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This study was important to improve proper biosecurity measures and controlling the spread of Aeromonas to prevent future outbreaks. This research sought to determine whether virulent Aeromans species were present in morbid rainbow trout, their resistance and their genetic relatedness. A total number of 542 tissue lesion specimens were collected from gill, liver, heart and kidneys in morbid domesticated fish in Duhok province, Iraq. The gyrB DNA sequence analysis was used to determine the species classification. Drug susceptibility testing was conducted for all isolated strains using disc diffusion technique. The genotyping analysis was carried out using enterobacterial repetitive intergenic consensus-polymerase chain reaction. Thirty-four isolates were found and they were classified into three species (Aeromonas veronii, Aeromonas sorbia, and Aeromonas allosaccharophila), where A. veronii stand as one of the most prevalent species. The most frequently affected organ by Aeromonas was the gills among four different organs. The detection frequencies of the virulence genes aerolysin, outer membrane protein, glycerophospholipid-cholesterol acyltransferase, elastase, flagella, serine protease, cytotonic heat-labile, and hemolysin were 100%, 100%, 79.41%, 64.70%, 76.47%, 67.64%, 70.58%, and 41.17, respectively. None of the strains possessed all of the virulence markers. All isolates were completely resistant to ceftazidime, amoxicillin and doxycycline. All isolates were found to be multi-drug-resistant. Regardless of the nearest geographic source area of samples and the same Aeromonas species, there was a high genetic diversity. The results of this study could help farmers and researchers make informed decisions about measures of biosecurity and proper therapeutic drugs to apply to prevent current outbreaks and prevent them from recurring again. [ABSTRACT FROM AUTHOR]

Simple Summary: Hemorrhagic septicemia (HS) is an acute, fatal, and septicemic bacterial disease of cattle and buffaloes caused by Pasteurella multocida (P. multocida). The present study aimed to carry out HS surveillance through multi-stage random sampling constituting 692 cattle and buffalo serum samples sourced from two Indian states, four districts, eight clusters, 56 epiunits, and 306 households (HHs) by indirect enzyme-linked immunosorbent assay (iELISA). Significantly higher (p < 0.0001) iELISA positives were observed in Gujarat compared to Karnataka state. Of the 306 households visited, 9 of 27 epiunits (33.33%) in Karnataka and 24 out of 29 epiunits in Gujarat were iELISA positive (82.75%) and an association was found to be significant (p = 0.0002). However, a non-significant association to species, age, or lactation was recorded, although indigenous cattle breeds had a higher HS sero-prevalence compared to crossbreeds. This study highlights important baseline data on HS sero-prevalence in two major milk-producing states of India at different strata. Hemorrhagic septicemia (HS) is a highly contagious and fatal disease of cattle and buffaloes caused by P. multocida. Both conventional and molecular methods are applied in parallel for rapid diagnosis of HS outbreaks and the periodical surveillance strategy to identify risk areas for HS is ignored. The current cross-sectional study aimed to estimate sero-prevalence and associated risk factors for HS in cattle and buffaloes in non-vaccinated regions of two Indian states. HS surveillance was carried out through the multi-stage random sampling technique at different strata. The study employed a questionnaire incorporating host factors (species, breed, sex, age, and lactation) and demographic parameters (state, district, block/cluster and village/epiunits, and household). First, two Indian states known for high milk production were selected followed by two districts within each state, subsequently four clusters within each district, finally 5–10 epiunits within clusters and 5–8 households within clusters were randomly selected to collect cattle and buffalo samples. The chi-square/p values and maps were prepared to represent disease prevalence and to correlate disease risk factors at different strata. A total of 692 cattle and buffalo serum samples were sourced from two states of the country (Karnataka-285 and Gujarat-407). In the first strata, antibodies to P. multocida were high in Gujarat (14.49%, CI: 11.22–18.30) compared to Karnataka (3.85%, CI: 1.94–6.80) with significant (p < 0.0001) association between the states. In the second strata, one of the four districts investigated revealed the highest sero-prevalence (18.61%, CI: 13.81–24.24) with statistical significance (p = 0.01) between the districts. Among clusters, one out of eight clusters showed the highest sero-prevalence (23.02%, CI: 16.59–30.54) with statistical significance (p = 0.03) between the clusters in the third strata. At epiunit level (fourth strata), 9 out of 27 epiunits (33.33%) visited in Karnataka and 24 out of 29 epiunits sampled in Gujarat were sero-positive (82.75%) in iELISA. At the household level, out of 306 HH visited, 40 HH had at least one positive animal (13.07%) and the p value between HH in the two states was highly significant (p = 0.0002). Chi-square analysis did not find any association of HS sero-prevalence to species, age, and lactation. However, significantly higher (p < 0.05) sero-prevalence was recorded in indigenous cattle breeds (16.56%) compared to crossbreeds (6.59%). Various immunoprophylactics and antibiotic therapies are effective against HS, but inappropriate disease reporting and failure to implement adequate vaccination control measures are the gaps identified. The present study highlights the current scenario of HS sero-prevalence in two of the high milk-producing states of India, which will be useful for stakeholders for undertaking the implementation of surveillance and control strategies for the regions. [ABSTRACT FROM AUTHOR]

Background: Pasteurella multocida is a bacterial pathogen that causes a variety of infections across diverse animal species, with one of the most devastating associated diseases being hemorrhagic septicemia. Outbreaks of hemorrhagic septicemia in cattle and buffaloes are marked by rapid progression and high mortality. These infections have particularly harmful socio-economic impacts on small holder farmers in Africa and Asia who are heavily reliant on a small number of animals kept as a means of subsistence for milk and draft power purposes. A novel vaccine target, PmSLP-3, has been identified on the surface of hemorrhagic septicemia–associated strains of P. multocida and was previously shown to elicit robust protection in cattle against lethal challenge with a serogroup B strain. Methods: Here, we further investigate the protective efficacy of this surface lipoprotein, including evaluating the immunogenicity and protection upon formulation with a variety of adjuvants in both mice and cattle. Results: PmSLP-3 formulated with Montanide ISA 61 elicited the highest level of serum and mucosal IgG, elicited long-lasting serum antibodies, and was fully protective against serogroup B challenge. Studies were then performed to identify the minimum number of doses required and the needed protein quantity to maintain protection. Duration studies were performed in cattle, demonstrating sustained serum IgG titres for 3 years after two doses of vaccine and full protection against lethal serogroup B challenge at 7 months after a single vaccine dose. Finally, a serogroup E challenge study was performed, demonstrating that PmSLP-3 vaccine can provide protection against challenge by the two serogroups responsible for hemorrhagic septicemia. Conclusion: Together, these data indicate that PmSLP-3 formulated with Montanide ISA 61 is an immunogenic and protective vaccine against hemorrhagic septicemia-causing P. multocida strains in cattle. [ABSTRACT FROM AUTHOR]

