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Acute septicaemic pasteurellosis in Vietnamese pigs.

Sixteen isolates of Pasteurella multocida were cultured from cases diagnosed as acute septicaemic pasteurellosis in Vietnamese pigs. The HSB-PCR assay provided rapid presumptive determination of 10 isolates of P. multocida identified as haemorrhagic septicaemia (HS) causing type B cultures (B:2, B:5, B:2,5). Serological designation using the Carter and Heddleston typing systems confirmed these findings, and identified the six HSB-PCR negative cultures as either A:1, A:3 or D:3,4. Biochemical fermentation and REP-PCR revealed phenotypic and genotypic identity between P. multocida type A:1 isolated from Vietnamese pigs and poultry. Marked homogeneity was also demonstrated among HSB-PCR positive swine isolates, which were shown to possess genotypic identity with P. multocida type B:2 from buffaloes diagnosed with HS.

Animals↗

The immunogenicity and pathogenicity of Pasteurella multocida isolated from poultry in Indonesia.

Of 13 field isolates of Pasteurella from chickens and ducks in Indonesia, 10 were confirmed as P. multocida subspecies multocida, one as P. multocida subspecies gallicida and one as P. multocida subspecies septica. Nine were capsular Type A four were Serotype 1, one was Serotype 4, one was Serotype 11, one was Serotypes 4,12, and the remaining six were untypable. Five isolates were pathogenic for mice and two were pathogenic for chickens. Both a trivalent vaccine which included local field isolates and an imported commercial vaccine, were efficacious in layer chickens against challenge with virulent reference and local field strains. Though not statistically significant, the protection provided by the trivalent vaccine against virulent field isolate challenge was slightly better and could provide an improvement over the currently used imported vaccine although further field trials are required. A bacterin vaccine produced from a Serotype 1 field isolate grown in the allantoic sac of embryonated chicken eggs provided chickens with good cross protection against heterologous serotype challenge.

Animals↗

The virulence and protective efficacy for chickens of pasteurella multocida administered by different routes.

The relative virulence for chickens of five strains of Pasteurella multocida was evaluated. Twenty groups, each of ten chickens, were inoculated with a standard dose of 10(5) of each of five strains by the intramuscular (I.m.), intravenous (I.v.), intratracheal (I.tr.) or conjunctival (Co) routes. The highest mortality occurred in the groups dosed I.m. and I.v., followed by I.tr. inoculation. The relative virulence of each strain did not change when inoculated by the different routes. The most virulent strain, VP161, caused 100% mortality by all except the Co route. The least virulent strain, VP17, caused a single mortality by the I.v. route, but gave a high level of protection to birds inoculated by both the I.m. and I.v. routes, when challenged by intramuscular injection with (VP161). There was no protection against I.m. challenge in the birds inoculated by the I.tr. or Co routes. Serum antibody levels measured by ELISA correlated with the level of protection against virulent challenge for groups inoculated I.m. or I.v., but not I.tr. Western blots of pooled sera from each group did not show any specific antigen recognition that might explain the observed differences in protection. Inoculation with strain VP17, (both I.m. and I.tr.) also gave a high level of protection to birds challenged with strain VP161 by intratracheal instillation.

Animals↗

PCR detection and analysis of Pasteurella multocida from the tonsils of slaughtered pigs in Vietnam.

A total of 36 tonsil swab samples were collected from healthy swine prior to slaughter at the abattoirs in Can tho and Tien giang provinces of Southern Vietnam. The presence of Pasteurella multocida in these samples was detected by the combination of direct cultivation and isolation, mouse inoculation and the polymerase chain reaction (PM-PCR). P. multocida was detected in 16 samples by PCR, with 17 strains ultimately isolated. All samples were negative for serogroup B by HSB-PCR and conventional serotyping, with isolates identified as A:3, D:1 or D:3. In addition, all samples were determined to be negative for the P. multocida toxin (PMT). Characterisation of isolated P. multocida by REP-PCR and biotyping revealed nine distinct REP profiles and seven biotypes among the 17 isolates. Some correlation was seen with P. multocida isolated from a previous Australian outbreak of acute swine pasteurellosis, and those isolated from fowl cholera outbreaks in Vietnamese poultry.

