Reduction in the colonization of central venous cannulae by mupirocin

In an in-vitro simulation of an intravascular cannula enclosed in a fibrin sheath, 0.03 mg1(-1) of mupirocin prevented significant colonization [greater than 15 colony forming units (cfu)] by two clinical isolates of Staphylococcus epidermidis and one each of S. saprophyticus, S. hominis and S. haemolyticus. This suggests that in vivo, where protein binding of mupirocin is 95-97%, 1 mg 1(-1) of mupirocin at the cannula surface would be required to prevent colonization. These results support the findings of our previously published prospective controlled trial, in which mupirocin applied to the insertion sites of 172 internal jugular cannulae reduced the rate of colonization of cannula tips to 5%, compared with 25% for the 186 controls (P less than 0.001). Of the 46 colonized cannula tips from 110 control patients, the same species was isolated from the skin of the insertion site in 67% and from the lumen flush in only 15%. Analysed by patient, mupirocin reduced the proportion of patients with colonized tips from 17% to 3% after 24 h of infection, and from 35 to 10% after 48 h (P = 0.002). The use of agar containing charcoal, as a mupirocin neutralizer, and the incubation of tip-culture plates flooded with the Oxford staphylococcus, gave no evidence of carry over of mupirocin onto cannulae removed from mupirocin-treated patients

Minimal dose requirements for nasal mupirocin and its role in the control of epidemic MRSA

Staphylococci are still a leading cause of hospital infection. The success of nasal mupirocin for the control of epidemic methicillin- resistant Staphylococcus aureus (EMRSA), the prevention of colonization of central venous cannulae, and the prevention of septicaemia in haemodialysis patients should encourage the use of minimal dose regimens to minimize the emergence of mupirocin resistance. Mupirocin applied to the anterior nares 4-times daily usually eliminates S. aureus, including EMRSA, within 48 h. Elimination is sustained for several weeks in patients and staff. We recently found that a single dose, or a regimen of 4-times daily for 2 days, eliminated nasal carriage of S. aureus within 24 h; 7 days after a single dose, 92% of the subjects were still cleared; 7 days after the 2-day course, 96% remained free of nasal S. aureus. Ward personnel who are nasal carriers of EMRSA can, provided that other carriage sites are negative, return to work after 2 days of a 4-times daily intranasal regimen. The UK guidelines, recently published in this Journal, recommend an aggressive approach to identifying and eliminating EMRSA, including the elimination of nasal carriage. This approach is increasingly associated with the control of EMRSA in the UK and elsewhere

The status and future of EUV astronomy

The Extreme Ultraviolet wavelength range was one of the final windows to be opened up to astronomy. Nevertheless, it provides very important diagnostic tools for a range of astronomical objects, although the opacity of the interstellar medium restricts the majority of observations to sources in our own galaxy. This review gives a historical overview of EUV astronomy, describes current instrumental capabilities and examines the prospects for future facilities on small and medium-class satellite platforms.Comment: Published in Advances in Space Researc

Irradiated brown dwarfs

We have observed the post common envelope binary WD0137-349 in the near infrared $J$, $H$ and $K$ bands and have determined that the photometry varies on the system period (116 min). The amplitude of the variability increases with increasing wavelength, indicating that the brown dwarf in the system is likely being irradiated by its 16500 K white dwarf companion. The effect of the (primarily) UV irradiation on the brown dwarf atmosphere is unknown, but it is possible that stratospheric hazes are formed. It is also possible that the brown dwarf (an L-T transition object) itself is variable due to patchy cloud cover. Both these scenarios are discussed, and suggestions for further study are made.Comment: 5 pages, 2 figures. Proceedings from "Brown dwarfs come of age" meeting in Fuerteventura 201

Origin of electron cyclotron maser-induced radio emissions at ultra-cool dwarfs: magnetosphere-ionosphere coupling currents

