Pasteurella Multocida Type Research Articles

The first report of concurrent infection of hemorrhagic septicemia with foot and mouth disease in cattle in Bangladesh

This study aimed to investigate the concurrent infection of Pasteurella multocida (P. multocida) type B:2, which causes Hemorrhagic Septicemia (HS), with cases of Foot and Mouth Disease (FMD) outbreaks in cattle in Bangladesh between March and December 2023. Samples were collected from 11 distinct outbreak areas, totaling 102 samples. These included 54 FMD samples (saliva, tissue epithelium, and morbid tissues such as lung, spleen, and heart) and 54 HS samples (nasal swabs and morbid tissues) from 50 cattle of various ages and sexes, all showing clinical signs of suspected concurrent HS and FMD infection. After sample processing, molecular detection of FMDV and its serotypes was performed using Reverse Transcriptase PCR (RT-PCR) with universal and serotype-specific primers. The HS-causing agent, P. multocida type B:2, was initially identified through cultural and morphological characteristics on various media, followed by Gram’s and methylene blue staining, biochemical tests, and pathogenicity tests through inoculation of isolates into mice. Finally, molecular detection of P. multocida type B:2 was confirmed using PCR with specific primers. Forty-five (83 %) of the 54 FMD suspected samples tested positive for FMDV, with 53 % of these positive for serotype ‘O,’ 17 % for serotype ‘A,’ and 6 % for mixed serotypes ‘O’ and ‘A.’ Among the FMDV-positive samples, 17 (38 %) of the HS-suspected samples tested positive for concurrent infection with P. multocida type B:2. The study reveals that FMDV-induced acute immunosuppression in cattle can lead to complications from concurrent infections, particularly those caused by P. multocida type B:2, resulting in HS alongside FMD.

Exploring the Genetic Diversity of Mycoplasma hyopneumoniae in Pigs with Pneumonia and Pleurisy at Slaughter.

Mycoplasma (M.) hyopneumoniae is the key pathogen of the porcine respiratory disease complex (PRDC) and contributes to pleurisy in pigs. Due to its limited metabolism and laborious cultivation, molecular tools are useful for diagnosis. This study investigated the genetic diversity of M. hyopneumoniae in slaughter pigs with pneumonia and pleurisy, and it assessed co-infections by Pasteurella multocida type A (PM), Actinobacillus pleuropneumoniae (APP), and swine influenza virus A (sIVA). Lungs (n = 70) with different pleurisy scores and lesions compatible with M. hyopneumoniae infection were collected for convenience. Macroscopic and microscopic evaluations were performed. M. hyopneumoniae was detected using qPCR, and MLST was used for genetic characterization. Co-infections with PM and APP were also evaluated by qPCR, while the immunohistochemistry assessed sIVA infection. All lungs were positive for M. hyopneumoniae. Histopathology confirmed M. hyopneumoniae-associated lesions. MLST characterization was possible in 25 lungs and revealed 10 distinct allelic profiles, with none matching known sequence types in the public database. Co-infections were detected in 40% of the samples with APP and 32% with PM, with 12% showing both pathogens and 52% of the samples presenting microscopic lesions compatible with sIVA infection. The diverse genetic profiles found underscore the need for research on isolation and potential pathogenic variations.

Identification and Antibiotic Resistance of Pasteurella multocida Isolated from Infected Layer Chickens in West Java, Indonesia

Bacterial infections, such as those caused by Pasteurella multocida serotype A, pose significant threats to poultry farming. The use of antibiotics to treat these infections can lead to antibiotic resistance. The present study aimed to identify Pasteurella multocida from 14 Hisex Brown layer chicken hen farms, with chikens aged 25-55 weeks, in West Java, Indonesia, and to evaluate their resistance to various antibiotics. Three samples from each farm were collected from dead chickens having symptoms of fowl cholera. Initially, the study involved isolating and identifying isolates from liver, heart, and lung organs via polymerase chain reaction. The colony was then tested for antibiotic resistance using the disk diffusion method. The results showed that 13 samples were Pasteurella multocida and nine were serotype A. The test results also indicated that all isolates were resistant to colistin (10 µg) and sensitive to tetracycline (30 µg), amoxicillin (25 µg), enrofloxacin (5 µg), sulfamethoxazole (25 µg), lincomycin (109 µg), and ciprofloxacin (5 µg). The study concluded that none of the Pasteurella multocida type A isolates were any longer sensitive to colistin, with some isolates still sensitive to tetracycline, amoxicillin, enrofloxacin, sulfamethoxazole, lincomycin, and ciprofloxacin, and two isolates showing multidrug resistance patterns. Keywords: Antibiotic, Fowl cholera, Pasteurella multocida, Layer chicken

