIONS: Simulations suggest the proposed MR method is sound with binary risk factors and outcomes, and comparable to 2SPS and 2SRI in terms of bias. The proposed method also provides more natural framework for hypothesis testing compared to 2SPS or 2SRI, which require ad-hoc variance adjustments.

Somatic Symptoms in Adolescents With an Ill Parent.

OBJECTIVE: Parent chronic illness may increase somatic symptomology risk in children. The current study examines this association in relation to a variety of chronic illnesses and also considers possible related parental and adolescent background factors. METHODS: Secondary analyses used longitudinal data from the University of North Carolina National Longitudinal Study of Adolescent to Adult Health. Interviews were used to assess demographics, adolescent somatic symptoms, living situation, and parental illness and general physical health. Somatic symptoms in adolescents with no ill parents (n = 2302 adolescents; Mage = 15.3) were compared with adolescents with ill mothers (n = 2336; Mage = 15.3), ill fathers (n = 1304; Mage = 15.3), or two ill parents (n = 3768; Mage = 15.3) using Poisson regression models. We also examined the role of living status, adolescent sex, and parent general physical health on somatic symptom outcomes. RESULTS: Elevated somatic symptoms were observed in adolescents with ill mothers (mean ratio [MR] = 1.15, p = .015) and with both parents ill (MR = 1.10, p < .001). Among adolescents with ill parents, females had more symptoms than males (ill mother: MR = 1.12, p < .001; ill father: MR = 1.23, p < .001; and both parents ill: MR = 1.23, p < .001). Poorer maternal physical health also increased somatic symptom risk (MR = 1.12, p = .02). Longitudinally, adolescents with ill mothers (MR = 1.14, p < .001), ill fathers (MR = 1.13, p < .001), or both parents ill (MR = 1.16, p < .001) had increased somatic symptom risk. Wave I somatic symptoms also increased future risk: ill mother (MR = 1.19, p < .001), ill father (MR = 1.22, p < .001), or both parents ill (MR = 1.20, p < .001). CONCLUSIONS: The results highlight that having an ill parent is a risk factor for adolescent somatic symptoms. In addition, other factors such as adolescent sex play an additional role in adolescent somatic symptoms.

Intraoperative prediction of postanaesthesia care unit hypotension.

BACKGROUND: Postoperative hypotension is associated with adverse outcomes, but intraoperative prediction of postanaesthesia care unit (PACU) hypotension is not routine in anaesthesiology workflow. Although machine learning models may support clinician prediction of PACU hypotension, clinician acceptance of prediction models is poorly understood. METHODS: We developed a clinically informed gradient boosting machine learning model using preoperative and intraoperative data from 88 446 surgical patients from 2015 to 2019. Nine anaesthesiologists each made 192 predictions of PACU hypotension using a web-based visualisation tool with and without input from the machine learning model. Questionnaires and interviews were analysed using thematic content analysis for model acceptance by anaesthesiologists. RESULTS: The model predicted PACU hypotension in 17 029 patients (area under the receiver operating characteristic [AUROC] 0.82 [95% confidence interval {CI}: 0.81-0.83] and average precision 0.40 [95% CI: 0.38-0.42]). On a random representative subset of 192 cases, anaesthesiologist performance improved from AUROC 0.67 (95% CI: 0.60-0.73) to AUROC 0.74 (95% CI: 0.68-0.79) with model predictions and information on risk factors. Anaesthesiologists perceived more value and expressed trust in the prediction model for prospective planning, informing PACU handoffs, and drawing attention to unexpected cases of PACU hypotension, but they doubted the model when predictions and associated features were not aligned with clinical judgement. Anaesthesiologists expressed interest in patient-specific thresholds for defining and treating postoperative hypotension. CONCLUSIONS: The ability of anaesthesiologists to predict PACU hypotension was improved by exposure to machine learning model predictions. Clinicians acknowledged value and trust in machine learning technology. Increasing familiarity with clinical use of model predictions is needed for effective integration into perioperative workflows.

Polyclonality, Shared Strains, and Convergent Evolution in Chronic Cystic Fibrosis Staphylococcus aureus Airway Infection.

