Plasma membrane association and resistosome formation of plant helper immune receptors.

Intracellular plant immune receptors, termed NLRs (Nucleotide-binding Leucine-rich repeat Receptors), confer effector-triggered immunity. Sensor NLRs are responsible for pathogen effector recognition. Helper NLRs function downstream of sensor NLRs to transduce signaling and induce cell death and immunity. Activation of sensor NLRs that contain TIR (Toll/interleukin-1receptor) domains generates small molecules that induce an association between a downstream heterodimer signalosome of EDS1 (EnhancedDisease Susceptibility 1)/SAG101 (Senescence-AssociatedGene 101) and the helper NLR of NRG1 (NRequired Gene 1). Autoactive NRG1s oligomerize and form calcium signaling channels largely localized at the plasma membrane (PM). The molecular mechanisms of helper NLR PM association and effector-induced NRG1 oligomerization are not well characterized. We demonstrate that helper NLRs require positively charged residues in their N-terminal domains for phospholipid binding and PM association before and after activation, despite oligomerization and conformational changes that accompany activation. We demonstrate that effector activation of a TIR-containing sensor NLR induces NRG1 oligomerization at the PM and that the cytoplasmic pool of EDS1/SAG101 is critical for cell death function. EDS1/SAG101 cannot be detected in the oligomerized NRG1 resistosome, suggesting that additional unknown triggers might be required to induce the dissociation of EDS1/SAG101 from the previously described NRG1/EDS1/SAG101 heterotrimer before subsequent NRG1 oligomerization. Alternatively, the conformational changes resulting from NRG1 oligomerization abrogate the interface for EDS1/SAG101 association. Our data provide observations regarding dynamic PM association during helper NLR activation and underpin an updated model for effector-induced NRG1 resistosome formation.

The Hospitalist-Oncologist co-ManagemEnt (HOME) system improves hospitalization outcomes of patients with cancer.

BACKGROUND: The hospitalist system has been introduced to improve the quality and safety of inpatient care. As its effectiveness has been confirmed in previous studies, the hospitalist system is spreading in various fields. However, few studies have investigated the feasibility and value of hospitalist-led care of patients with cancer in terms of quality and safety measures. This study aimed to evaluate the efficacy of the Hospitalist-Oncologist co-ManagemEnt (HOME) system. METHODS: Between January 1, 2019, and January 31, 2021, we analyzed 591 admissions before and 1068 admissions after the introduction of HOME system on January 1, 2020. We compared the length of stay and the types and frequencies of safety events between the conventional system and the HOME system, retrospectively. We also investigate rapid response system activation, cardiopulmonary resuscitation, unplanned intensive care unit transfer, all-cause in-hospital mortality, and 30-day re-admission or emergency department visits. RESULTS: The average length of stay (15.9 days vs. 12.9 days, P < 0.001), frequency of safety events (5.6% vs. 2.8%, P = 0.006), rapid response system activation (7.3% vs. 2.2%, P < 0.001) were significantly reduced after the HOME system introduction. However, there was no statistical difference in frequencies of cardiopulomonary resuscitation and intensive care unit transfer, all-cause in-hospital morality, 30-day unplanned re-admission or emergency department visits. CONCLUSIONS: The study suggests that the HOME system provides higher quality of care and safer environment compared to conventional oncologist-led team-based care, and the efficiency of the medical delivery system could be increased by reducing the hospitalization period without increase in 30-day unplanned re-admission.

Antibiotic Prescription in Patients With Coronavirus Disease 2019: Analysis of National Health Insurance System Data in the Republic of Korea.