P. multocida B: 2 is a Gram-negative, small, non-flagellated, pleomorphic coccobacillus. It does possess different types of outer membrane proteins (OMP’s) which assist in interaction with host cells. The outer membrane protein H (OmpH) of Pasteurella multocida B:2 is a major transmembrane porin that can be used as a subunit vaccine and development of diagnostic kit against hemorrhagic septicemia (HS) because of its immunogenic nature. Pasteurella multocida has economic importance because of endemic and epizootic diseases in domestic and wild animals. This bacterium is an opportunistic pathogen of upper respiratory tracts of wild and domestic animals and birds as well as in livestock . The ompH gene was amplified with in-house designed primers, the amplified gene (1002 bp) was cloned into pET 40-b (+) vector and transformed into E. coli BL21 (DE3) competent cells using heat shock transformation method to get expression. The product size was confirmed by restriction digestion. The rOmpH protein was purified by immobilized metal affinity chromatography by using His-Ni resins to get desired protein and characterized qualitatively by SDS-PAGE by using His antibodies and western blotting. Once purified the immunogenicity of rOmpH was evaluated in BALB/c mice. The expression of recombinant OmpH protein (rOmpH) resulted in its accumulation in cytosol. The purified rOmpH protein had a molecular weight of 36 kDa and concentration around 0.973 mg/mL. The BALB/c mice group injected with 100 ng of purified rOmpH exhibited significant protection (80%) when challenged with LD50 of P. multocida B:2. From the obtained results it is evident that rOmpH can be used as subunit vaccine against P. multocida B:2 and the purified rOmpH can also be further used to develop diagnostic test i.e., ELISA to screen and assess the immune response of cattle and buffaloes against P. multocida B:2 in developing countries like Pakistan. [ABSTRACT FROM AUTHOR]

BackgroundPasteurella multocida is a bacterial pathogen that causes a variety of infections across diverse animal species, with one of the most devastating associated diseases being hemorrhagic septicemia. Outbreaks of hemorrhagic septicemia in cattle and buffaloes are marked by rapid progression and high mortality. These infections have particularly harmful socio-economic impacts on small holder farmers in Africa and Asia who are heavily reliant on a small number of animals kept as a means of subsistence for milk and draft power purposes. A novel vaccine target, PmSLP-3, has been identified on the surface of hemorrhagic septicemia–associated strains of P. multocida and was previously shown to elicit robust protection in cattle against lethal challenge with a serogroup B strain.MethodsHere, we further investigate the protective efficacy of this surface lipoprotein, including evaluating the immunogenicity and protection upon formulation with a variety of adjuvants in both mice and cattle.ResultsPmSLP-3 formulated with Montanide ISA 61 elicited the highest level of serum and mucosal IgG, elicited long-lasting serum antibodies, and was fully protective against serogroup B challenge. Studies were then performed to identify the minimum number of doses required and the needed protein quantity to maintain protection. Duration studies were performed in cattle, demonstrating sustained serum IgG titres for 3 years after two doses of vaccine and full protection against lethal serogroup B challenge at 7 months after a single vaccine dose. Finally, a serogroup E challenge study was performed, demonstrating that PmSLP-3 vaccine can provide protection against challenge by the two serogroups responsible for hemorrhagic septicemia.ConclusionTogether, these data indicate that PmSLP-3 formulated with Montanide ISA 61 is an immunogenic and protective vaccine against hemorrhagic septicemia-causing P. multocida strains in cattle.

Hemorrhagic septicemia (HS) is a highly contagious and fatal disease of cattle and buffaloes caused by P. multocida. Both conventional and molecular methods are applied in parallel for rapid diagnosis of HS outbreaks and the periodical surveillance strategy to identify risk areas for HS is ignored. The current cross-sectional study aimed to estimate sero-prevalence and associated risk factors for HS in cattle and buffaloes in non-vaccinated regions of two Indian states. HS surveillance was carried out through the multi-stage random sampling technique at different strata. The study employed a questionnaire incorporating host factors (species, breed, sex, age, and lactation) and demographic parameters (state, district, block/cluster and village/epiunits, and household). First, two Indian states known for high milk production were selected followed by two districts within each state, subsequently four clusters within each district, finally 5–10 epiunits within clusters and 5–8 households within clusters were randomly selected to collect cattle and buffalo samples. The chi-square/p values and maps were prepared to represent disease prevalence and to correlate disease risk factors at different strata. A total of 692 cattle and buffalo serum samples were sourced from two states of the country (Karnataka-285 and Gujarat-407). In the first strata, antibodies to P. multocida were high in Gujarat (14.49%, CI: 11.22–18.30) compared to Karnataka (3.85%, CI: 1.94–6.80) with significant (p < 0.0001) association between the states. In the second strata, one of the four districts investigated revealed the highest sero-prevalence (18.61%, CI: 13.81–24.24) with statistical significance (p = 0.01) between the districts. Among clusters, one out of eight clusters showed the highest sero-prevalence (23.02%, CI: 16.59–30.54) with statistical significance (p = 0.03) between the clusters in the third strata. At epiunit level (fourth strata), 9 out of 27 epiunits (33.33%) visited in Karnataka and 24 out of 29 epiunits sampled in Gujarat were sero-positive (82.75%) in iELISA. At the household level, out of 306 HH visited, 40 HH had at least one positive animal (13.07%) and the p value between HH in the two states was highly significant (p = 0.0002). Chi-square analysis did not find any association of HS sero-prevalence to species, age, and lactation. However, significantly higher (p < 0.05) sero-prevalence was recorded in indigenous cattle breeds (16.56%) compared to crossbreeds (6.59%). Various immunoprophylactics and antibiotic therapies are effective against HS, but inappropriate disease reporting and failure to implement adequate vaccination control measures are the gaps identified. The present study highlights the current scenario of HS sero-prevalence in two of the high milk-producing states of India, which will be useful for stakeholders for undertaking the implementation of surveillance and control strategies for the regions.

