- Email: [email protected]
Reply to Dr Marks
Letters to the Editor
63
Reply from Or Marks In my paper on ‘Ending the routine guinea-pig test’ it was indicated that this step is possible only when culture methods are equally effective. The members of the Working Group should not be content with the methods they are now using for culture. Their data and the last two sentences of their communication provide evidence of an unsatisfactory situation. J. Marks 121 Heathwood Road, Cardiff CF4 4BJ.
Reply to Dr Marks : With regard to the comments by Marks, we wish to stress the following
points :
(a) The variation of sulphuric acid concentration according to the degree of contamination, as recommended by Marks, is very difficult to realize in all laboratories, particularly in those operating on a large scale. We believe this target, even assuming it were a generally desirable one, is not achieved in a number of laboratories in the United Kingdom either; indeed, it is not the official technique of the British Medical Research Council. (b) There is information dating back to 1940 which indicates that when using eight tubes of Petragnani’ medium the difference in yield of positive results between culture and guinea pig-tests approached zero (Whitehead, 1940). This discussion will without doubt continue, as illustrated by a report from Czechoslovakia (Srb, 1978) : depending on geographic, case and specimen differences, specimens positive by guinea pig-test only ranged between 9.3 and 54.4 per cent, stressing the need to continue the diagnostic animal experiment in the future. (c) The selection of a diagnostic procedure can hardly be the same for a public health laboratory as for a university or research institute laboratory. The latter often receives specimens from cases which are difficult to diagnose, particularly with extrapulmonary localization, which require the use of the guinea-pig test. Working Group ‘Mycobacteria’ References Srb, V. (1978). Has the end of the guinea-pig test arrived (in Czech). Studia Pneumologica et Phtiseologica Czechoslovaca. 39,110. Whitehead, H. G. (1940). Bacteriological diagnosis of tuberculosis. American Review of Tuberculosis, 42, 795.
63
Reply from Or Marks In my paper on ‘Ending the routine guinea-pig test’ it was indicated that this step is possible only when culture methods are equally effective. The members of the Working Group should not be content with the methods they are now using for culture. Their data and the last two sentences of their communication provide evidence of an unsatisfactory situation. J. Marks 121 Heathwood Road, Cardiff CF4 4BJ.
Reply to Dr Marks : With regard to the comments by Marks, we wish to stress the following
points :
(a) The variation of sulphuric acid concentration according to the degree of contamination, as recommended by Marks, is very difficult to realize in all laboratories, particularly in those operating on a large scale. We believe this target, even assuming it were a generally desirable one, is not achieved in a number of laboratories in the United Kingdom either; indeed, it is not the official technique of the British Medical Research Council. (b) There is information dating back to 1940 which indicates that when using eight tubes of Petragnani’ medium the difference in yield of positive results between culture and guinea pig-tests approached zero (Whitehead, 1940). This discussion will without doubt continue, as illustrated by a report from Czechoslovakia (Srb, 1978) : depending on geographic, case and specimen differences, specimens positive by guinea pig-test only ranged between 9.3 and 54.4 per cent, stressing the need to continue the diagnostic animal experiment in the future. (c) The selection of a diagnostic procedure can hardly be the same for a public health laboratory as for a university or research institute laboratory. The latter often receives specimens from cases which are difficult to diagnose, particularly with extrapulmonary localization, which require the use of the guinea-pig test. Working Group ‘Mycobacteria’ References Srb, V. (1978). Has the end of the guinea-pig test arrived (in Czech). Studia Pneumologica et Phtiseologica Czechoslovaca. 39,110. Whitehead, H. G. (1940). Bacteriological diagnosis of tuberculosis. American Review of Tuberculosis, 42, 795.