Pasteurella multocida subsp. multocida and P. multocida subsp. septica differentiation by PCR fingerprinting and alpha-glucosidase activity

Pasteurella multocida strains of a novel capsular serotype and lethal to Marmota himalayana on Qinghai-Tibet plateau in China

Pasteurella multocida is a zoonotic pathogen causing serious diseases in humans and animals. Here, we report P. multocida from wildlife on China's Qinghai-Tibet plateau with a novel capsular serotype, forming a single branch on the core-genome phylogenetic tree: four strains isolated from dead Himalayan marmot (Marmota himalayana) and one genome assembled from metagenomic sequencing of a dead Woolly hare (Lepus oiostolus). Four of the strains were identified as subspecies multocida and one was septica. The mouse model showed that the challenge strain killed mice within 24 h at an infectious dose of less than 300 bacteria. The short disease course is comparable to septicemic plague: the host has died before more severe pathological changes could take place. Though pathological changes were relatively mild, cytokine storm was obvious with a significant rise of IL-12p70, IL-6, TNF-αand IL-10 (P < 0.05). Our findings suggested P. multocida is a lethal pathogen for wildlife on Qinghai-Tibet plateau, in addition to Yersinia pestis. Individuals residing within the M. himalayana plague focus are at risk for P. multocida infection, and public health warnings are necessitated.

Screening and purification of NanB sialidase from Pasteurella multocida with activity in hydrolyzing sialic acid Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal

Study on sialidases as antiviral agents has been widely performed, but many types of sialidase have not been tested for their antiviral activity. Pasteurella multocida NanB sialidase is one such sialidase that has never been isolated for further research. In this study, the activity of NanB sialidase was investigated in silico by docking the NanB sialidase of Pasteurella multocida to the Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal ligands. Additionally, some local isolates of Pasteurella multocida, which had the NanB gene were screened, and the proteins were isolated for further testing regarding their activity in hydrolyzing Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal. Silico studies showed that the NanB sialidase possesses an exceptional affinity towards forming a protein–ligand complex with Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal. NanB sialidase of Pasteurella multocida B018 at 0.129 U/mL and 0.258 U/mL doses can hydrolyze Neu5Acα(2–6)Gal and Neu5Acα(2–3)Gal better than other doses. In addition, those doses can inhibit effectively H9N2 viral binding to red blood cells. This study suggested that the NanB sialidase of Pasteurella multocida B018 has a potent antiviral activity because can hydrolyze sialic acid on red blood cells surface and inhibit the H9N2 viral binding to the cells.

Development of a multiplex PCR assay for the detection of key genes associated with Pasteurella multocida subspecies

The ability to distinguish among the subspecies of Pasteurella multocida isolates is important epidemiologically; however, classification at the subspecies level based on the results of conventional biochemical tests (fermentation of sorbitol and dulcitol) is reportedly not accurate in all cases. Therefore, we developed a rapid, multiplex PCR assay to differentiate among the 3 subspecies of P. multocida. The PCR assay includes the P. multocida species-specific primers KMT1SP6 and KMT1T7 as an internal amplification control, with a newly designed gatD (galactitol-1-phosphate-5-dehydrogenase)-specific primer pair (unique for subsp. gallicida), and primers targeting a 16S rRNA gene region specific for subsp. septica. The subspecies specificity of the PCR was demonstrated by applying the test to a collection of 70 P. multocida isolates, including the Heddleston serovar reference strains; all isolates and strains were assigned correctly. The PCR assay is a sensitive, specific, and highly effective method for the identification of P. multocida subspecies, and an alternative to biochemical test-based differentiation. A possible relationship was noticed between P. multocida subspecies and lipopolysaccharide (LPS) genotype; all but one of the subsp. gallicida strains were isolated only from avian hosts and represented L1 LPS genotype. Subsp. multocida and subsp. septica isolates were classified into 5 and 4 different LPS genotypes, respectively, of which L3 was the only LPS genotype shared between these 2 subspecies.