Outer membrane proteins (OMPs) of Pasteurella multocida play an important role in virulence and are important for vaccine development due to immunogenicity. Here, we evaluated immunoprotection in mice, immunized with native OmpH, recombinant OmpH and HS alum precipitated vaccine of P. multocida P52 against P. multocida challenge. Protection studies were performed in mice of groups I (OmpH); II (recombinant OmpH); and III (HS alum precipitated vaccine). Group IV was control group administered with sterile PBS. The protection percentage was recorded as 83.33% protection in Gr. I & III, and 66.66% in Gr. II. The control group (Gr. IV) showed 100% mortality. The mean antibodies titers were detected at day 7, 14, 21 and 28 postimmunization, and compared with the control group. All immunized groups showed significantly high immune protection compared to the control group. [ABSTRACT FROM AUTHOR]

Outer membrane proteins (OMPs), usually found in Gram-negative bacteria, have long been shown to elicit immune responses in infected hosts. This tendency of OMPs to generate immune reactions makes them ideal candidates for vaccine development against pathogenic bacteria. Pasteurella multocida is a Gram-negative pathogen responsible for the economically significant veterinary disease, hemorrhagic septicemia (HS). HS is an endemic and highly fatal disease affecting buffaloes and cattle. In Malaysia, outbreaks of this disease cost about half a million USD each year. Thus, despite current treatment and prevention measures, HS is a prevalent issue that needs to be overcome. Pasteurella multocida subsp. multocida PMTB2.1, a Malaysian strain of the pathogen, has recently had its entire genome sequenced after being isolated from HS outbreaks in the region. Antigenic OMPs from this strain have since been identified and published for further characterisation. LptD, Wza, and TbpA are integral membrane proteins, while Pal is a peripheral membrane protein that has not been characterised in-depth. This study, therefore, aims to analyse these OMPs through in silico methods. First, protein homology modelling was performed using SWISS-MODEL, whereafter, the structures generated were validated using the SWISS-MODEL structure assessment page, PROCHECK, ERRAT, and PROSA programs. The Pal, Wza, and TbpA structures were good models, while the LptD structure was found to be a near-good model based on the validation performed. Analyses using BCPREDS, NetMHCpan4.1, and NetBoLAIIpan1.0 revealed that these four OMPs could potentially elicit humoral and cellular immune responses. [ABSTRACT FROM AUTHOR]

Pasturella multocida (P. multocida) , a gram-negative bacterium, has long been a focus of interest in animal health because of its capacity to cause different infections, including hemorrhagic septicemia. Yaks, primarily found in high-altitude environments, are among the several livestock animals affected by these bacteria. Yaks are essential to the socioeconomic life of the people who depend on them since they are adapted to the cold and hypoxic conditions of highland environments. Nevertheless, these terrains exhibit a greater incidence of P. multocida despite the severe environmental complications. This predominance has been linked to the possible attenuation of the yak's immunological responses in such circumstances and the evolution of some bacterial strains to favor survival in the respiratory passages of the animals. Moreover, these particular strains threaten other cattle populations that interact with yaks, which might result in unanticipated outbreaks in areas previously thought to be low risk. Considering these findings, designing and executing preventative and control strategies suited explicitly for these distinct biological environments is imperative. Through such strategies, yaks' health will be guaranteed, and a larger bovine population will be safeguarded against unanticipated epidemics. The current review provides thorough insights that were previously dispersed among several investigations. Its distinct method of connecting the ecology of yaks with the dynamics of infection offers substantial background information for further studies and livestock management plans. [Display omitted] • P. multocida threatens yak health in high-altitude areas due to weakened immune responses. • Unique strains of the bacterium adapt to yak respiratory passages, posing risks to other cattle. • Environmental factors exacerbate P. multocida prevalence despite harsh conditions. [ABSTRACT FROM AUTHOR]

The present study was conducted to determine the antibacterial resistance profile of Aeromonas hydrophila (n = 42) isolated from the 100 hemorrhagic septicemia‐suspected carp in Gilan, Iran. The prevalence of class 1 and 2 integrons, antibiotic resistance genes (ARG) and virulence factor genes (VFG) among these isolates was investigated using PCR. Also, the possible association between the presence of VFGs and the antibiotic resistance profile of isolates was assessed. The majority of A. hydrophila isolates (83·33%) exhibited multi‐drug resistance (MDR) profile, and all isolates were resistant to clindamycin, while all isolates were susceptible to amikacin. intI1 and intI2 gene was found in 26·2 and 4·8% isolates, respectively. This is the first report of the presence of the intI2 gene in A. hydrophila isolates in Iran. The blaTEM (40·5%) and tetA (33·3%) genes were found as the predominant ARGs. The most frequently detected VFGs were lip and ahh1(90·5%), while the examined isolates carrying at least three VFGs and the most prevalent VFGs profile was ast+, act+, alt+, ahhl+, aerA+, ahyB+ and lip+. The results of this study indicate a positive association between the presence of VFGs and antibiotic resistance, and most MDR A. hydrophila isolates showed high frequencies of VFGs. [ABSTRACT FROM AUTHOR]

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Hemorrhagic septicemia (pasteurellosis) in animals, caused by Pasteurella multocida Trevisan 1887, is a significant but previously undocumented disease in Mongolian camels. Pasteurella multocida , a small Gram-negative coccobacillus, typically exists commensal in the nasopharynx of camels but can cause severe illness under certain environmental stressors. This study reports the first case of cameline hemorrhagic septicemia in Gobi region of Mongolia, specifically in Umnugobi province, where acute septicemia affected 26 camels, resulting in 10 deaths within 24-48 hours. Clinical signs included depression, inappetence, lethargy, increased rectal temperature, and paralysis of the lower lip. Surviving camels responded to treatment with Lactate Ringer solution and antibiotics. Postmortem examinations revealed acute pulmonary congestion and necrotic liver. Molecular diagnostic test, PCR, confirmed the presence of P. multocida with the identification of the KMT1 gene. This case underscores the potential for significant economic losses due to hemorrhagic septicemia in camels and highlights the need for early detection and treatment to mitigate its impact. The initial attempt at implementing a vaccination program effectively controlled the potential further outbreak. This study emphasizes the importance of continuous surveillance and preventive measures in managing hemorrhagic septicemia in livestock., Competing Interests: Conflict of interests: The authors declare no conflicts of interest.

