ABSTRACT
Objective To investigate the antibiotic resistance and the phenotype and genotype of metallo-β-lactamase in clinical isolates Chryseobacterium spp.Methods The MIC of 18 antibiotics in 50 Chryseobacterium spp.isolates was detected by agar dilution method.Phenotype of metallo-β-laetamase was detected by three-disc synergy test and modified three dimension test.Polymerase chain reaction(PCR)detection for metallo-β-lactamase gene was conducted for all isolates,and then the DNA sequence analysis was conducted for the PCR products which are positive for metallo-β-lactamase and identify genotype.conjugation experiment was used to study the transmission of metallo-β-lactamase encoding gene.pIs of β-lactamase was measured by isoelectric focusing assay. Results The antibiotic resistance of 50 clinical isolates of Chryseobacterium spp.against imipenem,Meropenem was 82.0%and 82.0%respectively.However,these isolated had high resistance to gatifloxacin.levofloxacin and rifampin compared with other antibiotics.Phenotype detection showed 33 isolated produced metallo-β-lactamase using three-disc synergy test and modified three dimension test,and the incidence of producing metallo-β-lactamase was 66.0%.Twenty isolateds producing Chryseobacterium indologenes were detected to have metallo-β-laetamase genotype by PCR amplification,among them 9 isolates containing blaIND-1 genotype and 10 isolateds containing blaIND-2 genotype.Strain CI-25 was identified to represent blaIND-LIKE genotype.Fourteen Chryseobacterium meningosepticum were detected to have metallo-β-lactamase genotype by PCR amplification,including 15 blaB and 2 blaGOB. The number of strain producing blaB1,blaB2,blaB3 and blaB11 in Chryseobacterium meningosepticum was 2,5,4 and 4,respectively. Conjugation experiments showed that metallo-β-lactamase encoding gene cannot be transfered. The extracted plasmid of 4 strains did not harbor metallo-β-lactamase gene.Strain C-5 was proved to have blaIND-1 gene,but its phenotype and IEF of metallo-β-lactamase was negative.Conclusions Chryseobacterium spp.had high frequency of multidrug resistance and high incidence for producing metallo-β-lactamase,and thus it was difficult to be treated.The gene of metallo-β-lactamase located on chromosome of Chryseobacterium spp.and cannot be transfered.There was negative or low lever of expression of blaIND-1.
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.