Development and acceptability of PETS-Now, an electronic point-of-care tool to monitor treatment burden in patients with multiple chronic conditions: a multi-method study.

BACKGROUND: The aim of this study was to develop a web-based tool for patients with multiple chronic conditions (MCC) to communicate concerns about treatment burden to their healthcare providers. METHODS: Patients and providers from primary-care clinics participated. We conducted focus groups to identify content for a prototype clinical tool to screen for treatment burden by reviewing domains and items from a previously validated measure, the Patient Experience with Treatment and Self-management (PETS). Following review of the prototype, a quasi-experimental pilot study determined acceptability of using the tool in clinical practice. The study protocol was modified to accommodate limitations due to the Covid-19 pandemic. RESULTS: Fifteen patients with MCC and 18 providers participated in focus groups to review existing PETS content. The pilot tool (named PETS-Now) consisted of eight domains (Living Healthy, Health Costs, Monitoring Health, Medicine, Personal Relationships, Getting Healthcare, Health Information, and Medical Equipment) with each domain represented by a checklist of potential concerns. Administrative burden was minimized by limiting patients to selection of one domain. To test acceptability, 17 primary-care providers first saw 92 patients under standard care (control) conditions followed by another 90 patients using the PETS-Now tool (intervention). Each treatment burden domain was selected at least once by patients in the intervention. No significant differences were observed in overall care quality between patients in the control and intervention conditions with mean care quality rated high in both groups (9.3 and 9.2, respectively, out of 10). There were no differences in provider impressions of patient encounters under the two conditions with providers reporting that patient concerns were addressed in 95% of the visits in both conditions. Most intervention group patients (94%) found that the PETS-Now was easy to use and helped focus the conversation with the provider on their biggest concern (98%). Most providers (81%) felt they had learned something new about the patient from the PETS-Now. CONCLUSION: The PETS-Now holds promise for quickly screening and monitoring treatment burden in people with MCC and may provide information for care planning. While acceptable to patients and clinicians, integration of information into the electronic medical record should be prioritized.

Association of Burnout With Primary Care Clinician Perception of Team-Based Scheduling Support.

INTRODUCTION: Primary care clinician burnout is pervasive and detrimental. How components of teamwork and clinic culture might contribute to burnout remains unsettled. OBJECTIVE: To examine associations between primary care clinician perceptions of specific components of teamwork and of organizational culture, and perceived stress and burnout. METHODS: Cross-sectional survey study of primary care clinicians from 5 county health system clinics. Measures: Perceptions of teamwork related to coordination of care, and clinic provision of chronic disease self-management support; values alignment and workplace equity; and demographics. DATA ANALYSIS: Descriptive statistics and Spearman's correlations to examine associations, controlling for clinic and examining response variability by clinic. RESULTS: Of 72 clinicians, 64% were female and 32% non-white. About 56% had worked at least 4 years and half worked 5 to 6 half days/week or more in their clinic. Clinicians who reported having someone on the clinician's care team routinely schedule follow-up appointments for patients with complex chronic illnesses reported lower stress and burnout. Those who perceived greater values alignment with their clinic and greater personal and employee equitable treatment had lower stress and burnout. CONCLUSIONS: Teamwork among clinicians and non-clinical staff, a component of teamwork that is not well-considered in current literature, could be an important piece of the puzzle to decrease the persistent and challenging issue of stress and burnout among primary care clinicians.

Intersectionality and COVID-19: Academic Medicine Faculty's Lived Experiences of Well-Being, Workload, and Productivity During the Pandemic.

