从临床肺炎死亡树鼩中分离到致病性大肠埃希菌

Isolating Enteropathogenic E.coli from Clinical Pneumonia in Dead Tree Shrews

目的对6例1月内因肺炎死亡的树鼩采样进行病原菌分离培养鉴定分析。方法解剖死亡树鼩,利用无菌刀片切开肺组织,用无菌接种环插入肺内采样接种于营养琼脂培养基,另取两份样品进行细菌涂片革兰氏染色和抗酸染色。培养出来的细菌进行进一步分离和菌落生长情况的观察,并经革兰氏染色、抗酸染色、氧化酶试验、生化编码鉴定和9种药敏试验,初步确定树鼩肺部感染的致病菌及其药敏情况。结果样本革兰氏染色见到大量阴性杆菌,抗酸染色结果显示为非结核分枝杆菌,大小约为0.2μm×2～6μm。营养琼脂培养6例样品中均仅见1株旺盛生长的细菌,进一步分离培养经革兰氏染色为阴性杆菌,抗酸染色为非结核分枝杆菌,大小和染色结果与样本涂片相同,经鉴定为致病性大肠埃希菌。药敏试验表明该菌对头孢哌酮,呋喃妥因,氨苄西林,阿米卡星,氧氟沙星,诺氟沙星,磺胺甲噁唑/甲氧苄定高度敏感;对庆大霉素和青霉素G为低度敏感。结论 6例树鼩死亡原因均为细菌性肺炎,病原菌初步鉴定为致病性大肠埃希菌。药敏实验筛选出的药物可为临床治疗树鼩该类病例用药提供指导。

Objective To isolate, culture and identify the pathogenic bacterium from 6 cases of bacterial pneumonia within 1 month in tree shrews. Methods We Dissected the dead tree shrew, cut open the lung tissue with sterile blade to insert focus of infection in the lung with inoculating loop to get samples for inoculating on nutrient agar and another two samples for bacterial smear with Gram staining and acid-fast staining. The bacterium obtained was isolated and cultivated for bacterial growth observation, then the pathogenic bacterium of tree shrew and its antibiotic susceptibilities was initially identified by Gram staining, acid-fast staining, oxidase test, biochemistrical encoding identification system and 9- kind antibiotic susceptibility test. Results A amount of negative bacteria were observed from samples with Gram staining. Acid-fast staining appears it was nontuberculous mycobacterium about size 0.2 μm×2～6μm. Only 1 strain strong bacterium was observed in every 6 case on nutrient agar plate, it was verified as Gram-negative bacterium and nontuberculous mycobacterium, its size and staining results were the same as samples. It was identified as enteropathogenicE. coli. Antibiotic susceptibility test shows it is highly susceptibility to cefoperazone, furantoin, ampicillin, amikacin, ofloxacin, norfloxacin, sulfonamide methoxybenzyldine and low susceptibility to gentamicin and penicilin. Conclusion We conclude that Bacterial pneumonia is the cause of these 6 tree shrew death cases, the enteropathogenic E. coli. was initially identified as the reason. Drugs selected by antibiotic susceptibility could instruct clinical treatment like these cases in tree shrews.