Detection of AmpC-lactamases and AmpC gene of gram-negative bacillus

Aim To detect AmpC β-lactamases and ampC gene of 102 gram-negative bacillus strains.Methods β-lactamases of the 102 gram-negative bacillus strains were extracted by ultrasonic crushing,and AmpC β-lactamases was examined by cefoxitin in three dimensional test.The total DNA of the 102 gram-negative bacillus strains were extracted,and AmpC gene was amplified by polymerase chain reaction(PCR)The drug resistance was analysed by MIC method.Results There 11 straina were poaitive for AmpC gene both by three-dimensional test and PCR detection.These 11 strains were confirmed to be AmpC-producing strains of Acinetobacter baumannii,without showing significant difference between the two methods(χ~2=1.125,P0.05).The genotypes of AmpC β-lactamases were ACT-1(14.7%),CMY-G2(12.7%),FOX(4.9%),DHA(1.0%),CMY-G1(0).Amikacin(90.1%)was the highest sensitive of the AmpC-producing strains,followed by imipenem(54.6%).Conclusions There are no significant difference in the detection rate between three-dimensional test method and PCR method.The drug resistance of AmpC-producing strains is high and clinical application of drugs can only be used bsed on drug sensitivity tests.