Evaluating dyadic factors associated with self-care in patients with heart failure and their family caregivers: Using an Actor-Partner Interdependence Model.

Dyadic conditions of patients with heart failure and their caregivers may affect both patient self-care and caregiver contribution to patient self-care (CCPS). The purpose of this study was to examine the relationships of patient-caregiver physical function and depressive symptoms to the patient self-care (maintenance and management) and CCPS. Data from 55 were analyzed using an Actor-Partner Interdependence Model to address the aim through AMOS. Patient self-care was very poor. Better patient physical function was related to better patient self-care management (actor effect) and poorer CCPS maintenance (partner effect). Better caregiver physical function was related to CCPS management (actor effect). Severer patient depressive symptoms were related to poorer patient self-care maintenance (actor effect) and poorer CCPS management (partner effect). Physical function and depressive symptoms in patient-caregiver dyads were related to patient self-care and CCPS. To improve patient self-care and CCPS, dyadic support for physical function and depressive symptoms is needed.

Relationships of Multidimensional Factors to Diabetes Complications: A Cross-Sectional, Correlational Study.

BACKGROUND: Diabetes complications are prevalent in people with diabetes, causing considerable individual suffering and increased health costs. However, the relationships of multidimensional, modifiable, and nonmodifiable factors to diabetes complications and the role of diabetes distress have been rarely examined. OBJECTIVE: The aims of this study were to examine the associations of age, sex, knowledge, self-efficacy, self-compassion, resilience, self-esteem, depressive symptoms, diabetes distress, social support, and body mass index with diabetes complications and to investigate the mediating role of diabetes distress. METHODS: In this cross-sectional, correlational study, data on all study variables were collected from 148 people with diabetes through REDCap in 2023. Multiple regression analysis and the PROCESS macro for SPSS were used to address the aims. RESULTS: Older age and higher levels of diabetes distress were associated with more diabetes complications. Depressive symptoms were associated with diabetes distress; and diabetes distress, but not depressive symptoms, was associated with diabetes complications, controlling for all other variables. CONCLUSIONS: Depressive symptoms and diabetes distress were directly or indirectly associated with diabetes complications, and diabetes distress was a mediator in the relationship between depressive symptoms and diabetes complications. Health care providers can target reduction of depressive symptoms and diabetes distress to reduce diabetes complications.

Perspectives on advance care planning and related end-of-life care in people with heart failure: A Q methodology study.

Negative perspectives around advance care planning (ACP) prevent people with heart failure (HF) from preparing their end-of-life (EOL) effectively. A Q methodology study was conducted to identify types of ACP perspectives in Koreans with HF. The Q sample (31 statements representing ACP perspectives) was constructed through an extensive literature review and in-depth qualitative interview. The P sample (individuals with HF) completed each grid with a statement on the Q sorting table. The data were analyzed using the PQ program. Individuals with HF have both different and common perspectives on ACP. Three types of perspectives were identified: "positive acceptance," "contemplative support," and "hesitancy in acceptance." Common perspectives across types indicated that people with HF had positive attitudes toward ACP and emphasized their autonomy in EOL decisions. Clinicians need to consider these different and common perspectives on ACP to facilitate patients' engagement and provide relevant support.

Relationships of Psychosocial Factors to Diabetes Self-efficacy: A Cross-sectional, Correlational Study.

BACKGROUND: Self-care in people with diabetes is poor, which could be influenced by positive and negative psychosocial factors. Self-efficacy is an important factor affecting self-care, and depressive symptoms and diabetes distress may directly and indirectly affect self-efficacy. OBJECTIVE: The aim of this study was to examine the relationships of depressive symptoms, diabetes distress, age, sex, self-compassion, resilience, self-esteem, and social support to diabetes self-efficacy and the mediating roles of diabetes distress and depressive symptoms in the relationships among people with diabetes. METHODS: In this cross-sectional, correlational study, data on all the psychosocial and demographic factors were collected (N = 148; 57.6 years old) through Research Electronic Data Capture in 2023. The PROCESS macro for SPSS was used to address the purpose. RESULTS: The mean score of diabetes self-efficacy was 28.6 (range, 8-40). In 1 model, depressive symptoms were directly and indirectly associated with diabetes self-efficacy through diabetes distress (direct effect, -3.524; t = -3.020, P = .003; indirect effect, -2.089; 95% bootstrap confidence interval, -3.494 to -0.911). In another model, diabetes distress was directly and indirectly associated with diabetes self-efficacy through depressive symptoms (direct effect, -3.778; t = -3.638, P < .001; indirect effect, -0.785; 95% bootstrap confidence interval, -1.868 to -0.089). In addition, self-esteem was associated with both depressive symptoms and diabetes distress. Resilience was associated with diabetes self-efficacy in 1 model. CONCLUSIONS: Negative psychological factors were directly and indirectly associated with diabetes self-efficacy. Depressive symptoms, diabetes distress, self-esteem, and resilience can be important targets of interventions to improve diabetes self-efficacy.

