Mycoplasma hyopneumoniae is the cause of enzootic pneumonia in pigs. Pathological lesions of M. hyopneumoniae infection include ciliostasis, loss of cilia, exfoliation of epithelial cells and accumulation of mononuclear cells within alveolar spaces (cuffing pneumonia). M. hyopneumoniae may be causing damage to cilia by hydrogen peroxide production (Maes et al., 1996). However, there is a dearth of clear evidence to support this claim.
We aimed to determine whether two strains of M. hyopneumoniae, a lab strain and recent field isolate – both pathogenic, are capable of producing detectable hydrogen peroxide when exposed to glucose and glycerol. M. hyopneumoniae strain 232 (lab strain) and CB1/13 (field strain) were grown in modified Friis medium. Cells were washed and resuspended in 0.1M Na-phosphate buffered saline. M. hyopneumoniae cells were incubated with either 2 mM glucose, 2 mM glycerol or buffered saline, for 10 minutes at 37oC in 5% CO2. A solution of 100 µM Amplex UltraRed (Invitrogen) and 0.2 U/mL horseradish peroxidase were added and further incubated for 10 minutes and fluorescence was measured.
Both M. hyopneumoniae strains produced detectable hydrogen peroxide in buffered saline and this could be stimulated by glucose and glycerol. This result provides a rationale to search for transposon mutants that fail to produce hydrogen peroxide. A mutant would provide a means of determining the importance of hydrogen peroxide production in M. hyopneumoniae pathogenicity. Identified mutants could be screened for toxicity in cultured ciliated epithelium.