Multiplex PCR indicated they belong to Citrobacter freundii family. Sequencing of corresponding DNA revealed 99% identities of the deduced amino acid sequence with CMY-2 and CMY-7 respectively. It is a new CMY type cephalosporinase.

• 接合试验表明它们携带的AmpC酶具有转移性 ,多重PCR检测表明这些基因来源于费氏枸橼酸杆菌家族 ,DNA测序表明该基因和CMY 2以及CMY 7有 99%25的同源性 ,为一种新的CMY型头孢菌素酶。