不发酵或迟发酵乳糖型禽大肠埃希菌的分离鉴定

Isolation and Identification of Avian Escherichia coli with no or Weak Ability in Lactose Ferment

从临床疑似大肠埃希菌感染病鸡的肝脏,分离到24株能在麦康凯平板生长但呈灰白色菌落的革兰阴性中等大小杆菌。通过IMViC试验、糖发酵试验、三糖铁斜面接种试验确定为大肠埃希菌,且其中16株为不发酵乳糖型,8株为迟发酵乳糖型。血清学试验表明,其中12株(50%)为O78抗原型,9株(37.5%)为O1抗原型,3株(12.5%)未能定型。利用PCR方法检测了该24株大肠埃希菌的F1菌毛与P菌毛基因,结果表明,其中10株(41.67%)为F1+大肠埃希菌,未发现P+分离株。药敏试验发现,所有菌株均对头孢拉定和阿米卡星敏感,部分菌株对链霉素、庆大霉素、环丙沙星、复方新诺明敏感,而对新霉素均为耐药。

A total of 24 isolates of Gram-negative medium-sized bacteria were obtained from diseased poultry with colorless colonies on MacConkey agar. All the bacteria were confirmed to be Escherichia coli by culture characters and biochemical reaction, and thereinto 16 isolates were no ability in lactose ferment while 8 isolates were weak ability in lactose ferment. The data of O serotype test showed that 12 （50%） were 078 and 9 （37.5%） were O1, while 3 （12.5%） were undetermined. In addition, all the isolates were submitted to the PCR that specific for F1 fimbriae and P pilus, and the data showed that 10 isolates were F1- positive while no single P-positive isolate was detected. Furthermore, seven kinds of antibiotics were tested and all the isolates were highly sensitive to cephradine and amikacin, some isolates were sensitive to streptomycin, gentamicin, ciprofloxacin and compound sulfamethoxazole, while all were resistant to neomycin.