Psychometric Properties of the Advance Care Planning Engagement Survey-9 in Cardiovascular and Metabolic Diseases.

The purpose of this study was to test the reliability and validity of the Advance Care Planning Engagement Survey-9 Korean version in patients with cardiovascular diseases or metabolic syndrome. In this cross-sectional study, data on advance care planning engagement, registration of advance directives and the intention, and sociodemographic characteristics were collected from 105 patients (mean age, 66.3 years) at 4 medical institutions. Cronbach α was used to test the reliability. Confirmatory factor analysis and independent t tests were used to test the validity. Cronbach α s for the total scale and the self-efficacy and readiness dimensions were .93, .82, and .97, respectively. In confirmatory factor analysis with 2 factors, all indices of model fit were acceptable: comparative fit index, 0.995; Tucker-Lewis index, 0.989; standardized root-mean-square residual, 0.024; root-mean-square error of approximation, 0.059; and factor loadings > 0.65. Patients who registered advance directives ( P < .001) or had the intention ( P < .001) had higher scores of the Advance Care Planning Engagement Survey-9 Korean version than their counterparts. The findings demonstrate that the Advance Care Planning Engagement Survey-9 Korean version was a reliable and valid instrument. Health care providers, including nurses, can use this instrument to assess and manage advance care planning engagement in Korean patients with cardiovascular diseases or metabolic syndrome.

Relationships of multidimensional factors to self-management in patients with diabetes: A Cross-sectional, correlational study.

Poor self-management in patients with diabetes is a consistent issue, leading to diabetes complications. The purpose of this study was to examine the relationships of demographic, cognitive, psychological, social, and physiological factors to self-management in patients with diabetes. In this cross-sectional, correlational study, data were collected from 98 patients through REDCap in 2023. Multiple regression analysis was used to address the study purpose. In the sample, adherence to adequate self-management was poor. Knowledge, self-efficacy, and body mass index (BMI) were associated with overall diabetes self-management. Self-efficacy and BMI were associated with diet and exercise. Knowledge and self-efficacy were associated with blood glucose testing. No factors were associated with smoking and foot care. In conclusion, different factors were associated with different types of self-management, but BMI and self-efficacy were associated with most types of self-management. Clinicians and researchers can target BMI, self-efficacy, and knowledge to improve self-management in patients with diabetes.

Cold tolerance in Campylobacter jejuni and its impact on food safety.

Campylobacter jejuni is a major cause of foodborne illnesses worldwide and is primarily transmitted to humans through contaminated poultry meat. To control this pathogen, it is critical to understand its cold tolerance because poultry products are usually distributed in the cold chain. However, there is limited information regarding how this thermotolerant, microaerophilic pathogen can survive in cold and aerobic environments in the poultry cold chain. In this study, we investigated the cold tolerance of C. jejuni by measuring the viability of 90 C. jejuni strains isolated from retail raw chicken at 4 °C under aerobic and microaerobic conditions. Despite the microaerophilic nature of C. jejuni, under aerobic conditions, C. jejuni exhibited higher viability at 4 °C and required an extended inactivation time compared to microaerobic conditions. Some strains were highly tolerant to refrigeration temperatures and exhibited increased survival at 4 °C. These cold-tolerant strains mostly belonged to multilocus sequence typing (MLST) clonal complex (CC)-21 and CC-443, indicating that cold tolerance is associated with the phylogeny of C. jejuni. Notably, cold-tolerant strains had an increased probability of illness and were more likely to cause human infections due to their extended survival on refrigerated chicken meat compared to those sensitive to cold stress. Furthermore, the majority of cold-tolerant strains exhibited elevated aerotolerance, indicating that cold tolerance is related to aerotolerance. These findings suggest that refrigeration of chicken meat under aerobic conditions may not be effective at controlling C. jejuni and that cold-tolerant C. jejuni can pose an increased risk to food safety.