Purpose: The aim of this study was to utilize an intersectional framework to examine academic faculty's lived experiences during COVID-19. Specifically, we set out to: (1) describe the multiple intersectional identities (e.g., gender, race/ethnicity, rank, caregiver status, disability status) represented by the faculty, (2) examine potential disparities in well-being, workload, and productivity linked to these intersectional factors, and (3) identify qualitative themes endorsed by faculty as they relate to lived experiences during COVID-19. Methods: This was a cross-sectional mixed-methods research study. The Center for Women in Medicine and Science (CWIMS) at the University of Minnesota developed and implemented a survey between February-June of 2021 in response to national reports of disparities in the impacts of COVID-19 on faculty with lived experiences from multiple intersections. Results: There were 291 full-time faculty who participated in the study. Quantitative findings indicated that faculty with multiple intersectional identities (e.g., woman+assistant professor+caregiver+underrepresented in medicine) reported greater depression symptoms, work/family conflict, and stress in contrast to faculty with fewer intersectional identities. Furthermore, faculty with more intersectional identities reported higher clinical workloads and service responsibilities and lower productivity with regard to research article submissions, publications, and grant submissions in contrast to faculty with fewer intersectional identities. Qualitative findings supported quantitative findings and broadened understanding of potential underlying reasons. Conclusions: Findings confirm anecdotal evidence that faculty with lived experiences from multiple intersections may be disproportionately experiencing negative outcomes from the pandemic. These findings can inform decisions about how to address these disparities moving into the next several years with regard to promotion and tenure, burnout and well-being, and faculty retention in academic medical settings. Given these findings, it is also important to intentionally plan responses for future public health crises to prevent continued disparities for faculty with multiple intersectional identities.

Longitudinal trajectories of treatment burden: A prospective survey study of adults living with multiple chronic conditions in the midwestern United States.

Objectives: Determine whether there are different longitudinal patterns of treatment burden in people living with multiple chronic conditions (MCC) and, if so, explore predictors that might reveal potential routes of intervention. Methods: We analyzed data from a prospective mailed survey study of 396 adults living with MCC in southeastern Minnesota, USA. Participants completed a measure of treatment burden, the Patient Experience with Treatment and Self-management (PETS), and valid measures of health-related and psycho-social concepts at baseline, 6, 12, and 24 months. Latent class growth mixture modeling (LCGM) determined trajectories of treatment burden in two summary index scores of the PETS: Workload and Impact. Multivariable logistic regressions were used to identify independent predictors of the trajectories. Results: LCGM supported a 2-class model for PETS Workload, including a group of consistently high workload (N = 69) and a group of consistently low workload (N = 311) over time. A 3-class model was supported for PETS Impact, including groups of consistently high impact (N = 62), consistently low impact (N = 278), and increasing impact (N = 51) over time. Logistic regression analyses showed that the following factors were associated with patterns of consistently high or increasing treatment burden over time: lower health literacy, lower self-efficacy, more interpersonal challenges with others, and worse subjective reports of physical and mental health (all p < .05). Conclusions: Different longitudinal patterns of treatment burden exist among people with MCC. Raising health literacy, enhancing self-efficacy, and lessening the effects of negative social interactions might help reduce treatment burden.

Treatment Burden in People with Hypertension is Correlated with Patient Experience with Self-Management.

INTRODUCTION: New hypertension guidelines in the United States may require more people to take multiple medications or implement lifestyle changes. Increased treatment burden may be an unintended consequence and lead to worse health outcomes. Our study examined whether treatment burden is associated with factors related to self-management in those with hypertension. METHODS: We conducted a cross-sectional mailed survey of patients from 2 medical centers in Minnesota. Participants with 2 or more medical conditions completed the Patient Experience with Treatment and Self-management (PETS), a validated treatment burden questionnaire, as well as measures of confidence in self-management ability, health literacy, health care-related financial difficulties, and perception of provider interpersonal skills. We used partial correlation analyses, controlling for age, sex, race, and education, to test relationships among study variables. RESULTS: Of 254 respondents who had a diagnosis of hypertension, 54% were female, 74% were non-Hispanic White, and the mean age was 67 years. People with hypertension who reported having lower confidence in self-management ability, lower health literacy, more financial difficulties, and health care providers with poorer interpersonal skills reported higher treatment burden scores (PETS scales correlation magnitude range 0.09 to 0.62, P < .05 on all but 4). The strongest associations were observed for medical information and physical/mental exhaustion with self-management (correlation magnitudes from 0.25 to 0.54, P < .01). DISCUSSION: Hypertension treatment guideline stringent blood pressure criteria may lead to more interventions-medical or lifestyle-creating strains on populations already challenged by abstract disease self-management and at risk of experiencing disparities in cardiovascular health outcomes.

Super fragmented: a nationally representative cross-sectional study exploring the fragmentation of inpatient care among super-utilizers.

