Detection of Metallo-?-lactamase Produced by Chryseobacterium indologenes and Their Genotypes / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To investigate the antibiotical resistance and to understand the phenotype and genotype of metallo-?-lactamase in Chryseobacterium indologenes.METHODS The MIC to 25 C.!indologenes strains was detected by agar dilution method.Phenotype of metallo-?-lactamase was detected by three-disc synergy test and modified three dimension test.Polymerase chain reaction(PCR)amplification for both metallo?-lactamase and integrase gene was conducted for all isolates.Complete coding gene of metallo-?-lactamase and their DNA sequence analysis was conducted.Conjugation experiment was used to study the transmission of metallo-?-lactamase encoding gene.pIs Of ?-lactamase was measured by isoelectric focusing assay.RESULTS The antibiotical resistance of C.indologenes to imipenem and meropenem was 88.0%,respectively.However,gatifloxacin,levofloxacin and rifampin had better antimicrobiotial ability to C.indologenes compared with other antibiotics in MIC Nineteen strains were identified to produce metallo-?-lactamase using three-disc synergy test and modified three dimension test.Twenty strains were detected to have metallo-?-lactamase genotype by PCR amplification using IND-like common prime sets and four prime sets of complete coding gene.Among them,9 strains were detected to have blaIND-1 genotype and 10 strains to have blaIND-2 genotype,strain CI-25 was identified to have blaIND-like genotype.The mutation of base sequences and amino acid sequences in 5 strains were found simultaneously.Conjugation experiment showed that metallo-?-lactamase encoding gene couldn′t transfer.Nineteen strains had 1 or 2 bands on isoelectric focusing electrophoresis.Strain CI-5 was proved to have blaIND-1,but phenotype of metallo-?-lactamase was negative.CONCLUSIONS C.indologenes has high rate of metallo-?-lactamase producing,and thus it is difficult to treat.The major genotype of metallo-?-lactamase for C.indologenes is blaIND-1 and blaIND-2 in Hefei.The expression of blaIND could exist negative or low level occasionally.