The moderating effect of attitudes in the relationship between knowledge and self-efficacy in palliative care among nurses: A cross-sectional, correlational study.

Provision of palliative care to patients with advanced chronic diseases or old populations is suboptimal, which results in unnecessary suffering of and burden to patients, caregivers, and society. Low self-efficacy in palliative care among nurses is a factor affecting suboptimal utilization of palliative care. Poor knowledge is a factor affecting low self-efficacy in palliative care of nurses. Attitudes may contribute to the relationship between knowledge and self-efficacy in palliative care, but these relationships have been rarely examined in nurses. This study aimed to determine whether nurses' attitudes moderate the relationship between knowledge and self-efficacy in palliative care. In a cross-sectional, correlational study, online or offline survey on self-efficacy, knowledge, attitudes, and covariates was conducted from 282 nurses in South Korea. PROCESS v4.1 for SPSS was used to address the study aim. Higher levels of knowledge (p = .048) and attitudes (p < .001), and the interaction term of knowledge and attitudes (p = .025) were significantly associated with higher levels of self-efficacy (F = 6.12, p < .001, R2 = .152), indicating the moderating effects of attitudes. The relationships between higher levels of knowledge and self-efficacy were significant only in nurses with highly and moderately positive attitudes (R2 change = .016, F = 5.11, p = .025), but not nurses with lack of positive attitudes. Our results supported the moderating role of nurses' attitudes in the relationship between knowledge and self-efficacy. To improve self-efficacy in palliative care in nurses, improvement in knowledge and facilitation of positive attitudes are needed.

Effects of Meditation Intervention on Self-management in Adult Patients With Type 2 Diabetes: A Systematic Literature Review and Meta-analysis.

BACKGROUND: Diabetes complications are prevalent and cause adverse effects on the physical, psychological, and economic status of adult patients with type 2 diabetes. Meditation may positively affect self-management and, in turn, reduce diabetes complications. However, the systematic examination of the effects of meditation without additional components on self-management in this population have been rarely examined. PURPOSE: The aim of this study was to examine the effects of meditation interventions on self-management (ie, control of glucose, blood pressure, cholesterol, and obesity and self-management) among adult patients with type 2 diabetes in randomized controlled trials. METHODS: In this systematic review and meta-analysis, 6 electronic databases were searched using major keywords of meditation , diabetes , and self-management during March 2022. RESULTS: Eight studies (9 articles) using mindfulness-based meditation were included. The meta-analysis showed that meditation improved hemoglobin A 1c (effect size = -0.75; 95% confidence interval, -1.30 to -0.21; P = .007) but not fasting blood glucose. Only a few studies examined meditation effects on other types of self-management (eg, blood pressure, body mass index, cholesterol, diet, exercise, foot care, and monitoring of blood glucose), and the effects were inconsistent. In 1 study, meditation improved diabetes self-management. CONCLUSIONS: Mindfulness-based meditation reduced hemoglobin A 1c levels in adult patients with type 2 diabetes but did not consistently improve other types of self-management in a few studies examined. This may imply the need for additional intervention components to improve different types of self-management. Further studies are needed to examine the effects of different types of meditations with additional components on different types of self-management.

Structural Relationships Between Cognitive Function, Depressive Symptoms, Self-Care Confidence, and Maintenance in Patients With Heart Failure.

Introduction: In order to promote self-care maintenance behavior in patients with heart failure (HF), it is necessary to identify the direct and indirect effects of major latent variables. Objective: This study aimed to identify structural relationships between different domains of cognitive function, depression and self-care confidence, and self-care maintenance. Methods: This descriptive study involved a secondary analysis using data of 201 patients with HF from two observational studies in three hospitals in Korea. The structural equation model using AMOS version 24.0 was constructed to assess the relationships among the variables. The Seoul Neuropsychological Screening Battery was used to assess global cognition, immediate/delayed memory, and executive function, and the Self-Care of HF Index v.6.2. was used for self-care confidence and maintenance. Results: Self-care maintenance was affected by memory function with a significant direct effect (ß=.43, p = .006), as well as self-care confidence (ß=.70, p < .001). Memory function and global function indirectly affected self-care maintenance through self-care confidence (ß = -.37, p = .002; ß = .14, p = .030). Depressive symptoms also had an indirect effect through self-care confidence on self-care maintenance (ß = -.21, p = .005). Conclusion: This study confirmed that it is important to increase self-care confidence through supportive care and to maintain memory function for maintaining self-care in the chronic course of HF patients. In particular, this study suggests that it is necessary to perform periodic memory check-ups for chronic HF patients on an outpatient basis, and counseling and education are needed to improve memory and increase confidence in self-care.