BACKGROUND: Although coronavirus disease 2019 (COVID-19) is a viral infection, antibiotics are often prescribed due to concerns about accompanying bacterial infection. Therefore, we aimed to analyze the number of patients with COVID-19 who received antibiotic prescriptions, as well as factors that influenced antibiotics prescription, using the National Health Insurance System database. METHODS: We retrospectively reviewed claims data for adults aged ≥ 19 years hospitalized for COVID-19 from December 1, 2019 to December 31, 2020. According to the National Institutes of Health guidelines for severity classification, we calculated the proportion of patients who received antibiotics and the number of days of therapy per 1,000 patient-days. Factors contributing to antibiotic use were determined using linear regression analysis. In addition, antibiotic prescription data for patients with influenza hospitalized from 2018 to 2021 were compared with those for patients with COVID-19, using an integrated database from Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service cohort (K-COV-N cohort), which was partially adjusted and obtained from October 2020 to December 2021. RESULTS: Of the 55,228 patients, 46.6% were males, 55.9% were aged ≥ 50 years, and most patients (88.7%) had no underlying diseases. The majority (84.3%; n = 46,576) were classified as having mild-to-moderate illness, with 11.2% (n = 6,168) and 4.5% (n = 2,484) having severe and critical illness, respectively. Antibiotics were prescribed to 27.3% (n = 15,081) of the total study population, and to 73.8%, 87.6%, and 17.9% of patients with severe, critical, and mild-to-moderate illness, respectively. Fluoroquinolones were the most commonly prescribed antibiotics (15.1%; n = 8,348), followed by third-generation cephalosporins (10.4%; n = 5,729) and beta-lactam/beta-lactamase inhibitors (6.9%; n = 3,822). Older age, COVID-19 severity, and underlying medical conditions contributed significantly to antibiotic prescription requirement. The antibiotic use rate was higher in the influenza group (57.1%) than in the total COVID-19 patient group (21.2%), and higher in severe-to-critical COVID-19 cases (66.6%) than in influenza cases. CONCLUSION: Although most patients with COVID-19 had mild to moderate illness, more than a quarter were prescribed antibiotics. Judicious use of antibiotics is necessary for patients with COVID-19, considering the severity of disease and risk of bacterial co-infection.

Anti-Alpha-Toxin Antibody Responses and Clinical Outcomes of Staphylococcus aureus Bacteremia.

BACKGROUND: Alpha-toxin (AT), a major virulence factor of Staphylococcus aureus, is an important immunotherapeutic target to prevent or treat invasive S. aureus infections. Previous studies have suggested that anti-AT antibodies (Abs) may have a protective role against S. aureus bacteremia (SAB), but their function remains unclear. Therefore, we aimed to investigate the association between serum anti-AT Ab levels and clinical outcomes of SAB. METHODS: Patients from a prospective SAB cohort at a tertiary-care medical center (n = 51) were enrolled in the study from July 2016 to January 2019. Patients without symptoms or signs of infection were enrolled as controls (n = 100). Blood samples were collected before the onset of SAB and at 2- and 4-weeks post-bacteremia. Anti-AT immunoglobin G (IgG) levels were measured using an enzyme-linked immunosorbent assay. All clinical S. aureus isolates were tested for the presence of hla using polymerase chain reaction. RESULTS: Anti-AT IgG levels in patients with SAB before the onset of bacteremia did not differ significantly from those in non-infectious controls. Pre-bacteremic anti-AT IgG levels tended to be lower in patients with worse clinical outcomes (7-day mortality, persistent bacteremia, metastatic infection, septic shock), although the differences were not statistically significant. Patients who needed intensive care unit care had significantly lower anti-AT IgG levels at 2 weeks post-bacteremia (P = 0.020). CONCLUSION: The study findings suggest that lower anti-AT Ab responses before and during SAB, reflective of immune dysfunction, are associated with more severe clinical presentations of infection.

Con-Ca2+ -tenating plant immune responses via calcium-permeable cation channels.

Calcium serves as a second messenger in a variety of developmental and physiological processes and has long been identified as important for plant immune responses. We discuss recent discoveries regarding plant immune-related calcium-permeable channels and how the two intertwined branches of the plant immune system are intricately linked to one another through calcium signalling. Cell surface immune receptors carefully tap the immense calcium gradient that exists between apoplast and cytoplasm in a short burst via tightly regulated plasma membrane (PM)-resident cation channels. Intracellular immune receptors form atypical calcium-permeable cation channels at the PM and mediate a prolonged calcium influx, overcoming the deleterious influence of pathogen effectors and enhancing plant immune responses.