Genomic diversity and molecular epidemiology of Pasteurella multocida

Pasteurella multocida is a bacterial pathogen with the ability to infect a multitude of hosts including humans, companion animals, livestock, and wildlife. This study used bioinformatic approaches to explore the genomic diversity of 656 P. multocida isolates and epidemiological associations between host factors and specific genotypes. Isolates included in this study originated from a variety of hosts, including poultry, cattle, swine, rabbits, rodents, and humans, from five different continents. Multi-locus sequence typing identified 69 different sequence types. In-silico methodology for determining capsular serogroup was developed, validated, and applied to all genome sequences, whereby capsular serogroups A, B, D, and F were found. Whole genome phylogeny was constructed from 237,670 core single nucleotide variants (SNVs) and demonstrated an overall lack of host or capsular serogroup specificity, with the exception of isolates from bovine sources. Specific SNVs within the srlB gene were identified in P. multocida subsp. septica genomes, representing specific mutations that may be useful for differentiating one of the three known subspecies. Significant associations were identified between capsular serogroup and virulence factors, including capsular serogroup A and OmpH1, OmpH3, PlpE, and PfhB1; capsular serogroup B and HgbA and PtfA; and capsular serogroup F and PtfA and PlpP. Various mobile genetic elements were identified including those similar to ICEPmu1, ICEhin1056, and IncQ1 plasmids, all of which harbored multiple antimicrobial resistance-encoding genes. Additional analyses were performed on a subset of 99 isolates obtained from turkeys during fowl cholera outbreaks from a single company which revealed that multiple strains of P. multocida were circulating during the outbreak, instead of a single, highly virulent clone. This study further demonstrates the extensive genomic diversity of P. multocida, provides epidemiological context to the various genotyping schemes that have traditionally been used for differentiating isolates, and introduces additional tools for P. multocida molecular typing.

Pasteurella multocida: Genotypes and Genomics

Pasteurella multocida is a highly versatile pathogen capable of causing infections in a wide range of domestic and wild animals as well as in humans and nonhuman primates. Despite over 135 years of research, the molecular basis for the myriad manifestations of P. multocida pathogenesis and the determinants of P. multocida phylogeny remain poorly defined. The current availability of multiple P. multocida genome sequences now makes it possible to delve into the underlying genetic mechanisms of P. multocida fitness and virulence. Using whole-genome sequences, the genotypes, including the capsular genotypes, lipopolysaccharide (LPS) genotypes, and multilocus sequence types, as well as virulence factor-encoding genes of P. multocida isolates from different clinical presentations can be characterized rapidly and accurately. Putative genetic factors that contribute to virulence, fitness, host specificity, and disease predilection can also be identified through comparative genome analysis of different P. multocida isolates. However, although some knowledge about genotypes, fitness, and pathogenesis has been gained from the recent whole-genome sequencing and comparative analysis studies of P. multocida, there is still a long way to go before we fully understand the pathogenic mechanisms of this important zoonotic pathogen. The quality of several available genome sequences is low, as they are assemblies with relatively low coverage, and genomes of P. multocida isolates from some uncommon host species are still limited or lacking. Here, we review recent advances, as well as continuing knowledge gaps, in our understanding of determinants contributing to virulence, fitness, host specificity, disease predilection, and phylogeny of P. multocida.

Evaluation of the biofilm formation capacity of Pasteurella multocida strains isolated from cases of fowl cholera and swine lungs and its relationship with pathogenicity

ABSTRACT: Pasteurella multocida is a Gram-negative bacillus that causes economic losses due to the development of respiratory diseases in several animal species. Among the mechanisms of virulence, the formation of biofilms is an important factor for bacterial survival in hostile environments. Studies of biofilm formation by P. multocida are needed because P. multocida is an important pathogen involved in respiratory infections. However, in contrast to other microorganisms, few studies of biofilm formation have examined P. multocida. Studies comparing the pathogenicity of microbial strains as a function of their biofilm production capacity are also rare. Consequently, the aim of this study was to evaluate the biofilm formation capacity of 94 P. multocida strains isolated from cases of fowl cholera and from swine lungs on polystyrene plates. The associations of the biofilm formation capacity with the pathogenicity index (PI) in vivo and with the presence of four genes (screened by PCR) of the tad locus (tadB, tadD, tadE and tadG), described as adhesion markers, were also determined. Strains from both animal origins were able to form biofilms. However, most of the specimens (52.13%) were classified as weak producers, and more than 40% of the strains of P. multocida (40.42%) did not produce biofilms. There was no significant difference (p>0.05) in the degree of biofilm production between the two sources of isolation. Of the analyzed strains, 56.52% contained all four genes (tadB, tadD, tadE and tadG). The PI arithmetic mean of the strains classified as non-biofilm producers was significantly different (p<0.05) from the PI of moderate-producer strains. The PI of specimens classified as weak biofilm producers also differed significantly (p<0.05) from that of the moderate-producer strains. The results indicate that even though the P. multocida strains isolated from cases of fowl cholera and swine lungs formed biofilms on polystyrene surfaces, adhesion was usually weak. The genes tadB, tadD, tadE and tadG were not significantly associated (p>0.05) with the production of biofilms and with the origin of a given strain. Finally, low virulence strains may suggest a higher biofilm formation capacity on polystyrene plates.