Background: Bacterial diseases in aquaculture fishes are one of the most important risk factors in fish industry. Aeromonas hydrophila is the main causative agent of hemorrhagic septicemia in warm-water fishes, especially Cyprinidae that plays an important role in public health through consumption of contaminated fish meat that can cause gastroenteritis, traveler’s diarrhea, wound infection, pneumonia, and meningitis. Considering the importance of culturing Cyprinidae in Gilan province and the need to identify and detect the presence of A. hydrophila in Cyprinidae fishes suspected with hemorrhagic septicemia, this study aimed to isolate and identify A. hydrophila in Cyprinidae fishes suspected with hemorrhagic septicemia in Gilan province.Methods: In this Experimental study, during summer and autumn of 2020 by referring to 71 different warm fish farms of Gilan province, 100 specimens of Cyprinidae fishes were collected. A. hydrophila strains were isolated from the surface wounds (n=15) and kidney (n=85) of fish suspected to hemorrhagic septicemia by inoculation of samples on blood and MacConkey agar media.Results: Among samples from fish kidneys and skin wounds, 51 samples were positive for A. hydrophila. Forty two isolates were confirmed as A. hydrophila by PCR technique using specific primers which targeted 16S rDNA gene fragment.Conclusion: Due to the significant role of A. hydrophila in Cyprinidae mortality in Gilan province, preventive and diagnostic strategies are necessary to control the occurrence of hemorrhagic septicemia by undertaking identification tests of A. hydrophila in fish pools that can reduce costs in fish industry management.

Diseases represent a serious setback in cultured fish by directly affecting production and causing serious economic losses. Early detection and precise identification of pathogens by polymerase chain reaction (PCR) can help in the selection of preventive and early treatment measures and reduce the losses. In this study, a multiplex PCR assay was demonstrated for simultaneous detection of Edwardsiella tarda and Aeromonas hydrophila. The primer pairs of the major fimbrial subunit (etfA) gene from type I fimbrial gene cluster of E. tarda (415 bp) and cytotoxic enterotoxin (act) gene of A. hydrophila (232 bp) were selected as targets. The multiplex PCR using the target genes simultaneously detected E. tarda and A. hydrophila in different organs (muscle, spleen, liver, and head kidney) of challenged Pangasius pangasius. This method was also capable of simultaneously detecting E. tarda and A. hydrophila in naturally infected catfish, thus indicating mixed bacterial infection in 37.50 % of the diseased population. The results suggested the usefulness of etfA and act genes for the rapid detection of mixed A. hydrophila and E. tarda infection in diseased catfish, irrespective of species. The multiplex PCR method can be useful in commercial aquaculture for performing routine disease diagnosis and detection of these bacterial pathogens. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila is a bacterium associated with many diseases and disorders such as fin rot, skin ulcers and lethal hemorrhagic septicemia in fish. It bears several virulence factors including type III secretion system (T3SS), aerolysin, cytolytic enterotoxin and enzymes (e.g., hemolysins, lipase) that seem to play an important role in its pathogenesis. Detection of virulence markers by polymerase chain reaction (PCR) is a key procedure in defining the pathogenic ability of pathogenic bacteria and preparing a vaccine for its treatment. In this sense, this study was aimed to determine the frequency of virulence genes in isolates obtained from infected cultured carps in Khuzestan province. Out of 200 moribund carps with septicemic symptoms, 125 isolates were belonged to the motile aeromonads and 59 isolates were identified as A. hydrophila by biochemical methods. Finally, using PCR analysis, 31 isolates were identified as A. hydrophila. Five virulence genes were detected in these isolates including hemolysin, aerolysin, cytolytic enterotoxin and T3SS (aopB and ascV) by specific primers. Results showed that 23 (74.19%), 18 (58.06%), 16 (51.61%), 13 (41.63%) and 10 (32.25%) isolates possessed cytolytic enterotoxin, hemolysin, aerolysin, and T3SS genes, respectively. The results of the present study showed that among 31 isolates, only five isolates had all of dominant virulence genes. Thirteen other isolates had genotypes including hlyA+, aerA+, and act+. The remaining isolates had at least one virulence gene. This study showed that determination of the virulence genes by PCR can be a reliable method to identify a potential pathogenic Aeromonad strain. [ABSTRACT FROM AUTHOR]

The significance of Aeromonas hydrophila concerning hemorrhagic septicemia in aquaculture farms production in Duhok province, Iraq was investigated. Antibiotic-resistant profiles of isolates were also investigated with 8 antibiotics. Bacterial isolates were identified by using morphological and biochemical tests and confirmed molecularly by amplification of gcat gene. Out of 25 examined fish, only 19 fish were harbored A. hydrophila. Twenty-four A. hydrophila strains were isolates from 100 organ samples. Ninety-six percentages of the isolates were resistant to each of the imipenem and gentamicin, followed by doxycycline 92%, ciprofloxacin and trimethoprim-sulfamethoxazole 88%, norfloxacin 58% and ceftriaxone 33%. None were resistant to levofloxacin. Eighty-eight percentages were multiple antibiotics resistant. The high isolation rate of A. hydrophila in our study indicates that this species was the major cause of the outbreak in hemorrhagic septicemia’s cases in our area affecting carp farms and the high rate of resistance should be considered as these isolates can serve as a resistance source for human being during food series and make a great challenge for their therapeutic opportunity.

Abstract Background Pasteurella 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. Results Seventy-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. Conclusions In 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.