Characterization and genomic study of EJP2, a novel jumbo phage targeting antimicrobial resistant Escherichia coli.

The emergence of antimicrobial resistance (AMR) Escherichia coli has noticeably increased in recent years worldwide and causes serious public health concerns. As alternatives to antibiotics, bacteriophages are regarded as promising antimicrobial agents. In this study, we isolated and characterized a novel jumbo phage EJP2 that specifically targets AMR E. coli strains. EJP2 belonged to the Myoviridae family with an icosahedral head (120.9 ± 2.9 nm) and a non-contractile tail (111.1 ± 0.6 nm), and contained 349,185 bp double-stranded DNA genome with 540 putative ORFs, suggesting that EJP2 could be classified as jumbo phage. The functions of genes identified in EJP2 genome were mainly related to nucleotide metabolism, DNA replication, and recombination. Comparative genomic analysis revealed that EJP2 was categorized in the group of Rak2-related virus and presented low sequence similarity at the nucleotide and amino acid level compared to other E. coli jumbo phages. EJP2 had a broad host spectrum against AMR E. coli as well as pathogenic E. coli and recognized LPS as a receptor for infection. Moreover, EJP2 treatment could remove over 80% of AMR E. coli biofilms on 96-well polystyrene, and exhibit synergistic antimicrobial activity with cefotaxime against AMR E. coli. These results suggest that jumbo phage EJP2 could be used as a potential biocontrol agent to combat the AMR issue in food processing and clinical environments.

Stimulation of Surface Polysaccharide Production under Aerobic Conditions Confers Aerotolerance in Campylobacter jejuni.

The ability of a foodborne pathogen to tolerate environmental stress critically affects food safety by increasing the risk of pathogen survival and transmission in the food supply chain. Campylobacter jejuni, a leading bacterial cause of foodborne illnesses, is an obligate microaerophile and is sensitive to atmospheric levels of oxygen. Currently, the molecular mechanisms of how C. jejuni withstands oxygen toxicity under aerobic conditions have not yet been fully elucidated. Here, we show that when exposed to aerobic conditions, C. jejuni develops a thick layer of bacterial capsules, which in turn protect C. jejuni under aerobic conditions. The presence of both capsular polysaccharides and lipooligosaccharides is required to protect C. jejuni from excess oxygen in oxygen-rich environments by alleviating oxidative stress. Under aerobic conditions, C. jejuni undergoes substantial transcriptomic changes, particularly in the genes of carbon metabolisms involved in amino acid uptake, the tricarboxylic acid (TCA) cycle, and the Embden-Meyerhof-Parnas (EMP) pathway despite the inability of C. jejuni to grow aerobically. Moreover, the stimulation of carbon metabolism by aerobiosis increases the level of glucose-6-phosphate, the EMP pathway intermediate required for the synthesis of surface polysaccharides. The disruption of the TCA cycle eliminates aerobiosis-mediated stimulation of surface polysaccharide production and markedly compromises aerotolerance in C. jejuni. These results in this study provide novel insights into how an oxygen-sensitive microaerophilic pathogen survives in oxygen-rich environments by adapting its metabolism and physiology. IMPORTANCE Oxygen-sensitive foodborne pathogens must withstand oxygen toxicity in aerobic environments during transmission to humans. C. jejuni is a major cause of gastroenteritis, accounting for 400 million to 500 million infection cases worldwide per year. As an obligate microaerophile, C. jejuni is sensitive to air-level oxygen. However, it has not been fully explained how this oxygen-sensitive zoonotic pathogen survives in aerobic environments and is transmitted to humans. Here, we show that under aerobic conditions, C. jejuni boosts its carbon metabolism to produce a thick layer of bacterial capsules, which in turn act as a protective barrier conferring aerotolerance. The new findings in this study improve our understanding of how oxygen-sensitive C. jejuni can survive in aerobic environments.