Complete Genome Sequence of Type Strain Pasteurella multocida subsp. multocida ATCC 43137

Soft-tissue infection by Pasteurella multocida in humans is usually associated with a dog- or cat-related injury, and these infections can become aggressive. We sequenced the type strain P. multocida subsp. multocida ATCC 43137 into a single closed chromosome consisting of 2,271,840 bp (40.4% G+C content), which is currently available in the NCBI GenBank under the accession number CP008918.

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

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 (n = 116) 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.

Double zoonotic peritonitis

Background:

Peritonitis continues to be a major problem for peritoneal dialysis patients. The incidence of peritonitis has decreased in recent decades but uncommon organisms are inceasingly being reported.

Case Report:

We report an 83 year old man with history of diabetes mellitus, arterial hypertension, coronary artery disease and end stage renal disease on peritoneal dialysis, who developed recurrent peritonitis due to simultaneous presence of two uncommon organisms, Pasturella multocida and Capnocytophag. The patient was treated with antibiotics but he did not respond well and therefore his peritoneal dialysis catheter was removed. We discuss the microbiology of both organisms and review the literature.

Conclusions:

Peritonitis is a major problem for peritoneal dialysis patients and although improved technology has decreased the incidence of peritonitis, unusual organisms are increasingly reported. Pet owners who are on peritoneal dialysis, should be aware of the risks of association with animals

Phenotypic and genetic characterization of Pasteurella multocida and related isolates from rabbits in Switzerland

Several bacteria belonging to the family Pasteurellaceae are potential pathogens in rabbits. In particular, Pasteurella multocida is considered to be important, and outbreaks caused by this species result in considerable economic losses in rabbitries. However, Pasteurellaceae spp. isolated from rabbits are poorly characterized, and thus, proper identification of P. multocida isolates from these animals is problematic and often unsatisfactory, thereby hampering epidemiological investigations. Therefore, 228 isolates from rabbit populations originating from a breeding and fattening organization with group management and postmortem cases with pasteurellosis from individual owners were phenotypically and genotypically analyzed using biochemical tests and repetitive extragenic palindromic polymerase chain reaction (REP-PCR). Furthermore, 41 samples representing observed phenotypes were selected for phylogenetic analysis using 16S ribosomal RNA and rpoB genes. The REP-PCR typing and phylogenetic analyses correlated well and appeared to be distinct molecular methods for characterization of rabbit isolates. Phenotyping, however, diverged from molecular recognition, reflecting the problematic conventional diagnosis of these strains. The fermentation of sorbitol appeared to be an imprecise indicator for P. multocida subspecies classification. According to REP-PCR and sequencing results, 82% of the isolates were characterized as P. multocida subsp. multocida, 3% as P. multocida subsp. septica, and 5% as P. multocida. Further, 5% were identified as Pasteurella canis. The other 5% represented a homogeneous group of unknown species belonging to the Pasteurellaceae. Samples obtained from individual postmortem cases demonstrated a higher phenotypic and genetic heterogeneity than samples from group management rabbits.

Pasteurella multocidaand bovine respiratory disease

Pasteurella multocidais a pathogenic Gram-negative bacterium that has been classified into three subspecies, five capsular serogroups and 16 serotypes.P. multocidaserogroup A isolates are bovine nasopharyngeal commensals, bovine pathogens and common isolates from bovine respiratory disease (BRD), both enzootic calf pneumonia of young dairy calves and shipping fever of weaned, stressed beef cattle.P. multocidaA:3 is the most common serotype isolated from BRD, and these isolates have limited heterogeneity based on outer membrane protein (OMP) profiles and ribotyping. Development ofP. multocida-induced pneumonia is associated with environmental and stress factors such as shipping, co-mingling, and overcrowding as well as concurrent or predisposing viral or bacterial infections. Lung lesions consist of an acute to subacute bronchopneumonia that may or may not have an associated pleuritis. Numerous virulence or potential virulence factors have been described for bovine respiratory isolates including adherence and colonization factors, iron-regulated and acquisition proteins, extracellular enzymes such as neuraminidase, lipopolysaccharide, polysaccharide capsule and a variety of OMPs. Immunity of cattle against respiratory pasteurellosis is poorly understood; however, high serum antibodies to OMPs appear to be important for enhancing resistance to the bacterium. Currently availableP. multocidavaccines for use in cattle are predominately traditional bacterins and a live streptomycin-dependent mutant. The field efficacy of these vaccines is not well documented in the literature.

