Antibiotic susceptibility of canine Bordetella bronchiseptica isolates

The antimicrobial sensitivities of 78 recent (1995-1998) canine isolates of Bordetella bronchiseptica from 13 separate sources were determined. Minimum inhibitory concentrations were assessed using the E-test method or by agar dilution. All 78 isolates were sensitive to tetracycline, doxycycline, enrofloxacin, and amoxycillin/clavulanic acid; the majority were sensitive to ampicillin (63/78; 81%), trimethoprim (57/78; 73%), and sulphadiazine (63/78; 81%). Plasmids were detected in 14 out of the 24 isolates tested. There was no correlation between the presence of plasmids and antibiotic resistance, but there was some correlation between the presence of plasmids and the origin of the isolates. Three sizes of plasmid were found: 20, 14, and 5.5 kb. Eight of the isolates contained all three plasmids, the remainder one or two, Thirteen isolates demonstrated beta-haemolysis, of which six produced a soluble haemolysin. Except for one isolate, haemolysin production correlated with plasmid carriage. Pulsed-field gel electrophoresis showed that all except one isolate could be grouped in the same genotype. Within this genotype isolates could be divided into three subtypes, generally corresponding to their place of origin.     

Serologic survey for Bordetella bronchiseptica in Nebraska specific-pathogen-free pigs

The frequency of Bordetella bronchiseptica infection in Nebraska specific-pathogen-free (SPF) pigs was determined by serologic and bacteriologic cultural analysis. Serum samples from non-SPF herds were tested for comparison. A total of 1,282 of 1,397 (92%) of the SPF pigs tested had antibody to B bronchiseptica; 37 of 220 (17%) were culture-positive, and 67 of 4125 (1.6%) were considered suspicious for atrophic rhinitis during slaughter inspection. A higher percentage of the non-SPF pigs had titers to B bronchiseptica (642 of 659 pigs or 97% of the pigs tested). There was no relationship between the B bronchiseptica antibody titer, the isolation of B bronchiseptica, or the frequency of gross lesions of atrophic rhinitis from pigs within the herd. The serum agglutination test may be a more reliable procedure for determining the herd prevalence of B bronchiseptica than isolation of the organism by cultural methods.     

The pathogenesis of turbinate atrophy in pigs caused by Bordetella bronchiseptica

The pathogenicity of 3 strains of Bordetella bronchiseptica designated B58, PV6 and B65 was compared by intranasal infection of gnotobiotic piglets. Strain B58 was a phase 1 isolate that produced haemolysin, an adhesin for calf erythrocytes, adenylate cyclase, mouse lethal factor, dermonecrotic factor and cytotoxin. B65 was a variant of B58 that produced no detectable haemolysin, adhesin or adenylate cyclase and 10-fold smaller amounts than B58 of mouse lethal factor, dermonecrotic factor and cytotoxin. Strain PV6 was a phase 1 isolate that produced only haemolysin, adhesin and adenylate cyclase. After nasal infection of gnotobiotic pigs, 10(3.2)-10(6.2) colony forming units ml-1 (cfu ml-1) of strains B58 and PV6 were cultured from nasal washings during the next 25 days. In contrast, only 10(1.0)-10(2.8) cfu ml-1 of strain B65 were recovered during the same period. Only pigs infected with strain B58 had turbinate atrophy when they were slaughtered 25 days after infection and neutralising antibody to cytotoxin was detected only in these pigs. These results suggested that the cytotoxin, which may be the same as the mouse lethal and dermonecrotic factors, was the cause of turbinate atrophy. They also support the view that the adhesin for calf erythrocytes is required for colonisation of the nasal cavity in vivo.     

Immunogenicity and safety of an attenuated Bordetella bronchiseptica vaccine in pigs

The immunogenicity and safety of an attenuated Bordetella bronchiseptica vaccine for swine atrophic rhinitis (AR) was evaluated in 22 hysterectomy-produced, colostrum-deprived pigs and 18 conventional pigs. None of 8 pigs inoculated at 7 days of age intranasally with greater than or equal to 3 X 10(5) colony-forming units (CFU) of vaccinal strain/pig and 2 of 5 pigs inoculated at 7 days of age intranasally with 3 X 10(4) CFU of the vaccinal strain/pig developed AR after intranasal challenge exposure with a virulent strain at postinoculation week (PIW) 3. The remaining 3 vaccinated pigs and 4 nonvaccinated pigs developed AR. Thirteen pigs were inoculated intranasally with 3 X 10(6) to 3 X 10(9) CFU of the vaccinal strain at 7 days of age. At PIW 12, the pigs were killed and necropsied. None of the pigs had clinical signs of AR and/or pneumonia. Virulence was studied by transmission of vaccinal strain through 3 serial growing passages on the nasal mucosa of a litter of hysterectomy-produced colostrum-deprived pigs. Inoculum (nasal swab samples from 2 pigs 4 days after inoculation with 10(8) CFU of vaccinal strain at 5 days of age) was inoculated into the nasal cavity of 2 nonvaccinated pigs. This procedure was repeated 3 times. After the 1st passage, the vaccinal strain was recovered on postinoculation day 4, but after postinoculation day 4, the vaccinal strain was not recovered until the end of the 3rd passage. Turbinate atrophy or pneumonia was not recognized in these inoculated pigs. The vaccinal strain provided immunogenicity without ill effects.     

Bordetella bronchiseptica isolations from the nasal cavity of pigs in relation to atrophic rhinitis.

The occurrence of Bordetella bronchiseptica and atrophic rhinitis was studied during a one-year period in four Danish sow herds. In three of the heards, the epidemiological studies revealed a relation between the occurrence of B. bronchiseptica in 3--10-week-old pigs and the presence and severity of atrophic rhinitis at slaughter. In the fourth herd no such relation was found.     