BACKGROUND: Super-utilizers with 4 or more admissions per year frequently receive low-quality care and disproportionately contribute to healthcare costs. Inpatient care fragmentation (admission to multiple different hospitals) in this population has not been well described. OBJECTIVE: To determine the prevalence of super-utilizers who receive fragmented care across different hospitals and to describe associated risks, costs, and health outcomes. RESEARCH DESIGN: We analyzed inpatient data from the Health Care Utilization Project's State Inpatient and Emergency Department database from 6 states from 2013. After identifying hospital super-utilizers, we stratified by the number of different hospitals visited in a 1-year period. We determined how patient demographics, costs, and outcomes varied by degree of fragmentation. We then examined how fragmentation would influence a hospital's ability to identify super-utilizers. SUBJECTS: Adult patients with 4 or more inpatient stays in 1 year. MEASURES: Patient demographics, cost, 1-year hospital reported mortality, and probability that a single hospital could correctly identify a patient as a super-utilizer. RESULTS: Of the 167,515 hospital super-utilizers, 97,404 (58.1%) visited more than 1 hospital in a 1-year period. Fragmentation was more likely among younger, non-white, low-income, under-insured patients, in population-dense areas. Patients with fragmentation were more likely to be admitted for chronic disease management, psychiatric illness, and substance abuse. Inpatient fragmentation was associated with higher yearly costs and lower likelihood of being identified as a super-utilizer. CONCLUSIONS: Inpatient care fragmentation is common among super-utilizers, disproportionately affects vulnerable populations. It is associated with high yearly costs and a decreased probability of correctly identifying super-utilizers.

Health system interventions for adults with type 2 diabetes in low- and middle-income countries: A systematic review and meta-analysis.

BACKGROUND: Effective health system interventions may help address the disproportionate burden of diabetes in low- and middle-income countries (LMICs). We assessed the impact of health system interventions to improve outcomes for adults with type 2 diabetes in LMICs. METHODS AND FINDINGS: We searched Ovid MEDLINE, Cochrane Library, EMBASE, African Index Medicus, LILACS, and Global Index Medicus from inception of each database through February 24, 2020. We included randomized controlled trials (RCTs) of health system interventions targeting adults with type 2 diabetes in LMICs. Eligible studies reported at least 1 of the following outcomes: glycemic change, mortality, quality of life, or cost-effectiveness. We conducted a meta-analysis for the glycemic outcome of hemoglobin A1c (HbA1c). GRADE and Cochrane Effective Practice and Organisation of Care methods were used to assess risk of bias for the glycemic outcome and to prepare a summary of findings table. Of the 12,921 references identified in searches, we included 39 studies in the narrative review of which 19 were cluster RCTs and 20 were individual RCTs. The greatest number of studies were conducted in the East Asia and Pacific region (n = 20) followed by South Asia (n = 7). There were 21,080 total participants enrolled across included studies and 10,060 total participants in the meta-analysis of HbA1c when accounting for the design effect of cluster RCTs. Non-glycemic outcomes of mortality, health-related quality of life, and cost-effectiveness had sparse data availability that precluded quantitative pooling. In the meta-analysis of HbA1c from 35 of the included studies, the mean difference was -0.46% (95% CI -0.60% to -0.31%, I2 87.8%, p < 0.001) overall, -0.37% (95% CI -0.64% to -0.10%, I2 60.0%, n = 7, p = 0.020) in multicomponent clinic-based interventions, -0.87% (-1.20% to -0.53%, I2 91.0%, n = 13, p < 0.001) in pharmacist task-sharing studies, and -0.27% (-0.50% to -0.04%, I2 64.1%, n = 7, p = 0.010) in trials of diabetes education or support alone. Other types of interventions had few included studies. Eight studies were at low risk of bias for the summary assessment of glycemic control, 15 studies were at unclear risk, and 16 studies were at high risk. The certainty of evidence for glycemic control by subgroup was moderate for multicomponent clinic-based interventions but was low or very low for other intervention types. Limitations include the lack of consensus definitions for health system interventions, differences in the quality of underlying studies, and sparse data availability for non-glycemic outcomes. CONCLUSIONS: In this meta-analysis, we found that health system interventions for type 2 diabetes may be effective in improving glycemic control in LMICs, but few studies are available from rural areas or low- or lower-middle-income countries. Multicomponent clinic-based interventions had the strongest evidence for glycemic benefit among intervention types. Further research is needed to assess non-glycemic outcomes and to study implementation in rural and low-income settings.

