This is interesting although a bit dated.  Click on the link
for the full article.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=264771

This study demonstrates that viable Mycoplasma pneumoniae cells inhibit
catalase activity in several types of intact human cells as well as in
solution.
Human erythrocyte catalase was inhibited up to 72%, and the inhibition of
catalase in human cultured skin fibroblasts, lung carcinoma epithelial
cells, and
ciliated epithelial cells from human nasal polyps ranged between 75 and
80%. UV
light-killed mycoplasmas failed to inhibit catalase activity both in
intact cells and
in vitro. After M. pneumoniae infection of human cultured skin
fibroblasts, the
level of malonyldialdehyde, an indicator for membrane lipid
peroxidation, was 3.5
times higher than in control fibroblasts. Virulent M. pneumoniae completely
inhibited catalase activity in solution, whereas the nonvirulent strains
had a lesser
ability to inhibit catalase activity. These findings suggest that as a
result of host
cell catalase inhibition by M. pneumoniae, the toxicity of the hydrogen
peroxide
generated by the microorganism and the affected cell is enhanced, thereby
inducing host cell damage.