Animals↗

Molecular characterisation of avian Pasteurella multocida isolates from Australia and Vietnam by REP-PCR and PFGE.

A total of 95 isolates of Pasteurella multocida were analysed by pulsed field gel electrophoresis (PFGE) using the enzyme ApaI, including 73 avian isolates from Australia and 22 from Vietnam. The majority of field isolates were capsular Type A, with the predominant somatic serovars of 1, 3, 4 and 3,4. Twenty-one distinct profiles were evident among the Australian isolates, with only 3 profiles observed among the 22 P. multocida strains isolated from Vietnam. Within the Australian isolates, related and unrelated outbreaks could be identified by PFGE. These results correlated well with previously published studies, with greater discrimination shown by PFGE. Repetitive extragenic palindromic sequence PCR (REP-PCR) analysis of representative isolates from PFGE classifications yielded 21 profiles, with most of the subgroups in accordance with PFGE analysis. While REP-PCR was shown to be less discriminating than PFGE, the epidemiological relatedness of strains compared favourably between the techniques. Thus, the ease and rapidity of REP-PCR while maintaining a high level of differentiation, supports the use of REP-PCR as a competent alternative to the more labour-intensive PFGE system for strain identification and epidemiological studies of avian P. multocida.

Animals↗

Phagocytic uptake and killing of virulent and avirulent strains of Pasteurella multocida of capsular serotype A by chicken macrophages.

The susceptibility of two highly virulent (VP161 and VP138) and two less virulent (VP17 and VP21) strains of Pasteurella multocida to phagocytic uptake and killing by chicken macrophages was compared using in vitro phagocytosis and bactericidal assays. When compared with VP17 and VP21, particularly after they were preopsonised with specific immune serum, VP161 and VP138 were more resistant to phagocytosis by chicken macrophages. The uptake of these bacteria increased following the removal of the bacterial capsules with hyaluronidase. All strains preopsonised with specific immune serum were killed to some extent by chicken macrophages. However, the percentages of killing for VP17 and VP21 were higher than those of VP161 and VP138. When the capsules of VP161 and VP138 were removed, the susceptibility of the bacteria to bactericidal activity of chicken macrophages increased. It can be concluded that the virulent strains of P. multocida were more resistant to phagocytosis and phagocytic killing by chicken macrophages compared with the less virulent strains. The hyaluronic acid capsule was considered to be important in the resistance, but might not be the only factor contributing to the resistance since the less virulent strains of P. multocida also possess capsules.

Animals↗

Bacterial pneumonia.

Bacteria play a critical role in the severe pneumonia and fatalities associated with the bovine respiratory disease complex. Although numerous bacteria have the potential to cause pneumonia, only a small number of these are responsible for the majority of cases of disease. Virulence and immunogenic characteristics of these organisms are important determinants of the host response to infection. These bacterial characteristics are reviewed and applied to a discussion of the epidemiology, pathogenesis, and prevention of bacterial pneumonia is also discussed.

Animals↗

Functional characterization of HgbB, a new hemoglobin binding protein of Pasteurella multocida.

The biological function and role in pathogenesis of a Pasteurella multocida A:1 strain hemoglobin binding protein was investigated. The hgbB gene from the P. multocida A:1 strain, VP161, was cloned and characterized. hgbB was 2991 bp in length and encoded a mature length protein of 111 kDa. HgbB was predicted to be an outer membrane protein and shared 68 and 69% similarity to the hemoglobin/hemoglobin-haptoglobin binding protein, HI0712 from Haemophilus influenzae Rd and HgpC, from H. influenzae b, respectively. HgbB exhibited features typical of TonB dependent receptors, including seven conserved regions typical of these proteins, and conserved invariant residues. Escherichia coli expressing recombinant HgbB was found to bind hemoglobin in a solid phase dot blot binding assay. However, when a truncated form of the protein was expressed in E. coli, cells could no longer bind hemoglobin. Insertional inactivation of hgbB did not affect the ability of P. multocida to bind hemoglobin, nor its ability to produce disease in a mouse model. In addition, recombinant HgbB did not confer any protection against homologous or heterologous challenge.

