acriflavine and Swine-Diseases

Recently, a series of acute swine erysipelas outbreaks occurred in Eastern China. Eight strains isolated from cases of septicemia were determined as serotype 1a, and 4 of the isolates were resistant to acriflavine. One isolate strain named HX130709 was attenuated on agar media containing acriflavine dye. The 432-bp hypervariable region in spaA gene of the field and attenuated strains were amplified and sequenced. It was further compared with the vaccine strain G4T10, and thus, the eight field strains can be divided into four spaA-types. The partial spaA gene analysis also showed that no point mutations occurred among different archived passages of HX130709 during the attenuation. Results of pulsed-field gel electrophoresis showed that eight distinct patterns with 22 to 30 DNA fragment bands were produced from field strains, and twelve distinct patterns with 23 to 27 DNA fragment bands were produced from different passages of the attenuated strains. Mouse pathogenicity test showed that the mortality of the mice infected with 10(4) CFU field strains was 100% and the attenuation of strain HX130709 occurred between 46 and 50 passages. All the field and attenuated strains were highly sensitive to β-lactam antibiotics, tetracyclines and macrolides. So, we can make conclusions that the acute swine erysipelas outbreaks in Eastern China were caused by serotype 1a E. rhusiopathiae strains with different biochemical characteristics, and the virulence of serotype 1a E. rhusiopathiae strains is unrelated with some point mutations in 432-bp hypervariable region of the spaA gene.

Topics: Acriflavine; Animals; Antigens, Bacterial; Bacterial Proteins; Base Sequence; China; Disease Outbreaks; Electrophoresis, Gel, Pulsed-Field; Erysipelothrix; Erysipelothrix Infections; Mice; Microbial Sensitivity Tests; Molecular Sequence Data; Sequence Analysis, DNA; Species Specificity; Swine; Swine Diseases; Virulence

The objective of the present study was to characterize Erysipelothrix sp. strains from recent erysipelas outbreaks in Japan. Eighty-three (100%) strains were identified as E. rhusiopathiae, based on serotyping and spaA PCR. Fifty (60.3%), 5 (6.0%), and 28 (33.7%) strains were isolated from animals with acute, subacute and chronic outbreaks, respectively, of which 79 (95.2%), 1 (1.2%), and 3 (3.6%) belonged to serotypes 1a, 2a, and untypeable, respectively. Fifteen strains (including 3, 2, and 10 from acute, subacute, and chronic cases, respectively) were sensitive to acriflavine, and showed high levels of virulence in mice; of which strains from acute cases, and from subacute and chronic cases killed 100%, and 80 to 100% mice, respectively at challenge doses of 10(2) CFU per mouse. Based on sequence analysis of a 432-bp hypervariable region in spaA gene, 83 strains could be divided into 3 groups: (i) group 1 (3 strains of serotype 1a) had Ala-195 and Ile-203; (ii) group 2 (76 strains of serotype 1a and 3 of untypeable) had Asp-195 and Met-203; and (iii) group 3 (one strain of serotype 2a) had Asn-195 and Ile-203. The results of the present study suggest that the serotype 1a strains belonging to the group 2 might be widespread in pig populations in Japan.

Topics: Acriflavine; Animals; Antigens, Bacterial; Bacterial Proteins; Colony-Forming Units Assay; Complementarity Determining Regions; Disease Outbreaks; DNA Primers; Erysipelas; Erysipelothrix; Japan; Sequence Analysis, DNA; Serotyping; Species Specificity; Swine; Swine Diseases; Virulence

Haemophilus parasuis can cause pneumonia and systemic disease in swine but it is also a coloniser of the upper respiratory tract of healthy pigs. These differences in pathogenicity are probably the result of diverse mechanisms of virulence in different strains. Since serum-resistance is a feature frequently found in systemic pathogens, 31 H. parasuis strains of different clinical origin were tested and a variety of serum susceptibility levels detected. Nasal strains from healthy piglets were sensitive to the bactericidal effect of the serum, while systemic strains were mainly resistant. The pulmonary strains included both serum-sensitive and serum-resistant strains. Interestingly, the serum-resistant pulmonary strains were isolated from animals with systemic lesions. Heat-treatment of the sera abolished the bactericidal activity, indicating that complement is a key factor in this effect. Equivalent susceptibility was observed with rabbit and porcine sera, and the presence of H. parasuis specific antibodies did not increase the killing of the strains by serum. In an attempt to associate serum-resistance to a surface determinant of the bacteria, agglutination in acriflavine was tested but no direct link with serum susceptibility was found. The results indicate that serum-resistance is a virulence mechanism in H. parasuis.

Topics: Acriflavine; Animals; Anti-Infective Agents, Local; Drug Resistance, Microbial; Haemophilus Infections; Haemophilus parasuis; Microbial Sensitivity Tests; Rabbits; Respiratory Tract Infections; Serum Bactericidal Test; Swine; Swine Diseases

Erysipelothrix rhusiopathiae is the causative agent of swine erysipelas. Although an attenuated vaccine is used in Japan, recent increases in disease occurrence have cast doubts on its efficacy. We investigated the similarity between the vaccine strain and E. rhusiopathiae field isolates by the analysis of acriflavine resistance (the vaccine strain marker), serotype, DNA fingerprinting and pathogenicity to mice. Although 7 acriflavine resistant E. rhusiopathiae isolates were separated from arthritic lesions of slaughter pigs, we were unable to prove that they were identical to the vaccine strain.

Topics: Abattoirs; Acriflavine; Animals; Bacterial Vaccines; DNA Fingerprinting; DNA Primers; DNA, Bacterial; Drug Resistance; Erysipelothrix; Erysipelothrix Infections; Fluorescent Dyes; Mice; Polymerase Chain Reaction; Swine; Swine Diseases

Haemophilus parasuis strains isolated from the noses of apparently healthy animals and from animals with pathological conditions were examined for the presence of a capsule, for their ability to agglutinate in acriflavine or after boiling, and for their peptide profile after polyacrylamide gel electrophoresis (PAGE). The capsule was identified by precipitation against hexadecyl trimethylammonium bromide (Cetavlon), by demonstration of iridescence, and by means of a capsule-staining method. We found a group of capsulated strains showing a rather coccobacillary morphology compared with the morphology with polymorphism, varying from rod-like to filamentous, in strains without detectable capsules. The strains of the latter group were agglutinated by acriflavine or by boiling. Soluble antigens of capsulated strains reacting with Cetavlon were thermostable and resisted proteolytic enzymes, thus suggesting the presence of an acidic polysaccharide. A few of the capsulated strains did not precipitate with Cetavlon, which indicated that their chemical composition was different. Acriflavine-positive strains belonging to a definite PAGE pattern (type II) seemed to be associated with pathological conditions more frequently than were capsulated strains which were mostly isolated from nasal cavities of apparently healthy pigs. We put forward the hypothesis that the agglutinability in acriflavine, together with the PAGE profile type II, may be associated with particular structures responsible for virulence.

Topics: Acriflavine; Agglutination Tests; Animals; Electrophoresis, Polyacrylamide Gel; Haemophilus; Haemophilus Infections; Hot Temperature; Nasal Cavity; Polysaccharides, Bacterial; Precipitin Tests; Swine; Swine Diseases; Virulence

Topics: Acriflavine; Aminoacridines; Animals; Bacterial Vaccines; Cattle; Cattle Diseases; Cricetinae; Mice; Pasteurella; Pasteurella Infections; Sheep; Sheep Diseases; Swine; Swine Diseases