Interspecies differences in clinical characteristics and risk factors for third-generation cephalosporin resistance between Escherichia coli and Klebsiella pneumoniae bloodstream infection in patients with liver cirrhosis.

This retrospective study aimed to clarify the interspecies differences in the clinical characteristics and risk factors of bloodstream infection (BSI) due to third-generation cephalosporin-resistant (3GC-R) Escherichia coli (EC) and Klebsiella pneumoniae (KP) in patients with liver cirrhosis (LC). KP BSI had more comorbidities and higher treatment failure rate than EC BSI. Non-alcoholic LC was a risk factor for treatment failure in EC, whereas it was not associated with KP. Risk factors for BSI due to 3GC-R strain were nosocomial infection in EC, and ß-lactam/fluoroquinolone treatment ≤ 30 days in KP. These results could help predict outcomes of BSI and improve clinical practice.

Association between higher variability in kidney function and long-term mortality.

AIM: We evaluated whether estimated glomerular filtration rate variability in the general population could be associated with all-cause mortality. METHODS: Health examination data from 7842 individuals aged >20 years who visited for health check-ups at least thrice at ≥6-month intervals between May 1, 1995 and November 30, 2010 were collected. Estimated glomerular filtration rate variability was defined as the coefficient of variation of the estimated glomerular filtration rate, that is, standard deviation/mean value multiplied by 100. The study population was divided into three groups based on the coefficient of variation tertiles, and the mortality risks were compared across groups. RESULTS: The mean duration from the final visit to the outcome was 10.3 ± 2.9 years. The mean coefficient of variations of estimated glomerular filtration rate variability from the lowest to the highest variability group were 5.1 ± 1.8%, 9.0 ± 1.0%, and 14.4 ± 3.9%, respectively. There was a 1.3 times higher risk of mortality in the group with the highest variability (hazard ratio: 1.300, 95% confidence interval: 1.013-1.669) after adjustment. The findings were similar in patients with diabetes and those >60 years old (hazard ratio: 1.635, 95% confidence interval: 1.076-2.483; hazard ratio: 1.585, 95% confidence interval: 1.107-2.269). CONCLUSION: Higher estimated glomerular filtration rate variability was associated with increased 10-year mortality in the general population. This variability was very small, but considering the patients' long-term prognoses, it was significant.

A Smart Diaper System Using Bluetooth and Smartphones to Automatically Detect Urination and Volume of Voiding: Prospective Observational Pilot Study in an Acute Care Hospital.

BACKGROUND: Caregivers of patients who wear conventional diapers are required to check for voiding every hour because prolonged wearing of wet diapers causes health problems including diaper dermatitis and urinary tract infections. However, frequent checking is labor intensive and disturbs patients' and caregivers' sleep. Furthermore, assessing patients' urine output with diapers in an acute care setting is difficult. Recently, a smart diaper system with wetness detection technology was developed to solve these issues. OBJECTIVE: We aimed to evaluate the applicability of the smart diaper system for urinary detection, its accuracy in measuring voiding volume, and its effect on incontinence-associated dermatitis (IAD) occurrence in an acute care hospital. METHODS: This prospective, observational, single-arm pilot study was conducted at a single tertiary hospital. We recruited 35 participants aged ≥50 years who were wearing diapers due to incontinence between August and November 2020. When the smart diaper becomes wet, the smart diaper system notifies the caregiver to change the diaper and measures voiding volume automatically. Caregivers were instructed to record the weight of wet diapers on frequency volume charts (FVCs). We determined the voiding detection rate of the smart diaper system and compared the urine volume as automatically calculated by the smart diaper system with the volume recorded on FVCs. Agreement between the two measurements was estimated using a Bland-Altman plot. We also checked for the occurrence or aggravation of IAD and bed sores. RESULTS: A total of 30 participants completed the protocol and 390 episodes of urination were recorded. There were 108 records (27.7%) on both the FVCs and the smart diaper system, 258 (66.2%) on the FVCs alone, 18 (4.6%) on the smart diaper system alone, and 6 (1.5%) on the FVCs with sensing device lost. The detection rate of the smart diaper system was 32.8% (126/384). When analyzing records concurrently listed in both the FVCs and the smart diaper system, linear regression showed a strong correlation between the two measurements (R2=0.88, P<.001). The Bland-Altman assessment showed good agreement between the two measurements, with a mean difference of -4.2 mL and 95% limits of agreement of -96.7 mL and 88.3 mL. New occurrence and aggravation of IAD and bed sores were not observed. Bed sores improved in one participant. CONCLUSIONS: The smart diaper system showed acceptable accuracy for measuring urine volume and it could replace conventional FVCs in acute setting hospitals. Furthermore, the smart diaper system has the potential advantage of preventing IAD development and bed sore worsening. However, the detection rate of the smart diaper system was lower than expected. Detection rate polarization among participants was observed, and improvements in the user interface and convenience are needed for older individuals who are unfamiliar with the smart diaper system.

