Regulation of Hemolysin Expression and Virulence of Staphylococcus aureus by a Serine/Threonine Kinase and Phosphatase

Exotoxins, including the hemolysins known as the alpha (α) and beta (β) toxins, play an important role in the pathogenesis of Staphylococcus aureus infections. A random transposon library was screened for S. aureus mutants exhibiting altered hemolysin expression compared to wild type. Transposon insertions in 72 genes resulting in increased or decreased hemolysin expression were identified. Mutations inactivating a putative cyclic di-GMP synthetase and a serine/threonine phosphatase (Stp1) were found to reduce hemolysin expression, and mutations in genes encoding a two component regulator PhoR, LysR family transcriptional regulator, purine biosynthetic enzymes and a serine/threonine kinase (Stk1) increased expression. Transcription of the hla gene encoding α toxin was decreased in a Δstp1 mutant strain and increased in a Δstk1 strain. Microarray analysis of a Δstk1 mutant revealed increased transcription of additional exotoxins. A Δstp1 strain is severely attenuated for virulence in mice and elicits less inflammation and IL-6 production than the Δstk1 strain. In vivo phosphopeptide enrichment and mass spectrometric analysis revealed that threonine phosphorylated peptides corresponding to Stk1, DNA binding histone like protein (HU), serine-aspartate rich fibrinogen/bone sialoprotein binding protein (SdrE) and a hypothetical protein (NWMN_1123) were present in the wild type and not in the Δstk1 mutant. Collectively, these studies suggest that Stk1 mediated phosphorylation of HU, SrdE and NWMN_1123 affects S. aureus gene expression and virulence

Continuous vs Intermittent Meropenem Administration in Critically Ill Patients With Sepsis

Importance: Meropenem is a widely prescribed β-lactam antibiotic. Meropenem exhibits maximum pharmacodynamic efficacy when given by continuous infusion to deliver constant drug levels above the minimal inhibitory concentration. Compared with intermittent administration, continuous administration of meropenem may improve clinical outcomes. Objective: To determine whether continuous administration of meropenem reduces a composite of mortality and emergence of pandrug-resistant or extensively drug-resistant bacteria compared with intermittent administration in critically ill patients with sepsis. Design, setting, and participants: A double-blind, randomized clinical trial enrolling critically ill patients with sepsis or septic shock who had been prescribed meropenem by their treating clinicians at 31 intensive care units of 26 hospitals in 4 countries (Croatia, Italy, Kazakhstan, and Russia). Patients were enrolled between June 5, 2018, and August 9, 2022, and the final 90-day follow-up was completed in November 2022. Interventions: Patients were randomized to receive an equal dose of the antibiotic meropenem by either continuous administration (n = 303) or intermittent administration (n = 304). Main outcomes and measures: The primary outcome was a composite of all-cause mortality and emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28. There were 4 secondary outcomes, including days alive and free from antibiotics at day 28, days alive and free from the intensive care unit at day 28, and all-cause mortality at day 90. Seizures, allergic reactions, and mortality were recorded as adverse events. Results: All 607 patients (mean age, 64 [SD, 15] years; 203 were women [33%]) were included in the measurement of the 28-day primary outcome and completed the 90-day mortality follow-up. The majority (369 patients, 61%) had septic shock. The median time from hospital admission to randomization was 9 days (IQR, 3-17 days) and the median duration of meropenem therapy was 11 days (IQR, 6-17 days). Only 1 crossover event was recorded. The primary outcome occurred in 142 patients (47%) in the continuous administration group and in 149 patients (49%) in the intermittent administration group (relative risk, 0.96 [95% CI, 0.81-1.13], P = .60). Of the 4 secondary outcomes, none was statistically significant. No adverse events of seizures or allergic reactions related to the study drug were reported. At 90 days, mortality was 42% both in the continuous administration group (127 of 303 patients) and in the intermittent administration group (127 of 304 patients). Conclusions and relevance: In critically ill patients with sepsis, compared with intermittent administration, the continuous administration of meropenem did not improve the composite outcome of mortality and emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28. Trial registration: ClinicalTrials.gov Identifier: NCT03452839

Cardiovascular involvement in children with COVID-19 temporally related multisystem inflammatory syndrome (MIS-C): can cardiac magnetic resonance arrive to the heart of the problem?