Phenotypic and genotypic characterisation of Pasteurella multocida strains isolated from pigs in Hungary

A total of 146 Pasteurella multocida strains isolated from swine in Hungary in the last 20 years were examined. Biochemical characterisation and PCR-based techniques were used to determine species, subspecies, biovar, capsule type and presence of the toxA gene. Eighty-seven percent of the isolates belonged to P. multocida ssp. multocida, and 98% of these had biovar 3 or were trehalose- or lactose-fermenting or ornithine decarboxylase negative variants of that. Ten percent of the strains were P. multocida ssp. septica, and within this group 80% of the strains showed sorbitol-negative biovars (5, 6 and 7). The rest of the strains (20%) were lactose positive. Only 3% of the porcine isolates were P. multocida ssp. gallicida and 3 out of the 4 strains belonged to the dulcitol-fermenting biovar 8. Using a capsule-specific multiplex PCR, 60% of the strains belonged to capsule type D, 38% to capsule type A, and only 1 isolate had capsule type F. In contrast with data published in the literature, only 3% of capsule type D isolates carried the toxA gene, while this ratio was 41% for the type A strains. A remarkable regional distribution of toxA gene positive strains was observed. All but two isolates were found in swine herds located in the Transdanubian region, separated from other parts of Hungary by the river Danube.

Rapid and accurate identification of human isolates of Pasteurella and related species by sequencing the sodA gene

The identification of Pasteurella and related bacteria remains a challenge. Here, a 449- to 473-bp fragment (sodA(int)) internal to the sodA gene, encoding the manganese-dependent superoxide dismutase, was amplified and sequenced with a single pair of degenerate primers from the type strains of Pasteurella (18 strains), Gallibacterium (1 strain), and Mannheimia (5 strains) species. The sodA(int)-based phylogenetic tree was in general agreement with that inferred from the analysis of the corresponding 16S rRNA gene sequences, with members of the Pasteurella sensu stricto cluster (Pasteurella multocida, Pasteurella canis, Pasteurella dagmatis, and Pasteurella stomatis) forming a monophyletic group and Gallibacterium and Mannheimia being independent monophyletic genera. However, the sodA(int) sequences showed a markedly higher divergence than the corresponding 16S rRNA genes, confirming that sodA is a potent target to differentiate related species. Thirty-three independent human clinical isolates phenotypically assigned to 13 Pasteurella species by a reference laboratory were successfully identified by comparing their sodA(int) sequences to those of the type species. In the course of this work, we identified the first Gallibacterium anatis isolate ever reported from a human clinical specimen. The sodA(int) sequences of the clinical isolates displayed less than 2.5% divergence from those of the corresponding type strains, except for the Pasteurella pneumotropica isolates, which were closely related to each other (> 98% sodA(int) sequence identity) but shared only 92% sodA(int) identity with the type strain. The method described here provides a rapid and accurate tool for species identification of Pasteurella isolates when access to a sequencing facility is available.

Specific identification of Pasteurella multocida serogroup-A isolates by PCR assay

A polymerase chain reaction (PCR) assay targeting the hyaC-hyaD gene was developed and used to identify strains of Pasteurella multocida belonging to serogroup-A. A set of serogroup-specific-PCR primers amplified a 564 bp product from genomic DNA prepared from bacterial cells or directly from bacterial colonies. This method detected as low as 10 ng of bacterial DNA and had a specificity of 100% for P. multocida serogroup-A. A nested PCR method yielded a single 374 bp product. All fifty isolates were also shown to be identical by restriction fragment length polymorphism (RFLP) analysis of the PCR products after digestion with BglII.

tRNA-intergenic spacer PCR for the identification of Pasteurella and Mannheimia spp

tRNA-intergenic spacer PCR (tDNA-PCR) was evaluated for its effectiveness in differentiating Pasteurella and Mannheimia (sub)species predominantly of ruminant origin. For this purpose, 38 reference strains and 13 field isolates belonging to both genera were investigated. tDNA-PCR enabled discrimination of all Pasteurella species tested (Pasteurella (P.) aerogenes, P. avium, P. canis, P. lymphangitidis, P. multocida, P. trehalosi). For the differentiation of the subspecies of P. multocida, an additional dulcitol reaction was required. Two of the five so far-defined Mannheimia species, M. granulomatis and M. varigena, had a distinct fingerprinting profile. The remaining three phylogenetically highly related species (M. haemolytica, M. glucosida, and M. ruminalis) clustered together. Nevertheless, M. ruminalis is non-haemolytic, and M. haemolytica and M. glucosida can be differentiated on the basis of two additional phenotypic characteristics (beta-glucosidase and aesculin hydrolysis). In conclusion, tDNA-PCR is a useful tool in differentiating organisms belonging to the genera Pasteurella and Mannheimia.