Revealing the lethal effects of Pasteurella multocida toxin on multiple organ systems.

Pasteurella multocida toxin (PMT) is one of the most important virulence factors of Pasteurella multocida type D. Pasteurella multocida infection has caused enormous economic losses in the pig farming industry. Although it is well known that this bacterial infection causes progressive atrophic rhinitis, its effects on other organ tissues in pigs are unclear. In this study, PMT was expressed and purified, and the cytotoxic effects of PMT on four types of swine cells, LLC-PK1, PAM, IPEC, and ST, were investigated. LLC-PK1 exhibited the highest sensitivity to the cytotoxic effects of PMT. Our studies revealed that a PMT concentration of 0.1 μg/kg can lead to weight loss, whereas a PMT concentration of 0.5 μg/kg can lead to death in mice. PMT causes damage to the intestines, kidneys, lungs, livers, and spleens of mice. Furthermore, PMT caused acute death in pigs at treatment concentrations greater than 5 μg/kg; at PMT concentration of 2.5 μg/kg, weight loss occurred until death. PMT mainly caused damage to the hearts, lungs, livers, spleens and kidneys of pigs. The organ coefficient showed that damage to the heart and kidneys was the most severe and caused the renal pelvis and renal pyramid to dissolve and become cavitated. Pathology revealed hemorrhage in the lungs, liver, and spleen, and the kidneys were swollen and vacuolated, which was consistent with the damaged target organs in the mice. In conclusion, these findings demonstrate that PMT is extremely toxic in vitro and in vivo, causing damage to various organs of the body, especially the kidneys and lungs. This study provides a theoretical basis for the in-depth exploration of the cytotoxic effects of PMT on target organs.

Attenuated vaccine PmCQ2Δ4555–4580 effectively protects mice against Pasteurella multocida infection

Pasteurella multocida type A (PmA) mainly causes respiratory diseases such as pneumonia in bovines, leading to great economic losses to the breeding industry. At present, there is still no effective commercial vaccine against PmA infection. In this study, a mutant strain (PmCQ2Δ4555–4580) with brand-new phenotypes was obtained after serially passaging at 42 °C. Whole genome resequencing and PCR analysis showed that PmCQ2Δ4555–4580 missed six genes, including PmCQ2_004555, PmCQ2_004560, PmCQ2_004565, PmCQ2_004570, PmCQ2_004575, and PmCQ2_004580. Importantly, the virulence of PmCQ2Δ4555–4580 was reduced by approximately 2.8 × 109 times in mice. Notably, live PmCQ2Δ4555–4580 could provide 100%, 100% and 40% protection against PmA, PmB and PmF, respectively; and inactivated PmCQ2Δ4555–4580 could provide 100% and 87.5% protection against PmA and PmB. Interestingly, immune protection-related proteins were significantly upregulated in PmCQ2Δ4555–4580 based on RNA-seq and bioinformatics analysis. Meaningfully, by in vitro expression, purification and in vivo immunization, 12 proteins had different degrees of immune protective effects. Among them, PmCQ2_008205, PmCQ2_010435, PmCQ2_008190, and PmCQ2_004170 had the best protective effect, the protection rates against PmA were 50%, 40%, 30%, and 30%, respectively, and the protective rates against PmB were 62.5%, 42.9%, 37.5%, and 28.6%, respectively. Collectively, PmCQ2Δ4555–4580 is a potential vaccine candidate for the prevention of Pasteurellosis involving in high expression of immune protective related proteins.