Deriving and validating a brief measure of treatment burden to assess person-centered healthcare quality in primary care: a multi-method study.

BACKGROUND: In primary care there is a need for more quality measures of person-centered outcomes, especially ones applicable to patients with multiple chronic conditions (MCCs). The aim of this study was to derive and validate a short-form version of the Patient Experience with Treatment and Self-management (PETS), an established measure of treatment burden, to help fill the gap in quality measurement. METHODS: Patient interviews (30) and provider surveys (30) were used to winnow items from the PETS (60 items) to a subset targeting person-centered care quality. Results were reviewed by a panel of healthcare providers and health-services researchers who finalized a pilot version. The Brief PETS was tested in surveys of 200 clinic and 200 community-dwelling MCC patients. Surveys containing the Brief PETS and additional measures (e.g., health status, medication adherence, quality of care, demographics) were administered at baseline and follow-up. Correlations and t-tests were used to assess validity, including responsiveness to change of the Brief PETS. Effect sizes (ES) were calculated on mean differences. RESULTS: Winnowing and panel review resulted in a 34-item Brief PETS pilot measure that was tested in the combined sample of 400 (mean age = 57.9 years, 50% female, 48% white, median number of conditions = 5). Reliability of most scales was acceptable (alpha > 0.70). Brief PETS scores were associated with age, income, health status, and quality of chronic illness care at baseline (P < .05; rho magnitude range: 0.16-0.66). Furthermore, Brief PETS scores differentiated groups based on marital and education status, presence/absence of a self-management routine, and optimal/suboptimal medication adherence (P < .05; ES range: 0.25-1.00). Declines in patient-reported physical or mental health status over time were associated with worsening PETS burden scores, while improvements were associated with improving PETS burden scores (P < .05; ES range: 0.04-0.44). Among clinic patients, 91% were willing to complete the Brief PETS as part of their clinic visits. CONCLUSIONS: The Brief PETS (final version: 32 items) is a reliable and valid tool for assessing person-centered care quality related to treatment burden. It holds promise as a means of giving voice to patient concerns about the complexity of disease management.

Factors Associated with Reported Colorectal Cancer Screening Among Lao-American Immigrants in Minnesota.

Colorectal Cancer (CRC) is common in Lao Americans, but screening is suboptimal. To investigate CRC screening rates of Lao Americans in Minnesota, and how predisposing characteristics, enabling resources, and perceived need are associated with screening. We conducted a convenience-sample cross-sectional survey of 50-75-year-old Lao Americans, using step-wise multivariate logistic regression to identify factors associated with ever being screened. Of the 118 survey participants, 45% ever received CRC screening. In univariate regression, some enabling resources (having a primary care provider, higher self-efficacy in pursuing screening) and perceived needs (knowledge of who should be screened, higher number of chronic illnesses) were associated with screening. In multivariate logistic regression, the odds of ever being screened was 12.4 times higher for those with a primary care provider than for those without (p = 0.045). The findings reinforce a need for developing culturally tailored interventions focused on Lao-American immigrants to promote CRC screening.

Integrating Community Health Workers Into Medical Homes.

PURPOSE: Though evidence supports the value of community health workers (CHWs) in chronic disease self-management support, and authorities have called for expanding their roles within patient-centered medical homes (PCMHs), few PCMHs in Minnesota have incorporated these health workers into their care teams. We undertook a qualitative study to (1) identify facilitators and barriers to utilizing a CHW model among PCMHs in Minnesota, and (2) define roles played by this workforce within the PCMH team. METHODS: We conducted 51 semistructured, key-informant interviews of clinic leaders, clinicians, care coordinators, CHWs, and staff from 9 clinics (5 with community health workers, 4 without). Qualitative analysis consisted of thematic coding aligned with interview topics. RESULTS: Four key conceptual themes emerged as facilitators and barriers to utilizing a CHW model: the presence of leaders with knowledge of CHWs who championed the model, a clinic culture that favored piloting innovation vs maintaining established care models, clinic prioritization of patients' nonmedical needs, and leadership perceptions of sustainability. These health care workers performed common and clinic-specific roles that included outreach, health education and coaching, community resource linkage, system navigation, and facilitating communication between clinician and patient. CONCLUSIONS: We identified facilitators and barriers to adopting CHW roles as part of PCMH care teams in Minnesota and documented their roles being played in these settings. Our findings can be used when considering strategies to enhance utilization and integration of this emerging workforce.

