Multilocus sequence analysis of Pasteurella multocida demonstrates a type species under development

Abstract

The aim of the present study was to use multilocus sequence typing (MLST) of a diverse collection of Pasteurella multocida with regard to animal source, place and date of collection, including all available serovars of Carter, Heddleston, Little & Lyon, Namioka, Cornelius and Roberts, to further investigate the evolution of this species with a focus on two lineages, A (P. multocida subsp. multocida and P. multocida subsp. gallicida) and B (P. multocida subsp. septica), previously reported. Isolates of P. multocida (n5116) including reference strains of major serotyping systems were investigated by MLST based on partial sequences of the genes adk, est, gdh, mdh, pgi, pmi and zwf, and 67 sequence types (STs) were observed. Phylogenetic analysis of these concatenated sequences confirmed the separation of groups A (41 STs, 71 isolates) and B (22 STs, 38 isolates) out of the 67 STs. All Carter serovars, 12 Heddleston serovars, all three Little-Lyon types, six out of seven Namioka serovars, all five Roberts types and all four Cornelius serovars were allocated to the A group, while group B included the remaining four Heddleston serovars, 6, 7, 8 and 13, in addition to Namioka type 8 : A. The overrepresentation of reference strains of serotyping systems in the A group contrasts with the high number of isolates obtained from diseased birds in the B group, the effect of which should be addressed in future vaccine development. Isolates from birds (25) dominated the B group, which also included four isolates from Felidae, whereas group A included isolates from all types of hosts. The evolutionary implications of the lack of capsular type D, pig and bovine isolates in group B, as well as its association with Aves and Felidae that also applied to the whole Rural Industries Research and Development Corporation (RIRDC) MLST database, need further investigation. The combination of rpoB and 16S rRNA gene sequence comparison as well as the developed PCR test assigned isolates to lineage A, represented by the type strain of P. multocida subsp. Multocida, or lineage B represented by the type strain of P. multocida subsp. septica. It was not possible to circumscribe either the A or B lineages with a set of conserved phenotypic characters, calling into question the validity of subspecies within P. multocida. Phylogenetic analysis carried out on individual MLST genes showed deviations as to single or multiple genes for 17 % of group A and 43 % of group B, indicating that lineage A probably developed from lineage B, and that major changes are ongoing. From a genotypical point of view, we conclude that P. multocida subsp. gallicida represents an artificial unit.

An ST11 clone of Pasteurella multocida, widely spread among farmed rabbits in the Iberian Peninsula, demonstrates respiratory niche association

“…This study found respiratory niche association of some clonal isolates in rabbits, confirming the clonal nature and niche association of some P. multocida isolates in other previously reported animal hosts (Bisgaard et al, 2013;Davies et al, 2003Davies et al, , 2004Hotchkiss et al, 2011;Pors et al, 2011). Identification of the clones associated with specific clinical manifestations such as pneumonia probably could improve selection of vaccine candidates.…”

“…These findings seem to confirm the clonal nature of some respiratory P. multocida isolates in different hosts. Bovine and porcine respiratory isolates have also been found clonal in nature by MLST analysis (Bisgaard et al, 2013;Hotchkiss et al, 2011;Pors et al, 2011). Previously, Davies et al (2003) found subpopulations of P. multocida associated with porcine pneumonia and suggested that they could be virulent isolates playing a primary role in the pathogenesis of the disease rather than opportunistic pathogens.…”

“…Whether different lineages of P. multocida organisms are associated with specific disease manifestations is also unknown (Davies, 2004;Bisgaard et al, 2013). In the last few years, several studies have reported the clonal nature of some respiratory bovine and porcine P. multocida isolates (Bisgaard et al, 2013;Davies et al, 2003Davies et al, , 2004Hotchkiss et al, 2011;Pors et al, 2011).…”

Ocorrência de genes tad associados à formação de biofilme em isolados de Pasteurella multocida de pulmões de suínos com pneumonia

“…São descritos cinco sorotipos: A, B, D, E e F de acordo com os antígenos capsulares (Townsed et al 2001), sendo geralmente associado, mas não restrito, a um hospedeiro específico (Arumugam et al 2011). Diferentes técnicas de genotipificação têm sido utilizadas para classificar este microrganismo, como o RAPD (Lee et al 2011) e MLST (Silva et al 2012, Bisgaard et al 2013. Dada a importância econômica desta bactéria, principalmente em sistemas de produção de suínos, seus fatores de virulência têm sido amplamente estudados.…”

Molecular Epidemiology ofPasteurella multocidaCirculating in India by Multilocus Sequence Typing

“…septica is ancestral type from which P. multocida subsp. multocida developed (Bisgaard et al., ). Of the ten STs identified in this study, in phylogenetic analysis, only ST 281 was found to be closely related to STs belonging to P. multocida subsp.…”