Characterization of KMSP1, a newly isolated virulent bacteriophage infecting Staphylococcus aureus, and its application to dairy products.

Staphylococcus aureus is one of the major pathogens causing foodborne outbreaks and severe infections worldwide. Generally, various physical and chemical treatments have been applied to control S. aureus in the food industry. However, conventional treatments usually affected food quality and often produced toxic compounds. Therefore, bacteriophage (phage), a natural antimicrobial agent, has been suggested as an alternative strategy to control foodborne pathogens including S. aureus. In this study, KMSP1, a bacteriophage infecting S. aureus was isolated from a raw milk sample and characterized. Transmission electron microscopy (TEM) analysis revealed that phage KMSP1 belongs to the Myoviridae family. Phage KMSP1 efficiently inhibited bacterial growth for >28 h post-infection. In addition, phage KMSP1 could infect a broad spectrum of S. aureus strains, including methicillin-resistant S. aureus (MRSA) strains. Whole-genome sequence analysis showed that KMSP1 is a lytic phage with the absence of genes related to lysogen formation, toxin production, and antibiotics resistance, respectively. In the genome of KMSP1, the presence of putative tail lysin containing a cysteine/histidine-dependent amidohydrolase/peptidase (CHAP) domain could be one of the reasons for the effective antimicrobial activity of KMSP1. Furthermore, high stability of phage KMSP1 at temperature ranging from 4 to 55 °C and pH ranging from 5 to 11, suggested its potential use in various food systems. Receptor analysis revealed that KMSP1 utilized cell wall teichoic acid (WTA), one of the major virulence factors of S. aureus, as a host receptor. Application of phage KMSP1 at an MOI of 104 achieved a significant reduction of log 8.8 CFU/mL of viable cell number in pasteurized milk and log 4.3 CFU/cm2 in sliced cheddar cheese after 24 h. Taken together, the strong antimicrobial activity of phage KMSP1 suggested that it could be developed as a biocontrol agent in dairy products to control S. aureus contamination.

Factors associated with attitudes toward advance directives in nurses and comparisons of the levels between emergency nurses and palliative care nurses.

AIM: Little is known about attitudes toward advance directives and factors associated with them among emergency and palliative care nurses who often or daily face end-of-life circumstances. Thus, we aimed to compare the levels of attitudes toward advance directives, communication skills, knowledge about end-of-life care (knowledge), and awareness of the concept of a good death (good death awareness) between emergency and palliative care nurses, and to examine factors associated with attitudes toward advance directives in the total sample. METHODS: In this cross-sectional, correlational study, data were collected from 153 nurses (59 emergency and 94 palliative care nurses) at three tertiary hospitals using online or offline surveys and were analyzed using t-tests and multiple linear regression analysis. RESULTS: The levels of attitudes, communication skills, knowledge, and good death awareness were moderate in both groups. Attitudes in emergency compared to palliative care nurses were less positive (46.78 vs. 48.38; p = .044), and knowledge was significantly lower (13.64 vs. 15.00; p = .004). Communication skills and good death awareness between the two groups were similar. In the total sample, emergency practice (B = -1.59, p = .024), and lower levels of good death awareness (B = 0.30, p < .001), communication skills (B = 0.18, p = .001), and education (B = -2.84, p = .015) were associated with less positive attitudes (F = 9.52, p < .001; R2  = 0.35). CONCLUSIONS: The findings demonstrate the need for improvements in attitudes, knowledge, communication skills, and good death awareness in both groups, especially emergency nurses. Two modifiable targets of interventions to improve nurses' attitudes were also noted.

Characterization of the lytic phage MSP1 for the inhibition of multidrug-resistant Salmonella enterica serovars Thompson and its biofilm.