Back passage of haemorrhagic septicaemia (HS) vaccine seed C82 in cattle calf

Haemorrhagic septicaemia (HS) is caused by Pasteurella multocida serotypes B: 2, a Gram-negative coccobacilli bacterium. It causes fatal septicaemia with high mortality in cattle and buffaloes. Disease control and prevention are by effective HS vaccination in animals. A study was conducted on one mixed breed cattle calf for back passage of haemorrhagic septicaemia (HS) seed strain C82. Prior to bacterial inoculation in the calf, Mouse Protection Test (MPT) was conducted to ensure the calf is free from any HS antibody. The calf was injected subcutaneously with 0.5 ml dilutions of 10-3 of the bacteria incubated overnight (approximately 106 CFU/ml). After ±30 hours inoculation, post-mortem was conducted on the calf showing sign of HS. Heart blood and organ samples were collected and cultured on blood agar to determine bacteria purity. Blood and organ samples were also sent to the bacteriology laboratory in VRI for confirmatory tests. The death of the calf is confirmed by re-isolation of Pasteurella multocida Type B. Heart blood collected was processed, freeze-dried and keep as vaccine seed for further usage in vaccine production. Revival of vaccine seed is needed to ensure its pathogenicity and functionality for production purposes.

Formalin and ferric chloride inactivated Pasteurella multocida type a adjuvanted with bacterial DNA and alum as a new vaccine candidate in sheep pasteurellosis

The aim of the present study was to investigate humoral and cellular immune responses in sheep inoculated with inactivated P. multocida antigen with alum and bacterial DNA adjuvant by identifying IgG and cytokines from serum and cell culture. Sheep were immunized with iron and formalin-inactivated antigens at an interval of 2 weeks. These immunogens were mixed with alum adjuvant and P. multocida type A DNA (AbDNA). After injection and blood sampling, the serum antibody titer and cellular immune responses (IL-4, IFN-γ, and TNF-α) on serum samples and lymphocyte cell were tested by ELISA. The ELISA results showed a higher antibody titer in the bDNA adjuvant group compared to the alum adjuvant group and the control group. In general, the level of IgG in the serum of immunized animals was significantly increased compared to the control group. The peak antibody titer (1.794) was observed on the 28th day of injection in the IIV-AbDNA group. After immunization, inactivation with iron and bDNA adjuvant increased cytokine production compared to other experimental and control groups. High levels of lymphocyte and serum titers of IL-4, IFN-γ, and TNF-α were also obtained in the IIV-AbDNA group. The findings showed that killed P. multocida type A antigens formulated with bacterial DNA as an adjuvant are candidates for new immunogens against P. multocida infections in sheep. The inactivation of bacteria with iron also enhanced proper immune responses.

Prevalence of hemorrhagic septicemia in dromedary camel (Camelus dromedarius) of some selected farms at Benadir region, Somalia

Pasteurellosis (Hemorrhagic septicemia) is a common respiratory Disease of camel that is an acutely fatal disease caused by Pasteurella multocida type A or several serotypes of Mannheimia hemolytic, which also affect other animals. The disease had shown to spread between animals, across herds, and to humans. Meaning that the disease is Zoonosis. The study aimed at the establishment of seroprevalence of Pasteurellosis in some selected Districts of camel rearing in the Benadir Region. It was a cross-sectional study, where the study population was purposively chosen to consist of animals taken within three sub-Districts of Benadir Region, namely Sub-District (Daynile Township), Sub-District (Yaaqshid) Sub-District (kaxda). This was because they normally handle many camels in a day, thus making it easy for the investigator to access the required number conveniently; it was also assumed that data collected from these for-slaughter camels was representative of the situation in the sub-District/county. A total of one hundred and sixty camels were tested using four serological tests: Rose Bengal Plate Test (RBPT),) and Complex Fixation Test (CFT). The serological tests were purposively chosen to increase the chances of picking positive cases and also to compare their sensitivities, with respect to camel serum, since they were originally meant for use on bovine serum. Blood samples (15 ml) were collected for serum harvesting from the jugular veins of the animals as they were waiting to be examined. Rose Bengal plate test and CFT were run at a laboratory within the department of Veterinary Medicine, University of Horsed, 21 October campus; serum samples having been transported in a cool box. On average, out of an overall total of 300 serum samples tested, 180 samples were selected as sample procedures and were given eleven (11) positive results, amounting to a prevalence of 6.67%. For the three Districts, respective prevalence (averaged from the two (2) serological tests run) were: 7% (3/50) for Yaqshiid; 8% (3/60) for Deyniile, and 10% (3/70) for Kaxda. When sensitivities of the two (2) serological tests were compared, there was no significant difference between them, with respect to the picking of positive cases (p=0.05), The study has demonstrated presence of Pasterolosis in camels in the Benadir Region and the authors are, recommending the usage of RBPT and CFT as a screening test since they are cheap, quick, and easy to carry-out. Any of the other three involving tests can then be used if one wants to establish respective titers. Therefore, further detailed investigation needs to be conducted so as to understand specific etiological agents causing pasteurellosis in camels and can be instituted to optimize the benefit obtained from the camel sector.

