Characterization and comparison of Pasteurella multocida strains associated with porcine pneumonia and atrophic rhinitis

Abstract

One hundred and fifty-eight porcine strains of Pasteurella multocida, recovered primarily from cases of pneumonic pasteurellosis or progressive atrophic rhinitis (PAR) in England and Wales, were characterized by determination of their capsular types, presence or absence of the toxA gene and molecular mass heterogeneity of the heat-modifiable (OmpA) and porin (OmpH) proteins. Eighteen groups (clones) of strains were identified on the basis of specific combinations of capsular type, toxA status and outer-membrane protein (OMP)-type. The data provided evidence that different subpopulations of P. multocida are responsible for pneumonia and PAR in pigs. The majority (88 %) of cases of pneumonia were associated exclusively with non-toxigenic capsular type A strains of OMP-types 1.1, 2.1, 3.1 and 5.1 and capsular type D isolates of OMP-type 6.1. These strains were recovered from widespread geographical locations within England and Wales over a 12-year period and represented mostly single sporadic cases. The association of a small number of P. multocida variants with the majority of cases of porcine pneumonia suggests that these strains are not opportunistic pathogens of low virulence but represent primary pathogens with a relatively high degree of virulence. In contrast, the majority (76 %) of cases of PAR were associated with toxAcontaining capsular type D strains of OMP-type 4.1 and capsular type A and D strains of OMP-type 6.1. Toxigenic capsular type A strains associated with PAR and non-toxigenic capsular type A strains associated with pneumonia represent distinct subpopulations of P. multocida that can be differentiated by their OMP-types. The association of capsular types A and D with strains of the same OMP-types, and the absence and presence of the toxA gene in strains of the same OMP-types, suggest that horizontal transfer of capsular biosynthesis and toxA genes has occurred between strains representing certain subpopulations of P. multocida. INTRODUCTIONPasteurella multocida is the aetiological agent of progressive atrophic rhinitis (PAR) of swine and is of considerable economic importance to the pig-rearing industry throughout the world (Chanter & Rutter, 1989). PAR is characterized by atrophy of the nasal turbinate bones which, in severe cases, can lead to facial distortion. P. multocida strains associated with PAR usually produce a 145-kDa dermonecrotic toxin, which is encoded by the toxA gene (Lax et al., 1990;Buys et al., 1990). This toxin induces osteolysis in the turbinate bones and plays an important role in the pathogenesis of PAR (Kamp & Kimman, 1988). Toxigenic strains associated with PAR are most frequently of capsular type D (Eamens et al., 1988;Foged et al., 1988;Gardner et al., 1994;Lariviere et al., 1992), although toxigenic isolates of capsular type A can also be involved in the disease (Fussing et al., 1999;Sakano et al., 1992). Non-toxigenic P. multocida strains are not usually associated with PAR and confirmation of toxin production is important for the diagnosis and control of the disea...

Anatomopathological pneumonic aspects associated with highly pathogenic Pasteurella multocida in finishing pigs

“…These data are consistent with literature reports of a higher participation of serotype A in pneumonic cases (Borowski 2001, Davies et al 2003, Pijoan 2006, Borowski et al 2007, Bethe et al 2009, Boyce et al 2010 and corroborate the data of Heres (2009). However, Morés (2006) found a higher frequency of serotype D (27.3%) compared to serotype A (24%) in samples obtained in slaughterhouses.…”

“…Several researchers have used molecular techniques to compare isolates of P. multocida obtained from clinical cases and healthy animals. However, no conclusive results have been reported that would explain different clinical presentations (Borowski et al 2002, Chen et al 2002, Lainson et al 2002, Davies et al 2003, Bethe et al 2009, Tang et al 2009.…”

“…These authors suggested that there are different clones of P. multocida involved in pulmonary cases or progressive atrophic rhinitis, but little is known about them, however Pors et al (2016) demonstrated that different isolates inoculated in the same host specie in an experimental inoculation, could develop different clinical and pathological pictures. Davies et al (2003) suggested two theories regarding possible clinical-pathological manifestations of different strains of P. multocida. The first theory is that there is little genetic diversity among strains of P. multocida, as they represent the normal microbiota of the respiratory system of pigs that would be capable of causing clinical disease in predisposed animals.…”

“…It is necessary to determine the unknown virulence factors that lead to more severe clinical conditions than those that are traditionally known and reported, and to establish a clonal relationship among strains obtained from field samples (Borowski et al 2002, Boyce et al 2010. Davies et al (2003) stated that outer membrane proteins exhibit heterogeneity among strains and that this may be a good marker to determine epidemiological relationships between them. However, little is known about these proteins, including their role in pathogenicity in the organism.…”

Characterisation and comparison of Pasteurella multocida isolated from different species in the Czech Republic: capsular PCR typing, ribotyping and dermonecrotoxin production

“…This finding is in general agreement with earlier studies which report that serogroup A is the most common, followed by other serogroups (Dabo et al, 1999a;Dziva et al, 2001;Davies et al, 2003a). Serogroup F rabbits isolates included in this study have been already described in our previous work (Jaglic et al, 2004).…”