Amino Acid Sequence↗

Postantibiotic effects and postantibiotic sub-MIC effects of erythromycin, roxithromycin, tilmicosin, and tylosin on Pasteurella multocida.

When intermittent dosing is used during treatment, the concentrations of antibiotics fluctuate and subinhibitory concentrations may occur between doses. Postantibiotic effects (PAEs) and postantibiotic subinhibitory effects (PA SMEs) on bacteria may provide additional, valuable information for the rational use of a drug in clinical practice. In this study tilmicosin was the most active antibiotic tested against P. multocida type D with MICs ranging from 4-16 mg/l. Roxithromycin and tilmicosin induced a statistically significantly longer PAE than did tylosin against P. multocida types A and D (P < 0.05). The duration of PAEs and PA SMEs were proportional to the concentrations of drugs used for exposure. The PA SMEs were substantially longer than PAEs on P. multocida. Tilmicosin had a longer PA SME compared with erythromycin, roxithromycin and tylosin for P. multocida. The computerized incubator used in the present study provided an efficient and convenient determination of PAE and PA SME, allowing frequent measurements of the bacterial growth.

Anti-Bacterial Agents↗

In vitro susceptibility of Pasteurella multocida subspecies multocida strains isolated from swine to 42 antimicrobial agents.

The minimal inhibitory concentrations (MICs) of 42 antimicrobial agents were determined against 59 strains of Pasteurella multocida subspecies multocida, all isolated from swine lungs with lesions indicative of pneumonia. Penicillins (except cloxacillin), aminoglycosides, tetracyclines, erythromycin, josamycin, thiamphenicol, colistin, rifampin and mupirocin showed good activities, with ranging resistance between 0 and 6.8%. Higher resistance was observed for spiramycin and fosfomycin. Tylosin, vancomycin, metronidazole, dapsone and tiamulin, to which strains showed high rates of resistance, were ineffective. Cephalosporins (especially the third-generation cephalosporins) and quinolones (especially the fluorinated quinolones) were the most effective antimicrobial agents against P. multocida subsp. multocida strains and they might be of value for in vivo use.

Animals↗

Ecology and significance of Pasteurellaceae in animals.

The reservoir of eighty-one taxa/groups classified with the family Pasteurellaceae Pohl 1981 is reviewed based upon published data and own investigations. With the exception of certain strains of P. multocida, A. pleuropneumoniae and [H.] paragallinarum organisms belonging to this family are usually regarded as opportunistic, secondary invaders which under normal conditions coexist peacefully with the animal host on mucosal membranes of the upper respiratory- and lower genital tracts. Very little is known about factors that govern the ecological preferences that certain members of this family show for specific surfaces and hosts. Mechanisms of colonization, survival and multiplication, invasion and pathogenic action are incompletely understood. The significance of Pasteurellaceae in animals and man has recently been reviewed. Subsequent publications have underlined the significance of biovars 2 of P. canis and P. avium and ornithine negative P. multocida in pneumonia in cattle. In addition, differences in pathogenicity have been demonstrated for different serovars of [H.] parasuis. The disease potential of many taxa/groups is only incompletely known.

Actinobacillus↗

Cell surface characteristics and virulence in mice of Pasteurella multocida.

