Haemophilus parasuis detection by PCR and strain characterization by genotyping Fact sheet

1 The availability of this newly validated PCR test represents an important scientific advance because H. parasuis isolation by culture is frequently unsuccessful due to the fastidious nature of this bacterium and overgrowth by other pathogens, especially Streptococcus suis. We recently compared detection by PCR to bacterial isolation by using 245 clinical samples from pigs with clinical signs of systemic bacterial infection. Samples tested were fibrinous exudates on surfaces of thoracic and abdominal organs, and joint, peritoneal, pleural and meningeal fluids or swabs. H. parasuis was detected in 53.5 % of samples by PCR and in 13.5 % by bacterial isolation (Figure 1). All samples positive by isolation were also positive by PCR with one exception. Figure 1 – Detection of Haemophilus parasuis by PCR and bacterial culture. The PCR test was especially useful in identifying H. parasuis in 33 cases of polyserositis and meningitis when no bacterial pathogens were isolated (no growth). The PCR test also detected H. parasuis when other pathogens that could potentially confound diagnosis were isolated, such as Actinobacillus suis, Actinobacillus pleuropneumoniae, Arcanobacterium pyogenes, Bordetella bronchiseptica, Escherichia coli, Pasteurella multocida, Streptococcus suis, and Salmonella sp. Samples to be submitted for testing (refrigerated): 1. Tissues with fibrinous exudate on serosal surfaces (thoracic and abdominal organs). 2. Swabs of serosal surfaces, joint and meninges. 3. Fluids from joints, thoracic and abdominal cavities