The Pathogenicity of Penicillin-insensitive Infection

Abstract

PHYSIOLOGY OF VISION: RECENT ADVANCES MEDICAL URNA639properties of vision which up to now have been difficult to explain. One of these is the retinal direction effect of Stiles and Crawford. This aspect of the cluster hypothesis is to be dealt with in detail elsewhere. Using as test objects extremely small disks, it has been possible to identify the position of some of the clusters near the centre of a human fovea. This matter is also to be considered in detail elsewhere.Section V: The Antichromatic ResponsePhysiologists have long been puzzled by one property of the lens-system of the eye-namely, the absence of colour from the images of colourless obiects which itrproduces on the retina. A lens employed for photographic, microscopic, or similar purposes has to be achromatized by the use of convex crownglass lenses in conjunction with concave flint-glass ones. Such combinations of lenses bring light of different colours to the same focus. Such is not the case if a single lens, either of flint glass or of crown glass, is used by itself. Thus a convex lens brings the violet rays to a focus first; then follow in order the blue, the blue-green, the green, the yellow, the orange, and, lastly, furthest from the lens, the red. It has been shown by experiment that this is the order of the colours in the case of the eye. It has also been shown that it is the yellow-green rays that are sharply focused on the retina under normal circumstances. The consequence is that the orange and red ravs, which have not yet come to a focus, form blurs on the retina; so also do the violet, blue, blue-green, and green rays, because, having come to a focus, they diverge again before they reach the retina. The image on the retina of a small bright white light on a black background will thus take the form of a yellow spot of high intensity surrounded by a blue halo or fringe which consists of the unfocused colours. So far theory and observatiorj have been in close agreement; but now thev differ to a startling extent. For when the observer looks at a small bright light he does not see either the yellow spot or the blue fringe. What he sees is the white light unaccompanied by any colours. Similarly in the case of other objects, both black and white: when these are looked at, coloured fringes-yellow or blue-should be visible owing to the chromatic aberration of the eye. But observation shows that in fact all such effects are conspicuously absent. In the past numerous hypotheses have been advanced to explain the absence of chromatic fringes from vision, but none of these has been able to stand critical examination. The the blue is replaced by dark grey or black, while the yellow is replaced by white. Further details will be given elsewhere, together with the reasons for concluding that somewhere on the pathways between the retina and the brain there are situated nerve centres, one of which deals with blue while the other deals with yellow; and that these two in conjunction have the function of eliminating from vision the spurious colours produc...

Carriage of Penicillin-resistant Staph. Pyogenes in Healthy Adults

“…On the other hand, there is also evidence that strains of Staph. pyogenes exist which are naturally resistant to penicillin, having been isolated before the institution of penicillin treatment and in many instances having been shown to possess the power of inactivating penicillin by the production of penicillinase (Kirby, 1944;Spink et al, 1944aSpink et al, , 1944bBondi and Dietz, 1945;Gots, 1945;Gallardo, 1945;Harley et al, 1946). Further, it has been shown by Barber (1947aBarber ( , 1947b) that the incidence of infection with penicillin-resistant strains may be increasing, since in one hospital the percentage rose from 14.1 in 1946 to 38 in 1947.…”

Staphylococcal Infection due to Penicillin-resistant Strains

“…pyogenes is, however, fairlX common, and, as Harley et al (1946) have shown, penicillinresistant staphylococci occur far more often in patients who have been in hospital some time than in new admissions. In any hospital using large quantities of penicillin (and what hospital is not nowadays ?)…”

Bacteriophage Types in Penicillin-resistant Staphylococcal Infection

“…pyogenes, it seems likely (Barber and Rozwadowska-Dowzenko, 1948) that selection plays a large part in the increasing incidence of such strains in hospitals. The work of Harley et al (1946) and Forbes (1949) further makes it clear that the incidence of penicillin-resistant strains isolated from staphylococcal infections in hospital inpatients is much greater than that in out-patients. In the present study it will be seen that 20 of 49 in-patients yielded penicillin-resistant strains compared with 15 of 51 outpatients, and that there was a significantly higher incidence of penicillin-resiktant organisms in patients who had been under hospital treatment for more than a fortnight.…”

“…Many studies concerning the incidence of penicillin-resistant staphylococcal infection have been reported, and it is now generally agreed that this is increasing (Spink et al, 1944(Spink et al, , 1945Bondi and Dietz, 1945;Gallardo, 1945;Plough, 1945;Harley et al, 1946;Barber and Rozwadowska-Dowzenko, 1948). Results of investigations of a series of infections occurring in a single hospital, however, are difficult to assess, as such institutions often seem to be breeding-grounds of a particular strain of pathogenic staphylococcus.…”