Key predictors and burden of meticillin-resistant Staphylococcus aureus infection in comparison with meticillin-susceptible S. aureus infection in an Australian hospital setting.

BACKGROUND: Staphylococcus aureus is associated with significant mortality and increased burden on the healthcare system. Relatively few reliable estimates are available regarding the impact of meticillin-resistant S. aureus (MRSA) infection compared with meticillin-susceptible S. aureus (MSSA) infection. AIMS: To compare patients with MRSA infection and MSSA infection to identify differences in inpatient mortality, length of stay and costs of hospital services, and identify predictors of MRSA as a cause of S. aureus infection. METHODS: An analytical, retrospective, longitudinal study using non-identifiable linked data on adults admitted to hospitals of a health district in Australia with a diagnosis of S. aureus infection over a 10-year period. The main outcome measure was 30-day inpatient mortality. Secondary endpoints included total overnight stays, all-cause inpatient mortality, and hospitalization costs within 1 year of index admission. FINDINGS: Inpatient mortality at 30, 100 and 365 days was estimated to be significantly greater for patients with MRSA infection. The mean additional cost of MRSA infection when controlling for additional factors was $5988 and 4 nights of additional hospital stay per patient within 1 year of index admission. Key predictors of MRSA infection were: date of index admission; higher comorbidity score; greater socio-economic disadvantage; admission to hospital other than via the emergency department; older age; and prior admission to hospital within 28 days of index admission. CONCLUSIONS: MRSA infection is associated with increased inpatient mortality, costs and hospital length of stay compared with MSSA infection. Efforts are required to alleviate the additional burden of MRSA infection on patients and healthcare systems.

Climatic and ecological determinants of leaf lifespan in polar forests of the high CO2 Cretaceous 'greenhouse' world.

Polar forests once extended across the high-latitude landmasses during ice-free 'greenhouse' intervals in Earth history. In the Cretaceous 'greenhouse' world, Arctic conifer forests were considered predominantly deciduous, while those on Antarctica contained a significantly greater proportion of evergreens. To investigate the causes of this distinctive biogeographical pattern, we developed a coupled model of conifer growth, soil biogeochemistry and forest dynamics. Our approach emphasized general relationships between leaf lifespan (LL) and function, and incorporated the feedback of LL on soil nutrient status. The model was forced with a mid-Cretaceous 'greenhouse' climate simulated by the Hadley Centre GCM. Simulated polar forests contained mixtures of dominant LLs, which reproduced observed biogeographical patterns of deciduous, mixed and evergreen biomes. It emerged that disturbance by fire was a critical factor. Frequent fires in simulated Arctic ecosystems promoted the dominance of trees with short LLs that were characterized by the rapid growth and colonization rates typical of today's boreal pioneer species. In Antarctica, however, infrequent fires allowed trees with longer LLs to dominate because they attained greater height, despite slower growth rates. A direct test of the approach was successfully achieved by comparing modelled LLs with quantitative estimates using Cretaceous fossil woods from Svalbard in the European Arctic and Alexander Island, Antarctica. Observations and the model both revealed mixed Arctic and evergreen Antarctic communities with peak dominance of trees with the same LLs. Our study represents a significant departure from the long-held belief that leaf habit was an adaptation to warm, dark winter climates, and highlights a previously unrecognized role for disturbance (in whatever guise) in polar forest ecology.

Qualitative responses of children to environmental noise.

Results from recent quantitative research consistently demonstrate that children are a high risk group, vulnerable to the adverse effects of noise exposure, especially effects on cognitive performance, motivation and annoyance. The aims of the two qualitative studies reported in this paper are to explore children's a) perception of noise exposure; b) perceived risk of and attitudes towards noise pollution; c) coping strategies; and d) the annoyance response. The Millennium Conference Study involved focus group interviews with an international sample (n=36) unselected by exposure. The West London Schools Study involved individual interviews, conducted with a purposively selected sample (n=18) exposed to aircraft noise. The children in the focus groups reported being most affected by neighbours' noise and road traffic noise, whereas children exposed to aircraft noise were most affected by aircraft noise. As expected, the impact of noise pollution on everyday activities (e.g. schoolwork, homework and playing) was larger for the children exposed to high levels of aircraft noise compared with the low noise exposed children and focus group samples. The range of coping strategies that children employed to combat noise exposure in their lives was dependent upon the amount of control they had over the noise source. The emotional response of children describing the annoyance reaction to noise was consistent with adult reactions and it would seem that child noise annoyance is the same construct. Future research should employ qualitative methods to supplement quantitative investigations.

The West London Schools Study: the effects of chronic aircraft noise exposure on child health.

BACKGROUND: Previous field studies have indicated that children's cognitive performance is impaired by chronic aircraft noise exposure. However, these studies have not been of sufficient size to account adequately for the role of confounding factors. The objective of this study was to test whether cognitive impairments and stress responses (catecholamines, cortisol and perceived stress) are attributable to aircraft noise exposure after adjustment for school and individual level confounding factors and to examine whether children exposed to high levels of social disadvantage are at greater risk of noise effects. METHODS: The cognitive performance and health of 451 children aged 8-11 years, attending 10 schools in high aircraft noise areas (16 h outdoor Leq > 63 dBA) was compared with children attending 10 matched control schools exposed to lower levels of aircraft noise (16 h outdoor Leq < 57 dBA). RESULTS: Noise exposure was associated with impaired reading on difficult items and raised annoyance, after adjustment for age, main language spoken and household deprivation. There was no variation in the size of the noise effects in vulnerable subgroups of children. High levels of noise exposure were not associated with impairments in mean reading score, memory and attention or stress responses. Aircraft noise was weakly associated with hyperactivity and psychological morbidity. CONCLUSIONS: Chronic noise exposure is associated with raised noise annoyance in children. The cognitive results indicate that chronic aircraft noise exposure does not always lead to generalized cognitive effects but, rather, more selective cognitive impairments on difficult cognitive tests in children.