Validating the Patient Experience with Treatment and Self-Management (PETS), a patient-reported measure of treatment burden, in people with diabetes.

AIMS: To validate a comprehensive general measure of treatment burden, the Patient Experience with Treatment and Self-Management (PETS), in people with diabetes. METHODS: We conducted a secondary analysis of a cross-sectional survey study with 120 people diagnosed with type 1 or type 2 diabetes and at least one additional chronic illness. Surveys included established patient-reported outcome measures and a 48-item version of the PETS, a new measure comprised of multi-item scales assessing the burden of chronic illness treatment and self-care as it relates to nine domains: medical information, medications, medical appointments, monitoring health, interpersonal challenges, health care expenses, difficulty with health care services, role activity limitations, and physical/mental exhaustion from self-management. Internal reliability of PETS scales was determined using Cronbach's alpha. Construct validity was determined through correlation of PETS scores with established measures (measures of chronic condition distress, medication satisfaction, self-efficacy, and global well-being), and known-groups validity through comparisons of PETS scores across clinically distinct groups. In an exploratory test of predictive validity, step-wise regressions were used to determine which PETS scales were most associated with outcomes of chronic condition distress, overall physical and mental health, and medication adherence. RESULTS: Respondents were 37-88 years old, 59% female, 29% non-white, and 67% college-educated. PETS scales showed good reliability (Cronbach's alphas ≥0.74). Higher PETS scale scores (greater treatment burden) were correlated with more chronic condition distress, less medication convenience, lower self-efficacy, and worse general physical and mental health. Participants less (versus more) adherent to medications and those with more (versus fewer) health care financial difficulties had higher mean PETS scores. Medication burden was the scale that was most consistently associated with well-being and patient-reported adherence. CONCLUSION: The PETS is a reliable and valid measure for assessing perceived treatment burden in people coping with diabetes.

Healthcare provider relational quality is associated with better self-management and less treatment burden in people with multiple chronic conditions.

PURPOSE: Having multiple chronic conditions (MCCs) can lead to appreciable treatment and self-management burden. Healthcare provider relational quality (HPRQ) - the communicative and interpersonal skill of the provider - may mitigate treatment burden and promote self-management. The objectives of this study were to 1) identify the associations between HPRQ, treatment burden, and psychosocial outcomes in adults with MCCs, and 2) determine if certain indicators of HPRQ are more strongly associated than others with these outcomes. PATIENTS AND METHODS: This is a cross-sectional survey study of 332 people with MCCs. Patients completed a 7-item measure of HPRQ and measures of treatment and self-management burden, chronic condition distress, self-efficacy, provider satisfaction, medication adherence, and physical and mental health. Associations between HPRQ, treatment burden, and psychosocial outcomes were determined using correlational analyses and independent samples t-tests, which were repeated in item-level analyses to explore which indicators of HPRQ were most strongly associated with the outcomes. RESULTS: Most respondents (69%) were diagnosed with ≥3 chronic conditions. Better HPRQ was found to be associated with less treatment and self-management burden and better psychosocial outcomes (P<0.001), even after controlling for physical and mental health. Those reporting 100% adherence to prescribed medications had higher HPRQ scores than those reporting less than perfect adherence (P<0.001). HPRQ items showing the strongest associations with outcomes were "my healthcare provider spends enough time with me", "my healthcare provider listens carefully to me", and "I have trust in my healthcare provider". CONCLUSION: Good communication and interpersonal skills of healthcare providers may lessen feelings of treatment burden and empower patients to feel confident in their self-management. Patient trust in the provider is an important element of HPRQ. Educating healthcare providers about the importance of interpersonal and relational skills could lead to more patient-centered care.