De Novo Whole-Genome Sequencing of Two Pathogenic Pasteurella multocida Type D:6 Strains Isolated from Pigs.

Here, we report the complete genome sequences of Pasteurella multocida strains P504190 and P504188/1, which were isolated from the diseased lungs of a sow and her piglet, respectively. Despite the unusual clinical presentation, whole-genome sequence typing revealed both strains to be capsular type D and lipopolysaccharide (LPS) group 6, commonly found in pigs.

IMPACT OF GLYCEROL AND DIMETHYL SULFOXIDE ON THE PERSISTENCE OF PASTEURELLA MULTOCIDA DURING ITS PRESEVATION AT DIFFERENT TEMPERATURES

Bacterium Pasteurella multocida type B:2 is the causative agent of Hemorrhagic Septicemia in bovines in Pakistan. This organism is also being used for oil adjuvanted (Montanide ISA 50 V2) vaccine for mass vaccination in cattle & buffaloes in Punjab, Pakistan. A study was conducted to study the impact of glycerol and dimethyl sulfoxide (DMSO) on persistence of P. multocida duringits course of storage at 0, 4 and – 20 °C. Pure seed of P .multocida was grown in Brain Heart Infusion(BHI) broth at pH 7.4 and incubated at 37 °C for 18 hrs. in shaking incubator. The growth was observed for its purity microscopically as well as culturing on MacConkey’s & Nutrient agar slants. The pure culture was divided into three parts. One part was added with 5 % sterilized DMSO (final concentration) and second part was added with 10 % sterilized DMSO (final concentration) and 15 % glycerine (final concentration) while third part was kept as control without addition of DMSO and glycerine. All three parts were aliquoted (1 mL) in sterilized 1.5 mL eppendroff tubes and stored at three different temperatures i.e 0, 4 and – 20 °C. Eppendroff tubes from different temperatures were thawed in water bath (22 °C) and subjected to direct culturing on BHI broth, microscopic examination, purity testing on slants, culture turbidity / Optical Density (OD) values, dry biomass calculation and mice inoculation test for three months with 15 days intervals. The results indicated that pure P. multocida culture mixed with 10 % sterilized DMSO and 15 % sterilized glycerol stored at – 20 °C survived for three months and can be used for HS vaccine production without losing its survival.

Use of Inactivated Corynebacterium pseudotuberculosis as an Immunostimulant with Pneumobac Vaccine

