Résumé
Staphylococcal enterotoxins can act as allergens and stimulate production of specific IgE with subsequent development of allergic manifestations. In addition, they act as superantigens that induce cytokine secretion with more increase of IL-4/IFN-gamma ratio causing augmentation of allergic reactions. Herein we tested the hypothesis that exposure to Staphylococccus aureus and its enterotoxins induces immunological changes that contribute to the pathogenesis of allergic rhinitis and bronchial asthma. This study included 45 air way allergic patients, and 45 controls. The following were done: intradermal allergy skin testing, invitro effect of staphylococcal enterotoxin B [SEB] on cytokine secretion from separated peripheral blood mononuclear cells, detection of nasal carriage of S. aureus and its enterotoxin production by ELISA and serum levels of total IgE, SEB-specific IgE and eosinophil cationic protein [ECP] were measured. We found that nasal carriage of enterotoxin producing S. aureus in allergic patients was significantly higher than in control. Blood eosinophilia, total IgEand ECP levels were significantly higher in S. aureus nasal carrier than non-carrier patients. On in vitro exposure of PBMCs to [SEB], IFN-gamma secretion was significantly less in patients than control and IL-4 secretion was significantly more in patients than control. SEB-specific IgE was detected in 15.6% of patients and not detected in control. There was a significant positive correlation between SEB-specific IgE level in patients and markers of severity of allergic reaction including blood eosinophilia, ECP and total IgE level. This study suggests that nasal carriage of enterotoxin producing S. aureus has a potential role in the development and severity of allergic airway diseases
Sujets)
Adulte , Adolescent , Humains , Asthme/étiologie , Staphylococcus aureus/immunologie , Staphylococcus aureus/pathogénicité , Staphylococcus aureus/isolement et purification , Entérotoxines , SuperantigènesRésumé
Diarrhea is a frequent complication in patients with cancer. It may be caused by several factors including conventional gastrointestinal pathogens, suppression of normal intestinal flora as well as noninfectious causes such as mucositis and bowel ischemia, with neutropenic enterocolitis [NE] being the most serious. To study diarrhea in neutropenic cancer patients in the pediatric age group, with its underlying etiologies and risk factors especially the bacterial causes with special concern on NE. The study was carried out at the Pediatric Hematology and Oncology Units, Zagazig University Hospitals, Egypt, from Januray 2009 to September 2010. Neutropenic cancer patients who developed diarrhea were grouped into 2 groups: group [1], with NE, and group [2], with neutropenic diarrhea rather than NE, On the first day of diarrhea, patients were subjected to: complete blood count, blood cultures [if febrile], stool microscopy [for red and white blood cells, ova and parasites], and stool culture [for specific pathogens]. Abdominal ultrasonography was carriad out within 3 days of the onset of diarrhea. A total of 200 children = 12 year old, suffering of different malignancies with a total of 180 neutropenic episodes were followed. Diarrhea was observed in 100 episodes [55.5%], NE constituted 16% of these diarrheal episodes. Acute lymphoblastic leukemia was the most prevalent in neutropenic cancer patients with diarrhea [66.7%], while acute myeloid leukemia dominated in patients with NE [50%]. Most of diarrheal episodes occurred during the induction phase of chemotherapy [42%]. All patients with NE had significantly more severe neutropenia and of longer duration than the other group. All patients with NE were febrile with 100% positive blood culture, while only 38% of the other group was febrile of which only 37.5%, had positive blood culture. Stool analysis diagnosed giardiasis in 4.8% of non NE patients while stool culture was positive in 75% of NE patients compared to 40.5% of the other group with Klebsiella oxytoca and Candida being the most commonly isolated in NE patients, compared to E coli in the other group. Methotrexate and mitoxantrone were the most implicated chemotherapeutic agents both group. Diarrhea is a common complication in neutropenic cancer children. Gram negative bacteria and Candida are the most incriminated pathogens. Duration and severity of neutropenia carry a great risk for development of neutropenic enterocolitis