Engaging Minority Youth in Diabetes Prevention Efforts Through a Participatory, Spoken-Word Social Marketing Campaign.

PURPOSE: To examine the reach, efficacy, and adoption of The Bigger Picture, a type 2 diabetes (T2DM) social marketing campaign that uses spoken-word public service announcements (PSAs) to teach youth about socioenvironmental conditions influencing T2DM risk. DESIGN: A nonexperimental pilot dissemination evaluation through high school assemblies and a Web-based platform were used. SETTING: The study took place in San Francisco Bay Area high schools during 2013. SUBJECTS: In the study, 885 students were sampled from 13 high schools. INTERVENTION: A 1-hour assembly provided data, poet performances, video PSAs, and Web-based platform information. A Web-based platform featured the campaign Web site and social media. MEASURES: Student surveys preassembly and postassembly (knowledge, attitudes), assembly observations, school demographics, counts of Web-based utilization, and adoption were measured. ANALYSIS: Descriptive statistics, McNemar's χ2 test, and mixed modeling accounting for clustering were used to analyze data. RESULTS: The campaign included 23 youth poet-created PSAs. It reached >2400 students (93% self-identified non-white) through school assemblies and has garnered >1,000,000 views of Web-based video PSAs. School participants demonstrated increased short-term knowledge of T2DM as preventable, with risk driven by socioenvironmental factors (34% preassembly identified environmental causes as influencing T2DM risk compared to 83% postassembly), and perceived greater personal salience of T2DM risk reduction (p < .001 for all). The campaign has been adopted by regional public health departments. CONCLUSION: The Bigger Picture campaign showed its potential for reaching and engaging diverse youth. Campaign messaging is being adopted by stakeholders.

Development and early implementation of the bigger picture, a youth-targeted public health literacy campaign to prevent type 2 diabetes.

The prevalence of type 2 diabetes is rapidly rising, especially among minority and low-income youth. There is an unmet need to engage youth in identifying solutions to reverse this trajectory. Social marketing campaigns and entertainment education are effective forms of health communication for engaging populations in health-promoting behaviors. Critical to curbing the epidemic is moving the diabetes conversation away from individual behavior alone and toward a socioecologic perspective using a public health literacy framework. The authors developed an academic-community partnership to develop, implement, and evaluate a type 2 diabetes prevention campaign targeting minority and low-income youth. The Bigger Picture campaign uses hard-hitting, youth-generated spoken-word messages around key environmental and social drivers of the type 2 diabetes epidemic. Campaign goals included promoting health capacity and civic engagement. This article focuses on the development and implementation of the campaign, including (a) rationale and theoretical underpinnings, (b) steps in campaign creation, (c) testing the campaign messaging, and (d) campaign dissemination and evaluation planning. A youth-created health communication campaign using a public health literacy framework with targeted, relevant, and compelling messaging appears to be a promising vehicle for reaching at-risk youth to increase knowledge of and attitudes about preventing type 2 diabetes, change social norms, and motivate participation in health-promoting initiatives.

Diabetes peer coaching: do "better patients" make better coaches?

PURPOSE: The purpose of this study was to identify characteristics of peer coaches associated with improvement in diabetes control among low-income patients with type 2 diabetes. METHODS: Low-income patients with type 2 diabetes who spoke English or Spanish from 6 urban clinics in San Francisco, California, were invited to participate in the study. Twenty participants received training and provided peer coaching to 109 patients over a 6-month peer coaching intervention. Primary outcome was average change in patient glycosylated hemoglobin (A1C). Characteristics of peer coaches included age, gender, years with diabetes, A1C, body mass index (BMI), levels of diabetes-related distress, self-efficacy in diabetes self-management, and depression. RESULTS: Patient improvement in A1C was associated with having a coach with a lower sense of self-efficacy in diabetes management (P < .001), higher level of diabetes-related distress (P = .01), and lower depression score (P = .03). CONCLUSIONS: Coach characteristics are associated with patient success in improving A1C. "Better" levels of coach diabetes self-efficacy and distress were not helpful and, in fact, were associated with less improvement in patient A1C, suggesting that some coach uncertainty about his or her own diabetes might foster improved patient self-management. These coach characteristics should be considered when recruiting peer coaches.