The virulence of three avian strains of Pasteurella multocida was evaluated in mice. Strains P-1059I (serotype A:3) and its uncapsulated variant P-1059B and strain 2723 (serotype A:16) were compared. Capsular material thickness after polycationic ferritin labelling of dextrose starch agar (DSA)-grown P. multocida was shown to vary with the strain and was not always related to virulence. Addition of alpha,alpha' bipyridyl (BIP) (160 microM) to the culture medium did not affect capsule production but increased virulence of strains P-1059B and 2723. None of the strains tested showed dermonecrotic activity. Using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), outer membrane protein (OMP) profiles indicated for strains P-1059I and P-1059B three proteins of 30, 35, and 38 KDa with the 30 KDa protein being the major one. Strain 2723 showed the same OMP profile but the 38 KDa protein was the major one. DSA + BIP-grown strains showed the same OMP profiles. Whole cell profiles were similar for all strains tested. However, addition of BIP to the culture media increased the virulence of strains P-1059B and 2723 and for all strains a 39 KDa protein was induced by the iron chelator. The results indicate that encapsulation may be important for virulence, but other surface components such as OMPs may be required as well.

Animals↗

Phylogenetic analysis of Pasteurella multocida subspecies and molecular identification of feline P. multocida subsp. septica by 16S rRNA gene sequencing.

Pasteurella multocida is commonly found in the oral cavity of cats and dogs. In humans it is known as an opportunistic pathogen after bites from these animals. Phenotypic identification of P. multocida based on biochemical reactions is often limited and usually only done on a species level, even though 3 subspecies are described. For molecular taxonomy and diagnostic purposes a phylogenetic analysis of the three subspecies of P. multocida based on their 16S rRNA (rrs) gene sequence was therefore carried out. We found P. multocida subsp. septica on a distinguished branch on the phylogenetic tree of Pasteurellaceae, due to a 1.5% divergence of its rrs gene compared to the two other, more closely related subspecies multocida and gallicida. This phylogenetic divergence can be used for the identification of P. multocida subsp. septica by rrs gene determination since they form a phylogenetically well isolated and defined group as shown with a set of feline isolates. Comparison to routine phenotypic identification shows the advantage of the sequence-based identification over conventional methods. It is therefore helpful for future unambiguous identification and molecular taxonomy of P. multocida as well as for epidemiological investigations.

Animals↗

Acute disseminated encephalomyelitis associated with Pasteurella multocida meningitis.

OBJECTIVE: To describe a case of Pasteurella multocida meningitis associated with acute disseminated encephalomyelitis (ADEM). CASE REPORT: A 33-year-old woman employed in a dog pound presented herself to hospital with fever and meningismus and was found to have culture positive Pasteurella multocida meningitis. Despite appropriate antibiotic treatment her clinical course was characterized by a persistent fever and worsening encephalopathy, which prompted further neurological investigation. Spinal fluid exam and serial MRI scans as well as her one-year clinical course were found to be compatible with ADEM. CONCLUSION: Persistent fever and worsening encephalopathy in meningitis may indicate a para-infectious immune process such as ADEM, and may serve as indications for further neurological investigation.

Acute Disease↗

Antibiotic sensitivity patterns among Indian strains of avian Pasteurella multocida.

An investigation was carried out to study the antibiotic sensitivity of avian strains of Pasteurella multocida and to select an effective antimicrobial agent for control of avian pasteurellosis in India. A total of 123 strains of P. multocida recently isolated from different avian species (chicken, duck, turkey, quail, and goose), from different regions of India were subjected to antibiotic sensitivity tests using 20 different antibiotics. Absolute resistance was observed against sulfadiazine. The studies indicated that the strains were most sensitive to chloramphenicol (73.98%), followed by enrofloxacin (71.54%), lincomycin (64.23%), norfloxacin (61.79%) and doxycycline-HCl (56.91%). The majority of the strains were found to exhibit intermediate sensitivity. Chloramphenicol was selected and suggested for treatment. Antibiogram studies also revealed the emergence of multidrug-resistant strains of P. multocida among Indian poultry.

Animals↗