Pandemic (H1N1) 2009 influenza in hospitalized children in Manitoba: nosocomial transmission and lessons learned from the first wave.

OBJECTIVE: To review the experiences at Winnipeg Children's Hospital (WCH) during the 2009 influenza season, with an emphasis on nosocomial transmission and infection prevention and control responses. DESIGN: A case series of patients admitted to WCH who had laboratory-confirmed cases of influenza between January 1 and July 31, 2009, with a comparison of patients with seasonal influenza and those with pandemic (H1N1) 2009 influenza; a review of the impact of infection prevention and control modifications on nosocomial transmission. PATIENTS AND SETTING: A total of 104 inpatients with influenza, 81 of whom had pandemic (H1N1) 2009 influenza, were reviewed at a large Canadian pediatric tertiary care center. RESULTS: There were no differences in risk factors, presentation, or outcome between patients with seasonal influenza and those with pandemic (H1N1) 2009 influenza. There were 8 nosocomial cases of pandemic (H1N1) 2009 influenza. Excluding patients with nosocomial cases, mean length of hospital stay was significantly shortened to 3.7 days for individuals who had pandemic (H1N1) 2009 influenza and who received empiric oseltamivir on admission to the hospital, compared with 12.0 days for patients for whom treatment was delayed (P = .02). Treatment with oseltamivir of all patients with suspected cases of influenza and prompt modifications to infection control practices, including playroom closures and enhanced education of visitors and staff, terminated nosocomial transmission. CONCLUSIONS: Infection with pandemic (H1N1) 2009 influenza virus resulted in a substantial number of hospitalizations of pediatric patients in Manitoba, including those with nosocomial cases, thereby stressing the capacity of WCH. Immediate therapy with oseltamivir on admission to the hospital resulted in a significantly reduced length of hospitalization. This, coupled with intensified infection prevention and control practices, halted nosocomial transmission. These strategies should be considered in future pandemic influenza or other respiratory viral outbreaks.

Kinetic studies of unmodified individual Escherichia coli beta-galactosidase molecules in free solution.

Assays were performed on individual Escherichia coli beta-galactosidase molecules at 2 different concentrations of the substrate DDAO-beta-D-galactoside using a free zone capillary electrophoresis-based protocol with an in-laboratory-constructed instrument utilizing laser-induced fluorescence detection. In a typical run, 2 enzyme molecules were injected into the capillary. They were separated from each other by a brief period of electrophoresis and incubated on the capillary in the presence of the substrate. They were then mobilized on the capillary into a zone of substrate at a different concentration, re-incubated, and the product peaks mobilized past the detector . The relative change in activity as the concentration was increased differed between molecules, suggesting differences in Km. In a different experiment, the capillary was filled with on average 13 enzyme molecules per run, incubated, and the activities of the individual molecules determined. The shapes of the distribution curves of single molecule activities obtained at different concentrations of the substrate resorufin-beta-D-galactoside were indistinguishable, suggesting a homogeneous Km. To explain why individual enzyme molecules behaved as if they were heterogeneous with respect to Km but the population behaved as if it were homogeneous, theoretical Michaelis-Menten curves were constructed. The curves for populations with heterogeneous Km values were found to be indistinguishable from that of a homogeneous population.

Crystallization of beta-galactosidase does not reduce the range of activity of individual molecules.

By use of a capillary electrophoresis-based procedure, it is possible to measure the activity of individual molecules of beta-galactosidase. Molecules from the crystallized enzyme as well as the original enzyme preparation used to grow the crystals both displayed a range of activity of 20-fold or greater. beta-Galactosidase molecules obtained from two different crystals had indistinguishable activity distributions of 31,600 +/- 1100 and 31,800 +/- 1100 reactions min(-1) (enzyme molecule)(-1). This activity was found to be significantly different from that of the enzyme used to grow the crystals, which showed an activity distribution of 38,500 +/- 900 reactions min(-1) (enzyme molecule)(-1).