Pilus gene pool variation and the virulence of Corynebacterium diphtheriae clinical isolates during infection of a nematode.

Toxigenic Corynebacterium diphtheriae strains cause diphtheria in humans. The toxigenic C. diphtheriae isolate NCTC13129 produces three distinct heterotrimeric pili that contain SpaA, SpaD, and SpaH, making up the shaft structure. The SpaA pili are known to mediate bacterial adherence to pharyngeal epithelial cells. However, to date little is known about the expression of different pili in various clinical isolates and their importance in bacterial pathogenesis. Here, we characterized a large collection of C. diphtheriae clinical isolates for their pilin gene pool by PCR and for the expression of the respective pilins by immunoblotting with antibodies against Spa pilins. Consistent with the role of a virulence factor, the SpaA-type pili were found to be prevalent among the isolates, and most significantly, corynebacterial adherence to pharyngeal epithelial cells was strictly correlated with isolates that were positive for the SpaA pili. By comparison, the isolates were heterogeneous for the presence of SpaD- and SpaH-type pili. Importantly, using Caenorhabditis elegans as a model host for infection, we show here that strain NCTC13129 rapidly killed the nematodes, the phenotype similar to isolates that were positive for toxin and all pilus types. In contrast, isogenic mutants of NCTC13129 lacking SpaA-type pili or devoid of toxin and SpaA pili exhibited delayed killing of nematodes with similar kinetics. Consistently, nontoxigenic or toxigenic isolates that lack one, two, or all three pilus types were also attenuated in virulence. This work signifies the important role of pili in corynebacterial pathogenesis and provides a simple host model to identify additional virulence factors.

The diguanylate cyclase, Rrp1, regulates critical steps in the enzootic cycle of the Lyme disease spirochetes.

Rrp1 is the sole c-di-GMP-producing protein (diguanylate cyclase) of Borrelia burgdorferi. To test the hypothesis that Rrp1 regulates critical processes involved in the transmission of spirochetes between ticks and mammals, an rrp1 deletion mutant (B31-Δrrp1) and a strain that constitutively produces elevated levels of Rrp1 (B31-OV) were constructed. The strains were assessed for progression through the enzootic cycle using an Ixodes tick/C3H-HeJ mouse model and tick immersion feeding methods. B31-Δrrp1 infected mice as efficiently as wild type but had altered motility, decreased chemotactic responses to N-acetylglucosamine (NAG) and attenuated ability to disseminate or colonize distal organs. While this strain infected mice, it was not able to survive in ticks. In contrast, B31-OV displayed normal motility patterns and chemotactic responses but was non-infectious in mice. Using immersion feeding techniques, we demonstrate that B31-OV can establish a population in ticks and survive exposure to a natural bloodmeal. The results presented here indicate Rrp1, and by extension, c-di-GMP, are not strictly required for murine infection, but are required for the successful establishment of a productive population of B. burgdorferi in ticks. These analyses provide significant new insight into the genetic regulatory mechanisms of the Lyme disease spirochetes.

Adhesion by pathogenic corynebacteria.

Pathogenic members of the genus Corynebacterium cause a wide range of serious infections in humans including diphtheria. Adhesion to host cells is a crucial step during infection. In Corynebacterium diphtheriae, adhesion is mediated primarily by filamentous structures called pili or fimbriae that are covalently attached to the bacterial cell wall. C. diphtheriae produces three distinct pilus structures, SpaA-, SpaD- and SpaH-type pili. Similar to other types, the prototype SpaA pilus consists of SpaA forming the pilus shaft and two minor pilins SpaB and SpaC located at the base and at the tip, respectively. The minor pilins SpaB/SpaC are critical for bacterial binding to human pharyngeal cells, and thus represent the major adhesins of corynebacteria. Like pili of many other gram-positive microbes, the assembly of corynebacterial pili occurs by a two-step mechanism, whereby pilins are covalently polymerized by a transpeptidase enzyme named pilin-specific sortase and the generated pilus polymer is subsequently anchored to the cell wall peptidoglycan via the base pilin by the housekeeping sortase or a non-polymerizing sortase. This chapter reviews the current knowledge of corynebacterial adhesion, with a specific focus on pilus structures, their assembly, and the mechanism of adhesion mediated by pili.