Methods for the Grouping and Typing of Mycobacteria

Radiometric selective inhibition tests for differentiation of Mycobacterium tuberculosis, Mycobacterium bovis, and other mycobacteria

In the context of a busy reference laboratory, radiometric selective inhibition tests were evaluated for rapid differentiation of Mycobacterium tuberculosis and Mycobacterium bovis and of the M. tuberculosis complex from other mycobacteria. p-Nitro-alpha-acetylamino-beta-hydroxypropiophenone at 5 micrograms and hydroxylamine hydrochloride at 62.5 and 125 micrograms per ml of 7H12 medium were used to separate the M. tuberculosis complex from other mycobacteria (MOTT bacilli). Since it is important epidemiologically to distinguish M. tuberculosis from M. bovis, susceptibility to 1 microgram of thiophene-2-carboxylic acid per ml was also determined radiometrically. By using these three agents as selective inhibitors, M. tuberculosis, M. bovis, and MOTT bacilli were differentiated with a high degree of specificity by a BACTEC radiometric procedure. Results of tests performed on clinical isolates submitted on solid medium to our reference laboratory were available within 5 days.

The "atypical" mycobacteria: recognition and disease association

Although techniques based on immunologic or chromatographic analyses have been described for identifying mycobacteria in clinical laboratories, most microbiologists continue to rely on a series of specialized physiological and biochemical tests for this purpose. The recognition of additional significant species over the past decade has required the addition of more tests to the battery used for mycobacterial identification. This paper will review briefly the taxonomic status of species likely to be encountered in clinical specimens and the most useful tests for characterizing them. Strategies will be presented for using these tests in the most efficient way to provide optimal resolution of taxa without use of an unreasonably large battery of tests. A brief survey of techniques that may become more practical in the future will also be included.

"Classical" and "Asian" variants of Mycobacterium tuberculosis isolated in South East England 1977-1980

Strains of Mycobacterium tuberculosis were divided into 'classical' and 'Asian' types according to their susceptibility to thiophen-2-carboxylic acid hydrazide (TCH). A study of 6638 new cases of tuberculosis showed that there was a much higher incidence of non-pulmonary disease among Asian than among European patients, and that the TCH-sensitive 'Asian' type of organism was much commoner among the former. There was, however, no correlation between the site of disease and the type of organism. Resistance to antituberculosis drugs was more frequent among strains from Asian patients but there was no correlation between such resistance and susceptibility to TCH. No evidence was therefore found to link differences in the clinical features of tuberculosis in the two populations of patients to the type to organism.

Experimental male genital tuberculosis-appraisal of protective value of BCG vaccination

As part of an experimental study of the spread of urogenital tuberculosis, the development of tuberculous infection was compared in vaccinated and non-vaccinated guinea pigs after challenge with Mycobacterium tuberculosis strain H37Rv into the seminal vesicle. The animals were saccrified 35 days after challenge. Morphological observations indicate that tuberculous infection in an immunized animal is retarded, but spreads by the same routes as in an nonimmunized animal. On microbial enumeration significantly lower numbers of organisms were recovered from the inoculated seminal vesicle and regional iliac lymph nodes of the BCG-vaccinated guinea pigs.