Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Staphylococcus aureus Infections: Epidemiology, Pathophysiology, Clinical Manifestations, and Management

To prepare a dermatologic addendum to the 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides (CHCC2012) to address vasculitides affecting the skin (D‐CHCC). The goal was to standardize the names and definitions for cutaneous vasculitis.

Revised international Chapel Hill consensus conference nomenclature of vasculitides

BACKGROUND We observed a syndrome of intermittent fevers, early-onset lacunar strokes and other neurovascular manifestations, livedoid rash, hepatosplenomegaly, and systemic vasculopathy in three unrelated patients. We suspected a genetic cause because the disorder presented in early childhood. METHODS We performed whole-exome sequencing in the initial three patients and their unaffected parents and candidate-gene sequencing in three patients with a similar phenotype, as well as two young siblings with polyarteritis nodosa and one patient with small-vessel vasculitis. Enzyme assays, immunoblotting, immunohistochemical testing, flow cytometry, and cytokine profiling were performed on samples from the patients. To study protein function, we used morpholino-mediated knockdowns in zebrafish and short hairpin RNA knockdowns in U937 cells cultured with human dermal endothelial cells. RESULTS All nine patients carried recessively inherited mutations in CECR1 (cat eye syndrome chromosome region, candidate 1), encoding adenosine deaminase 2 (ADA2), that were predicted to be deleterious; these mutations were rare or absent in healthy controls. Six patients were compound heterozygous for eight CECR1 mutations, whereas the three patients with polyarteritis nodosa or small-vessel vasculitis were homozygous for the p.Gly47Arg mutation. Patients had a marked reduction in the levels of ADA2 and ADA2-specific enzyme activity in the blood. Skin, liver, and brain biopsies revealed vasculopathic changes characterized by compromised endothelial integrity, endothelial cellular activation, and inflammation. Knockdown of a zebrafish ADA2 homologue caused intracranial hemorrhages and neutropenia — phenotypes that were prevented by coinjection with nonmutated (but not with mutated) human CECR1. Monocytes from patients induced damage in cocultured endothelial-cell layers. CONCLUSIONS Loss-of-function mutations in CECR1 were associated with a spectrum of vascular and inflammatory phenotypes, ranging from early-onset recurrent stroke to systemic vasculopathy or vasculitis. (Funded by the National Institutes of Health Intramural Research Programs and others.)

/pdf/early-onset-stroke-and-vasculopathy-associated-with-1tqs8qvtts.pdf

Early-Onset Stroke and Vasculopathy Associated with Mutations in ADA2

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

Iconographies supplémentaires de l'article : Practice parameter for the diagnosis and management of primary immunodeficiency

Practice parameter for the diagnosis and management of primary immunodeficiency

BACKGROUND Polyarteritis nodosa is a systemic necrotizing vasculitis with a pathogenesis that is poorly understood. We identified six families with multiple cases of systemic and cutaneous polyarteritis nodosa, consistent with autosomal recessive inheritance. In most cases, onset of the disease occurred during childhood. METHODS We carried out exome sequencing in persons from multiply affected families of Georgian Jewish or German ancestry. We performed targeted sequencing in additional family members and in unrelated affected persons, 3 of Georgian Jewish ancestry and 14 of Turkish ancestry. Mutations were assessed by testing their effect on enzymatic activity in serum specimens from patients, analysis of protein structure, expression in mammalian cells, and bio physical analysis of purified protein. RESULTS In all the families, vasculitis was caused by recessive mutations in CECR1, the gene encoding adenosine deaminase 2 (ADA2). All the Georgian Jewish patients were homozygous for a mutation encoding a Gly47Arg substitution, the German patients were compound heterozygous for Arg169Gln and Pro251Leu mutations, and one Turkish patient was compound heterozygous for Gly47Val and Trp264Ser mutations. In the endogamous Georgian Jewish population, the Gly47Arg carrier frequency was 0.102, which is consistent with the high prevalence of disease. The other mutations either were found in only one family member or patient or were extremely rare. ADA2 activity was significantly reduced in serum specimens from patients. Expression in human embryonic kidney 293T cells revealed low amounts of mutant secreted protein. CONCLUSIONS Recessive loss-of-function mutations of ADA2, a growth factor that is the major extracellular adenosine deaminase, can cause polyarteritis nodosa vasculopathy with highly varied clinical expression. (Funded by the Shaare Zedek Medical Center and others.)

