Prediction of infection caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: development of a clinical decision-making nomogram.

OBJECTIVE: This study aimed to assess the population at risk of infection by extended-spectrum beta-lactamase (ESBL)-producing organisms, using clinical criteria. MATERIALS AND METHODS: All urine cultures positive for Enterobacteriaceae in a Spanish hospital department from January 2010 to 2014 were reviewed. All isolates with ESBL-positive strains were collected, and isolates received during the first week of each month with ESBL-negative strains from symptomatic patients hospitalized or admitted to the emergency room. Multivariate analysis of the factors involved was undertaken and a nomogram developed to predict the probability of infection by ESBL-producing microorganisms. RESULTS: The study included 1524 patients with urinary tract infection (UTI): 416 ESBL-positive and 1108 ESBL-negative. In univariate analysis, risk factors were: male gender (p = 0.036), age (p < 0.0001), nursing home (p < 0.0001), previous antimicrobial therapy (p < 0.0001) or hospitalization (p < 0.0001), diabetes (p < 0.0001), chronic renal insufficiency (p < 0.0001), severe underlying disease (p < 0.0001), neoplasia (p = 0.0005), urological (p < 0.0001) and non-urological invasive procedure (p = 0.0003), recurrent UTI (p < 0.0001), urological (p < 0.0001) or abdominal surgery (p < 0.0001) and permanent urethral catheter (p < 0.0001). In multivariate analysis, the data set was split into a development cohort of 1067 patients and a validation cohort of 457 cases. A nomogram was developed to predict the probability of infection by ESBL-producing bacteria, which included seven variables: age (p < 0.0001), gender (p = 0.004), nursing home (p < 0.0001), previous antimicrobial therapy (p = 0.04) or hospitalization (p < 0.0001), recurrent UTI (p < 0.0001) and non-urological invasive procedure (p = 0.005). The discriminative accuracy was 0.79 (95% confidence interval 0.77-0.83). CONCLUSIONS: A nomogram was developed that predicts the risk of infection by ESBL-producing Enterobacteriaceae with reasonable accuracy. It could improve clinical decision making and enable more efficient empirical treatment.

PARP-1/PARP-2 double deficiency in mouse T cells results in faulty immune responses and T lymphomas.

The maintenance of T-cell homeostasis must be tightly regulated. Here, we have identified a coordinated role of Poly(ADP-ribose) polymerase-1 (PARP-1) and PARP-2 in maintaining T-lymphocyte number and function. Mice bearing a T-cell specific deficiency of PARP-2 in a PARP-1-deficient background showed defective thymocyte maturation and diminished numbers of peripheral CD4+ and CD8+ T-cells. Meanwhile, peripheral T-cell number was not affected in single PARP-1 or PARP-2-deficient mice. T-cell lymphopenia was associated with dampened in vivo immune responses to synthetic T-dependent antigens and virus, increased DNA damage and T-cell death. Moreover, double-deficiency in PARP-1/PARP-2 in T-cells led to highly aggressive T-cell lymphomas with long latency. Our findings establish a coordinated role of PARP-1 and PARP-2 in T-cell homeostasis that might impact on the development of PARP-centred therapies.

N-ras couples antigen receptor signaling to Eomesodermin and to functional CD8+ T cell memory but not to effector differentiation.

Signals from the TCR that specifically contribute to effector versus memory CD8⁺ T cell differentiation are poorly understood. Using mice and adoptively transferred T lymphocytes lacking the small GTPase N-ras, we found that N-ras-deficient CD8⁺ T cells differentiate efficiently into antiviral primary effectors but have a severe defect in generating protective memory cells. This defect was rescued, although only partly, by rapamycin-mediated inhibition of mammalian target of rapamycin (mTOR) in vivo. The memory defect correlated with a marked impairment in vitro and in vivo of the antigen-mediated early induction of T-box transcription factor Eomesodermin (Eomes), whereas T-bet was unaffected. Besides N-ras, early Eomes induction in vitro required phosphoinositide 3-kinase (PI3K)-AKT but not extracellular signal-regulated kinase (ERK) activation, and it was largely insensitive to rapamycin. Consistent with N-ras coupling Eomes to T cell memory, retrovirally enforced expression of Eomes in N-ras-deficient CD8⁺ T cells effectively rescued their memory differentiation. Thus, our study identifies a critical role for N-ras as a TCR-proximal regulator of Eomes for early determination of the CD8⁺ T cell memory fate.

Candida albicans beta-glucan exposure is controlled by the fungal CEK1-mediated mitogen-activated protein kinase pathway that modulates immune responses triggered through dectin-1.

Innate immunity to Candida albicans depends upon the recognition of molecular patterns on the fungal cell wall. However, the masking of major components such as beta-glucan seems to be a mechanism that fungi have evolved to avoid immune cell recognition through the dectin-1 receptor. Although the role of C. albicans mitogen-activated protein kinase (MAPK) pathways as virulence determinants has been established previously with animal models, the mechanism involved in this behavior is largely unknown. In this study we demonstrate that a disruption of the C. albicans extracellular signal-regulated kinase (ERK)-like 1 (CEK1)-mediated MAPK pathway causes enhanced cell wall beta-glucan exposure, triggering immune responses more efficiently than the wild type, as measured by dectin-1-mediated specific binding and human dendritic cell (hDC)- and macrophage-mediated phagocytosis, killing, and activation of intracellular signaling pathways. At the molecular level, the disruption of CEK1 resulted in altered spleen tyrosine kinase (Syk), Raf-1, and ERK1/2 activations together with IkappaB degradation on hDCs and increased dectin-1-dependent activator protein 1 (AP-1) activation on transfected cells. In addition, concurring with these altered pathways, we detected increased reactive oxygen species production and cytokine secretion. In conclusion, the CEK1-mediated MAPK pathway is involved in beta-glucan exposure in a fungal pathogen, hence influencing dectin-1-dependent immune cell recognition, thus establishing this fungal intracellular signaling route as a promising novel therapeutic target.

Differential susceptibility of mitogen-activated protein kinase pathway mutants to oxidative-mediated killing by phagocytes in the fungal pathogen Candida albicans.

The role of four mitogen-activated protein (MAP) kinase pathways in the survival of Candida albicans following infection of human phagocytes has been addressed through the analysis of mutants defective in their respective MAP kinase. While the contribution of the cell integrity (Mkc1-mediated) or mating (Cek2-mediated) pathways is relatively minor to survival, clear and opposite effects were observed for cek1 and hog1 mutants, despite the fact that these two MAP kinases are important virulence determinants in the mouse model of experimental infection. The Cek1-mediated pathway is involved in sensitivity to phagocyte-mediated killing, while the HOG pathway contributes to the survival of the fungal cells in this interaction. Furthermore, reporter genes have been developed to quantify oxidative and nitrosative stress. hog1 mutants show an oxidative and nitrosative stress response augmented - albeit non-protective - when challenged with oxidants and NO donors in vitro or phagocytic cells (macrophages, neutrophils and the myelomonocytic cell line HL-60), suggesting this as the cause of their reduced virulence in the murine model of infection. These data have important consequences for the development of novel antifungal therapies to combat against fungal infection.