Predictive scoring models for persistent gram-negative bacteremia that reduce the need for follow-up blood cultures: a retrospective observational cohort study.

BACKGROUND: Although the risk factors for positive follow-up blood cultures (FUBCs) in gram-negative bacteremia (GNB) have not been investigated extensively, FUBC has been routinely carried out in many acute care hospitals. We attempted to identify the risk factors and develop a predictive scoring model for positive FUBC in GNB cases. METHODS: All adults with GNB in a tertiary care hospital were retrospectively identified during a 2-year period, and GNB cases were assigned to eradicable and non-eradicable groups based on whether removal of the source of infection was possible. We performed multivariate logistic analyses to identify risk factors for positive FUBC and built predictive scoring models accordingly. RESULTS: Out of 1473 GNB cases, FUBCs were carried out in 1268 cases, and the results were positive in 122 cases. In case of eradicable source of infection, we assigned points according to the coefficients from the multivariate logistic regression analysis: Extended spectrum beta-lactamase-producing microorganism (+ 1 point), catheter-related bloodstream infection (+ 1), unfavorable treatment response (+ 1), quick sequential organ failure assessment score of 2 points or more (+ 1), administration of effective antibiotics (- 1), and adequate source control (- 2). In case of non-eradicable source of infection, the assigned points were end-stage renal disease on hemodialysis (+ 1), unfavorable treatment response (+ 1), and the administration of effective antibiotics (- 2). The areas under the curves were 0.861 (95% confidence interval [95CI] 0.806-0.916) and 0.792 (95CI, 0.724-0.861), respectively. When we applied a cut-off of 0, the specificities and negative predictive values (NPVs) in the eradicable and non-eradicable sources of infection groups were 95.6/92.6% and 95.5/95.0%, respectively. CONCLUSIONS: FUBC is commonly carried out in GNB cases, but the rate of positive results is less than 10%. In our simple predictive scoring model, zero scores-which were easily achieved following the administration of effective antibiotics and/or adequate source control in both groups-had high NPVs. We expect that the model reported herein will reduce the necessity for FUBCs in GNB cases.

Toll-like receptor 2 downregulation and cytokine dysregulation predict mortality in patients with Staphylococcus aureus bacteremia.

