Haemorrhagic septicaemia is a disease caused by Pasteurella multocida serotype B: 2 and E: 2. The organism causes acute, highly fatal septicaemic disease with high morbidity and mortality in cattle and more susceptible in buffaloes. Lipopolysaccharide can be found on the outer cell wall of the organism. Lipopolysaccharide is released during multiplication which leads to inflammatory reaction. It represents the endotoxin of P. multocida type B: 2 and responsible for toxicity in haemorrhagic septicaemia which plays an important role in the pathogenesis of the disease. Therefore, the aim of this study was to investigate the clinical signs, blood parameters, gross post mortem lesions and histopathology changes caused by P. multocida type B:2 immunogen lipopolysaccharide infections initiated through intravenous and oral routes of infection. 9 buffalo heifers were divided equally into 3 treatment groups. Group 1 was inoculated orally with 10 ml of phosphate buffer saline (PBS); Group 2 and 3 were inoculated with 10 ml of lipopolysaccharide broth intravenously and orally respectively. For the clinical signs, there were significant differences (p < 0.05) in temperature between the control, intravenous and oral group. In hematology and biochemistry findings, there were significant differences (p < 0.05) in erythrocytes, haemoglobin, PCV, MCV, lymphocytes, monocytes, eosinophils, GGT and albumin between the control, intravenous and oral group. However, there were no significant differences (p > 0.05) in the MCHC, leukocytes, band neutrophils, basophils, thrombocytes, plasma protein, icterus index, total protein, globulin and A:G ratio between intravenous and oral group. For Group 2 buffaloes, there were gross lesions in the lung, trachea, heart, liver, spleen, and kidney. In contrast, lesions were only observed in the lung, trachea and liver of Group 3 buffaloes. There were significant differences (p < 0.05) in hemorrhage and congestion; necrosis and degeneration; and inflammatory cells infiltration between experimental groups and control group. However, there were no significant differences (p > 0.05) in edema lesion between groups. In conclusion, this study is a proof that oral route infection of P. multocida type B:2 immunogen lipopolysaccharide can be used to stimulate host cell responses where oral vaccine through feed could be developed in the near future.
Pasteurella multocida B:2 is a Gram-negative organism causing haemorrhagic septicaemia (HS) in buffaloes. It causes severe pulmonary infection, leading to infiltration of numerous macrophages and neutrophils. Despite the inflammatory response, buffaloes succumb to HS. This study aims to evaluate the in-vitro efficacy of macrophages and neutrophils of buffalo following exposure to P. multocida B:2. In-vitro infections were done using 107 cfu/ml of P. multocida B:2 for Group 1, Escherichia coli for Group 2 and Mannhaemia haemolytica A:2 for Group 3 cells. The inoculated cell cultures were harvested at 0, 30, 60 and 120 min post-exposure and the phagocytic, killing and cell death rates were determined. Both phagocytosis and killing rates of all bacteria increased over time. Phagocytosis involved between 71% and 73% neutrophils and between 60% and 64% macrophages at 120 min. Killing rate of all bacteria involved between 76% and 79% for neutrophils and between 70% and 74% for macrophages at 120 min. Death rate of neutrophils ranged between 67% in Group 3, and 88% in Group 1 at 120 min, significantly (p 0.05) than Group 2. Similar pattern was observed for death rate of macrophages. The phagocytosis and killing rates of P. multocida B:2 were similar to other bacterial species used in this study but more neutrophils and macrophages were dead following infection by P. multocida B:2 than M. haemolytica A:2.
One hundred and fourteen strains of Pasteurella multocida were isolated from different domestic animals species (cattle, buffalo, sheep, goat, pig, rabbit, dog, cat), avian species (chicken, duck, turkey) and wild animals (deer, tiger, orang utan, marmoset). The serogroups of P. multocida were determined by both conventional capsular serotyping and a multiplex PCR assay targeting specific capsular genes. Based on the conventional serotyping method, the 114 strains of P. multocida were subtyped into 55 species-specific (untypeable strains) P. multocida, 15 serogroup A, 23 serogroup B and 21 serogroup D. Based on the multiplex PCR assay on the specific capsular genes associated with each serogroup, the 114 strains were further divided to 22 species-specific P. multocida (KMT1 - 460 bp), 53 serogroup A (A - 1,044 bp), 33 serogroup B (B - 760 bp) and 6 serogroup D (D - 657 bp). No serogroup E (511 bp) or F (851 bp) was detected among the Malaysian P. multocida. PCR-based typing was more discriminative and could further subtype the previously untypeable strains. Overall, there was a significant and positive correlation between both methods in serogrouping P. multocida (r = 0.7935; p<0.4893). Various serogroups of P. multocida were present among the livestock with 75% of the strains belonging to serogroups A or B. PCR serotyping was therefore a highly species-specific, sensitive and robust method for detection and differentiation of P. multocida serogroups compared to conventional serotyping. To the best of our knowledge, this is the first report from Malaysia of the application of a PCR to rapidly define the species-specific P. multocida and its serogroups as an important zoonotic pathogen in Malaysia.