Sheep breeders in Egypt suffer from pneumonic pasteurellosis caused by Pasteurella trehalosi, Pasteurella multocida, and Mannheimia haemolytica. The disease is responsible for significant economic losses in the sheep industry according to the high mortality rate and reduced carcass values. Pneumobac® is the primary vaccine in Egypt used to control pasteurellosis in sheep. Therefore, the aim of the present study was to estimate the nonspecific immune stimulating impact of Corynebacterium pseudotuberculosis ovis against Pasteurella in sheep vaccinated with Pneumobac®. Nine sheep were classified into three groups, each with three animals. The sheep in the first and second groups were inoculated with the inactivated culture of Pneumobac® and a combined inactivated culture of Pneumobac® with Corynebacterium pseudotuberculosis ovis bacterin, respectively. The third group was nonvaccinated and kept in control. Indirect haemagglutination test (IHA) and enzyme-linked immunosorbent assay (ELISA) were used to measure the humoral immune response to the produced vaccines. The results of the present study confirmed that the antibodies titer against Pasteurella multocida type A, D, and B6, Pasteurella trehalosi type T, and Mannheimia haemolytica type A significantly increased in sheep vaccinated with a combined vaccine (Pneumobac® and Corynebacterium pseudotuberculosis ovis bacterin), compared to those vaccinated with Pneumobac® alone. It was concluded that the addition of Corynebacterium pseudotuberculosis ovis bacterin to inactivated Pneumobac® vaccine could increase the immune response against pneumonic pasteurellosis.

The Critical Role of Potassium Efflux and Nek7 in Pasteurella multocida-Induced NLRP3 Inflammasome Activation.

Pasteurella multocida is a zoonotic pathogen causing respiratory infection in different animal species such as cattle, sheep, pigs, chickens and humans. Inflammasome is a complex assembled by multiple proteins in the cytoplasm and plays an important role in the host defense against microbial infection. Bovine Pasteurella multocida type A (PmCQ2) infection induces NLRP3 inflammasome activation and IL-1β secretion, but the mechanism of PmCQ2-induced activation of NLRP3 inflammasome is still unknown. Therefore, the underlying mechanism was investigated in this study. The results showed that potassium efflux mediated PmCQ2-induced IL-1β secretion and blocking potassium efflux attenuated PmCQ2-induced caspase-1 activation and ASC oligomerization. Furthermore, NIMA-related kinase 7 (Nek7) was also involved in PmCQ2-induced caspase-1 activation and IL-1β secretion. In addition, PmCQ2 infection promoted Nek7-NLRP3 interaction, which is dependent on potassium efflux. In conclusion, our results indicate the critical role of potassium efflux and Nek7 in Pasteurella multocida-induced NLRP3 inflammasome activation, which provides useful information about Pasteurella multocida-induced host immune response.

Impacto econômico de lesões pleurais crônicas e consequente desqualificação de carcaças para exportação durante inspeção em frigoríficos de suínos

ABSTRACT: Chronic pleuritis is the main reason for sending pig carcasses to the Department of Final Inspection (DIF), condemnation and led to economic losses to industries and producers. Most pleura lesions detected after slaughter are sequelae from bacterial infections by agents that do not pose risks to pork consumers. The objective of the present study was to generate science-based information for decision making in the evaluation and destination of chronic pleuritis by the Federal Inspection Service (SIF). Therefore, 200 carcasses, with and without pleurisy, from a swine slaughterhouse with SIF were assessed following the visual classification of the inspection agent. The study was carried out in two stages. In stage 1, 50 carcasses with pneumonic lesions adjacent to chronic pleuritis and 50 carcasses with only chronic pleuritis lesions were evaluated, through macroscopy, histopathology, and bacterial culture. In stage 2, 50 swine carcasses with chronic pleuritis and 50 without this lesion were sampled in the parietal pleura region to bacterial culture and PCR. The economic impact of not exporting these carcasses with chronic pleuritis was also assessed. Considering the stages of evolution of the lesions, the macroscopic examination showed high correlation with the histological examination. There was no bacterial isolation through pleural swabs, regardless of the presence or not of adjacent pulmonary lesions. Isolation was restricted to the adjacent pulmonary lesions of 70% samples, with Pasteurella multocida type A found in 48% of them, followed by P. multocida type D and Streptococcus suis in 12%, and Actinobacillus pleuropneumoniae in 3%. Only Streptococcus suis DNA was detected in 5/100 samples, with no correspondence to the isolation of viable bacteria. The reliability demonstrated in the macroscopic evaluation carried out during inspection, the absence of viable bacteria in the chronic pleural lesions, and the negative economic impact suggest that carcasses with chronic pleuritis can be submitted to pleura removal, with no need of sending to DIF.

