OBJECTIVETo establish a rat model of mycoplasma pneumonia (MP) for investigating the pathogenesis of MP and its therapy with drugs.

METHODSThirty Wistar rats were randomly divided into 6 groups (n=5), including a control group, a MP model group, a erythromycin lactobionate group and 3 erythromycin microspheres groups (high, middle, and low dose groups). With the exception of those in the control group, all the rats received intranasal MP administration followed by corresponding treatments administered via tail vein injection. At different time points after inoculation of the pathogen, the lungs of the rats were taken for histopathological scoring.

RESULTSIn the MP model group, the lung pathology was characterized by patchy interstitial pneumonitis with predominantly lymphocyte infiltration and mucosal edema. The bronchiolar walls became thickened and the lumens narrowed. In erythromycin lactobionate and erythromycin microspheres treatment (high and middle dose) groups, clear cell boundaries were observed in the lungs where no obvious pathological changes were found. RT-PCR amplification showed positive results of MP RNA in the model group, erythromycin lactobionate group and erythromycin microsphere groups.

CONCLUSIONThe approach described is practicable to establish rat models of MP. Erythromycin microspheres can effectively relieve the lung inflammations and has therapeutic effect on MP.