Detection of metallo-β-lactamase produced by clinical Chryseobacterium spp.and their genotypes / 中华检验医学杂志

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.