Bordetella bronchiseptica phase variation induced by crystal violet

Crystal violet staining of Bordetella bronchiseptica colonies for differentiation of phase-I strains from variant strains in degraded phases

After 2 days of growth on Brain heart infusion agar (BHIA) at 38 degrees C, phase-I colonies and degraded-phase colonies of Bordetella bronchiseptica could be differentiated by their ability to take up crystal violet (CV). Phase-I colonies in X mode, but not colonies in degraded phases (phases II, III, and rough) bound CV. Phenotypically-altered C-mode colonies (grown at 32 degrees C or lower temperatures) also lacked this ability. CV staining offers an easy method for the recognition of different colony types that appear identical when observed on BHIA.

Nasal epithelial changes induced in piglets by acetic acid and by Bordetella bronchiseptica

Research on atrophic rhinitis of pigs has shown that both Bordetella bronchiseptica infection and experimental treatment with acetic acid predispose the nasal mucosa to colonization with Pasteurella multocida. Gnotobiotic piglets aged 3 days were dosed intranasally with either B. bronchiseptica (n = 6) or acetic acid 1 per cent (n = 10) and killed at intervals up to the 4th day after treatment. Samples of the ventral turbinates were examined by light microscopy and scanning and transmission electron microscopy. Within 12 h acetic acid induced loss of cilia, oedema, focal cell exfoliations, mitochondrial swelling and inflammatory cell infiltration. Bordetella bronchiseptica induced only a limited oedema and loss of cilia. Colonization of cilia by the bacteria was observed 96 h after infection. We conclude that, although acetic acid and B. bronchiseptica do not induce the same modifications of the nasal respiratory epithelium, their action causes stagnation of nasal mucus, which results in a nasal environment favourable to colonization by Pasteurella multocida.

Inhibitory effect of sulfamonomethoxine on capsule formation of Bordetella bronchiseptica

Bordetella bronchiseptica phase I organism possesses a capsule and has the ability to agglutinate with K antiserum, although phase III organism lacks both. The present study examines the effect of sulfamonomethoxine (SMMX) on capsule formation of B. bronchiseptica. I also investigated whether or not the organisms possessed a capsule by bacterial agglutination with K antiserum. Three SMMX-resistant strains of B. bronchiseptica phase I organisms showed loss of agglutinability with K antiserum by culturing them at a higher concentration of 1.56 micrograms/ml of SMMX. These results indicated that capsule formation of SMMX-resistant B. bronchiseptica is inhibited by SMMX.

Hydrophobic surface properties of Bordetella bronchiseptica X-mode cells and their possible role in adherence to porcine nasal mucosa

Bordetella bronchiseptica strains were examined to determine whether the surface hydrophobicity of the bacteria correlates with their adherence to porcine nasal epithelial cells. The relative hydrophobicity of the bacteria, measured by their retention to a column of hydrophobic phenyl-Sepharose gel and their aggregation in ammonium sulfate solution, correlated well with their adhesive properties. Phase I cells in X-mode, which adhered well to the epithelial cells, were conspicuously hydrophobic. The cells in C-mode and degraded phases, which adhered poorly to the epithelial cells, were relatively hydrophilic. These observations provide evidence for the suspected role of hydrophobic interactions in the adherence of B. bronchiseptica to porcine nasal mucosa.

Novel phase-shift marker in cell surface proteins of Bordetella bronchiseptica

Cell surface proteins of phase I cultures of Bordetella bronchiseptica strains from various species of animals were compared with those of isogenic phase III cultures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A protein band with a molecular mass of 74 kilodaltons was found only in various phase I cultures. This protein disappeared in parallel with antigenic modulation and had strong antigenicity. We found it to be an appropriate phase-shift marker for two reasons: it was readily extracted and recognized, and it was specifically identified by its distinct antigenicity.

Decrease in antimicrobial susceptibility of Bordetella bronchiseptica caused by antigenic modulation and phase variation

The susceptibilities to 20 antimicrobial agents of Bordetella bronchiseptica variants in C mode and degraded phases were compared with those of their parents in X mode. Increases in MICs of 4- to 32-fold were observed for ampicillin, carbenicillin, erythromycin, novobiocin, rifampin, chloramphenicol, nalidixic acid, and oxolinic acid.

Clonal diversity and host distribution in Bordetella bronchiseptica

A total of 303 isolates of Bordetella bronchiseptica recovered from 11 host species were characterized by the electrophoretic mobilities of 15 metabolic enzymes, and 21 distinctive multilocus genotypes (electrophoretic types) were distinguished on the basis of allele profiles at the enzyme loci. The population structure of B. bronchiseptica is clonal, and its genetic diversity is limited in comparison with most other pathogenic bacteria, perhaps reflecting a relatively recent origin of the species. Electrophoretic types mark clones which are, in many cases, nonrandomly associated with host species. Clones differing only slightly in overall chromosomal genetic character may have pronounced differences in virulence potential. There was considerable variation among individual clones and clone families in degree of host specificity and among various species of hosts in the diversity of clones causing disease. The diversity of clones infecting dogs was an order of magnitude greater than that of clones infecting pigs. Most bordetellosis in pigs in the United States and Japan was found to be caused by strains of a single multilocus genotype.