Glaesserella parasuis PCR: A useful adjunct to bacterial culture

Hugh Cai, Durda Slavic, Josepha DeLay

Animal Health Laboratory, University of Guelph, Guelph, ON. 

AHL Newsletter 2025;29(1):17.

Isolation of Glaesserella parasuis from clinical samples is challenging using routine bacterial culture techniques. The inherent fragility of the organism and its fastidious growth requirements have a significant influence on successful culture, necessitating special media and conditions. Use of PCR techniques can increase the sensitivity of G. parasuis detection. For clinical cases (Fig. 1) with potential G. parasuis involvement, both G .parasuis PCR and routine culture for other bacteria are recommended to increase the likelihood of detecting bacterial pathogens. 

G. parasuis PCR can be carried out on a range of samples including joint fluid, joint capsule, swabs from joints or other serous surfaces, lung, or tonsil. For swab samples, viral transport swabs (VTM swabs) should be used. Avoid gel-based culture swabs for G. parasuis PCR testing, as the gel has an inhibitory effect on PCR results. Mycoplasma hyorhinis PCR can be carried out on the same VTM swab samples for those cases with polyserositis or other lesions where this organism is also a potential etiologic agent. Concurrent routine bacterial culture is recommended using gel-based swabs or other samples from the same clinical sites, in order to investigate other pathogens not detected by organism-specific PCR tests.

Please contact the AHL with any questions regarding the use of G. parasuis PCR in diagnostic test plans for polyserositis and other bacterial diseases.    

Figure 1. Fibrinosuppurative pleuritis in a grower pig, typical of Glaesserella parasuis infection