A Critical Survey and Experimental Study of Methods of Isolating Tubercle Bacilli From Sputum

O'Hea, A. J (1958) A Critical Survey and Experimental Study of Methods of Isolating Tubercle Bacilli From Sputum. MD thesis, University of Glasgow.

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Abstract

This thesis contains the following chapters. Introduction. This chapter sketches briefly the reasons why methods of isolating tubercle bacilli from sputum should be re-examined. The reasons are: a) laboratory procedures play an important part in the diagnosis, treatment and control of tuberculosis; b) present methods of isolating tubercle bacilli from sputum are unsatisfactory - most methods are time-consuming, and many are dangerous to the operator; c) although much has been written about the efficiency of methods of isolating tubercle bacilli from sputum, little attention has been paid to other important criteria by which methods should be judged -simplicity and safety. 2. Literature. I have reviewed the literature concerning methods of isolating tubercle bacilli from sputum or other specimens obtained from patients suffering from pulmonary tuberculosis. In addition I have assessed the simplicity and safety of laboratory procedures commonly used for the diagnosis, treatment and control of tuberculosis. The following conclusions are reached. a) Significant differences between methods of isolating tubercle bacilli from sputum can be demonstrated by comparing the results obtained by the methods from series of specimens of sputum likely to contain only small numbers of tubercle bacilli . b) Trials with, series of specimens of sputum establish only the relative efficiency of methods and therefore fail to indicate whether it is worthwhile to search for more efficient methods. c) The results of studies made by means of viable counting procedures do not always agree with the results of studies made with series of specimens of sputum. Information obtained by means of a viable counting procedure - a relatively artificial method - must therefore be supplemented by studies with series of specimens of sputum a procedure which is closely related to routine laboratory practice. d) Because they do not involve centrifugation, Saxholm's pancreatin-desogen method and Nassau's swab method are the most attractive of the recently described procedures for preparing sputum for the culture of tubercle bacilli. e) Microcultural methods yield earlier results than standard methods. They are unsuitable for routine application because they require additional laboratory space and greater numbers of skilled technicians. f) Laryngeal swab culture is the simplest method of isolating tubercle bacilli from patients who are unable to produce sputum. g) Methods of isolating tubercle bacilli from sputum and methods of determining the sensitivity of tubercle bacilli to antituberculous drugs expose the operator to the danger of infection with tubercle bacilli. This danger can be reduced in two ways: first, by a search for methods which, reduce the likelihood of liberating tubercle bacilli in the form of aerosols and second, by preventing the inhalation of aerosols containing tubercle bacilli. The second way of reducing the danger of laboratory infection depends mainly on the provision of ventilated safety-hoods for the manipulation of tuberculous material. Experiments. This chapter contains an account of my own experiments. The following points are established. a) Methods of isolating tubercle bacilli from sputum should be assessed by comparison with a standard method in series of specimens of sputum. For this purpose the most suitable standard method is the sodium hydroxide method. b) The selection of specimens of sputum is of vital importance in comparing methods of isolating tubercle bacilli from sputum. I evolved a critical procedure for assessing the efficiency of methods; 3 replicate specimens are examined from each of 40 to 50 patients whose sputum is likely to contain very few tubercle bacilli. This procedure can be applied with very small resources of technical assistance ana will snow clearly any important difference in the efficiency of two methods. c) Viable counting procedures are of little value in the assessment of methods of isolating tubercle bacilli from sputum. (Abstract shortened by ProQuest.).

Item Type: Thesis (MD)
Qualification Level: Doctoral
Keywords: Medicine, Microbiology
Date of Award: 1958
Depositing User: Enlighten Team
Unique ID: glathesis:1958-79233
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 05 Mar 2020 11:26
Last Modified: 05 Mar 2020 11:26
URI: http://theses.gla.ac.uk/id/eprint/79233

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