Modern climatic changes, weakening of the anthropogenic pasture load, and an increase in steppe fires have led to the expansion and dominance of grasses (graminoids) vegetation on the steppe pastures of Russia and Kazakhstan since the end of the 20th century. This resulted in deterioration of the forage quality of pasture vegetation, a factor in the depression of the saiga population that may have affected the increase in cases of saiga die-offs. A die-off occurred in Kazakhstan in 2015, when about 200 000 animals died. A large number of different versions have been put forward about the reasons for these deaths: an infectious disease (hemorrhagic septicemia), toxic forage plants, unfavorable weather conditions, and the destructive effect of rocket fuel. In this article, we consider a different version of death associated with the negative effect of low-quality food on the sites of saiga death. It is shown that the food supply for saigas on steppe pastures consistently decreases with an increase in the abundance of grasses in forage vegetation. Suitable, nutritious food for breeding saigas include pastures in which the share of grasses in the aboveground phytomass is no more than 30%. If this level is exceeded, the pastures do not provide the necessary level of nutrition for breeding saigas and are unsuitable for them. It is possible that the saigas found themselves during spring migration in steppe regions with a predominance of turf grasses (65–75%), which exceeds their permissible (threshold) abundance (30%). This pasture condition did not provide the necessary nutrition, caused a weakening of animals during the rearing period, and promoted the activation of infectious septicemia in breeding saigas, which, with the combined action of both factors, may have led to their die-off. [ABSTRACT FROM AUTHOR]

Buffaloes and other bovines suffer from a fatal disease, "Hemorrhagic septicemia" (HS), which is produced by a gram-negative bacterium "Pasteurella multocida." Existing literature has established bacteria's pathogenesis, but still, the literature about the role of bacteria and its immunogens on the demonstration of clinical signs, hematology and serum biochemistry in Nili Ravi buffaloes under subtropics is lacking. This study was designed to fulfill this gap by analyzing the effects of exposure to the bacterial culture of Pasturella multocida (P. multocida) type B:2 and its immunogens, i.e., lipopolysaccharide (LPS) and outer membrane protein (OMP) on Nili Ravi buffaloes. Prepubertal Nili Ravi female buffaloes (N=18) of 10-12 months age in good health condition were divided into five treatment groups (n=3 each) and a control group (n=3). Treatment groups' animals were exposed to P. multocida bacterial culture and its immunogens, i.e., LPS (oral and intravenous) and OMP (oral and subcutaneous). Animals were analyzed for the development of clinical signs, hematology and serum biochemistry. All treatment groups exhibited clinical signs (ranging from mild to acute) like increased temperature, variation in rumen motility, mucous membrane, salivation, edema, dullness, depression, nasal discharge, respiratory distress and recumbence or death. A significant change in complete blood count (CBC) including packed cell volume (PCV), hemoglobin (Hgb) concentration, red blood cells (RBCs) count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC) platelets count, mean platelet volume (MPV), white blood cells (WBCs) count, monocytes count, lymphocytes count and granulocytes count. Serum biochemistry profiles (total protein, Albumin and creatinine) of treatment group animals were also changed significantly. Cumulatively it was revealed that P. multocida B: 2 and its Immunogens (LPS and OMP) affect the hematology and serum biochemistry profiles of Neeli-Ravi buffaloes. These findings prove that OMP and LPS from P. multocida B: 2 may be considered for vaccine development. [ABSTRACT FROM AUTHOR]

Pasteurella multocida causes hemorrhagic septicemia (HS), an acute, often fatal, septicaemic disease in ruminants. It is commonly observed in the world's tropical regions, especially in Asian and African countries. In the present study, eleven blackbucks (Antilope cervicapra) were diagnosed positive for hemorrhagic septicemia by using Leishman stain of blood smear showing bipolar organisms. The blackbucks were treated with bolus sulphadimidine @ 5 gm, powder uniselit @ 5 gm and liquid ostovet @ 25 mL per animal/day for seven days and after that bolus sulphadimidine @ 2.5 gm was given for the next three days. Following treatment eight blackbucks recovered and became normal. A post-mortem examination was performed on three blackbucks one died on first day and two blackbucks on the third day, which confirmed the changes typical of HS in lungs, liver and kidneys. [ABSTRACT FROM AUTHOR]

Aeromonosis is an infectious disease of high occurrence in captive fish. It manifests mainly as hemorrhagic septicemia. This study aimed to evaluate the physiopathology manifestations of septic aeromonosis in Piaractus mesopotamicus, considering its clinical manifestations, mortality rates, anatomopathology, and anti-iNOS immunolabeling in the brain. Fish were inoculated in the coelomic cavity with increasing concentrations of A. hydrophila: 1.5 × 108; 1.8 × 108; 2.1 × 108; 2.4 × 108; 2.7 × 108 CF mL−1, histopathology, and anti-iNOS immunolabeling in brain. The animals present erratic swimming (swirling), depigmentation, petechiae, skin suffusions, and high mortality rates up to 100% according to the inoculum concentration. The DL50-96 h was estimated in 1.806 × 108 CFU mL−1. Fish inoculated with 2.1 × 108 CFU mL−1 presented 100% mortality rate. Fish presented neurological signs, congestion, extensive hemorrhage, and glial cells activity confirmed by the anti-iNOS labelling. In addition, the inoculated bacteria was reisolated from the brains. The results demonstrated that aeromonosis physiopathology is multifactorial and the observed neurological signs were caused by the inoculated bacteria. These findings highlight the need for differential diagnosis with other infections that produce encephalitis. [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate sensitivity (Se) and specificity (Sp) of a novel enzyme-linked immunosorbent assay (ELISA) test (using a coating antigen from Pasteurella multocida M-1404 via heat extraction) and an indirect hemagglutination (IHA) test for detection of Hemorrhagic septicemia (HS) in dairy cows, under Thai conditions, using a Bayesian approach. Dairy cow sera with a total of 1236 samples from 44 farms were tested with the two tests to detect immune responses against the HS. Percentages of positive samples for the ELISA and IHA tests were 73% (901/1236) and 70% (860/1236), respectively. Estimated sensitivity and estimated specificity of the ELISA test were 90.5% (95% posterior probability interval (PPI) = 83.2-95.4%) and 70.8% (95% PPI = 60.8-79.8%), respectively. Additionally, estimates for the Se and Sp values of the IHA test were 77.0% (95% PPI = 70.8-84.1%) and 51.1% (PPI = 36.8-66.3%), respectively. The estimated prevalence of the disease was 71.7% (95% PPI = 62.7-82.6%). These results demonstrate that the ELISA test can be a useful tool for the detection of the presence of an antibody against the HS in dairy cows. Notably, the cows in this area indicated a high percentage of exposure to Pasteurella multocida. [ABSTRACT FROM AUTHOR]