In vitro experiments were undertaken to study the adhesion and colonization to tracheal mucosa, lung and aorta explants from freshly killed rabbits of two different strains of Pasteurella multocida. Serotype A:3 (capsulated, fimbriae +, haemagglutination -, dermonecrotic toxin -) isolated from a rabbit with rhinitis, and serotype D:1 (non-capsulated, fimbriae +, haemagglutination +, dermonecrotic toxin +) isolated from a dead rabbit with septicaemia, were used. When the explants were observed under the scanning electron microscope, the type D strain was highly adherent to trachea and aorta explants compared to the type A strain. Adhesion to lung explants was best achieved by the type A strain after 45 min incubation, but after 2 h incubation no significant difference was observed between the strains. Our data indicate that the presence of fimbriae and the absence of capsule seem to enhance the adherence of P. multocida type D strain to tracheal tissue. The capsular material of P. multocida type A strain and the toxin of the type D strain seem to influence the adherence to lung tissue in rabbit. Adhesion of strain D to aorta may indicate the expression of receptors on the endothelium to that strain and may also explain the ability of certain strains to cause septicaemia.
This study aimed to determine the effect of intranasal exposure to low doses of Pasteurella multocida B:2 on survival of goats challenged with high doses of the same organism. Eighteen goats were selected and divided into three groups. Goats of group 1 were exposed intranasally twice, with a two-week interval, to 7 x 10(6) cfu/ml of live P. multocida B:2. Goats of group 2 were not exposed to P. multocida B:2 but were kept together with the exposed group 1. Goats of group 3 remained as unexposed controls and were kept separated from the other two groups. Serum samples were collected at weekly intervals to determine the antibody levels. At week 5 post exposure, all goats were challenged subcutaneously with 3.7 x 10(10) cfu/ml of live P. multocida B:2. Following challenge exposure, 8 (67%) goats (4 goats from each of groups 1 and 2) were killed owing to haemorrhagic septicaemia. Four goats were killed peracutely within 48 h post challenge, while the other four goats were killed acutely between 2 and 4 days post challenge. None of the goats of group 3 were killed for haemorrhagic septicaemia. Goats of groups 1 and 2 showed significantly (p < 0.05) higher antibody levels following the first intranasal exposure to P. multocida B:2. However, only group 1 retained the significantly (p < 0.05) high antibody levels following a second intranasal exposure, and remained significantly (p < 0.05) higher than groups 2 and 3 at the time of challenge. P. multocida B:2 was successfully isolated from various organs of goats that were killed between 1 and 4 days post challenge.
The objectives of this study were to determine the prevalence, characterization and antibiotic resistance of Pasteurella multocida isolated from calves with respiratory infection in Iran. P. multocida was detected in 141/169 bovine respiratory infection cases on Iranian dairy and beef farms. P. multocida were grouped into serogroups A (126/141), D (12/141), and B (3/141). Of the P. multocida isolates, all harboured the psl, ompH, oma87, fimA, ptfA, nanB, and nanH genes, 139/141 had hsf-2, and 115/141 pfhA, and tadD. The isolates were most frequently resistant to penicillin G (43/141 resistant isolates; 30.5%) and streptomycin (31/141; 22%).
Sixteen 8- to 9-week-old Pasteurella multocida-free New Zealand White rabbits were divided into two equal groups. The first group was inoculated intranasally with P multocida serotype D:1 strain and the second group that was inoculated with phosphate-buffered saline (PBS) only was used as a control group. Pasteurella multocida was isolated from the nasal cavity of all infected rabbits in group 1 and from tracheal swabs of seven rabbits in this group. Four rabbits in group 1 died with clinical signs of septicaemia, two rabbits had mucopurulent nasal discharge and pneumonic lesions and the other two did not show any clinical signs or gross lesions. The ultrastructural changes detected were deciliation or clumping of cilia of ciliated epithelium, cellular swelling, vacuolation and sloughing. The subepithelial capillaries showed congestion, intravascular fibrin deposition, platelets aggregation and endothelial injury. Pasteurella multocida was observed attached to the injured endothelial cells. Heterophils, mast cells, vacuolated monocytes and macrophages infiltrated the lamina propria and between the degenerated epithelial cells.