BACKGROUND: Staphylococcus aureus bacteremia (SAB) presents heterogeneously, owing to the differences in underlying host conditions and immune responses. Although Toll-like receptor 2 (TLR2) is important in recognizing S. aureus, its function during S. aureus infection remains controversial. We aimed to examine the association of TLR2 expression and associated cytokine responses with clinical SAB outcomes. METHODS: Patients from a prospective SAB cohort at two tertiary-care medical centers were enrolled. Blood was sampled at several timepoints (≤5 d, 6-9 d, 10-13 d, 14-19 d, and ≥ 20 d) after SAB onset. TLR2 mRNA levels were determined via real-time PCR and serum tumor necrosis factor [TNF]-α, interleukin [IL]-6, and IL-10 levels were analyzed with multiplex-high-sensitivity electrochemiluminescent ELISA. RESULTS: TLR2 levels varied among 59 SAB patients. On days 2-5, TLR2 levels were significantly higher in SAB survivors than in healthy controls (p = 0.040) and slightly but not significantly higher than non-survivors (p = 0.120), and SAB patients dying within 7 d had lower TLR2 levels than survivors (P = 0.077) although statistically insignificant. IL-6 and IL-10 levels were significantly higher in non-survivors than in survivors on days 2-5 post-bacteremia (P = 0.010 and P = 0.021, respectively), and those dying within 7 d of SAB (n = 3) displayed significantly higher IL-10/TNF-α ratios than the survivors did (P = 0.007). CONCLUSION: TLR2 downregulation and IL-6 and IL-10 concentrations suggestive of immune dysregulation during early bacteremia may be associated with mortality from SAB. TLR2 expression levels and associated cytokine reactions during early-phase SAB may be potential prognostic factors in SAB, although larger studies are warranted.

Impact of a delirium prevention project among older hospitalized patients who underwent orthopedic surgery: a retrospective cohort study.

BACKGROUND: Postoperative delirium (POD) is a common clinical syndrome with significant negative outcomes. Thus, we aimed to evaluate the feasibility and effectiveness of a delirium screening tool and multidisciplinary delirium prevention project. METHODS: A retrospective cohort study was conducted at a single teaching center in Korea. A cohort of patients who underwent a delirium prevention program using a simple delirium screening tool from December 2018 to February 2019 (intervention group, N = 275) was compared with the cohort from the year before implementation of the delirium prevention program (December 2017 to February 2018) (control group, N = 274). Patients aged ≥65 years who were admitted to orthopedic wards and underwent surgery were included. The incidence rates of delirium before and after implementation of the delirium prevention program, effectiveness of the delirium screening tool, change in the knowledge score of nurses, and length of hospital stay were assessed. RESULTS: The sensitivity and specificity of the screening tool for the incidence of POD were 94.1 and 72.7%, respectively. The incidence rates of POD were 10.2% (control group) and 6.2% (intervention group). The odds ratio for the risk reduction effect of the project related to the incidence of POD was 0.316 (95% confidence interval: 0.125-0.800, p = 0.015) after adjustment for possible confounders. The delirium knowledge test score increased from 40.52 to 43.24 out of 49 total points (p < 0.001). The median length of hospital stay in the intervention and control groups was 6.0 (interquartile range, 4-9) and 7.0 (interquartile range, 4-10) days, respectively (p = 0.062). CONCLUSION: The screening tool successfully identified patients at a high risk of POD at admission. The POD prevention project was feasible to implement, effective in preventing delirium, and improved knowledge regarding delirium among the medical staff. TRIAL REGISTRATION: None.

Effects of Phage Endolysin SAL200 Combined with Antibiotics on Staphylococcus aureus Infection.

Phages and their derivatives are increasingly being reconsidered for use in the treatment of bacterial infections due to the rising rates of antibiotic resistance. We assessed the antistaphylococcal effect of the endolysin SAL200 in combination with standard-of-care (SOC) antibiotics. The activity of SAL200 when it was combined with SOC antibiotics was assessed in vitro by checkerboard and time-kill assays and in vivo with murine bacteremia and Galleria mellonella infection models. SAL200 reduced the SOC antibiotic MICs and showed a ≥3-log10-CFU/ml reduction of Staphylococcus aureus counts within 30 min in time-kill assays. Combinations of SAL200 and SOC antibiotics achieved a sustained decrease of >2 log10 CFU/ml. SAL200 significantly lowered the blood bacterial density within 1 h by >1 log10 CFU/ml in bacteremic mice (P < 0.05 versus untreated mice), and SAL200 and SOC antibiotic combinations achieved the lowest levels of bacteremia. The bacterial density in splenic tissue at 72 h postinfection was the lowest in mice treated with SAL200 and SOC antibiotic combinations. SAL200 combined with SOC antibiotics also improved Galleria mellonella larva survival at 96 h postinfection. The combination of the phage endolysin SAL200 with SOC antistaphylococcal antibiotics showed synergistic effects in vitro and in vivo The combination of SAL200 with SOC antibiotics could help in the treatment of difficult-to-treat S. aureus infections.

