Pathogens associated with pleuritic pig lungs at an abattoir in Queensland Australia

Abstract

Objective Pleurisy in pigs has economic impacts in the production stage and at slaughter. This study sought to establish if some micro‐organisms can be found in high numbers in lungs with pleurisy by assessing batches of pigs at an abattoir in Queensland Australia. Design Samples of lung (including trachea/bronchus and lymph nodes) from a maximum of 5 pleurisy affected pigs were collected from 46 batches of pigs representing 46 Queensland farms. Procedure Pleurisy‐affected lung areas were cultured by traditional bacteriological methods and bacteria quantified by plate scores. Additionally, tracheal or bronchial swabs and apical lobe fluid were tested for Mycoplasma hyopneumoniae DNA and the superior tracheobronchial lymph nodes were tested for porcine circovirus type 2 DNA by polymerase chain reaction (PCR). All apparently significant bacteria were identified via PCR or sequencing. Typing was undertaken on some of the bacterial isolates. Results The most prevalent pathogens were M. hyopneumoniae, Streptococcus suis and Porcine Circovirus type 2, being found in 34, 38 and 31 batches, respectively. Other bacteria found were Actinobacillus species (29 batches), Pasteurella multocida (24 batches), Mycoplasma flocculare (9 batches), Actinobacillus pleuropneumoniae (7 batches), Mycoplasma hyorhinis (4 batches), Bisgaard Taxon 10 (1 batch), Glaesserella parasuis (1 batch), Streptococcus minor (1 batch) and Streptococcus porcinus (1 batch). Most batches had more than one bacterial species. Conclusion The high percentage of batches infected with S. suis (83%), M. hyopneumoniae (74%) and PCV2 (70%) and clustering by a batch of these pathogens, as well as the presence of many secondary pathogens, suggests synergy between these organisms may have resulted in pleurisy.

Associations between Pleurisy and the Main Bacterial Pathogens of the Porcine Respiratory Diseases Complex (PRDC)

“…Additionally, a large percentage of animals tested positive for M. hyopneumoniae in lung samples across all scores of lesions. In the pleura, an increase in the percentage of positive samples was observed in scores 3 and 4, which is consistent with the findings of Turni, et al [59], who suggested that the prevalence of the pathogen increases with the severity of pleuritis scores. Mycoplasma hyopneumoniae alone causes bronchopneumonia, but when there are coinfections with primary pathogens such as A. pleuropneumoniae or secondary pathogens such as P. multocida, suppurative bronchopneumonia occurs, which is associated with pleurisy [60].…”

“…The most common pathogens in lung and pleura samples were G. parasuis and S. suis, and the prevalence of S. suis was also observed in studies conducted in Canada and Australia [59,61]. Ruggeri et al [25] reported that S. suis is associated with pleural and pericardial lesions, mainly in post-weaning pigs.…”

Recombinant-attenuated Salmonella enterica serovar Choleraesuis vector expressing the PlpE protein of Pasteurella multocida protects mice from lethal challenge

“…As with other opportunistic pathogens, P . multocida has the potential to proliferate and infect the lungs when host immunity is compromised due to stress or other pathogens infections [ 6 , 7 ]. Because P .…”

“…As an important pathogen of pigs, P . multocida can coinfect with other pathogens including porcine reproductive and respiratory syndrome, porcine circovirus and Mycoplasma hyopneumoniae [ 6 , 7 ]. This coinfection may cause immunosuppression to reduce the host’s immunity and resistance to other diseases.…”

Detection of Porcine Circovirus Type 2a and Pasteurella multocida Capsular Serotype D in Growing Pigs Suffering from Respiratory Disease

“…However, the type of combinations and kind of associated infectious agents vary with local weather conditions, region, and breeding conditions, which generally complicates the severity, prevention, and control of the disease [ 18 ]. P. multocida is one of the most common bacterial agents isolated from respiratory clinical cases worldwide and often is a secondary or opportunistic pathogen of PRDC [ 19 , 20 ]. Five capsular serotypes (A, B, D, E and F) are recognized, with A and D comprising most swine isolates [ 21 , 22 ].…”