猪源嗜麦芽寡养单胞菌分离鉴定及致肺脏病理损伤分析

Isolation,Identification and Lung Pathological Injury Analysis of Stenotrophomonas maltophilia from Swine

为确定山西省某猪场患有猪呼吸道疾病综合征(PRDC)病死猪的病原,经PCR检测、细菌分离、染色镜检、生化试验和16S rRNA序列分析,确定感染病原为猪圆环病毒2型(PCV2)和嗜麦芽寡养单胞菌。为研究嗜麦芽寡养单胞菌在PRDC发生中的耐药特征和对肺脏损伤,药敏试验发现该分离菌株对头孢曲松和阿莫西林等20种抗生素耐药;对多黏菌素B、阿奇霉素、多西环素、链霉素、米诺环素、氧氟沙星、恩诺沙星和加替沙星敏感。小鼠致病性试验发现,试验组小鼠临床症状表现为精神沉郁、被毛粗乱、呼吸急促和死亡。剖检可见肺脏实变和明显出血点,病理切片显示肺脏出血、充血、肺泡消失、肺炎等严重病理组织变化。说明嗜麦芽寡养单胞菌分离株呈多重耐药性,感染小鼠可引起严重的肺炎、呼吸道症状和死亡。

To determine the pathogens of dead pigs suffered from Porcine respiratory disease complex(PRDC)in a pig farm of Shanxi province,PCR identification,bacterial isolation,Gram staining,biochemical tests and 16S rRNA sequence analysis were used,and the pathogens were diagnosed as PCV2 and Stenotrophomonas maltophilia.To address the effect of Stenotrophomonas maltophilia infection on pathogenesis of PRDC,the drug resistance and pathogenicity of isolated strain were analyzed.The results showed that the isolated strain was found to be highly resistant to 20 antimicrobials including ceftriaxone and amoxycillin.In contrast,the isolate was sensitive to polymyxin B,azithromycin,doxycycline,streptomycin,and minocycline,ofloxacin,enrofloxacin and gatifloxacin.Additionally,the pathogenicity of the isolate in mice was found that the clinical symptoms of mice infected with bacteria were depression,rough coat,shortness of breath and death.After necropsy,pathological lesions such as lung consolidation and obvious hemorrhage spots could be seen.Histopathological examination of lungs showed hemorrhage,congestion,alveolar disappearance,and pneumonia.These results indicated that the Stenotrophomonas maltophilia showed multi-drug resistance characteristics,and mice infected with the bacteria exhibited severe pneumonia,respiratory symptoms and death.