An Acute Medical Unit in a Korean Tertiary Care Hospital Reduces the Length of Stay and Waiting Time in the Emergency Department.

A hospitalist-run acute medical unit (AMU) opened at a tertiary care hospital on August 2015 for the first time in Korea. Patients visiting the emergency department (ED) with acute medical problems are admitted to the AMU. They stay in that unit for less than 72 hours and are discharged or transferred to specialty wards if longer treatment is necessary. We reviewed 19,450 medical admissions through the ED from January 2014 to September 2016. The median length of stay (LOS) significantly decreased from 10.0 days (interquartile range [IQR], 5.5-16.7) to 9.1 days (IQR, 5.1-15.0) (P < 0.001) after the establishment of the AMU. The median waiting time in the ED significantly shortened by 40% (P < 0.001). Future studies on the impact of AMU on in-patient morbidity, mortality, re-admission rate, and patient or staff satisfaction are necessary.

Pepper pathogenesis-related protein 4c is a plasma membrane-localized cysteine protease inhibitor that is required for plant cell death and defense signaling.

Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis-related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT-triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease-inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H2 O2 and significant induction of some defense-response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT-triggered resistance responses, and enabled Xcv proliferation in infected leaves. H2 O2 accumulation, cell-death induction, and defense-response gene expression were distinctly reduced in CaPR4c-silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling.

Pepper heat shock protein 70a interacts with the type III effector AvrBsT and triggers plant cell death and immunity.

Heat shock proteins (HSPs) function as molecular chaperones and are essential for the maintenance and/or restoration of protein homeostasis. The genus Xanthomonas type III effector protein AvrBsT induces hypersensitive cell death in pepper (Capsicum annuum). Here, we report the identification of the pepper CaHSP70a as an AvrBsT-interacting protein. Bimolecular fluorescence complementation and coimmunoprecipitation assays confirm the specific interaction between CaHSP70a and AvrBsT in planta. The CaHSP70a peptide-binding domain is essential for its interaction with AvrBsT. Heat stress (37°C) and Xanthomonas campestris pv vesicatoria (Xcv) infection distinctly induce CaHSP70a in pepper leaves. Cytoplasmic CaHSP70a proteins significantly accumulate in pepper leaves to induce the hypersensitive cell death response by Xcv (avrBsT) infection. Transient CaHSP70a overexpression induces hypersensitive cell death under heat stress, which is accompanied by strong induction of defense- and cell death-related genes. The CaHSP70a peptide-binding domain and ATPase-binding domain are required to trigger cell death under heat stress. Transient coexpression of CaHSP70a and avrBsT leads to cytoplasmic localization of the CaHSP70a-AvrBsT complex and significantly enhances avrBsT-triggered cell death in Nicotiana benthamiana. CaHSP70a silencing in pepper enhances Xcv growth but disrupts the reactive oxygen species burst and cell death response during Xcv infection. Expression of some defense marker genes is significantly reduced in CaHSP70a-silenced leaves, with lower levels of the defense hormones salicylic acid and jasmonic acid. Together, these results suggest that CaHSP70a interacts with the type III effector AvrBsT and is required for cell death and immunity in plants.

Pathogenesis-related protein 4b interacts with leucine-rich repeat protein 1 to suppress PR4b-triggered cell death and defense response in pepper.

