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Published on: September 28, 2016
Isolation of Mycoplasma hyopneumoniae from different sampling sites in experimentally infected and contact SPF
C Marois1, J Le Carrou, M Kobisch
1Agence Française de Sécurité Sanitaire des Aliments, Laboratoire d'Etudes et de Recherches Avicoles et Porcines, Unité Mycoplasmologie-Bactériologie, BP 53, 22440 Ploufragan, France.
Abstract:
The purpose of this study was to determine the optimal route of infection and the optimal sampling sites for the recovery of M. hyopneumoniae, the etiological agent of enzootic porcine pneumonia. Virulence of two strains, BQ 14 and 116, isolated in France in 1975 and 2003, respectively, was also compared. Groups of specific pathogen free piglets were experimentally infected by the intratracheal or intranasal route. One non-inoculated pig was placed in each group of infected pigs to study direct transmission. Two groups were kept uninfected. Coughing was recorded daily. Blood samples, nasal, tonsillar and tracheal swabs and tracheobronchiolar washings were collected weekly. Pigs were killed 27-37 days post-infection. Lung lesions were scored and swabs were collected from nasal cavities, tonsils, trachea, lung, liver and spleen. All the samples, collected from live and dead pigs, were cultured for M. hyopneumoniae recovery. Results showed that both experimentally infected pigs and contact pigs developed enzootic pneumonia, whatever the route of infection and the strain tested. Direct contact transmission occurred quickly. No difference between the two routes of infection or between the two strains tested was evidenced, but high individual variations were observed between pigs. Tracheal swabs and tracheobronchiolar washings were the most effective samples to detect M. hyopneumoniae compared to nasal or tonsillar swabs. Our results also suggested that tracheobronchiolar washings could have an influence on the lesion extent observed at necropsy. M. hyopneumoniae could be re-isolated from liver and spleen of experimentally infected pigs and contact pigs.
Insights
The optimal sampling sites for detecting M. hyopneumoniae in pigs are tracheal swabs and tracheobronchiolar washings. Direct transmission of enzootic porcine pneumonia occurred rapidly between pigs.
Area of Science:
- Veterinary Microbiology
- Swine Infectious Diseases
- Respiratory Pathogens
Background:
- Enzootic porcine pneumonia (EPP) is a significant respiratory disease in swine.
- Mycoplasma hyopneumoniae is the primary causative agent of EPP.
- Understanding optimal diagnostic methods is crucial for disease control.
Purpose of the Study:
- Determine the best infection route and sampling sites for M. hyopneumoniae recovery.
- Compare the virulence of two M. hyopneumoniae strains (BQ 14 and 116).
- Investigate direct contact transmission dynamics.
Main Methods:
- Experimental infection of specific pathogen-free piglets via intratracheal or intranasal routes.
- Inclusion of contact-exposed pigs to assess transmission.
- Weekly collection of various samples (blood, swabs, washings) and necropsy samples.
- Culture-based detection of M. hyopneumoniae from all sample types.
Main Results:
- Both experimentally infected and contact pigs developed EPP, irrespective of infection route or strain.
- Rapid direct contact transmission was observed.
- Tracheal swabs and tracheobronchiolar washings were superior for M. hyopneumoniae detection compared to nasal or tonsillar swabs.
- M. hyopneumoniae was re-isolated from liver and spleen tissues.
Conclusions:
- Tracheal swabs and tracheobronchiolar washings are the most effective diagnostic samples for M. hyopneumoniae.
- Direct contact transmission is efficient, leading to rapid disease spread.
- Further research is needed to explore the influence of sampling on lesion severity and M. hyopneumoniae dissemination to organs like the liver and spleen.