Rationale:Staphylococcus aureus is the most common respiratory pathogen isolated from patients with cystic fibrosis (CF) in the United States. Although modes of acquisition and genetic adaptation have been described for Pseudomonas aeruginosa, resulting in improved diagnosis and treatment, these features remain more poorly defined for S. aureus.Objectives: To characterize the molecular epidemiology and genetic adaptation of S. aureus during chronic CF airway infection and in response to antibiotic therapy.Methods: We performed whole-genome sequencing of 1,382 S. aureus isolates collected longitudinally over a mean 2.2 years from 246 children with CF at five U.S. centers between 2008 and 2017. Results were integrated with clinical and demographic data to characterize bacterial population dynamics and identify common genetic targets of in vivo adaptation.Measurements and Main Results: Results showed that 45.5% of patients carried multiple, coexisting S. aureus lineages, often having different antibiotic susceptibility profiles. Adaptation during the course of infection commonly occurred in a set of genes related to persistence and antimicrobial resistance. Individual sequence types demonstrated wide geographic distribution, and we identified limited strain-sharing among children linked by common household or clinical exposures. Unlike P. aeruginosa, S. aureus genetic diversity was unconstrained, with an ongoing flow of new genetic elements into the population of isolates from children with CF.Conclusions: CF airways are frequently coinfected by multiple, genetically distinct S. aureus lineages, indicating that current clinical procedures for sampling isolates and selecting antibiotics are likely inadequate. Strains can be shared by patients in close domestic or clinical contact and can undergo convergent evolution in key persistence and antimicrobial-resistance genes, suggesting novel diagnostic and therapeutic approaches for future study.

Occurrence and Timing of Subsequent Severe Acute Respiratory Syndrome Coronavirus 2 Reverse-transcription Polymerase Chain Reaction Positivity Among Initially Negative Patients.

Using data for 20 912 patients from 2 large academic health systems, we analyzed the frequency of severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction test discordance among individuals initially testing negative by nasopharyngeal swab who were retested on clinical grounds within 7 days. The frequency of subsequent positivity within this window was 3.5% and was similar across institutions.

Prevalence and impact of comorbid chronic pain and cigarette smoking among people living with HIV.

Rates of chronic pain and cigarette smoking are each substantially higher among people living with HIV (PLWH) than in the general population. The goal of these analyses was to examine the prevalence and impact of comorbid chronic pain and cigarette smoking among PLWH. Participants included 3289 PLWH (83% male) who were recruited from five HIV clinics. As expected, the prevalence of smoking was higher among PLWH with chronic pain (41.9%), than PLWH without chronic pain (26.6%, p < .0001), and the prevalence of chronic pain was higher among current smokers (32.9%), than among former (23.6%) or never (17%) smokers (ps < .0001). PLWH who endorsed comorbid chronic pain and smoking (vs. nonsmokers without chronic pain) were more likely to report cocaine/crack and cannabis use, be prescribed long-term opioid therapy, and have virologic failure, even after controlling for relevant sociodemographic and substance-related variables (ps < .05). These results contribute to a growing empirical literature indicating that chronic pain and cigarette smoking frequently co-occur, and extend this work to a large sample of PLWH. Indeed, PLWH may benefit from interventions that are tailored to address bidirectional pain-smoking effects in the context of HIV.

Psychological and behavioral pathways between perceived stress and weight change in a behavioral weight loss intervention.

Black women have a higher prevalence of obesity and tend to have suboptimal outcomes in behavioral weight loss programs for reasons that are not fully understood. Studies have shown a potential relationship between perceived psychological stress and weight loss in behavioral interventions. This study sought to assess whether baseline stress was directly or indirectly associated with 6-month weight change among Black women participating in a behavioral weight loss study. Indirect pathways of interest included depressive symptoms and dietary intake. A secondary analysis of data (n = 409) collected from a cluster, randomized behavioral weight loss trial was conducted. Demographics, anthropometry, surveys, and dietary data were collected at baseline and 6 months. Path analysis was used to test for direct and indirect effects of baseline stress on 6-month weight change while controlling for sociodemographic factors and intervention group. Baseline stress was not directly associated with 6-month weight change nor was it indirectly associated via depressive symptoms in the adjusted model. However, each of the direct paths linking baseline stress to weight loss were statistically significant. Stress was not associated with 6-month weight change via dietary intake. Baseline stress was positively associated with 6-month depressive symptoms which in turn was associated with less weight change. Depressive symptoms may offer an additional psychosocial target to consider when designing behavioral weight loss interventions for Black women.