| Rabbit Bordetella disease is a common respiratory tract diseases in rabbits, which is caused by Brodetella bronchiseptica. The main symptoms of the disease are bronchitis,pneumonia, and pustular pneumonia in adult rabbits and can also result in acute death in weaning pups and lactation of rabbits. The Bordetella bronchial infection rates have increased significantly because of the rapid development of large-scale farming rabbit in recent years.Brodetella bronchiseptica was often resident with Staphylococcus aureus and Pasteurella multocida in the process of infected rabbits. It is one of important results of the increased morbidity and mortality, which caused significant economic losses in rabbit farming.Antibiotic therapy is an important mean of prevention in livestock and poultry farming. Drug abuse has led to growing bacterial resistance, and bacterial resistance could cause the failure of drug treatment. Raising awareness of the situation in the sensitivity bacterial resistance and drug resistance is significantly important for correct analysis and suitable drug useage in clinical cases. According to the results of bacterial isolation experiments, drug susceptibility,higher rates of antibiotic resistance genes were screened for underlying the propagation mechanisms. Studies included the following aspects:1. In this study, acquisition samples from nasal secretions and lung disease pathological in some part rabbit farms from Zhejiang province were studied, according to the bacterial morphology, cultural characteristics, biochemical tests, as well as PCR method, 22 strains of Bordetell isolates during 2012-2014 were identified. Drug susceptibility results showed that the isolated bacteria is resistant to penicillin G, cephradine, streptomycin, lincomycin,clindamycin, pyrimidine methicillin seriously, while sensitive to polymyxin B, levofloxacin,doxycycline, tetracycline et al.2. Specific primers were designed for resistance-drugphenotype gene, The resistance genes were amplified by PCR method and sequences were analyzed. All the isolates were detected betalactam type of drug resistance gene blaTEM, the detection rate is 100%. 17 isolates were detected sulfa drug resistant gene sul1, the detection rate is 77%. The detected resistance genes were consistent with the resistance phenotype. 17 isolates were detectedⅠclass integron integrase gene int1, the detection rate is 77%, which explains that the integron plays a role in Brodetella bronchiseptica’s resistance transmission mechanism. 20 isolates were detected multiple drug resistance genes MarC, the detection rate is 91%,because MarC gene’s detection rate is higher, so we infer that Bb’s resistance transmission mechanism was associated with the active efflux system of chromosome mutation mediated.9 isolates were detected transposon’s genetic marker gene merA, the detection rate is41%.This experiment also explores the propagation mechanism of resistance genes with the acquisition of unknown sequence which adjacent to a known sequence by inverse PCR technique, acquired part transposase sequence of Tn3.The detection of MerA and reverse PCR showed that TEM spreading of resistance genes were correlate with transposons.3. 22 strains of the isolates were all carrying plasmid, after the plasmid elimination experiment, part bacteria resistance were changed, the bacteria’s drug sensitivity to ampicillin, cefazolin, tetracycline and polymyxin B were enhancement. This proves the plasmid mediated the partial resistance bacteria.Results showed that Brodetella bronchiseptica was a major pathogen in respiratory tract diseases in rabbit. The isolate is multi-drug resistant and has high resistance rates. The detected resistance genes were consistent with the resistance phenotype. Plamid, integron and transposons, the detection of this three kinds of teansfer factor explain that rabbit Bordetella bronchiseptica has multiple drug resistance mechanisms. |
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