广东省鸭疫里默氏杆菌流行病学监测及遗传进化关系

【目的】明确广东地区鸭疫里默杆菌Riemerella anatipestifer的血清型、耐药状况及遗传进化关系。【方法】从规模化鸭场分离鉴定鸭疫里默氏杆菌,通过玻片凝集试验鉴定血清型;利用试管两倍稀释法测试抗菌药物的最低抑菌浓度,分析药物的敏感性;采用全基因组测序技术分析序列特征并构建核心基因组遗传进化树。【结果】共分离鉴定鸭疫里默氏杆菌168株,血清1、2、3、5、6、7、8、10型均有流行,血清1型的菌株高达54.17%(91/168),其次为2型,占27.97%(47/168)。48株代表性菌株对庆大霉素、卡那霉素、盐酸环丙沙星表现高度耐药,耐药率均超过80%;对土霉素、盐酸四环素、盐酸金霉素、氧氟沙星、诺氟沙星、磺胺二甲嘧啶、磺胺对甲氧嘧啶的耐药率均在60%以上;对阿莫西林、头孢噻肟和大观霉素的耐药率低于30%。受试菌株对5～12种药物耐药,共有44种耐药谱型。成功获得46株菌株全基因组序列,共检出6种耐药基因,其中,耐药基因erm(F)和tet(X)的检出率较高,分别为73.91%(34/46)和82.60%(38/46),同时携带2种以上耐药基因的菌株占95.65%(44...

Epidemiological surveillance and genetic evolution of Riemerella anatipestifer in Guangdong Province

Objective To clarify serotype, drug resistance and genetic evolution of Rimerella anatipestifer in Guangdong.Method The isolates of R. anatipestifer were isolated and identified from samples of the large-scale duck farms. Serotype was identified by glass agglutination test. The minimum inhibitory concentration was tested by double dilution method in test tube, and the drug sensitivity was analyzed. Whole genome sequencing technology was used to analyze the sequence characteristices and construct the genetic evolution tree of the core genome.Result A total of 168 isolates of R. anatipestifer were isolated and identified. All serotype 1, 2, 3, 5, 6, 7, 8 and 10 were prevalent. Serotype 1 was dominant, reaching 54.17%(91/168), followed by serotype 2 (27.97%, 47/168). The 48 representative isolates were used for drug sensitivty test and sequence analysis. The isolates showed high drug resistance to gentamicin, kanamycin and ciprofloxacin hydrochloride, and the drug resistance rates were all more than 80%. The drug resistance rates to oxytetracycline, tetracycline hydrochloride, chlortetracycline hydrochloride, ofloxacin, norfloxacin, sulfadimidine and sulfamethoxydiazine were all more than 60%, and the drug resistance rates to amoxicillin, cefotaxime and spectinomycin were all less than 30%. The 48 representative isolates were resistant to 5−12 kinds of drugs, and there were 44 types of drug resistance spectrum. The whole genome sequences of 46 isolates were obtained successfully, and six drug-resistant genes were detected. The detection rates of drug-resistant genes erm(F) and tet(X) were 73.91% (34/46) and 82.60% (38/46), respectively. In addition, 95.65% (44/46) of the isolates carried more than two drug-resistant genes at the same time. Total 18 isolates (39.13%, 18/46) were typed successfully with 11 kinds of ST. Further genetic tree construction based on the core genome showed that all the sequenced isolates had a high similarity with the isolates from China in the multi-locus sequence typing (MLST) database, and mainly existed in the dominant clones of Clade 1 and Clade 3.Conclusion Serotype 1 is superior in the investigated R. anatipestifer isolates, and the drug resistance is serious. The drug-resistant genes and resistant phenotype have certain relevance. ST type has a high diversity. The genetic background of tested strains was similar with Chinese strains in MLST database. The results of this study can provide a basis for vaccine immunity prevention and drug therapy of R. anatipestife disease as well as for understanding the genetic evolution characteristics of R. anatipestife.