Development and testing of a vaccine against infectious atrophic rhinitis and pasteurellosis in pigs

This work presents the results of the development and testing of a domestic vaccine against infectious atrophic rhinitis and pasteurellosis in pigs caused by Bordetella bronchiseptica and Pasteurella multocida type A and D. A drug was designed with the following antigenic composition: B. bronchiseptica (strain B-1341) - 6 * 109 m.c. / dose; antigen of P. multocida type A (strain B-1303) - 3 * 109 m.c. / dose; antigen of P. multocida type D (strain B-1308) - 3 * 109 m. c. / dose. A 3% solution of Aluminum hydroxide in a proportion of 10% was used as an adjuvant. One immunizing dose is 2 cm3. In the course of the study, it was found that the survival of piglets obtained from vaccinated sows is 97.16%, which is comparable with the same indicator in the group of animals immunized with the reference drug - 96.96%. Despite the fact that the average weight of piglets in the experimental group on the 45th day of life was 130 g less than of those in the control group, by the 180th day of life, the experimental piglets were 4.33 kg heavier than the animals in the control group. The average daily gain in the experimental group was 33 g more than the one in the control group. Thus, the selected antigenic composition for the inactivated vaccine is optimal, and is capable of providing high immunogenic and protective activity, both in a vivarium and in an industrial pig-breeding enterprise.

Decision tree analysis for pathogen identification based on circumstantial factors in outbreaks of bovine respiratory disease in calves

Respiratory tract infections continue to be a leading cause of economic loss, hampered animal welfare and intensive antimicrobial use in cattle operations, worldwide. To better target antimicrobial therapy, control and prevention towards the involved pathogens, there is a growing interest in microbiological tests on respiratory samples. However, these tests are time consuming, cost money and sampling might compromise animal welfare. Therefore, the objective of the present study was to develop immediately applicable decision trees for pathogen identification in outbreaks of bovine respiratory disease based on circumstantial factors. Data from a cross sectional study, involving 201 outbreaks of bovine respiratory disease in dairy and beef farms between 2016 and 2019 was used. Pathogens were identified by a semi-quantitative PCR (polymerase chain reaction) on a pooled non-endoscopic broncho-alveolar lavage sample from clinically affected animals. Potential risk factors of involved animals, environment, management and housing were obtained by enquiry. Classification and regression tree analysis was used for decision tree development with cross-validation. Different trees were constructed, involving a general 3-group classification tree (viruses, Mycoplasma bovis or Pasteurellaceae family) and a tree for each single pathogen. The general 3- group classification tree was 52.7 % accurate and had a sensitivity of 81.5 % and a specificity 52.2 % for viruses, respectively 51.7 % and 84.4 % for M. bovis and 28.9 % and 93.6 % for Pasteurellaceae. The single-pathogen trees were more specific than sensitive: Histophilus somni (Se = 25.8 %; Sp = 94.5 %), Mannheimia haemolytica (Se = 69.2 %; Sp = 70.6 %), bovine coronavirus (Se = 42.2 %; Sp = 89.6 %) and bovine respiratory syncytial virus (Se = 34.0 %; Sp = 96.6 %). For Pasteurella multocida, M. bovis and parainfluenzavirus type 3 no meaningful tree was obtained. The concept and trees are promising, but currently lack sensitivity and specificity in order to be a reliable tool for practice. For now, the obtained trees can already be informative for decision making to some extend depending on the end node in which an outbreak falls.