To control defense and cell-death signaling, plants contain an abundance of pathogen recognition receptors such as leucine-rich repeat (LRR) proteins. Here we show that pepper (Capsicum annuum) LRR1 interacts with the pepper pathogenesis-related (PR) protein 4b, PR4b, in yeast and in planta. PR4b is synthesized in the endoplasmic reticulum, interacts with LRR1 in the plasma membrane, and is secreted to the apoplast via the plasma membrane. Binding of PR4b to LRR1 requires the chitin-binding domain of PR4b. Purified PR4b protein inhibits spore germination and mycelial growth of plant fungal pathogens. Transient expression of PR4b triggers hypersensitive cell death. This cell death is compromised by co-expression of LRR1 as a negative regulator in Nicotiana benthamiana leaves. LRR1/PR4b silencing in pepper and PR4b over-expression in Arabidopsis thaliana demonstrated that LRR1 and PR4b are necessary for defense responses to Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis (Hpa) infection. The mutant of the PR4b Arabidopsis ortholog, pr4, showed enhanced susceptibility to Hpa infection. Together, our results suggest that PR4b functions as a positive modulator of plant cell death and defense responses. However, the activity of PR4b is suppressed by interaction with LRR1.

The pepper phosphoenolpyruvate carboxykinase CaPEPCK1 is involved in plant immunity against bacterial and oomycete pathogens.

Phosphoenolpyruvate carboxykinase, a member of the lyase family, is involved in the metabolic pathway of gluconeogenesis in organisms. Although the major function of PEPCK in gluconeogenesis is well established, it is unclear whether this enzyme is involved in plant immunity. Here, we isolated and identified the pepper (Capsicum annuum) PEPCK (CaPEPCK1) gene from pepper leaves infected with Xanthomonas campestris pv. vesicatoria (Xcv). CaPEPCK1 was strongly expressed in pepper leaves during the incompatible interaction with avirulent Xcv and in response to environmental stresses, especially salicylic acid (SA) treatment. PEPCK activity was low in healthy leaves but dramatically increased in avirulent Xcv-infected leaves. Knock-down expression of CaPEPCK1 by virus-induced gene silencing resulted in high levels of susceptibility to both virulent and avirulent Xcv infection. CaPEPCK1 silencing in pepper compromised induction of the basal defense-marker genes CaPR1 (pathogenesis-related 1 protein), CaPR10 (pathogenesis-related 10 protein) and CaDEF1 (defensin) during Xcv infection. SA accumulation was also significantly suppressed in the CaPEPCK1-silenced pepper leaves infected with Xcv. CaPEPCK1 in an Arabidopsis overexpression (OX) line inhibited the proliferation of Pseudomonas syringae pv. tomato (Pst) and Hyaloperonospora arabidopsidis (Hpa). CaPEPCK1-OX plants developed more rapidly, with enlarged leaves, compared to wild-type plants. The T-DNA insertion Arabidopsis orthologous mutants pck1-3 and pck1-4 were more susceptible to the bacterial Pst and oomycete Hpa pathogens than the wild type. Taken together, these results suggest that CaPEPCK positively contributes to plant innate immunity against hemibiotrophic bacterial and obligate biotrophic oomycete pathogens.

Inappropriate continued empirical vancomycin use in a hospital with a high prevalence of methicillin-resistant Staphylococcus aureus.

Vancomycin is frequently inappropriately prescribed, especially as empirical treatment. The aim of this study was to evaluate (i) the amount of inappropriate continued empirical vancomycin use as a proportion of total vancomycin use and (ii) the risk factors associated with inappropriate continued empirical vancomycin use. We reviewed the medical records of adult patients who had been prescribed at least one dose of parenterally administered vancomycin between January and June 2012, in a single tertiary care hospital. When empirically prescribed vancomycin treatment was continued after 96 h without documentation of beta-lactam-resistant Gram-positive microorganisms in clinical specimens with significance, the continuation was considered inappropriate, and the amount used thereafter was considered inappropriately used. We identified risk factors associated with inappropriate continued empirical vancomycin use by multiple logistic regression. During the study period, the amount of parenterally administered vancomycin prescribed was 34.2 defined daily doses (DDDs)/1,000 patient-days (1,084 prescriptions for 971 patients). The amount of inappropriate continued empirical vancomycin use was 8.5 DDDs/1,000 patient-days, which represented 24.9% of the total parenterally administered vancomycin used (8.5/34.2 DDDs/1,000 patient-days). By multivariate analyses, inappropriate continued empirical vancomycin use was independently associated with the absence of any documented etiological organism (adjusted odds ratio [aOR], 1.60 [95% confidence interval {CI}, 1.06 to 2.41]) and suspected central nervous system (CNS) infections (aHR, 2.33 [95% CI, 1.20 to 4.50]). Higher Charlson's comorbidity index scores were inversely associated with inappropriate continued empirical vancomycin use (aHR, 0.90 [95% CI, 0.85 to 0.97]). Inappropriate continued empirical vancomycin use represented 24.9% of the total amount of vancomycin prescribed, which indicates room for improvement.