Hemorrhagic septicemia (HS) caused by Pasteurella multocida B:2 and E:2 is among the fatal bacterial diseases in cattle and buffaloes that are economically valuable in Asian and African countries. The current work aims to study the prevalence of HS among buffaloes, cattle, sheep, and goats in 41 countries in 2005–2019. The data analysis revealed that 74.4% of the total infection rate in the world was distributed among cattle, followed by buffaloes (13.1%). The mortality of HS among cattle and buffaloes increased in 2017–2019 compared to the period between 2014 and 2016. The best measure to control the disease is through vaccination programs. Current commercial vaccines, including live-attenuated vaccines and inactivated vaccines, have some shortcomings and undesirable effects. Virus-like particles (VLPs) have more potential as a vaccine platform due to their unique properties to enhance immune response and the ability to use them as a platform for foreign antigens against infectious diseases. VLPs-based vaccines are among the new-generation subunit vaccine approaches that have been licensed for the human and veterinary fields. However, most studies are still in the late stages of vaccine evaluation.

Hemorrhagic septicemia is a highly fatal, acute septicemic disease in buffaloes and cattle caused by Pasteurella multocida (Shivachandra, et al., 2008). A lactating non-pregnant 2-year old Holstein-Friesian x Jersey imported cow weighing 423 kg (BCS 3/5) was observed to be exhibiting tachypnea, hyper salivation, and edema on the neck and thorax on October 9, 2017. As hypocalcemia or acidosis was suspected, medication and prescription given were according to these two metabolic disorders. On October 20, 2017, a blood sample was collected which resulted in a positive Pasteurella multocida antibody ELISA test. Long-acting oxytetracycline (200 mg/mL) was injected IM once the following day. On October 24, the patient exhibited nasal flaring with clear discharge, frothy tachypnea, pyrexia, sunken orbits, and dullness while standing. Medication and prescription given were 10% marbofloxacin (2 mg/kg) IM once daily for three days and tolfenamic acid (2mg/kg) IM once. Unfortunately, the cow died the following morning. Upon necropsy, the significant gross lesions were neck and brisket swelling, lung consolidation, pneumonia, and petechial hemorrhages on the heart. This disease could have been prevented through vaccination and strict biosecurity. [ABSTRACT FROM AUTHOR]

Background: Pasteurella 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. Results: Seventy-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. Conclusions: In 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. [ABSTRACT FROM AUTHOR]

Les fistules carotidocaverneuses sont une pathologie peu fréquente, le plus souvent dues à un violent traumatisme de l'étage antérieur de la base du crâne. Ces fistules post-traumatiques se traduisent par une symptomatologie bruyante faite d'une exophtalmie pulsatile avec un chémosis hémorragique associé à des signes neurologiques non spécifiques (céphalées, acouphène, etc.) – et ce contrairement aux fistules spontanées, dont le tableau clinique reste plus discret. Le diagnostic positif est d'abord orienté par le scanner orbitaire, éliminant les autres causes d'orbitopathies inflammatoires (Basedow), puis confirmé par l'artériographie qui permet de classer la fistule, selon la classification de Barrow, en fistules directe/indirecte (branches méningées de la carotide interne et/ou carotide externe), haut débit/bas débit. Le traitement actuel des fistules repose sur l'embolisation par ballonnet par voie artérielle ou coils par voie veineuse. L'abstention thérapeutique est parfois préférée pour les fistules à bas débit, qui peuvent se thromboser spontanément, contrairement aux fistules à haut débit qui peuvent mettre en jeu le pronostic vital et fonctionnel en l'absence de traitement. [ABSTRACT FROM AUTHOR]

The global ornamental fish trade carries important risk factors for spreading pathogens between different countries and regions, not only for ornamental fish but also for cultured fish and even other animal species. In the current study, we reported the capacity of Aeromonas veronii and A. hydrophila isolated from ornamental fish to experimentally infect the reared Amazonian fish Colossoma macropomum. For this, those bacteria were identified, and a primary characterization was performed. Fish were inoculated with 0.1 mL of increasing concentrations of A. hydrophila or A. veronii (C1 = 1 × 102; C2 = 1.8 × 104; C3 = 2.1 × 106; C4 = 2.4 × 108 bacterial cells per mL) in the coelomic cavity. In the control group, fish received the same volume of sterile saline solution (0.9 %). Fish presented petechiae, skin suffusions, and mortality rates up to 100 % according to the inoculum concentration. Histopathologically, fish presented necrosis with karyolysis, loss of the cytoplasmic delimitation of cells of the renal tubules and hepatocytes, hemorrhage, cellular edema, and the presence of bacterial cells. The LD 50–96h of A. veronii on C. macropomum was estimated at 2.4 × 106 CFU mL−1 and of A. hydrophila at 1.408 × 105 CFU mL−1. The results demonstrated that it is possible that Aeromonas species isolated from ornamental fish affect C. macropomum, causing similar clinical signs and lesions. This shows the importance of promoting risk control measures worldwide regarding the trade of ornamental fish. • Aeromonas species from ornamental fish can infect Colossoma macropomum, the most produced Amazonian fish species. • The mortality rate can reach up to 100 % when C. macropomum is experimentally infected with A. hydrophila or A. veronii. • Ornamental fish trade is a major risk factor for disease transmission in aquaculture. [ABSTRACT FROM AUTHOR]

