Catalase-peroxidase activity has no influence on virulence in a murine model of tuberculosis

The capacity to generate a chronic and persistent infection in the experimental murine model of tuberculosis induced aerogenically by a low-dose inoculum was determined in eight isoniazid-resistant clinical strains of Mycobacterium tuberculosis showing different catalase-peroxidase (C-P) activities. Determination of bacillary concentration in lung and spleen and the percentage of pulmonary parenchyma occupied by granulomas were monitored. Data showed no relation between the lack of C-P activity and the ability to develop a persistent infection, highlighting the potential of C-P negative strains to spread through the community.