猪萎缩性鼻炎支气管败血波氏杆菌PCR检测方法的建立

对表现猪萎缩性鼻炎临床症状的猪群中分离得到的34株支气管败血波氏杆菌(Bordetella bronchiseptica,Bb),采用针对Bb flagellum gene的一对引物进行PCR扩增,结果所有分离物均能扩增出237bp特异性DNA条带,与传统生化鉴定结果相一致,且其最小检出量为0.64pg;而猪鼻腔和肺组织中常见的多杀性巴氏杆菌、金黄色葡萄球菌、枯草芽胞杆菌、铜绿假单胞菌、变形杆菌及大肠埃希氏菌均未能出现任何DNA条带。这表明,本试验建立的PCR方法具有特异性强、灵敏度高、可靠性好等特点,可用于猪萎缩性鼻炎的临床诊断。     

Detection of type III secretion system genes in animal isolates of Bordetella bronchiseptica

A cosmid clone bank of Bordetella bronchiseptica genomic DNA was screened for the presence of type III secretion (TTS) genes using a probe derived from the TTS system genes of Ralstonia solanacearum. A 3.35kb PstI fragment, sub-cloned from a hybridising cosmid clone, was sequenced and found to contain a 97bp overlap with the previously reported B. bronchiseptica bscIJKLNO TTS gene cluster. DNA and predicted protein homology analysis suggests that a bscPQRST cluster lies immediately downstream of bscIJKLNO. A PCR amplification assay indicated that the bscT locus was present in 27 B. bronchiseptica animal isolates tested (100%). Dot-blot DNA hybridisation using probes for bscT and bscP confirmed the presence of these loci in six canine isolates associated with a variety of clinical signs. Although TTS has been implicated in the pathogenicity of B. bronchiseptica, it is likely that different clinical manifestations may be due to variations in gene expression or host factors, rather than the absence or presence of TTS genes.     

Diversity of swine Bordetella bronchiseptica isolates evaluated by RAPD analysis and PFGE

The degree of genetic diversity in 45 Bordetella (B.) bronchiseptica strains comprised of a vaccine strain (N = 1), reference strains (N = 3) and field isolates (N = 41) was evaluated using random amplified polymorphic DNA (RAPD) fingerprinting and pulsed-field gel electrophoresis (PFGE). Three candidate primers were selected for RAPD analysis after screening 20 random decamer oligonucleotides for their discriminatory abilities. The OPA-07, OPA-08 and OPA-18 primers yielded 10, 10, and 6 distinct fingerprint patterns, respectively. The most common identical RAPD pattern was produced by OPA-07 which was shared by 32 isolates (71.1%), the pattern produced by OPA-08 was shared by 26 isolates (57.8%), and the pattern produced by OPA-18 was shared by 40 isolates (88.9%). The RAPD patterns of the vaccine strain and the 3 reference strains did not match any of the patterns produced by the field isolates when primers OPA-07 and OPA-08 were used. PFGE using the restriction endonuclease XbaI produced a total of 15 patterns consisting of 4 PFGE types (A, B, B1 and C, differing by ≥ 4 bands) and 11 A subtypes (differing by ≤ 3 bands). Most of the field isolates exhibited identical type A and B patterns, suggesting that they were related. The vaccine strain and the three reference strains showed different PFGE patterns as compared to the identical type A strains.     

猪支气管败血波氏杆菌PCR诊断方法的建立及应用

根据支气管败血波氏杆菌（Bordetella bronchiseptica）鞭毛蛋白基因的上游序列设计了1对引物flal和fla2，扩增出大小为237bp的目的基因片段，建立了快速检测支气管败血波氏杆菌的PCR方法。特异性和敏感性试验表明，该方法对大肠埃希氏菌、金黄色葡萄球菌和D型多杀性巴氏杆菌均无交叉性反应；最低能够检出112．5pg的模板DNA。用该PCR法检测了从延边州采集的48份表现不同临床症状的猪鼻黏液；结果，检出支气管败血波氏杆菌阳性42例，阳性率为87．5％。同时与传统的细菌检查法、微量凝集法进行了比较；结果显示，该PCR法的检出率是细菌检查法的5．25倍，是微量凝集法的1．75倍。     

Interactions between Bordetella bronchiseptica and toxigenic Pasteurella multocida in atrophic rhinitis of pigs

Three strains of Bordetella bronchiseptica were compared for their ability to assist colonisation of the nasal cavity of gnotobiotic pigs by toxigenic Pasteurella multocida. Toxigenic P multocida (counted in nasal washings) colonised the cavity in large numbers in pigs previously infected with a cytotoxic phase I strain of B bronchiseptica (B58), whereas it colonised only in small numbers in those previously infected with B65, a phenotypic phase III variant of B58. Toxigenic P multocida colonised pigs infected with a non-cytotoxic phase I strain of B bronchiseptica (PV6) in fewer numbers than were seen in pigs infected with the cytotoxic phase I strain but in greater numbers than in pigs infected with the phase III strain. The turbinates of pigs infected with the cytotoxic phase I strain of B bronchiseptica and toxigenic P multocida were most severely affected and those in pigs infected with the non-cytotoxic phase I strain and toxigenic P multocida were moderately reduced in size. The turbinates of pigs infected with the phase III strain and toxigenic P multocida were slightly reduced in size except for one piglet whose turbinates were severely affected. Pigs infected with the non-cytotoxic phase I strain of B bronchiseptica alone showed no signs of atrophy and their turbinates were used to calculate reductions (per cent) in those infected with P multocida. The reduction (per cent) in size of turbinates and total numbers of P multocida isolated from the nasal washings of each pig were linearly related.(ABSTRACT TRUNCATED AT 250 WORDS)