Abstract Background Hemorrhagic septicemia is a fatal disease of cattle and buffaloes caused by P. multocida. Although the pathogenesis of the bacteria has been well established in literature, there is a paucity of information on the possible role of the bacteria and its immunogens; lipopolysaccharide (LPS) and outer membrane proteins (OMPs) on the reproductive capacity of buffalo heifers. Methods In this study, twenty one healthy prepubertal female buffaloes aged 8 months were divided into seven groups of 3 buffaloes each (G1-G7). Group 1 (G1) served as the negative control group and were inoculated orally with 10 mL sterile Phosphate Buffer Saline (PBS), groups 2 (G2) and 3 (G3) were inoculated orally and subcutaneously with 10 mL of 1012 colony forming unit (cfu) of P.multocida type B: 2, while groups 4 (G4) and 5 (G5) received 10 mL of bacterial LPS orally and intravenously, respectively. Lastly, groups 6 (G6) and 7 (G7) were orally and subcutaneously inoculated with 10 mL of bacterial OMPs. Whole blood was collected in EDTA vials at stipulated time points (0, 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, 120, 168, 216, 264, 312, 360, 408, 456 and 504 h), while tissue sections of the pituitary glands were collected and transported to the histopathology laboratory in 10% buffered formalin for processing and Hematoxylin and eosin staining. Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), progesterone (PG), estradiol (EST) and gonadotrophin releasing hormone (GnRH) were determined. Results The histopathological lesions observed in the pituitary gland included hemorrhage, congestion, inflammatory cell infiltration, hydropic degeneration, necrosis and edema. These changes were higher (p

Abstract Mass mortality events in wildlife are a growing concern. Under conditions of rapid global change, opportunistic responses in bacterial commensals, triggered by environmental stressors, may be increasingly implicated in die‐offs. In 2015, over 200,000 saiga antelope died of hemorrhagic septicemia caused by the pathogen Pasteurella multocida serotype B. We use this case to explore die‐offs from commensal bacteria more broadly, looking at factors which might favor such extreme events. We review other recorded disease outbreaks caused by Pasteurellaceae organisms, firstly in saiga and secondly in other wild ungulates, and ask whether the 2015 die‐off was unprecedented in terms of mortality rates, numbers dead, spatial scale, and in the nature of the predisposing or environmental factors involved. We also compare these outbreaks with mass mortality events associated with commensal bacteria in wildlife more generally. We identify three additional major die‐offs in saiga in which Pasteurellaceae organisms may be implicated, of which one in 1988 closely resembles the 2015 hemorrhagic septicemia event. No other recorded cases in wild ungulates approach the magnitude of these cases for any of the metrics considered, possible exceptions being die‐offs in Mongolian gazelles, in which the role of these pathogens is poorly substantiated. Environmental triggers were the most commonly suggested factor leading to pathogenesis, with warm humid conditions most commonly associated with hemorrhagic septicemia. Life history may also be significant—saigas are migratory and the largest pasteurellosis outbreaks outside this species also occur in migratory species of bird or other temperate ungulates aggregating in large numbers. Cases provoked by other commensals tend to be small in magnitude. Exceptions involve interactions between multiple pathogens and climatic conditions or sets of climatic conditions acting on different stages of the host–pathogen life cycle, leading to time lags between infection and subsequent disease. Overall, the scale and rapidity of the saiga die‐offs appear unprecedented among mortality events caused by bacterial commensals in wild mammals. Experimental research into the genetics and microbiology of host–pathogen interactions upon changes in the external environment, and monitoring of animals and conditions at calving sites, may eventually reveal the underlying causes of these die‐offs.

The article focuses on transcription profiles of skin and head kidney from goldfish suffering hemorrhagic septicemia with an emphasis on the Toll-like Receptors (TLR) signaling pathway. It mentions that quantitative polymerase chain reaction (qPCR) was carried out to measure irf3 gene expression with the iTaq Universal SYBR Green Supermix.

In piggery, septic pasteurellosis caused by Pasteurella multocida (B:2) is an issue of concern, which needs an effective vaccine. Here, we prepared a double emulsified (DE) vaccine containing 2.5 mg inactivated antigenic mass of pig field strain (B:2) (named as soron) isolated from an outbreak of septicaemic death in pigs and P. multocida P52 cattle strain (B:2) and studied their efficiency in terms of immunity to direct challenge, duration of immunity and the role of humoral and cellmediated immunity. Both of these strains showed presence of hgbB, pfhA, nanH, ptfA, and tbPA virulence genes. The sequence analysis of bands of 760 bp product using capsular primers were obtained for soron and P52 revealed 99.2% homology between these two strains, indicating differences at genetic level. nanH and pfhA genes of soron shared 99.2% and 92.7% homology with P52, respectively suggesting differences between these two strains at genetic level. SDS-PAGE analysis of cell wall of both strains showed presence of about 15 major protein bands whereas Western blot analysis with 21 day soron immunized pig serum showed 16, 33, 47, 63 and 83 kDa polypeptides in both strains. The duration of immune responses were monitored at 3, 6 and 9 months post immunization in pigs. By direct challenge, pigs showed that the vaccines were protective at 21 days and up to 270th day post immunization. Vaccines induced a serum ELISA IgG response that peaked on 60 DPI which declined gradually up to 270th DPI in both vaccines. Stimulation index measured by lymphocyte proliferation test (LTT) indicated that the vaccine, induced cell-mediated immune response and in general percent stimulation index (SI) was higher in pigs immunized with soron vaccine at 15 days post challenge infection. The results showed that pig strain (soron) would be a potential homologous strain of P. multocida for the vaccine against pasteurellosis in place of use of cattle P. multocida P52 strain. [ABSTRACT FROM AUTHOR]

Hemorrhagic septicemia (HS) is an acute septicemic disease principally affecting cattle and buffaloes caused by specific serotypes B:2 and E:2 of Pasteurella multocida in Asia and Africa, respectively. Despite continuing researches on pathogenesis of P. multocida for several decades, the mechanisms by which these bacteria develop the diseases are poorly understood. Although the involvement of the nervous system in the disease progress of HS is rare under natural conditions, few reports indicated the involvement of the nervous system in outbreaks of HS in cattle and buffaloes. Additionally, recent pathogenesis studies in both mouse and buffalo experimental models reported the involvement of nervous system due to P. multocida B:2, with bacteriological and histopathological evidences. In this review, we summarized and discussed the updates on the involvement of the nervous system in pathogenesis of HS focusing on clinical signs, pathological and pathophysiological changes. [J Adv Vet Anim Res 2015; 2(3.000): 252-262]

