Relationship of Hydrogen Peroxide Production by Mycoplasma pulmonis to Virulence for Catalase-deficient Mice

摘要

Mycoplasma pulmonis, an etiological agent of murine pneumonia, produced about 0.065 μmoles of hydrogen peroxide (H₂O₂) per hr per 1010 colony-forming units. When glucose was present at a concentration of 0.01 m, H₂O₂ production was increased by 50%. To determine if H₂O₂ production by M. pulmonis could be correlated with virulence, normal, acatalasemic, and acatalatic mice were infected with the organism. Three days after infection with M. pulmonis significantly more acatalatic mice had pneumonia than did normal or acatalasemic mice. The pneumonia in acatalatic mice was also more severe than in the other two groups. Five days after infection, pneumonia in the acatalatic mice was resolved, whereas normal mice were severely affected. The presence of pneumonia and the severity were correlated with the recovery of M. pulmonis from the lesions. In vitro studies of the effect of catalase on M. pulmonis showed that exogenously supplied catalase stimulated the growth of M. pulmonis at 37 C and prolonged its survival at 25 C. Hemolysis of sheep blood, guinea pig blood, rabbit blood, and normal and acatalasemic mouse blood by M. pulmonis was inversely related to the catalase activity of the erythrocytes. These findings suggest that H₂O₂ secretion contributes to the virulence of M. pulmonis and to the death of the microorganism in the absence of host catalase.