The increasing prevalence of multidrug-resistant (MDR) Salmonella is a serious public health threat. Intervention strategies available to control Salmonella mostly target Salmonella enterica serovars Typhimurium and Enteritidis, and little has been investigated to control serovars in serogroup C, such as S. enterica serovar Thompson, despite their increasing prevalence. Here, we isolated phages targeting MDR S. Thompson and characterized the antimicrobial activities of MSP1 phage, a virulent phage with a broad host range. MSP1 phage strongly infected S. Thompson and S. Mbandaka isolates from retail chicken and also other serovars, including Dublin, Enteritidis, Heidelberg, Paratyphi, and Typhimurium. MSP1 phage was able to inhibit the biofilm formation on stainless steel and glass formation by around 42.7-47.9 %. MSP1 phage was robust to withstand wide ranges of pH (4-12) and temperature (30-60 °C), and no genes associated with antibiotic resistance and virulence were found in the phage genome, suggesting that this phage is suitable for food application. When MSP1 phage was tested on foods (chicken meat and milk), MSP1 phage significantly reduced the level of MDR S. Thompson below the detection limit. Our findings suggest that MSP1 phage is a promising antimicrobial agent for the control of food contamination by MDR S. Thompson.

Factors Related to Patients' Self-care and Self-care Confidence in Korean Patients With Heart Failure and Their Caregivers: A Cross-sectional, Correlational Study.

BACKGROUND: The relationships of patient factors and caregiver contribution to patients' self-care to different types of self-care have been rarely examined in Korean patients with heart failure. OBJECTIVE: The aim of this study was to examine patient (ie, age, depressive symptoms, and self-care confidence) and caregiver (ie, caregiver contribution to self-care maintenance and self-care management, and caregiver confidence in contributing to self-care) factors related to different types of self-care (ie, self-care maintenance, symptom perception, and self-care management) and self-care confidence in Korean patients with heart failure. METHODS: In this cross-sectional, correlational study, data from 41 pairs of patients (mean age, 68.0 years) and caregivers (mean age, 54.1 years) were collected and analyzed using multiple regression. RESULTS: Higher levels of self-care confidence in patients were related to higher levels of self-care maintenance in patients. Higher levels of self-care confidence in patients were related to higher levels of symptom perception. Higher levels of self-care confidence in patients and caregiver contribution to self-care maintenance were related to higher levels of self-care management. Less severe depressive symptoms in patients and higher levels of caregiver confidence in contributing to self-care were related to higher levels of self-care confidence. CONCLUSION: Different patient and caregiver factors were related to different types of self-care and self-care confidence in Korean patients, but patients' self-care confidence was related to all types of self-care. Clinicians and researchers need to develop and deliver effective interventions to both patients and their caregivers to improve patients' self-care confidence and, in turn, self-care, considering different factors associated with each type of self-care.

Reliability and validity of the Self-Efficacy in Palliative Care Scale among nurses.

OBJECTIVES: To provide appropriate palliative care, nurses should have appropriate level of self-efficacy in palliative care, but the levels among nurses were low. To improve the levels effectively, self-efficacy in palliative care should be assessed using reliable and valid instruments. The purpose of this study was to examine the reliability and validity of the Self-Efficacy in Palliative Care Scale in Korean nurses. METHODS: In this cross-sectional, observational study, 272 nurses (mean age: 30 years) were enrolled from 6 university-affiliated medical centers or community hospitals in South Korea. Data on self-efficacy and demographic characteristics were collected. Validity was assessed by exploratory and confirmatory factor analyses (SPSS and Mplus). Reliability and homogeneity were assessed by Cronbach's alpha and item analyses (SPSS), respectively. RESULTS: The exploratory and confirmatory factor analyses supported the 4-factor structure (communication, assessment and symptom management, psychosocial and spiritual management of patient and family, and multiprofessional teamworking) with factor loadings >.60 and with good model fit: root mean square error of approximation =.07, Tucker-Lewis index =.94, comparative fit index =.95, and standardized root mean square residual =.04. Cronbach's alphas for the total scale and each of the subscales ranged from .883 to .965. The corrected item-total correlation coefficients of all items ranged from .61 to .90. SIGNIFICANCE OF RESULTS: The findings of this study supported the reliability and validity of this instrument among Korean nurses. This instrument can be used to assess nurses' self-efficacy in palliative care and to test intervention effects on it.

Phylogenetic Association and Genetic Factors in Cold Stress Tolerance in Campylobacter jejuni.

