Contribution of acquired meticillin-resistant Staphylococcus aureus bacteraemia to overall mortality in a general intensive care unit.

During a period of 11 years, 77 patients had meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia > or =5 days after admission to the intensive care unit (ICU). Ten had no prior growth of MRSA, 13 had positive screens on admission and 54 initially tested negative for MRSA in ICU before positive blood culture. These 54 constituted 20.2% [95% confidence interval (CI): 15.6-25.0] of 267 who acquired MRSA > or =5 days after admission. Mortality among 77 patients with MRSA bacteraemia was 57.1% (46.0-68.2). Nineteen of these 77 patients with MRSA bacteraemia had growth of a second pathogen from blood. Those with only MRSA bacteraemia were each matched with five controls by diagnosis and initial Acute Physiological and Chronic Health Evaluation II score. Mortality was greater in bacteraemic patients [53.6% (40.5-66.7)] than in controls [31.8% (26.3-37.3)] [relative risk (RR) 1.69 (1.25-2.26), P < 0.01], implying an additional absolute mortality of 21.8% (8.0-40.1). Application of this estimate to all 77 patients suggests that ICU-acquired MRSA bacteraemia caused 17 (6-31) deaths, adding 0.3% (0.1-0.6) to the 30.1% hospital mortality of all admissions. Incidence of MRSA bacteraemia increased with length of stay, contributing an estimated 3.1% (1.1-5.7) towards 37.9% mortality of the 198 patients remaining > or =25 days. These data emphasise the importance of preventing initial MRSA colonisation/infection of long-stay patients.

Decline in the rates of meticillin-resistant Staphylococcus aureus acquisition and bacteraemia in a general intensive care unit between 1996 and 2008.

Analysis of admission and weekly screening and other cultures for meticillin-resistant Staphylococcus aureus (MRSA) taken in the intensive care unit (ICU) demonstrated a 75% reduction in the estimated rate of acquisition of MRSA between 1996 and June 2008. Four periods were defined by three events: a new ICU (December 1997); addition of a two-bed bay (January 2001); and extra infection control measures in ICU and the hospital generally, including screening of all admissions (December 2006). In ICU, acquisition/1000 bed-days decreased promptly in each successive period, 49.0 (34.4-63.6), 28.3 (21.7-34.9), 19.3 (16.3-22.3) and 11.8 (7.3-16.3) respectively, and MRSA bacteraemias/1000 bed-days decreased between the last three periods, 7.6 (4.7-10.5), 3.7 (2.6-4.8) and 0.4 (0-2.9) with no change in the proportion colonised progressing to bacteraemia and a small increase in the rate of other bacteraemias. From December 2006 prevalence of MRSA in admissions to ICU from general wards decreased from 13.5% (11.6-15.4) to 6.4% (4.0-8.8) consequent upon a reduction in estimated pre-ICU acquisition rate from 26.0 (22.7-29.3) to 9.4 (6.0-12.8)/1000 bed-days. These results suggest that the improved environment of the new ICU and its extension and the recent changes in infection control each contributed to the observed reductions in MRSA acquisition and subsequent bacteraemia within ICU. Improved infection control in the hospital was associated with decreased acquisition of MRSA on the general wards.

Experimental and theoretical investigations of the spontaneous infrared radiation fluctuations of a high-pressure, high-current argon discharge.

The equations describing the spontaneous fluctuations of photon radiation are given by the Bose-Einstein statistics. These equations are applied to calculate the statistical fluctuations of photon radiation emitted by a nonhomogeneous plasma. By using a photodetector, the radiation fluctuations are transformed into corresponding output current fluctuations. The detector must have special properties as to sensitivity, noise, frequency response, and transmission characteristics. The InSb photodetector described here has the required properties. As a radiation source, the plasma of a stationary argon arc discharge at high pressure was used. By measuring and calculating the continuous photon radiation, it is possible to determine the temperature distribution in the plasma. Investigations of the electrical conductivity confirm the temperature distributions. Because of the high temperatures, as well as the sufficient optical thickness in the infrared spectral range, determination of the fluctuation factors is made possible. Considering the experimental difficulties, the agreement between measured and calculated factors is good. Instabilities in the plasma have been considered and eliminated in the experimental procedure.

Ethnic variation in type of genital herpes simplex virus infection in a South London genitourinary medicine clinic.

The aims of this study were to investigate the prevalence of herpes simplex virus (HSV) types 1 and 2 in the study population and correlate the results with clinical and demographic details. Consecutive HSV isolates from 334 clinic attendees were typed by immunofluorescence. Patient information was collected from the case notes. Overall, HSV-1 was isolated from 48 and HSV-2 from 287 samples, respectively. There was no significant difference in isolation rates according to gender. However, 33% of white patients' isolates typed as HSV-1, while only 6% of the isolates from the black population were HSV-1 (P < 0.001). Initial infections were seen in 81% of HSV-1 infections and 48% of HSV-2 infections, respectively. A wide discrepancy was observed in the prevalence of HSV-1 and HSV-2 infections between the ethnic groups in this population, which was not explained in terms of gender or age. This may reflect different exposure to HSV-1 in childhood or different sexual practices. The increased prevalence in genital HSV-1 reported in recent studies was not seen in this population. However, the differing proportions of primary and first episode infections may reflect a changing epidemiology.

Audit of scope and culture techniques applied to samples for the diagnosis of Mycobacterium bovis by hospital laboratories in England and Wales.

This audit examines the ability of English and Welsh laboratories to diagnose Mycobacterium bovis infection. All 164 clinical laboratories submitting samples to the PHLS Mycobacterium Reference Unit and Regional Centres for Mycobacteriology were surveyed. Twenty per cent of responding centres did not use a pyruvate-containing medium or incubate for the minimum recommended period of 8 weeks. This study demonstrates the potential for the underdiagnosis of M. bovis infection in England and Wales. Possible reasons for underdiagnosis are discussed together with strategies to optimize recovery of M. bovis.