A number of ultra-cool dwarfs emit circularly polarised radio waves generated by the electron cyclotron maser instability. In the solar system such radio is emitted from regions of strong auroral magnetic field-aligned currents. We thus apply ideas developed for Jupiter's magnetosphere, being a well-studied rotationally-dominated analogue in our solar system, to the case of fast-rotating UCDs. We explain the properties of the radio emission from UCDs by showing that it would arise from the electric currents resulting from an angular velocity shear in the fast-rotating magnetic field and plasma, i.e. by an extremely powerful analogue of the process which causes Jupiter's auroras. Such a velocity gradient indicates that these bodies interact significantly with their space environment, resulting in intense auroral emissions. These results strongly suggest that auroras occur on bodies outside our solar system.Comment: Accepted for publication in the Astrophysical Journa

WD0837+185:the formation and evolution of an extreme mass ratio white dwarf-brown dwarf binary in Praesepe

There is a striking and unexplained dearth of brown dwarf companions in close orbits (< 3AU) around stars more massive than the Sun, in stark contrast to the frequency of stellar and planetary companions. Although rare and relatively short-lived, these systems leave detectable evolutionary end points in the form of white dwarf - brown dwarf binaries and these remnants can offer unique insights into the births and deaths of their parent systems. We present the discovery of a close (orbital separation ~ 0.006 AU) substellar companion to a massive white dwarf member of the Praesepe star cluster. Using the cluster age and the mass of the white dwarf we constrain the mass of the white dwarf progenitor star to lie in the range 3.5 - 3.7 Msun (B9). The high mass of the white dwarf means the substellar companion must have been engulfed by the B star's envelope while it was on the late asymptotic giant branch (AGB). Hence, the initial separation of the system was ~2 AU, with common envelope evolution reducing the separation to its current value. The initial and final orbital separations allow us to constrain the combination of the common envelope efficiency (alpha) and binding energy parameters (lambda) for the AGB star to alpha lambda ~3. We examine the various formation scenarios and conclude that the substellar object was most likely to have been captured by the white dwarf progenitor early in the life of the cluster, rather than forming in situ.Comment: Accepted for publication in ApJ

Spectroscopically confirmed brown dwarf members of Coma Berenices and the Hyades

We have obtained low- and medium-resolution spectra of nine brown dwarf candidate members of Coma Berenices and the Hyades using SpEX on the NASA InfraRed Telescope Facility and Long Slit Intermediate Resolution Infrared Spectrograph on the William Herschel Telescope. We conclude that seven of these objects are indeed late M or early L dwarfs, and that two are likely members of Coma Berenices and four of the Hyades. Two objects, cbd40 and Hy3, are suggested to be field L dwarfs, although there is also a possibility that Hy3 is an unresolved binary belonging to the cluster. These objects have masses between 71 and 53MJup, close to the hydrogen-burning boundary for these clusters; however, only an optical detection of lithium can confirm if they are truly substellar

Mupirocin for the reduction of colonization of internal jugular cannulae: a randomized controlled trial

In a prospective study, 218 cardiothoracic patients, in whom 'Abbocath-T' cannulae had been inserted preoperatively into the internal jugular vein, were randomized to receive skin preparation of the insertion site with tincture of iodine (108 controls) or tincture of iodine followed by application of sterile 2% calcium mupirocin ointment (110 test patients). Cannulae were usually removed within 48 h of the operation. Patients receiving mupirocin were less likely to develop significant colonization of one or more of their cannulae as judged by Maki's criterion of a yield of greater than 15 colony forming units (cfu) from a cannula segment rolled on an agar plate (17% of mupirocin treated patients compared with 54% of the controls, P less than 0.001). Coagulase-negative staphylococci, micrococci, or both, were the commonest isolates and were cultured from 70% of the 186 control cannulae compared with 24% of 172 cannulae inserted through mupirocin-treated skin (P less than 0.001). A count of more than 15 cfu was found on the tips of 25% control cannulae compared with 5% of the cannulae from mupirocin-treated patients, an effect which was independent of in-situ time (P less than 0.001). For cannulae with colonized tips, the same species was isolated from the skin of the insertion site in 67%, from the exterior of the hub in 61% and from the lumen in only 15%. There were no side effects attributed to mupirocin or superinfection with resistant organisms. We conclude that in cardiothoracic patients the application of mupirocin after standard skin preparation with tincture of iodine significantly reduces the colonization of central venous cannulae by organisms derived from the skin insertion site