Abstract Aliivibrio salmonicida is the causative agent of cold-water vibriosis, a hemorrhagic septicemia of salmonid fish. The bacterium has been shown to rapidly enter the fish bloodstream, and proliferation in blood is seen after a period of latency. Although the pathogenesis of the disease is largely unknown, shedding of high quantities of outer-membrane complex VS-P1, consisting of LPS and a protein moiety, has been suggested to act as decoy and contribute to immunomodulation. To investigate the role of LPS in the pathogenesis, we constructed O-antigen deficient mutants by knocking out the gene encoding O-antigen ligase waaL. As this gene exists in two copies in the Al. salmonicida genome, we constructed single and double in-frame deletion mutants to explore potential effects of copy number variation. Our results demonstrate that the LPS structure of Al. salmonicida is essential for virulence in Atlantic salmon. As the loss of O-antigen did not influence invasive properties of the bacterium, the role of LPS in virulence applies to later stages of the pathogenesis. One copy of waaL was sufficient for O-antigen ligation and virulence in experimental models. However, as a non-significant decrease in mortality was observed after immersion challenge with a waaL single mutant, it is tempting to suggest that multiple copies of the gene are beneficial to the bacterium at lower challenge doses. The loss of O-antigen was not found to affect serum survival in vitro , but quantification of bacteria in blood following immersion challenge suggested a role in in vivo survival. Furthermore, fish challenged with the waaL double mutant induced a more transient immune response than fish challenged with the wild type strain. Whether the reduction in virulence following the loss of waaL is caused by altered immunomodulative properties or impaired survival remains unclear. However, our data demonstrate that LPS is crucial for development of disease. Highlights • LPS structure is essential for the virulence of Al. salmonicida. • Invasion of Atlantic salmon does not depend on LPS. • LPS contributes to the immune response raised towards Al. salmonicida. [ABSTRACT FROM AUTHOR]

Pasteurella multocida is a gram-negative, non-motile bacterial pathogen, which is associated with chronic and acute infections as snuffles, pneumonia, atrophic rhinitis, fowl cholera and hemorrhagic septicemia. These diseases affect a wide range of domestic animals, leading to significant morbidity and mortality and causing significant economic losses worldwide. Due to the interest in deciphering the genetic diversity and process adaptive between P . multocida strains, this work aimed was to perform a pan-genome analysis to evidence horizontal gene transfer and positive selection among 23 P . multocida strains isolated from distinct diseases and hosts. The results revealed an open pan-genome containing 3585 genes and an accessory genome presenting 1200 genes. The phylogenomic analysis based on the presence/absence of genes and islands exhibit high levels of plasticity, which reflects a high intraspecific diversity and a possible adaptive mechanism responsible for the specific disease manifestation between the established groups (pneumonia, fowl cholera, hemorrhagic septicemia and snuffles). Additionally, we identified differences in accessory genes among groups, which are involved in sugar metabolism and transport systems, virulence-related genes and a high concentration of hypothetical proteins. However, there was no specific indispensable functional mechanism to decisively correlate the presence of genes and their adaptation to a specific host/disease. Also, positive selection was found only for two genes from sub-group hemorrhagic septicemia, serotype B. This comprehensive comparative genome analysis will provide new insights of horizontal gene transfers that play an essential role in the diversification and adaptation mechanism into P . multocida species to a specific disease. [ABSTRACT FROM AUTHOR]

Haemorrhagic septicaemia (HS) is a globally renowned disease that affects cattle and buffaloes. Its effects on the reproductive system have not been previously studied. The present study evaluated the pathological responses in pre-pubertal female buffaloes infected with immunogens; lipopolysaccharide (LPS) and outer membrane protein (OMP) derived from P. multocida type B:2. Fifteen healthy pre-pubertal female buffaloes were divided into 5 equal groups. Buffaloes in groups 1 and 2 were intravenously and orally inoculated with P. multocida LPS, while those in groups 3 and 4 were subcutaneously and orally inoculated with P. multocida OMP. Buffaloes in group 5 were inoculated with sterile phosphate buffered saline (negative control). During the post infection period, all buffaloes were examined for clinical signs throughout 21 days and surviving animals were euthanised for postmortem evaluation. Histopathological evaluation of buffaloes inoculated intravenously with LPS showed a significantly higher occurrence (P<0.05) of necrosis and degeneration in the uterine horn and supramammary glands . Following inoculation with OMP, haemorrhage and congestion was significantly higher (P<0.05) in the ovaries, cervix, vagina, mammary and supra-mammary glands of buffaloes inoculated subcutaneously, while necrosis and degeneration and inflammatory cell infiltration in different organs was also significantly increased in the same group. The findings showed that both P. multocida bacterial LPS and OMP affected the uterine horn, ovaries, cervix, mammary gland and supramammary lymph nodes of buffalo calves inoculated either intravenously or subcutaneously, as compared to those inoculated orally. [ABSTRACT FROM AUTHOR]

The ELISA is recognized as an efficient diagnostic tool for antibody detection, but there is no standard ELISA assay for detection of antibodies against hemorrhagic septicemia (HS) in cattle. The present study reports on an indirect ELISA assay for antibody detection of HS in dairy cows, and evaluates the sensitivity (Se) and specificity (Sp) of the method using a Bayesian approach. An indirect ELISA was developed with two types of heat extract antigens, Pasteurella multocida strains P-1256 and M-1404, as coating antigens. A checkerboard titration was employed using dairy cow sera immunized with P. multocida bacterin and colostrum-deprived calf sera. The concentrations of heat extract antigen (160 μg/mL), sample serum (1:100) and goat anti-bovine immunoglobulin G labeled with horseradish peroxidase (1:2000) were optimal for the assay. The cut-off values were 0.147 and 0.128 for P-1256 and M-1404 coating antigens, and there were no differences in the results of tests with positive and negative sera ( p < 0.05). The characteristics of three diagnostic tests were evaluated using a one-population Bayesian model, assuming conditional dependence between two types of coating antigen-based ELISAs and indirect hemagglutination assay (IHA). A total of 415 sera samples from dairy cows without HS vaccination and no history of disease were tested. The Se and Sp of the P-1256 and M-1404 ELISAs were higher than those of the IHA. The Se and Sp of the P-1256 ELISA were 90.3% and 90.1%, while the Se and Sp of the M-1404 ELISA were 92.1% and 71.9%. The median values of Se and Sp from the IHA were 36.0% and 58.2%. [ABSTRACT FROM AUTHOR]