Agents of pneumonia in slaughtered pigs in southern Brazil

ABSTRACT: A high prevalence of pneumonic lesions has been reported to affect slaughtered pigs in southern Brazil. In order to identify which microorganisms have been causing those lesions, 30 pig lungs presenting pneumonic gross lesions were collected from five different slaughterhouses, totaling 150 lungs. Samples for bacterial isolation, molecular, histopathologic and immunohistochemistry (IHC) evaluation were taken from each lung. The pneumonic lesion scoring ranged from 1.53 to 2.83. The most frequent histopathological lesions found was the concomitant Influenza A virus (IAV) and Mycoplasma hyopneumoniae infection, corresponding to 55.3% (83/150), and Pasteurella multocida type A was isolated in 54.2% (45/83) of these cases. In 102 samples (68%), there was histopathologic suggestion of involvement of more than one infectious agent. M. hyopneumoniae was the most frequent agent associated with pneumonic lesions, being present in 92.1% (94/102) of the lungs with coinfections, followed by IAV in 89.2% (91/102). Besides the coinfections, IAV lesions were observed also in six samples without another pathogenic microorganism detected. A total of 46 samples with acute and subacute IAV suspected lesions in histopathological examination were assessed for IHC and real time RT-PCR for IAV. A total of 35% (16/46) of them were positive by IHC and 13% (6/46) by real time RT-PCR. Regarding M. hyopneumoniae, 79.3% (119/150) of samples were positive by qPCR and 84.9% (101/119) of them also presented M. hyopneumoniae suspected lesions in the histopathological examination. The results of this study suggest the importance of IAV in respiratory diseases in finishing pigs, even though this virus is more frequently reported in the nursery phase. In addition, our results emphasize the importance of lung coinfections in finishing pigs.

Clinicopathological and Hematological Changes in Consequence to Experimental Infection of Rabbits with Pasteurella Multocida Type A

The current research aimed to study clinical, hematological and pathological changes occurred due to experimentally challenged rabbits with Pasteurella multocida type A. Twelve healthy Pasteurella multocida free rabbits were divided into control and challenged groups. Rabbits of the challenged group were intra-nasally inoculated with 0.5 ml of 1x105 CFU of Pasteurella multocida type A, while rabbits of the control group were inoculated with 0.5 ml of brain heart infusion broth (BHI). Clinical signs, hematological parameters and histopathological lesions were recoded for 14 days. Rabbits of challenged group showed nasal rubbing with minimal mucus discharge, conjunctivitis and reduction in spontaneous activity, but no mortality occurred. Hematologically, there was highly significant low RBCs count with concomitant significantly reduction of PCV in challenged rabbits, but hemoglobin concentration was insignificantly low in challenged animals as compared to control. Although, there was insignificant increase of WBCs count in challenged group, neutrophils and monocytes recorded significant and highly significant high value in challenged rabbits than control, respectively. Challenged rabbits, however demonstrated highly significant lymphopenia, but other blood parameters did not show any significant differences between challenged and control rabbits. Histopathologically, challenged animals showed meningitis, congestion and degenerative changes in respiratory epithelium, bronchopneumonia, vacuolar degeneration of hepatocytes and vascular changes in heart and spleen. Conclusively, the current study verified that challenging rabbits with Pasteurella multocida serotype A was not lethal and although it was essentially pneumotropic in nature, it caused lesions in other visceral organs, which in absence of bacteremia, could be caused by bacterial endotoxin liberated during disease pathogenesis.

Antimicrobial resistance of Pasteurella multocida type B isolates associated with acute septicemia in pigs and cattle in Spain

BackgroundPasteurella multocida is the etiological agent responsible for several diseases in a wide range of hosts around the world and thus, causes serious economic losses. Acute septicemia associated with capsular type B P. multocida has recently emerged in Europe and continuous outbreaks of these acute processes have been described in Spain since they were first detected in pigs in 2009 and cattle in 2015. The scarcity of studies on the antimicrobial susceptibility of this capsular type of P. multocida and growing concern about the general increase of antimicrobial resistance mean that studies related to the performance of type B P. multocida against antibiotics are necessary to establish accurate treatments and to monitor antimicrobial resistances.ResultsSeventy-six isolates of P. multocida type B from pigs and cattle with acute septicemia were tested for susceptibility to 10 different antimicrobials. Bovine isolates were susceptible to all the antibiotics we tested except for lincomycin (94.4% of isolates were resistant). However, the antimicrobials we tested were less effective against swine isolates, of which none were susceptible to lincomycin. Furthermore, 29.3% swine isolates were resistant to tetracycline, 27.6% to penicillin, 20.7% to oxytetracycline, 17.3% to chloramphenicol, 15.5% to gentamicin, and 3.4% to enrofloxacin; no resistance to ceftiofur was detected. No multidrug resistant isolates were detected from cattle, while 25.86% of swine isolates were resistant to three or more antibiotic classes.ConclusionsIn this study, the lower resistance rates and multidrug resistant isolates reported for P. multocida type B derived from cattle compared to those isolated from pigs may be related to the increased use of antibiotics in the porcine industry in Spain. Lincomycin is not recommended for the treatment of acute septicemia in pigs or cattle, rather, the use of ceftiofur, enrofloxacin, or gentamicin is indicated as an emergency treatment in the early stages of disease; once the susceptibility results are known, the use of tetracyclines, penicillin, or chloramphenicol should be prioritized. The increase in multidrug resistant isolates and antimicrobial resistance rates indicates that more attention should be paid to prevention as well as the responsible use of antibiotics.