https://www.nejm.org/doi/pdf/10.1056/NEJMoa1307362

Mutant Adenosine Deaminase 2 in a Polyarteritis Nodosa Vasculopathy

Background We evaluated the effect of adding dexamethasone to antibiotic therapy in the clinical course of septic arthritis in children. Methods A randomized double-blind placebo-controlled trial was performed. The study group included 49 children with septicarthritis. In addition to antibiotic therapy given, patients were randomly assigned to receive intravenous dexamethasone 0.15 mg/kg every 6 hours for 4 days or placebo. The groups were compared for clinical and laboratory parameters, length of hospital stay, and late sequelae. Results Mean age was 33±42 months (range: 6 to 161 mo). There was no significant difference between the dexamethasone and placebo groups in age, duration of symptoms, joint affected, or levels of acute phase reactants. Bacteria were isolated from joint fluid in 17 patients (35%) and from blood in 4 patients. Compared with the placebo group, patients treated with dexamethasone had a significantly shorter duration of fever (P=0.021; mean first day without fever 1.68 vs 2.83) and local inflammatory signs (P=0.021; mean first day without pain 7.18 vs 10.76), lower levels of acute phase reactants (P=0.003; mean last day of erythrocyte sedimentation rate>25 mm/h 3.76 vs 8.40), shorter duration of parenteral antibiotic treatment (P=0.007; mean of 9.91 d vs 12.60 d), and shorter hospital stay. No side effects of treatment were recorded in either group. Conclusions A 4-day course of dexamethasone given at the start of antibiotic treatment in children with septic arthritis, is safe, and leads to a significantly more rapid clinical improvement, shortening duration of hospitalization compared with those treated with antibiotics alone. Level of evidence I.

Dexamethasone Therapy for Septic Arthritis in Children: Results of a Randomized Double-blind Placebo-controlled Study

Purpose The incidence of Haemophilus influenzae type B (HIB) infection, once the most common cause of periorbital cellulitis, declined dramatically after the introduction of HIB vaccine in 1990. The aim of the current study was to determine the predisposing factors and agents in the pathogenesis of periorbital cellulitis in hospitalized children in the post-HIB vaccination era. Methods Children with clinical findings of periorbital inflammation who were hospitalized in a tertiary pediatric hospital in Israel in 2000-2001 were observed prospectively. Special attention was directed to the predisposing medical condition in each case. Results One hundred sixty-three patients had a final discharge diagnosis of periorbital cellulitis. Mean age was 34 months (median = 24 months). The predisposing conditions were conjunctivitis (42.9%), infected wound or trauma (20.9%), insect bites (9.8%), sinusitis (8%), dacryostenosis (4.9%), and Streptococcus pneumoniae bacteremia (0.6%). Children with conjunctivitis and sinusitis had the most severe inflammatory signs. None of the cultures was positive for HIB, although only 71% of the children had complete immunization. Conclusion The epidemiology of periorbital cellulitis in children has changed in the post-HIB vaccine era. The most common predisposing medical conditions are conjunctivitis or an infected wound in the vicinity of the eye. Bacteremia is rarely a source of the disease. These findings have important clinical implications in terms of choice of treatment.

Vered Hoffer

Papers

Mutant Adenosine Deaminase 2 in a Polyarteritis Nodosa Vasculopathy

Dexamethasone Therapy for Septic Arthritis in Children: Results of a Randomized Double-blind Placebo-controlled Study

Periorbital cellulitis in the era of Haemophilus influenzae type B vaccine: predisposing factors and etiologic agents in hospitalized children.