Retrospective Analysis of Bacterial and Viral Co-Infections in Pneumocystis spp. Positive Lung Samples of Austrian Pigs with Pneumonia

Abstract

Aim of this study was the retrospective investigation of viral (porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), torque teno sus virus type 1 and 2 (TTSuV1, TTSuV2)) and bacterial (Bordetella bronchiseptica (B. b.), Mycoplasma hyopneumoniae (M. h.), and Pasteurella multocida (P. m.)) co-infections in 110 Pneumocystis spp. positive lung samples of Austrian pigs with pneumonia. Fifty-one % were positive for PCV2, 7% for PRRSV, 22% for TTSuV1, 48% for TTSuV2, 6% for B. b., 29% for M. h., and 21% for P. m. In 38.2% only viral, in 3.6% only bacterial and in 40.0% both, viral and bacterial pathogens were detected. In 29.1% of the cases a co-infection with 1 pathogen, in 28.2% with 2, in 17.3% with 3, and in 7.3% with 4 different infectious agents were observed. The exposure to Pneumocystis significantly decreased the risk of a co-infection with PRRSV in weaning piglets; all other odds ratios were not significant. Four categories of results were compared: I = P. spp. + only viral co-infectants, II = P. spp. + both viral and bacterial co-infectants, III = P. spp. + only bacterial co-infectants, and IV = P. spp. single infection. The evaluation of all samples and the age class of the weaning piglets resulted in a predomination of the categories I and II. In contrast, the suckling piglets showed more samples of category I and IV. In the group of fattening pigs, category II predominated. Suckling piglets can be infected with P. spp. early in life. With increasing age this single infections can be complicated by co-infections with other respiratory diseases.

Comparison of Pneumocystis nucleic acid and antibody profiles and their associations with other respiratory pathogens in two Austrian pig herds

“…The second aim of this study was the investigation of possible associations with other respiratory pathogens. Results of prior studies suggested causative relation hips [ 3 , 6 ]. On Farm A, pigs were positive for PRRSV, HPS and MH concurrently with the PCS infection in the 1 st week of life.…”

“…Furthermore, they identified three PCS positive pigs with concurrent bacterial infection. In a study by Weissenbacher-Lang et al (2016) [ 6 ], PRRSV was detected in 7% and MH in 29% of PCS positive animals. In suckling piglets, significantly more samples were positive for PCS in combination with viruses, such as PCV2, PRRSV, and torque teno sus virus, whereas older pigs had polymicrobial co-infections with these viruses as well as bacterial pathogens such as Bordetella bronchiseptica , Pasteurella multocida , and MH.…”

“…The PCR for the detection of PCS [ 9 ] was performed as previously described. For PCV2 [ 10 ], PRRSV [ 6 ], HPS [ 11 ] and MH [ 3 ] published protocols were modified.…”

“…The PCR was performed as previously described [ 6 ]. The only difference to the published PRRSV RT-PCR protocol was that in the present study the RNA extract was used undiluted.…”

“…The pathogens involved can vary considerably between different production sites. PCS can frequently be detected in pigs co-infected with other respiratory pathogens [ 3 , 6 ]. In these previous studies, only single lung tissue samples were investigated, and the results did not allow any conclusions to be drawn about the epidemiology of the various pathogens within a production site.…”