Campylobacter jejuni is a major foodborne pathogen transmitted to humans primarily via contaminated poultry meat. Since poultry meat is generally processed, distributed, and stored in the cold chain, the survival of C. jejuni at refrigeration temperatures crucially affects human exposure to C. jejuni. Here, we investigated genetic factors associated with cold stress tolerance in C. jejuni. Seventy-nine C. jejuni strains isolated from retail raw chicken exhibited different survival levels at 4°C for 21 days. Multilocus sequence typing (MLST) clonal complex 21 (CC-21) and CC-443 were dominant among cold stress-tolerant strains, whereas CC-45 was common among cold stress-sensitive strains. Genome-wide average nucleotide identity (ANI) analysis identified a phylogenetic cluster associated with cold stress tolerance. Moreover, a pangenome analysis revealed 58 genes distinctively present in the cold stress-tolerant phylogenetic cluster. Among these 58 genes, cfrA, encoding the ferric enterobactin receptor involved in ion transport and metabolism, was selected for further analysis. Remarkably, the viability of a ΔcfrA mutant at 4°C was significantly decreased, while the levels of total reactive oxygen species and intracellular iron exceeded those of the wild type. Additionally, a knockout mutation of cfrA also significantly decreased the viability of three cold stress-tolerant isolates at 4°C, confirming the role of cfrA in cold stress tolerance. The results of this study demonstrate that unique phylogenetic clusters of C. jejuni associated with cold stress tolerance exist and that cfrA is a genetic factor contributing to cold stress tolerance in C. jejuni. IMPORTANCE The tolerance of foodborne pathogens to environmental stresses significantly affects food safety. Several studies have demonstrated that C. jejuni survives extended exposures to low temperatures, but the mechanisms of cold stress tolerance are not fully understood. Here, we demonstrate that C. jejuni strains in certain phylogenetic groups exhibit increased tolerance to cold stress. Notably, cfrA is present in the phylogenetic cluster associated with cold stress tolerance and plays a role in the survival of C. jejuni at low temperatures by alleviating oxidative stress. This is the first study to discover phylogenetic associations involving cold stress tolerance and to identify genetic elements conferring cold stress tolerance to C. jejuni.

Sugar Modification of Wall Teichoic Acids Determines Serotype-Dependent Strong Biofilm Production in Listeria monocytogenes.

Biofilm production is responsible for persistent food contamination by Listeria monocytogenes, threatening food safety and public health. Human infection and food contamination with L. monocytogenes are caused primarily by serotypes 1/2a, 1/2b, and 4b. However, the association of biofilm production with phylogenic lineage and serotype has not yet been fully understood. In this study, we measured the levels of biofilm production in 98 clinical strains of L. monocytogenes at 37°C, 25°C, and 4°C. The phylogenetic clusters grouped by core genome multilocus sequence typing (cgMLST) exhibited association between biofilm production and phylogenetic lineage and serotype. Whereas clusters 1 and 3 consisting of serotype 4b strains exhibited weak biofilm production, clusters 2 (serotype 1/2b) and 4 (serotype 1/2a) were composed of strong biofilm formers. Particularly, cluster 2 (serotype 1/2b) strains exhibited the highest levels of biofilm production at 37°C, and the levels of biofilm production of cluster 4 (serotype 1/2a) strains were significantly elevated at all tested temperatures. Pan-genome analysis identified 22 genes unique to strong biofilm producers, most of which are related to the synthesis and modification of teichoic acids. Notably, a knockout mutation of the rml genes related to the modification of wall teichoic acids with l-rhamnose, which is specific to serogroup 1/2, significantly reduced the level of biofilm production by preventing biofilm maturation. Here, the results of our study show that biofilm production in L. monocytogenes is related to phylogeny and serotype and that the modification of wall teichoic acids with l-rhamnose is responsible for serotype-specific strong biofilm formation in L. monocytogenes. IMPORTANCE Biofilm formation on the surface of foods or food-processing facilities by L. monocytogenes is a serious food safety concern. Here, our data demonstrate that the level of biofilm production differs among serotypes 1/2a, 1/2b, and 4b depending on the temperature. Furthermore, sugar decoration of bacterial cell walls with l-rhamnose is responsible for strong biofilm production in serotypes 1/2a and 1/2b, commonly isolated from foods and listeriosis cases. The findings in this study improve our understanding of the association of biofilm production with phylogenetic lineage and serotype in L. monocytogenes.