Virulence in the Guinea-Pig, Susceptibility to Hydrogen-Peroxide, and Catalase Activity of Isoniazid-Sensitive Tubercle Bacilli from South Indian and British Patients.
DA Mitchison, JB Selkon, J Lloyd - 1963 - cabidigitallibrary.org
DA Mitchison, JB Selkon, J Lloyd
1963•cabidigitallibrary.orgThis study was undertaken to examine the association between virulence in the guineapig
and susceptibility to the bactericidal action of hydrogen peroxide of isoniazid-sensitive
pretreatment cultures of tubercle bacilli from Indian patients.; previous studies had shown
that these strains were on average less virulent than tubercle bacilli from British patients [this
Bulletin, 1962, v. 37, 632]. 10 Indian and 2 British cultures were examined and the
examination included determination of the catalase activity they were niacin-positive and …
and susceptibility to the bactericidal action of hydrogen peroxide of isoniazid-sensitive
pretreatment cultures of tubercle bacilli from Indian patients.; previous studies had shown
that these strains were on average less virulent than tubercle bacilli from British patients [this
Bulletin, 1962, v. 37, 632]. 10 Indian and 2 British cultures were examined and the
examination included determination of the catalase activity they were niacin-positive and …
Abstract
This study was undertaken to examine the association between virulence in the guineapig and susceptibility to the bactericidal action of hydrogen peroxide of isoniazid-sensitive pretreatment cultures of tubercle bacilli from Indian patients. ; previous studies had shown that these strains were on average less virulent than tubercle bacilli from British patients [this Bulletin, 1962, v. 37, 632]. 10 Indian and 2 British cultures were examined and the examination included determination of the catalase activity they were niacin-positive and identified as human tubercle bacilli. Virulence was based on the rate of progression of tuberculosis in guineapigs and recorded as the "root-index" of virulence [ibid., 1962, v. 37, 632]. Susceptibility to hydrogen peroxide was measured by determining the percentage of bacilli surviving 90 minutes' exposure to 0.02% H2O, at 37°C, and the catalase activity was measured manometrically.
The results show that the 2 British strains and 3 of the Indian strains were highly virulent, and these cultures contained 48-87% of organisms resistant to the peroxide. The other 7 Indian strains were attenuated and the cultures contained only 0.8-5% of peroxide-resistant organisms. No significant difference was found between the catalase activities of the 12 strains.
The association between virulence and peroxidesusceptibility of these Indian isoniazid-sensitive strains is of interest in view of the known increased susceptibility to peroxide of isoniazid-resistant strains the nature of the attenuation of these Indian strains would therefore seem to be similar to that of isoniazid-resistant strains. These strains were not deficient in catalase activity but their increased susceptibility could be explained by increased permeability of the cell wall to hydrogen peroxide. The increased susceptibility supports the suggestion by COLEMAN and MIDDLEBROOK [ibid., 1957, v. 32, 84] that diminished virulence of tubercle bacilli is due to increased susceptibility to hydrogen peroxide in host macrophages. S. R. M. Bushby.
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