Biomedical subjects
Publications and source records attributed to M J Shield.
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A proposal is made that there are 2 mechanisms of cell mediated response to mycobacteria, both of which produce positive tuberculin tests and that one of them is more protective against mycobacterial infection than is the other. These are referred to respectively as the Listeria-type and the Koch-type of responses. Contact with environmental mycobacteria will induce one or other of these types of response and BCG vaccination will enhance it. Thus in those places where the environmental species prime for the Listeria-type of response subsequent BCG vaccination will afford good protection from both tuberculosis and leprosy. Where the Koch-type of response frequently results from environmental contact BCG will be ineffective. Evidence if presented that a large contact with Mycobacterium scrofulaceum is prejudicial to at least one marker of BCG efficacy in Burma.
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The results from the bacteriological monitoring of 464 ITU patients are presented. The specimens analysed include urine, sputa, tracheostomy swabs, central venous pressure line catheter tips, blood cultures, wound drainage fluid, cerebro-spinal fluid, pleural fluid and peritoneal dialysate samples. Guidelines which may be used to differentiate between colonisation and infection and factors, notably those related to antibiotic usage, which are associated with increased risk of infection are described. Certain bacterial and fungal infections which are more peculiar to the compromised host are also discussed.
Four hundred and seventy tuberculosis patients were each skin tested with four of a range of 17 mycobacterial reagents in four countries in all of which tuberculosis and leprosy were endemic. Sixteen of the reagents were new tuberculins prepared from extracts of living mycobacteria disrupted by ultrasonic disintegration and the last was PPD, RT23.The effect that tuberculosis exerted on the delayed-type skin test response to these antigens was assessed by comparing results for tuberculosis patients with those for Tuberculin positive and Tuberculin negative control populations. Tuberculosis patients on Rifampicin therapy showed no difference in their skin test responses to any of the antigens from those patients on other forms of antituberculosis treatment.Amongst the normal population it was found that possession of Tuberculin positivity was associated with an enhanced response to all the other mycobacterial antigens with the exception of A(*)-in which demonstrated a reciprocal relationship with Tuberculin in Burma. It was also noted, in Burma particularly, that sensitization to mycobacterial species other than Mycobacterium tuberculosis, especially to the slow growers, plays a role in determining responses to different mycobacterial species.In tuberculosis patients enhanced skin test responses were also seen but only in those countries, e.g. Libya, where the prevalence of mycobacterial species was low. Where mycobacteria were common, as in Burma, the converse was true and tuberculosis was associated with a diminished skin test response to each antigen. The high prevalence of A(*)-in positivity in Burma, its reciprocal relationship with Tuberculin there and the results for all the antigens in the tuberculosis patients indicate that the cell mediated skin test response may have a threshold. If this is exceeded the skin test becomes negative so that non-reactors then include those who have been excessively sensitized as well as those who have not been sensitized. Despite this, a greater percentage of tuberculosis patients in each country responded to the specific reagent Tuberculin than did the control populations and their mean positive induration sizes were consistently larger. Nevertheless, amongst the tuberculosis patients in Burma 13% were complete non-reactors to Tuberculin and this apparent anergy also applied to the other reagents with which these individuals were tested.This differs from lepromatous leprosy where the anergic state pertains exclusively to M. leprae and a few seemingly closely related species. The breadth of anergy in M. ulcerans infection has not been measured but it is known to effect both Burulin and the PPD, RT23.Just as in leprosy and M. ulcerans infection, tuberculosis can be shown to have a disease spectrum here detected by multiple skin testing. The significance of this spectrum and its similarities with and differences from that of the other mycobacterioses is discussed.
This study was carried out to investigate the effect of desert conditions on the pattern of delayed hypersensitivity to mycobacteria in school children aged 6-10 and 11-18 years. A new range of tuberculins prepared from ultrasonic lysates of living mycobacteria belonging to 12 different species was employed. Three centres were chosen for study, a sea port and two desert towns differing greatly from each other. The results obtained were compared with those of a previous study using the same reagents in Kenya. As expected both the range of mycobacterial species to which the children reacted, the rate of acquisition of specific hypersensitivity with age and the total percentage of children reacting to individual reagents differed from centre to centre. The harsh desert conditions of Ajdabia produced the least, and the proximity of the people's dwellings to those of their farm animals in Kufra produced the most positive reactors to essentially environmental species. The greatest number of reactions to our Tuberculin were found in Benghazi where the cosmopolitan urban conditions probably lead to a high contact with open cases of tuberculosis. As assessed by skin test reactivity, immunization with BCG in Libya was much less effective than in Kenya. The interpretation of the differences between the results from the different test centres and between those for Libya and Kenya are discussed.
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Explore the source record for details and available documents.