agr dysfunction affects staphylococcal cassette chromosome mec type-dependent clinical outcomes in methicillin-resistant Staphylococcus aureus bacteremia.

Staphylococcal cassette chromosome mec element (SCCmec) type-dependent clinical outcomes may vary due to geographical variation in the presence of virulence determinants. We compared the microbiological factors and mortality attributed to methicillin-resistant Staphylococcus aureus (MRSA) bacteremia between SCCmec types II/III and type IV. All episodes of MRSA bacteremia in a tertiary-care hospital (South Korea) over a 4.5-year period were reviewed. We studied the microbiological factors associated with all blood MRSA isolates, including spa type, agr type, agr dysfunction, and the genes for Panton-Valentine leukocidin (PVL) and phenol-soluble modulin (PSM)-mec, in addition to SCCmec type. Of 195 cases, 137 involved SCCmec types II/III, and 58 involved type IV. The mortality attributed to MRSA bacteremia was less frequent among the SCCmec type IV (5/58) than that among types II/III (39/137, P = 0.002). This difference remained significant when adjusted for clinical factors (adjusted odds ratio [aOR], 0.14; 95% confidence interval [CI], 0.04 to 0.49; P = 0.002). Of the microbiological factors tested, agr dysfunction was the only significant factor that showed different positivity between the SCCmec types, and it was independently associated with MRSA bacteremia-attributed mortality (aOR, 4.71; 95% CI, 1.72 to 12.92; P = 0.003). SCCmec type IV is associated with lower MRSA bacteremia-attributed mortality than are types II/III, which might be explained by the high rate of agr dysfunction in SCCmec types II/III in South Korea.

GLYCINE-RICH RNA-BINDING PROTEIN1 interacts with RECEPTOR-LIKE CYTOPLASMIC PROTEIN KINASE1 and suppresses cell death and defense responses in pepper (Capsicum annuum).

Plants use a variety of innate immune regulators to trigger cell death and defense responses against pathogen attack. We identified pepper (Capsicum annuum) GLYCINE-RICH RNA-BINDING PROTEIN1 (CaGRP1) as a RECEPTOR-LIKE CYTOPLASMIC PROTEIN KINASE1 (CaPIK1)-interacting partner, based on bimolecular fluorescence complementation and coimmunoprecipitation analyses as well as gene silencing and transient expression analysis. CaGRP1 contains an N-terminal RNA recognition motif and a glycine-rich region at the C-terminus. The CaGRP1 protein had DNA- and RNA-binding activity in vitro. CaGRP1 interacted with CaPIK1 in planta. CaGRP1 and CaGRP1-CaPIK1 complexes were localized to the nucleus in plant cells. CaPIK1 phosphorylated CaGRP1 in vitro and in planta. Transient coexpression of CaGRP1 with CaPIK1 suppressed the CaPIK1-triggered cell death response, accompanied by a reduced CaPIK1-triggered reactive oxygen species (ROS) burst. The RNA recognition motif region of CaGRP1 was responsible for the nuclear localization of CaGRP1 as well as the suppression of the CaPIK1-triggered cell death response. CaGRP1 silencing in pepper conferred enhanced resistance to Xanthomonas campestris pv vesicatoria (Xcv) infection; however, CaPIK1-silenced plants were more susceptible to Xcv. CaGRP1 interacts with CaPIK1 and negatively regulates CaPIK1-triggered cell death and defense responses by suppressing ROS accumulation.