Mycoplasma hyopneumoniae is one of the simplest self-replicating prokaryotes between bacteria and viruses without cell walls. When pigs are infected with mycoplasma hyopneumoniae during feeding management, the weight and feed conversion rate of pigs are not reduced, and the increase of body fat and protein in pigs is not affected. It will not affect the growth of pigs in the short term. However, when mycoplasma hyopneumoniae co-infected with other pathogens, clinical symptoms in pigs increased. At the International Pig Congress, a professional expert explained the method of diagnosing mycoplasma pneumonia in pigs.

The diagnosis of mycoplasma hyopneumoniae is as follows:

1. Clinical diagnosis of mycoplasma hyopneumoniae

The main clinical symptoms of mycoplasma hyopneumoniae are chronic dry cough, stunted growth, developmental retardation, high morbidity, low mortality, slow spread, and easy to recur after infection. However, mycoplasma hyopneumoniae is easily mixed with other pathogens, which complicates the clinical symptoms of mycoplasma hyopneumoniae, and some infected pigs do not show clinical symptoms. mycoplasma hyopneumoniae can only be suspected by clinical symptoms.

2. Pathologic diagnosis mycoplasma hyopneumoniae

Pathological examination showed that the lesions were mainly in the lungs, hilar lymph nodes and mediastinal lymph nodes, and no special lesions were found in other tissues and organs. The characteristic lesions were pulmonary enlargement, emphysema and edema of different degrees. Symmetric fusion bronchopneumonia lesions appeared in the heart, apical and middle lobes of both lungs and in some cases in the anterior lower margin of the diaphragmatic lobe. The heart lobe was the most obvious, followed by the apical and middle lobes.

3. Pathogen detection technology for diagnosis of mycoplasma hyopneumoniae

1) Pathogen isolation and culture

The isolation of mycoplasma pneumoniae from the diseased site is a specific method for the diagnosis of MPS in pigs. But mycoplasma hyopneumoniae is one of the most difficult pathogens to isolate and identify, it grows slowly and is often masked by overgrowth of mycoplasma rhinoplasma, and it is also difficult to isolate mycoplasma hyopneumoniae in pigs after drug treatment or recovery. Although the isolation rate of mycoplasma hyopneumoniae from the lesion site has gradually increased through improved isolation media and isolation methods, isolation culture diagnosis is still not feasible in most cases.

2) Immunoenzyme technology

The use of enzyme-linked immunoperoxidase and indirect immunoperoxidase tests for the detection of mycoplasma pneumoniae in diseased lungs overcomes the shortcomings of fluorescent antibody techniques for the effective detection of chronically infected pigs, the need for fresh frozen tissue and fluorescence microscopy, and the inability of long-term storage of samples. When ELIP was used to examine frozen lung sections and bronchial smears, mycoplasma was stained to reddish brown multiform particles and the response was stable. Doster et al. embedded pig lungs with paraffin fixed by formalin and detected Mhp by indirect peroxidase test. Mhp with clear structure could be observed by optical microscope, and the samples could be stored for long-term re-evaluation, which was more sensitive than fluorescent antibody method. This method can be used when fresh tissue or other specific tests are not available.

Summary: There are many diagnostic methods for mycoplasma hyopneumoniae. The above are several commonly used detection techniques widely reported at home and abroad. Each method has its own advantages and disadvantages. In clinical application, in addition to selecting the appropriate detection technology according to the test conditions and purposes, the comprehensive diagnosis should be combined with clinical symptoms and histopathological lesions to obtain correct and reliable diagnosis results.

If you want to learn more about the pig industry, please visit the International Pig Congress website for more information.

Source: Jiangsu New Xicheng Biotechnology Co., Ltd

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