First outbreak of bovine haemorrhagic septicaemia caused by Pasteurella multocida type B in Spain - Short communication.

This paper describes the first documented outbreak of haemorrhagic septicaemia (HS) caused by Pasteurella multocida type B in cattle in Spain. This acute, highly fatal septicaemia causes major economic losses in cattle and buffaloes in many areas of Asia and Africa. In other species and in European countries it is an infrequently reported disease. Acute septicaemic pasteurellosis occurred in a free-range farm of 150 cattle and 70 beef calves in Southern Spain. Twenty-one calves and one cow were affected, of which three calves and the adult cow died. Postmortem examination revealed characteristic oedema in the ventral area of the neck and the brisket region, and widespread haemorrhages in all organs. Pure cultures of P. multocida were obtained from all tissues and organs studied. The aetiological agent was further confirmed by molecular and biochemical analysis as P. multocida capsular type B, biovar 3. Although the source of infection could not be determined, wildlife may play an important role. The use of tulathromycin in the initial stage of the disease might be related to the low morbidity and mortality of this outbreak. After using an autogenous vaccine no more cases of HS were observed.

Localization of Pasteurella multocida antigens in the brains of pigs naturally infected with Pasteurellosis revealing a newer aspect of pathogenesis

Pasteurella multocida is an economically important respiratory pathogen of pigs confronting swine industry worldwide. Despite extensive research over the decades, its pathogenesis is still poorly understood. Recent reports have demonstrated the nervous system affection as a newer aspect of pathogenesis by Pasteurella multocida type B:2 in Haemorrhagic Septicemia, but there are no reports of the involvement of nervous system by P. multocida in pigs. Therefore, the study was aimed to explore the neurovirulence of Pasteurella multocida in naturally infected pigs. A total of 15 brains were collected from the natural cases of pig mortality suggestive of Pasteurellosis. Grossly, the leptomeninges were markedly congested and brains were oedematously swollen. Histologically, there was moderate to severe fibrinohaemorrhagic and mononuclear cells exudates present in the leptomeningeal tissue and cerebrospinal spaces. Similar vascular inflammatory lesions (perivascular and perineuronal) along with gliosis, neuronal degeneration and necrosis were noted in various subanatomical sites of the brain (cerebrum, cerebellum, brainstem and spinal cord). The culture and biochemical tests showed the presence of P. multocida within the brain tissue. P. multocida type specific antibody staining in the brain tissues revealed intense distribution of antigens in the inflammatory exudates of meningeal vessels, neurons, glial cells and endothelial cells of the blood vessels contributing its association with neuropathological lesions. Pasteurella multocida specific PCR amplification of capsular polysaccharide gene yielded 460 bp and multiplex PCR showed the involvement of capsular serogroups A &D. All the isolates showed the presence of 10 genes for virulence factors. The disease confirmation of both serotypes was proven by Koch's postulates using Swiss albino mice. Further, histopathological brain lesions along with the immunohistochemical detection of bacterial antigens were corroborated with natural cases of P. multocida as described above. To the best of our knowledge, we first time report the neuroinvasion of P. multocida in naturally infected pigs.