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Luminol-dependent chemiluminescence was used as a monitor of reactive oxidant generation during phagocytosis of Staphylococcus aureus by human neutrophils. Reactive oxidants play a crucial role in the killing of this organism because : (a) S. aureus was killed most rapidly when the rate of increase of chemiluminescence was greatest; (b) neutrophils which had been activated to generate reactive oxidants by re-aeration of anaerobic suspensions killed this bacterium more efficiently than control suspensions; and (c) neutrophils from a patient with chronic granulomatous disease could neither generate reactive oxidants nor kill S . aureus.

BACKGROUNDHuman rotavirus, an important causative agent of severe gastroenteritis in infants and young children worldwide, leads to high morbidity in both developing and developed countries, including Saudi Arabia, and high mortality in developing countries. Effective control depends upon an accurate understanding of disease burden and the relative importance of circulating serotypes.METHODSWe examined the epidemiology and disease burden of rotavirus in Saudi Arabia through a review of 22 published studies of rotavirus and the aetiology of diarrhoea carried out from 1982 to 2003.RESULTSThe prevalence of rotavirus infection ranged between 10% to 46% with a median of 30%. Most cases were among children less than 2 years of age, and particularly in the first year of life. There were significant differences in seasonality within Saudi Arabia, with increased infection during winter in some cities and during summer in others. G1 was the predominant serotype followed by G4, G3 and G2, in 4 studies where strains had been G-typed. The prevalence of nontypeable strains ranged from 11.0% to 31.3%. No data were available on P types. Results of electropherotyping in 4 studies revealed that the long electropherotype was predominant.CONCLUSIONRotavirus is an important cause of severe diarrhoea in Saudi children. However, the available data on rotavirus strains in circulation are limited and there is an urgent need for up-to-date and comprehensive studies to evaluate rotavirus strains in circulation and identify unusual types that could be incorporated into future vaccines.

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Staphylococcal enterotoxins have marked effects on the properties of T cells and monocytes and have recently been reported to affect neutrophil function. In this study, we investigated the abilities of staphylococcal enterotoxins A and B and toxic shock syndrome toxin 1 to affect respiratory burst activity and to delay apoptosis in human neutrophils. When cultures containing approximately 97% neutrophils were tested, the toxins all delayed neutrophil apoptosis in a dose-dependent manner and induced the expression of FcγRI on the neutrophil cell surface. These effects on apoptosis and expression of FcγRI were largely abrogated by the addition of a neutralizing anti-gamma interferon antibody. Similarly, the effects of these toxins on phorbol ester-induced chemiluminescence were decreased after neutralization of gamma interferon. These effects on neutrophil function were mimicked by the addition of conditioned medium from peripheral blood mononuclear cells incubated with the toxins, and again, neutralizing anti-gamma interferon antibodies largely negated the effects. However, when highly purified neutrophils prepared by immunodepletion of T cells and major histocompatibility complex class II-expressing cells were analyzed, the toxins were without effect on apoptosis and FcγRI expression, but granulocyte-macrophage colony-stimulating factor and gamma interferon could still delay apoptosis. These data indicate that these toxins have no direct effect on neutrophil apoptosis but can act indirectly via the production of T-cell-derived and monocyte-derived cytokines. It is noteworthy that such effects are detected in neutrophil suspensions containing only 3% contamination with T cells and other mononuclear cells.