Background: Multisystem inflammatory syndrome in children (MIS-C) shows a significant overlap of symptoms with other hyper-inflammatory diseases such as Kawasaki disease (KD), but the real difference of the two conditions is still matter of debate. Coronary artery lesions (CAL) are the most relevant complication in KD. Nonetheless, CAL, myocarditis, pericarditis, arrhythmia are the main cardiovascular complications in MIS-C. A close clinical assessment is mandatory, both at the diagnosis and during the follow-up, by ECG and echocardiography. Cardiac magnetic resonance (MRI) adds important data to ultrasound findings. However, cardiac MRI studies in MIS-C are limited to a small number of cohorts. Methods: We enrolled 20 children (age:1-16 years; 11 F; 9 M) with cardiac involvement secondary to MIS-C, all evaluated by cardiac MRI. Results: 8 children showed pathological cardiac MRI: 2 showed pericardial effusion; 2 showed myocardial oedema; 1 showed aortic insufficiency; 3 showed delayed enhancement (one for acute myocarditis with oedema; 2 for myocardial fibrosis). Delayed enhancement was reduced significantly 5.6-9 months after the first MRI evaluation. 25% of patients with pathological MRI had CAL associated with valvular insufficiency of 2 valves. 17% of patients with normal MRI had CAL, associated with valvular insufficiency of 1 valve in 1 patient. The correlations between haematological, clinical, cardiologic parameters, treatment, did not reach the statistical significance. 4 patients were treated with anakinra. Among those, 2 patients showed a normal cardiac MRI. Cardiac lesions resolved in all the patients during the follow-up. Some patients with pathological cardiac MRI could not underwent a control with MRI, for the low compliance. However, echocardiography and ECG, documented the resolution of the pathological data in these cases. Conclusions: A higher risk of CAL was documented in patients with an association of other cardiac lesions. Cardiac MRI is difficult to perform routinely; however, it is useful for evaluating the acute myocardial damage and the outcome of patients with MIS-C

Implementation of low glycemic index diet together with cornstarch in post-gastric bypass hypoglycemia: Two case reports

Post-bariatric hypoglycemia (PBH) is an increasingly recognized long-term complication of bariatric surgery. The nutritional treatment of PBH includes a high-fiber diet and the restriction of soluble and high-glycemic index carbohydrates; however, these measures are not always enough to prevent hypoglycemia. We evaluated the efficacy of uncooked cornstarch, a low-glycemic index carbohydrate characterized by slow intestinal degradation and absorption, in addition to a high-fiber diet, for the treatment of PBH. We report the cases of two young women suffering from severe postprandial and fasting hypoglycemia following Roux-en-Y gastric bypass (RYGB). The patients underwent Continuous Glucose Monitoring (CGM) before and 12⁻16 weeks after the administration of uncooked cornstarch (respectively 1.25 g/kg b.w. and 1.8 g/kg b.w.) in addition to a high-fiber diet. In both patients, CGM showed more stable glucose levels throughout monitoring, a remarkable reduction of the time spent in hypoglycemia

Differential Contribution of Toll-Like Receptors 4 and 2 to the Cytokine Response to Salmonella enterica Serovar Typhimurium and Staphylococcus aureus in Mice

The contribution of murine Toll-like receptors 2 and 4 (TLR2 and -4, respectively) to cytokine induction by heat-killed bacteria was analyzed in vitro and in vivo. Gram-negative bacteria induced cytokines primarily via TLR4; the contribution of TLR2 was only minor. Neither TLR4 nor, surprisingly, TLR2 was required in the MyD88-dependent response to Staphylococcus aureus

Glycemic control and microvascular complications in adults with type 1 diabetes and long-lasting treated celiac disease: A case-control study

Aims: To investigate whether in type 1 diabetes (T1DM) patients the concomitance of long-lasting celiac disease (CD) treated with a gluten free diet (GFD) impacts glycaemic control and the prevalence/severity of microvascular complications. Methods: A case-control, observational study was performed in 34 patients with T1DM and GFD-treated CD and 66 patients with T1DM alone matched for age, gender, and T1DM duration. Anthropometric parameters, glucose control (HbA1c), status of chronic complications and concomitant autoimmune diseases were evaluated. Results: HbA1c level was similar in T1DM + CD and T1DM alone (7.8 ± 1.0 vs 7.7 ± 1.1%, P = 0.57); insulin requirement was significantly higher in T1DM + CD compared with T1DM (P = 0.04). There were no differences in systolic blood pressure while diastolic blood pressure was significantly lower in T1DM + CD (P = 0.003). The prevalence/severity of microvascular complications was similar between the two groups. Glomerular filtration rate (eGFR) was significantly lower in T1DM + CD (100 ± 20 vs 110 ± 16 ml/min/1.73 m2, P = 0.007). Conclusions: In patients with T1DM, the co-occurrence of long-term GFD-treated CD neither worsens glycemic control nor negatively impacts chronic microvascular complications. However, patients with T1DM + CD have lower eGFR values than those with T1DM alone

Glycemic control and microvascular complications in adults with type 1 diabetes and long-lasting treated celiac disease: A case-control study

Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) is one of the most important pathogen vectors on maize, but its courtship behavior has never been documented. In the present study, we recorded length of courtship and mating periods and behavioral transitions for D. maidis. According to these observations, we built ethograms for both sexes to create a comprehensive description of their courtship behavior. The mean courtship duration was 110.04 (±66.84) min and the mean mating period was 51.61 (±19.75) min. Both sexes showed similar, stereotyped behavioral transitions. However, females exhibited a lower frequency of several behavioral transitions and behaviors compared with males. Before mating, females were more frequently resting or performing an abdomen movement. Less frequently, they were walking or flapping the wings (wing fanning). Meanwhile, males exhibited three main behaviors before mating; the most frequent was wing fanning, followed by walking and approaching. However, during courtship, rapprochement between individuals of both sexes was not common so it is deduced that physical contact is not essential. In this regard, we discuss possible acoustic and chemical communication during the courtship process of D. maidis. © 2014, Springer Science+Business Media New York